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Notes: A Low Pass Gate (LPG) can be a low pass filter, a VCA or a combination of both. This means both the harmonic content and volume can be controlled simultaneously which resembles the behaviour of many instruments: the louder, the more harmonics.

The A-101-2's mode of operation is set with a switch: left position is low pass, right is VCA and the combo mode is in the centre. Alternatively, you can activate the modes with gate signals which is the reason for two gate inputs; this is very interesting in combination with clock dividers or trigger sequencers.

- Gate 1 high & gate 2 low = low pass mode
- Gate 1 low & gate 2 high = VCA mode
- Both Gate 1 & 2 high = combo mode

The A-101-2 has an aggressive sound, compared to other LPGs and its resonance goes up to self-oscillation which not many LPGs offer. The oscillation is rather dirty and far from being a sine wave.

3U Eurorack module, 8HP wide, 50mm deep.

Notes: A-101-6 is a new filter module that uses so-called opto FET's to control the filter frequency. Opto FET's are very similar to Vactrols, but use light dependent field effect transistors (FET's) instead of light dependent resistors (LDR's). An opto FET is a combination of a light-dependent FET and an LED, both put into a small light-proof case. The advantage, compared to vactrols, is a much faster response of opto FET's compared to LDR's - this allows much faster attack/decay times and even FM effects.

The variable resistors corresponds to the opto FET. The brightness of the Opto FET LED's, and consequently the filter frequency, can be adjusted manually (Frequ. control) and controlled by means of an external control voltage (CV) with attenuator. The LED at the front panel reflects the LED brightness inside the opto FET's.

The type of filter is chosen by jumpers on the PC board (factory setting: low pass). The type of filter determined by the jumpers positions can be marked by means of a water-resistant felt pen at the front panel.

The resonance is controlled by the Feedback control up to self-oscillation. By means of a trimming potentiometer the maximal feedback can be adjusted. High feedback values can be used mainly in the all-pass mode to obtain very extreme self-oscillation sounds. Even an external feedback signal can be used instead of the internal feedback connection (FB In socket). Whenever the filter type is changed by means of the jumpers the trimming potentiometer for the maximal feedback has to be re-adjusted.

The Mix control is used to pan between the original signal (CCW position) and the effect signal (CW position). In filter mode (LP/HP) this control is usually set fully CW. In the all-pass modes one obtains phasing sounds at centre position or "pure" all-pass sound in fully CW position.

Notes: Module A-101-8 is a 8-stage phase shifter which uses light-sensitive resistors (LDR) and is a replica of the Compact Phasing A manufactured by the company Schulte in the seventies. The actual phasing circuit is identical to the historic model. Only the illumination control of the LDRs is different: the A-101-8 uses LEDs to illuminate the LDRs, the historic model used incandescent miniature lamps. And the A-101-8 has no built-in LFO but can be controlled by any external control voltage source (e.g. LFO, ADSR, random, Theremin, ribbon controller, sequencer, midi). The phasing offset (i.e. the base value for the phase shifting) and the modulation depth of the external control signal can be adjusted separately. The Compact Phasing A had no offset control but only a depth control for the built-in LFO. Feedback and mixing ratio of the output signal are set by two controls. The audio input is equipped with an attenuator. The module has two audio outputs available (same as the historic model) and a visual display of the phase shifting.

The module has these controls and in/outputs available:

Control Man. : manual control of the phase shift offset (base value)

Control CV: attenuator for the signal applied to the CV socket

Control Feedb.: Feedback or Resonance (similar function as filter resonance/feedback/emphasis)

Control Mix: sets the mixing ratio between original and phase shift signal appearing at output 1

fully CCW: only the modified input signal appears at output 1 (see note below *)

center: a mixture between the modified input signal and the phase shift signal appears at output 1, that's the standard position for the classical phasing effect

fully CW: the pure phase shifted signal appears at output 1 (e.g. for vibrato effects)

Control Input Level: attenuator for signal applied to the In socket

Socket In: audio input

Socket CV: control voltage input

Socket Out 1: audio output 1 (mix signal)

Socket Out 2: audio output 2 (modified input signal)

LED: visual control of the phase shift

The module has some peculiarities (same as the historic model):

The input signal is processed at first by a pre-stage which outputs a "modified" input signal (*). This signal is not processed by the phase shift stages but is affected by the feedback setting. Only when feedback is set to zero this signal is identical to the input signal. Otherwise it contains feedback components.

This signal is output on socket Out 2.

When both output sockets Out 1 and Out 2 are used as stereo channels one obtains a spatial stereo sound effect.

The same signals is also used for the CCW position of the mix control. With mix control fully CCW the unmodified signal appears only if the feedback control is set to zero. Otherwise it contains feedback components.

The historic model had two audio inputs: one 5-pin DIN socket and a 1/4" jack socket. The DIN socket was intended for high-level line signals. When the 1/4" jack socket was used the amplification of the pre-stage increased by about 100. The 1/4" jack socket was intended for low level signals (e.g. electric guitars or microphones). For this feature the A-101-8 has an internal jumper that can be used to increase the amplification. As long as the module is used within the A-100 system usually the lower amplification is used to avoid distortion.

The 8 photo resistors and LEDs are assembled within an small lighproof box. In addition the pc boards are made of lighproof black material to avoid interfering light from other modules or the bus board.

Dimensions
4 HP
45 mm deep

Current Draw
30 mA +12V
30 mA -12V

Notes: Module A-103 is a voltage controlled low pass filter with 18dB/octave slope. The circuit is based on a modified transistor ladder (Moog ladder) and is a reproduction of the legendary TB303 filter.

As for the rest the A-103 is identical to the A-120 Moog low pass filter (same controls, inputs/outputs) only the filter sound is different.

Notes: Module A-105-2 is a voltage controlled low pass filter with 24dB/octave slope.

It is the successor of the A-105 which had to be discontinued because the obsolete SSM2044 filter circuit. The A-105-2 is based on the SSI2144 which is in turn the successor circuit of the SSM2044. The features of both modules are nearly the same. The main difference is the clearly reduced front panel width of the A-105-2 (4HP instead of 8HP) and the associated changes of the controls and sockets positions. In addition the A-105-2 is equipped with 2 audio inputs.

The module has these controls and in/outputs available:

Control Frequ: manual frequency control
Control FCV2: attenuator for the frequency control voltage applied to socket FCV2
Control Q: manual resonance control
Control QCV: attenuator for the resonance control voltage applied to socket QCV
Control Input 1 Level: attenuator for the audio input signal applied to socket Input 1
Socket Input 1: audio input 1 (with attenuator)
Socket Input 2: audio input 2 (without attenuator)
Socket FCV1: frequency control voltage 1 (without attenuator, about 1V/oct scale)
Socket FCV2: frequency control voltage 2 (with attenuator)
Socket QCV: resonance control voltage (with attenuator)
Socket Out: audio output
Technical notes:

Frequency range: about 15Hz ... 15 kHz
Resonance up to self oscillation
Max. input voltage at Input 2 without clipping/distortion: about 15Vpp
Max. output voltage without clipping/distortion: about 15Vpp
The signals of both inputs are mixed before they are processed by the filter. This saves an external mixer for small setups.
Depth: 45 mm

HP : 4

Notes: Module A-106-5 is a 12dB multimode filter that is based on the filter circuit of the Oberheim SEM module.

The filter is equipped with a band pass output and a combined low/notch/high pass output. For this output a control knob defines the relation between low and high pass signal. If both signals appear at the same level (i.e. middle position of the Mix knob) one obtains a notch filter. Otherwise the low or high pass signal predominates.

The module does not feature self-oscillation in contrast to most of the other filters of the A-100 system.

The module generates a distorted audio signal if the level control is set to about 50% (i.e. centre position) or more with A-100 standard signals like VCOs.

Notes: Module A-108 is a completely new voltage-controlled low pass filter based on the well-known transistor ladder (Moog ladder). The module has internally an 8-stage low pass filter with different slopes available: 6, 12, 18, 24, 30, 36, 42 and 48 dB per octave. In addition, it features a band pass output (i.e. band pass with transistor ladder). In the factory, the 4 low pass outputs of the A-108 are internally connected to the filter stages 6, 12, 24 and 48dB.

Resonance (Emphasis or Q) can be adjusted manually right up to self-oscillation, in which case the filter will behave like a sine wave oscillator. The A-108 features an external feedback input that enables the insertion of additional modules into the feedback path (e.g. VCA for voltage-controlled resonance or phaser/frequency shifter for phase/frequency shifting effects). The socket is normalized and internally connected to the 48dB low pass output if no cable is inserted into the feedback socket.

The frequency can be adjusted manually, or by voltage control. Three CV inputs (CV1, CV2, CV3) are available. CV2 and CV3 are equipped with attenuators.

The filter audio input is very sensitive so that distortion - if desired - is possible even with normal A-100 levels (e.g. VCO output). Self-oscillation will break off at high distortion levels as the internal feedback signal is drown out by the distorted audio signal. This feature may intentionally be used to create new sounds.

In combination with the Voltage Controlled Mixer A-135 and the Morphing Controller A-144 a filter with voltage-controlled slope can be realized (i.e. controlling the slope from 6dB to 48dB via CV).

Notes: VCO:

- Tune: manual tune control (with an internal jumper the range can be set to ~ +/-1 half an octave or ~ +/-2.5 octaves)
- Oct: range switch -1 / 0 / +1 octave
- Mod: modulation depth (attenuator wired to the Mod. socket)
- Dest: switch that is used to address the modulation to frequency modulation (position FM) or pulsewidth modulation (positon PM), in centre positon no modulation
- PW: manual pulsewidth control for rectangle waveform, PW can be also modulated by the Mod. input as mentioned above
- Wave: waveform switch (sawtooth / off / triangle), the sum of the waveform chosen by this switch and the rectangle is fed into the VCF (to turn the rectangle off the PW control has to be set fully CCW or fully CW)
- 1V/Oct. (socket): external CV input for VCO frequency (1V/octave)
- Access to internal bus CV (via jumper, optional, please remove the bus jumper if this feature is not used to avoid unwanted frequency modulation as then the unused CV line of the bus works as a kind of antenna)
- Triangle core VCO, frequency range about 32Hz ... 8kHz

Balance unit:

- The balance unit is made of two VCAs which are controlled by the sum of manual Balance control and the balance CV input in the opposite direction.
- The audio input of VCA1 is hard-wired to the VCO output, audio input 2 is connected to the socket Ext.In.
- The output of the balance unit is used as audio input for the VCF
- Bal.: manual balance control, fully CCW the internal VCO is used, fully CW the external signal (Ext.In) is used, at centre position both signals have about the same level
- CV Bal.: CV input for balance (range about 0...+5V)
- Ext. In: external audio input for VCA2, about 5 Vpp level required for similar loudness as the internal VCO
- This socket is normalled to the internal VCO suboctave f/2 signal (rectangle with half the frequency), if no external signal is applied the suboctave signal is used as the second signal for the balance unit

VCF:

- 24 dB low pass
- Frq: manual frequency control
- FM1: frequency modulation depth (attenuator wired to the VCF FM1 socket, the socket is normalled to the internal Envelope signal and then FM1 controls the modulation depth of the internal envelope applied to the filter)
- FM2 (socket) : second CV input for VCF without attenuator (about 1V/octave), can be used e.g. for VCF tracking by connecting the same CV which is used also for the VCO frequency
- Res: manual resonance control (up to self oscillation)
- If the VCO is turned off (waveform switch = centre position, pulsewidth control = fully CCW or CW) and the VCF resonance is set to maximum the module can be used as a sine oscillator, the tracking at socket VCF FM2 is about 1V/octave (not as precise as the VCO but much better than most other filters)
- ~ 11 octaves frequency range (~ 10 Hz ... 20kHz)

VCA:

- Gain: manual amplitude control (initial gain), can be used to open the VCA without envelope signal
- VCA (switch): used to switch between gate and envelope as control signal for the VCA, in centre position the VCA is not controlled by envelope or gate
- Note: when gate is used the VCA is controlled directly by the gate signal (i.e. hard on/off), this may lead to clicking noise under certain conditions (especially with low VCO/VCF frequencies)
- Special control scale: exponential scale in the range from about -20dB to -80/90dB, linear scale from about -20dB to 0dB
- Remark: this special control scale results in a loudness behaviour that is a bit different from pure linear or exponential VCAs
- Out: audio output of the module (= VCA output)

Envelope:

- Gate (socket): Gate input (min. +5V), can be normalled to the bus gate signal by means of a jumper
- Att: manual control for Attack
- D/R: manual control for Decay/Release
- Env. (switch): used to switch between A/D, ADSR and A/R mode of the envelope generator, in centre position (ADSR) the sustain level is fixed to about 50%
- Envelope (socket): envelope output (about +10V)
- CVT (socket): CV input for time control, by means of two internal jumpers one can select which time parameters are controlled by the CVT input (e.g. A only or D/R only or A/D/R) and in which direction (i.e. if an increasing CVT shortens or stretches the time parameter in question)
- Envelope LED display
- Attack time range: ~ 1ms ... 5 sec (can be extended by using the CVT input)
- Decay/Release time range: ~ 1ms ... 15 sec (can be extended by using the CVT input)

Notes: VCO:

- Tune: manual tune control (with an internal jumper the range can be set to ~ +/-1 half an octave or ~ +/-2.5 octaves)
- Oct: range switch -1 / 0 / +1 octave
- Mod: modulation depth (attenuator wired to the Mod. socket)
- Dest: switch that is used to address the modulation to frequency modulation (position FM) or pulsewidth modulation (positon PM), in centre positon no modulation
- PW: manual pulsewidth control for rectangle waveform, PW can be also modulated by the Mod. input as mentioned above
- Wave: waveform switch (sawtooth / off / triangle), the sum of the waveform chosen by this switch and the rectangle is fed into the VCF (to turn the rectangle off the PW control has to be set fully CCW or fully CW)
- 1V/Oct. (socket): external CV input for VCO frequency (1V/octave)
- Access to internal bus CV (via jumper, optional, please remove the bus jumper if this feature is not used to avoid unwanted frequency modulation as then the unused CV line of the bus works as a kind of antenna)
- Triangle core VCO, frequency range about 32Hz ... 8kHz

Balance unit:

- The balance unit is made of two VCAs which are controlled by the sum of manual Balance control and the balance CV input in the opposite direction.
- The audio input of VCA1 is hard-wired to the VCO output, audio input 2 is connected to the socket Ext.In.
- The output of the balance unit is used as audio input for the VCF
- Bal.: manual balance control, fully CCW the internal VCO is used, fully CW the external signal (Ext.In) is used, at centre position both signals have about the same level
- CV Bal.: CV input for balance (range about 0...+5V)
- Ext. In: external audio input for VCA2, about 5 Vpp level required for similar loudness as the internal VCO
- This socket is normalled to the internal VCO suboctave f/2 signal (rectangle with half the frequency), if no external signal is applied the suboctave signal is used as the second signal for the balance unit

VCF:

- 24 dB low pass
- Frq: manual frequency control
- FM1: frequency modulation depth (attenuator wired to the VCF FM1 socket, the socket is normalled to the internal Envelope signal and then FM1 controls the modulation depth of the internal envelope applied to the filter)
- FM2 (socket) : second CV input for VCF without attenuator (about 1V/octave), can be used e.g. for VCF tracking by connecting the same CV which is used also for the VCO frequency
- Res: manual resonance control (up to self oscillation)
- If the VCO is turned off (waveform switch = centre position, pulsewidth control = fully CCW or CW) and the VCF resonance is set to maximum the module can be used as a sine oscillator, the tracking at socket VCF FM2 is about 1V/octave (not as precise as the VCO but much better than most other filters)
- ~ 11 octaves frequency range (~ 10 Hz ... 20kHz)

VCA:

- Gain: manual amplitude control (initial gain), can be used to open the VCA without envelope signal
- VCA (switch): used to switch between gate and envelope as control signal for the VCA, in centre position the VCA is not controlled by envelope or gate
- Note: when gate is used the VCA is controlled directly by the gate signal (i.e. hard on/off), this may lead to clicking noise under certain conditions (especially with low VCO/VCF frequencies)
- Special control scale: exponential scale in the range from about -20dB to -80/90dB, linear scale from about -20dB to 0dB
- Remark: this special control scale results in a loudness behaviour that is a bit different from pure linear or exponential VCAs
- Out: audio output of the module (= VCA output)

Envelope:

- Gate (socket): Gate input (min. +5V), can be normalled to the bus gate signal by means of a jumper
- Att: manual control for Attack
- D/R: manual control for Decay/Release
- Env. (switch): used to switch between A/D, ADSR and A/R mode of the envelope generator, in centre position (ADSR) the sustain level is fixed to about 50%
- Envelope (socket): envelope output (about +10V)
- CVT (socket): CV input for time control, by means of two internal jumpers one can select which time parameters are controlled by the CVT input (e.g. A only or D/R only or A/D/R) and in which direction (i.e. if an increasing CVT shortens or stretches the time parameter in question)
- Envelope LED display
- Attack time range: ~ 1ms ... 5 sec (can be extended by using the CVT input)
- Decay/Release time range: ~ 1ms ... 15 sec (can be extended by using the CVT input)

Notes: Module A-118-2 is the slim version of module A-118-1 and offers essentially the same features as the A-118-1. But the distances between the controls are smaller and rubberized small-sized knobs are used. In return the front panel has 4 HP only which is half the width of the A-118-1. The module is primarily planned for applications where only limited space is available. The functional difference between A-118-1 and A-118-2 is the additional T&H/S&H unit which is not included in the A-118-1.

The module generates the signals white noise, colored noise, continuous random voltage and stepped random voltage (derived from the continuous random voltage by means of a S&H/T&H unit).

The noise signal is generated 100% analog by amplification of the noise of a transistor. White and colored noise are usually used as audio sources. The random voltages are normally used as control voltages (e.g. for filter frequency or any other voltage controlled parameter).
The A-118-2 gives you the ability to mix the relative amounts of Red (low frequency component) and Blue noise (high frequency component) in the colored noise output.

For the continuous random voltage the rate of change (Rate) and amplitude (Level) of the random voltage can be adjusted. The continuous random voltage is derived from the colored noise signal by low pass filtering. Consequently the settings of the controls for the colored noise (Blue, Red) affect the behavior of the random voltage! A dual color LED (red = positive / yellow = negative output voltage) indicates the continuous random voltage.

The continuous random voltage is used as source for the S&H/T&H unit. The type of operation can be set to S&H (sample and hold) or T&H (track and hold). When T&H is chosen the output signal follows the input signal (= continuous random voltage) as long as the Clock input is "high". As soon as the clock signal changes to "low" the last voltage is stored. When S&H is chosen the input signal (= continuous random voltage) is sampled at the rising edge of the Clock signal.

For the Clock signal a "digital" signal (e.g. Clock, Gate, rectangle output of an LFO) is required. It does not work with slowly changing continuous CV signals. Another dual color LED (red = positive / yellow = negative output voltage) indicates the stepped random voltage.

Controls:

Blue: share of the high frequencies in the the colored noise output
Red: share of the low frequencies in the the colored noise output
Rate: rate of change of the continuous random voltage
Level: amplitude of the continuous random voltage
TH/SH: switches between T&H and S&H

Inputs and outputs:

RND: continuous random voltage output (with LED display)
TH/SH: stepped random voltage output (with LED display)
Clk: Clock input of the S&H/T&H unit
C Noise: colored noise output
W Noise: white noise output

Important notes:

After power on it takes a few minutes until the two noise signals and the random signals are generated. The module is not faulty when after power on the signals do not appear immediately!

The S&H/T&H function is realized by pure analog circuitry (electronic switch followed by a holding capacitor and buffer). Consequently the output voltage drifts a bit in the holding state because the capacitor is discharged by parasitic resistors. The drift depends also upon environmental conditions like humidity or temperature.

Dimensions
4 HP
40 mm deep

Current Draw
20 mA +12V
20 mA -12V

Notes: Module A-119 (External Input / Envelope Follower) is designed to allow external audio signals to be integrated into the System A-100. It comprises a pre-amp, envelope follower, and comparator.

The pre-amp has two inputs: an unbalanced input for line level signals, with a gain factor of from 0 to 20, and a balanced input with a gain factor of from 0 to 500, for insertion of low level signals, for instance from a microphone or electric guitar.

The Envelope Follower reads the signal level of the input, and puts out a proportional voltage as an envelope at its own output.

The comparator generates a gate signal whenever the input goes above an adjustable trigger threshold.

Three LED's help you keep track of overload, the envelope, and the gate signal.

Notes: Module A-119-2 is a Dual external input amplifiers with only 4HP module width. The module contains two amplifiers with separately adjustable amplification levels. Each channel is equipped with an overload display. The module can also be used for stereo signals, e.g. the stereo output of a smartphone.

Controls and displays:

Level 1/2: manual control of the amplification in the range 0 - about 45.
Overload 1/2: overload LED, begins to light up for output levels beyond about 10Vpp (+/-5V)
In 1: audio input 1 (monophonic or stereophonic, see technical details)
In 2: audio input 2 (monophonic)
Out 1/2: audio output (monophonic)

Technical Details:

For higher amplifications the two amplifiers can be daisy-chained
Different normallling options are available via the rear of the modules with jumpers.
All inputs and outputs are DC coupled. Thus the module can be used also for the amplifications of control voltages.

Power consumption: 20mA at +12V and 20mA at -12V
Depth: 30mm
4 HP

Notes: Module A-121d is a special dual multimode filter which can be used for parallel or serial organized dual mono filters. Even stereo applications are imaginable. The filters are based on two special circuits: one with highpass and bandpass outputs, the other with lowpass and bandpass outputs. It's a new filter design that is not used so far in any other A-100 filter module.

We attached great importance to the usability of the manual controls and CV inputs for dual filter applications: for the filter frequencies of both filters a common control (Frequ.) and a difference control (Delta, filter spread) are available. For both parameters even CV inputs are available (FCV, DCV). The resonance (Q1, Q2), the sensitivity of the individual frequency control input (FCV1, FCV2) and the level of the audio input (In1, In2) are adjusted by means of the individual controls for each filter.

The module has a simple audio mixing unit available with the inputs Mx1 and Mx2, and the output MxO. Provided that the mixer inputs are open bandpass 1 and bandpass 2 are normalised to the sockets Mx1 and Mx2. All other filter types are realized by connecting the other filter outputs (H1 = highpass 1, L2 = lowpass 2) to the mixer inputs.

Controls:
Frequ.: master frequency control for both filters
Delta: controls the difference between the frequencies of the two filters manually (frequency spread), at centre position the frequencies are about the same
Q1 / Q2: resonance controls for filter 1 and 2
FCV1 / FCV2: attenuators for the individual frequency control inputs FCV1 (filter 1) and FCV2 (filter 2)
In 1 / In 2: attenuators for the audio inputs of filter 1 and 2

Sockets:
Mx1 / Mx2: audio inputs of the mixer, Mx1 is normalised to bandpass 1 (B1), Mx2 is normalised to bandpass 2 (B2)
MxO: audio output of the mixer
In1 / In2: audio input of filter 1 and 2 (In2 is normalised to In1)
H1: highpass output filter 1
L2: lowpass output filter 2
B2: bandpass output filter 2
DCV: control voltage input for frequency spread (Delta)
FCV1 / FCV2: individual frequency control inputs, processed by the attenuators FCV1 and FCV2, socket FCV2 is normalised to socket FCV1
FCV: common frequency control input for both filters (~ 1V/oct)

Triangle symbols indicate the normalising of sockets (B1>Mx1, B2>Mx2, In1>In2, FCV>FCV2). The four outputs are inverse labelled.

Technical note:
Ex factory the module is adjusted so that the resonance of the two filters does not reach self-oscillation. If desired the filters can be modified by the user by means of two trimming potentiometers so that self-oscillation is possible.

Dimensions
8 HP
41 mm deep

Notes: Module A-121s is a dual multimode filter which can be used for stereo applications as well as for parallel or serial organized dual mono filters. The core is a 12dB multimode filter identical to the modules A-121-2 and A-121-3. The selection of the filter type is continuously from lowpass via notch and highpass to bandpass. We attached great importance to the usability of the manual controls and CV inputs for both stereo and dual mono applications. For the filter parameters frequency (F), resonance (Q) and type (T) common controls and CV inputs as well as single controls and CV inputs are available. For the filter frequency in addition a manual control and CV input for the filter spread (frequency difference or delta F) is available.

Controls:
F: master frequency control for both filters (large knob)
Type 1 / Type 2: filter type panning/morphing L-N-H-B
Link to 1: Toggle switch so that Type 1 also controls type of filter 2 (i.e. simultaneous filter type control for both filters)
SFM1 / SFM2: Single Frequency Modulation controls (polarizers), connected to the corresponding sockets SFM1/SFM2 (socket SFM1 is normalled to a fixed positive voltage, SFM2 is normalled to SFM1, that way the controls SFM1/SFM2 work as frequency controls for each filter provided that no modulation signals are patched to the SFM1/SFM2 sockets)
CFM: common frequency control, controls two VC-polarizers which process the signals connected to the two sockets CFM1/CFM2, CFM2 is normalled to CFM1, that way also the same modulation signal (e.g. an envelope generator) can be used for both filters and the level controlled simultaneously by the CFM control
Delta F: controls the difference between the frequencies of the two filters manually (frequency "spread"), at centre position the frequencies are the same
Delta FM: controls the level of the Delta FM signal (socket), which allows to control the spread between the frequencies also by an external control voltage (e.g. by an LFO or ADSR)
Q: controls the resonance of both filters simultaneously
Level 1 / Level 2: attenuators for the two audio inputs
QM/TM1, QM/TM2: attenuators for the modulation inputs QM/TM1 and QM/TM2

Sockets:
In1 / In2: audio inputs (In2 is normalled to In1)
Out1 / Out2: audio outputs
F: common frequency control input for both filters (~ 1V/oct)
Delta FM: Control voltage for frequency spread, processed by the polarizer Delta FM
SFM1 / SFM2: single frequency modulation inputs, processed by the polarizers SFM1 and SFM2, SFM1 is normalled to a fixed positive voltage, SFM2 is normalled to SFM1#
CFM1 / CFM2: common frequency modulation inputs, processed by the two voltage controlled polarizers controlled by CFM knob, CFM2 is normalled to CFM1
QM/TM1, QM/TM2: the addressing of these sockets/attenuators is defined by internal jumpers. QM means Q modulation (i.e. resonance modulation), TM means filter type modulation (QM1 = resonance modulation filter 1, QM2 = resonance modulation filter 2, TM1 = filter type modulation filter 1, TM2 = filter type modulation filter 2), socket QM/TM1 is normalled to a fixed positive voltage, QM/TM2 is normalled to QM/TM1
A 45 degrees triangle next to a socket means that the switching contact of the socket is normalled to a fixed positive voltage (SFM1, QM/TM1).
A vertical triangle indicates the normalling of two sockets (In1>In2, SFM1>SFM2, CFM1>CFM2, QM/TM1>QM/TM2).

If the filters do not behave as expected please pay attention to these peculiarities:

For the controls SFM1, SFM2, CFM, Delta F and Delta FM the centre position is the neutral position as these are polarizers. If the filter behaves unexpected these controls should be set to centre positions for the time being.

For the controls F, Q, Level 1, Level 2, QM/TM1 und QM/TM2 the fully CCW position is the neutral position as these are standard attenuators. If the filter behaves unexpected at least the controls QM/TM1 and QM/TM2 should be set to fully CCW. Via the normalling of the sockets QM/TM1 and QM/TM2 and the associated controls the filter parameters adjusted by the major controls (e.g. Type 1, Type 2 or Q) may be overwritten.

By means of small circles at the bottom right side of the front panel the user can mark the function of the QM/TM inputs. These assignments are possible:
QM/TM1 controls QM1, QM/TM2 controls QM2, the filter types are not controlled by external CVs
QM/TM1 controls TM1, QM/TM2 controls TM2, the resonances are not controlled by external CVs
QM/TM1 controls QM1 and QM2 simultaneously, QM/TM2 controls TM1 and TM2 simultaneously

Notes: Module A-124 is a special 12dB multimode filter using the "strange" filter circuit of the "EDP Wasp" (an analog synthesizer with black/yellow case built end of the seventies, manufactured by the UK company "Electronic Dream Plant" with Chris Huggett und Adrian Wagner). This design "abuses" digital inverters as analog operational amplifiers leading to distortions and other "dirty" effects that generate the specific sound of this filter. The filter is equipped with a band pass output and a combined low/notch/high pass output. For this output a control knob defines the relation between low and high pass signal. If both signals appear at the same level (i.e. middle position of the Mix knob) one obtains a notch filter. Otherwise the low or high pass signal predominates. The module does not feature self-oscillation in contrast to most of the other filters of the A-100 system.

Inputs: Audio In, CV In (2x)
Outputs: Bandpass Out, Low/Highpass Mix-Out
Controls: Audio and CV attenuator, Frequency, Resonance, LP/HP Mix

The function and operation of this module is very similar to the module SEM VCF A-106-5. But the sound of both filters is very different! The only functional difference is the position of the sockets and controls, and the function of the controls CV2 (A-124: normal attenuator, A-106-5: polarizer).

- 3U Eurorack module, 8HP wide, 45mm deep
- Current draw 30mA

Notes: Module A-124-2 is the slim version of the Wasp filter module A-124.

The main difference compared to the A-124 are the small controls for Mix and Input Level because for lack of space. And the lowpass or highpass signal is available at a separate socket. A jumper is used to determine if lowpass or highpass appears at the socket.

All other features are the same as the A-124.

Dimensions:
4 HP
20 mm deep

Notes: Module A-124-2 is a special 12dB multimode filter using the "strange" filter circuit of the "EDP Wasp" (an analog synthesizer with black/yellow case built end of the seventies, manufactured by the UK company "Electronic Dream Plant").

The A-124-2 is the Slim Line version, which is only 4hp wide.

This design "abuses" digital inverters as analog operational amplifiers leading to distortions and other "dirty" effects that generate the specific sound of this filter. The filter is equipped with a band pass output and a combined low/notch/high pass output. For this output a control knob defines the relation between low and high pass signal. If both signals appear at the same level (i.e. middle position of the Mix knob) one obtains a notch filter. Otherwise the low or high pass signal predominates. The module does not feature self oscillation in contrast to most of the other filters of the A-100 system.

Dimensions:
4 HP
20 mm deep

Notes: The Doepfer A-126-2exp is an expander for the A-126-2 Voltage Controlled Frequency Shifter.

It adds two outputs from the Dome filter (+45 and -45 degrees) as well as separate outputs from the ring modulators 1 and 2, and from the internal envelope generator. Furthermore, it offers dedicated outputs for Up and Down Shift, allowing the module to be patched in stereo.

*Note: The expander can only be used in conjunction with the module A-126-2.

HP : 2

Notes: The Doepfer A-126-2exp is an expander for the A-126-2 Voltage Controlled Frequency Shifter.

It adds two outputs from the Dome filter (+45 and -45 degrees) as well as separate outputs from the ring modulators 1 and 2, and from the internal envelope generator. Furthermore, it offers dedicated outputs for Up and Down Shift, allowing the module to be patched in stereo.

*Note: The expander can only be used in conjunction with the module A-126-2.

HP : 2

Notes: Module A-130-2 is the slim version of module A-132-3 and offers essentially the same features. But the distances between the controls are smaller and rubberized small-sized knobs are used. In return the front panel has 4 HP only which is half the width of the A-132-3. The module is primarily planned for applications where only limited space is available.

The module is composed of two identical voltage controlled amplifiers (VCA). Each VCA has a manual gain control (also named Initial Gain) and a control voltage input with attenuator. The character of the control scale can be switched to linear or exponential. All inputs and outputs are DC coupled. Consequently the VCAs can be used to process both audio and control voltages (e.g. for voltage control of the level of LFO or envelope signals). The signal input has no attenuator available but is capable to process up to 16Vpp signals (i.e. -8V...+8V) without distortion. For the processing of higher levels an external attenuator (e.g. A-183-1) is recommended.

The amplification range is 0...1. Even with a higher external control voltage the amplification remains at 1 (kind of "amplification clipping" at 1).

Controls (for each of both units):

- Gain: manual gain control (Initial Gain) in the range 0...1
- CV: attenuator for the CV input
- Lin/Exp: switches the VCA characteristic to linear or exponential, in center position the VCA is off (mute function)

Inputs and outputs (for each of both units):

- CV: control voltage input, min. +5V required for max. amplification (1) with CV control fully CW and Gain fully CCW
- In: signal input, max. 16Vpp (+8V...-8V) without distortion
- Out: signal output

Notes: Module A-130-2v is composed of two identical voltage controlled amplifiers (VCA). Each VCA has a manual gain control (also named Initial Gain) and a control voltage input with attenuator. The character of the control scale can be switched to linear or exponential. All inputs and outputs are DC coupled. Consequently the VCAs can be used to process both audio and control voltages (e.g. for voltage control of the level of LFO or envelope signals). The signal input has no attenuator available but is capable to process up to 16Vpp signals (i.e. -8V...+8V) without distortion. For the processing of higher levels an external attenuator (e.g. A-183-1) is recommended.

The amplification range is 0...1. Even with a higher external control voltage the amplification remains at 1 (kind of "amplification clipping" at 1).

Controls (for each of both units):

Gain: manual gain control (Initial Gain) in the range 0...1
CV: attenuator for the CV input
lin/exp: switches the VCA characteristic to linear or exponential, in center position the VCA is off (mute function)
Inputs and outputs (for each of both units):

CV: control voltage input, min. +5V required for max. amplification (1) with CV control fully CW and Gain fully CCW
In: signal input, max. 16Vpp (+8V...-8V) without distortion
Out: signal output

A-130-2v is the slim version of module A-132-3 and offers essentially the same features. But the distances between the controls are smaller and rubberized small-sized knobs are used. In return the front panel has 4 HP only which is half the width of the A-132-3. The module is primarily planned for applications where only limited space is available.

Power consumption: 30mA at +12V and 30mA at -12V

Depth: 50mm

HP : 4

Notes: Module A-130-4 contains four linear VCAs with a common level control section for all four VCAs. It can be used for all applications of simultaneous amplitude/level control of up to four different audio or CV signals. A-130-4 is the replacement of the no longer available module A-132-2. Compared to the A-132-2 the width has been reduced from 8HP to 4HP.

The module has these controls and in/outputs available:

Control Man.: manual control of the amplification

Control CV: attenuator for the control voltage applied to socket CVo socket Input 1

Sockets In 1...4: VCA inputs 1...4

Sockets Out 1...4: VCA outputs 1...4

Application examples:

simultaneous amplitude/level control of up to four different audio or CV signals

polyphonic application 1: simultaneous control of the frequency modulation depth of 4 VCOs (Quad-LFO A-145-4 or Quad-VCLFO A-147-5 > A-130-4 > FM inputs A-111-4)

polyphonic application 2: simultaneous control of the pulsewidth modulation depth of 4 VCOs (Quad-LFO A-145-4 or Quad-VCLFO A-147-5 > A-130-4 > PWM inputs A-111-4)

simultaneous control of quadrophonic signals

Technical notes:

The maximum amplification for each VCA is about 1 ("Man." control fully CW). Even with an external control voltage applied to the CV input the maximum amplification is limited to 1.

The module is equipped with two internal connectors (pin headers with 4 pins each). Pin header #1 can be used to normalize the four inputs to other modules (e.g. Quad LFO A-145-4 or A-147-5, Quad ADSR A-143-2). Pin header #2 can be used to connect the four outputs to other modules.

The max. level at the VCA inputs without clipping/distortion is about 20Vpp or +/-10V.

Width: 4 HP / 20.0 mm
Depth: 45 mm (measured from the rear side of the front panel)
Current: +30 mA (+12V) / -30 mA (-12V)

Notes: Module A-130-8 contains eight linear voltage controlled amplifiers (VCAs). Each VCA features a control voltage input (CV), a signal input (In) and a signal output (Out). In addition three mixers are included: the socket labelled "1-4" outputs the sum of the VCAs 1-4, the socket labelled "5-8" outputs the sum of the VCAs 5-8, the socket labelled "1-8" outputs the sum of all eight VCAs.

The signal inputs are able to process levels up to about 20Vpp without clipping (20Vpp = 20V peak-to-peak or about -10V...+10V) . Each CV input is equipped with a trimming potentiometer that is used to adjust the sensitivity of the CV input in question. In the factory the module is adjusted for the CV range 0...+5V but can be re-adjusted by the user for other control voltage ranges (e.g. 0...+10V).

The amplification range for each single VCA is 0...1. The signals of the sum outputs have a lower amplification to avoid distortion at the sum outputs.

The VCAs and mixers are fully DC coupled, i.e. the module can be used for the processing of both audio and control voltage signals. The control voltage and signal inputs can be normalled by means of small solder pads (e.g. 1 > 2 > 3 > 4 and so on, or 1 > 5, 2 > 6, 3 > 7, 4 > 8 for the stereo application mentioned below).

Typical applications

any kind of VCA application (e.g. voltage controlled attenuation of audio or control voltage signals)
two voltage controlled mixers with four channels each
voltage controlled stereo mixer with four channels each, for this the control voltage inputs have to be correspondingly patched or internally normalled: CV1=CV5 /CV 2=CV6 / CV3=CV7 / CV4=CV8
voltage controlled mixer with eight channels
add-on for the Joystick module A-174-4
Technical notes

The following document shows the positions and functions of the jumpers and trimming potentiometers of the module: A130_8_trimming_potentiometers_and_jumpers.pdf
When the trimming potentiometer in question is moved CCW (counterclockwise) the sensitivity of the CV input in question increases (view to the top edge of the module).
Trimming procedure: apply the max. CV voltage that will occur in your application (e.g. +8V) to the CV input and a constant audio signal to the audio input (e.g. a VCO sawtooth). Then adjust the trimming potentiometer in question until the max. output level is reached and does not become higher even if the trimming potentiometer is turned further. Possible the the trimming potentiometer has to be turned back again a bit to find the correct position.
With the trimming potentiometer adjusted to max. sensitivity the linear amplification starts at about +0.1 control voltage (CV). We introduced this small dead range of about 100 mV to make sure that the VCA fully closes with CV = 0V.
It's possible to change the amplifications of the internal mixers used for the sum outputs (1-4, 1-8, 5-8) also to 1. Pay attention that then clipping/distortion may occur at the sum outputs. For this the 22k resistors R41 (Sum 1-4), R44 (Sum 5-8) und R51 (Sum 1-8) have to be replaced by 47k. As they are smd resistors sufficient experience with soldering/desoldering of smd parts is essential. And we have to point out that warranty is void if such modifications are carried out by the customer. The positions of the resistors are shown in the document A130_8_trimming_potentiometers_and_jumpers.pdf.
If multiple exponential VCAs are required module A-132-4 is recommended.

Width: 6 HP / 30.1 mm
Depth: 40 mm (measured from the rear side of the front panel)
Current: +50 mA (+12V) / -50 mA (-12V)

Notes: A-135-2 is a miniature version of the A-135-1. Behind a front panel with 8 HP only four linear VCAs (voltage controlled amplifiers) and a voltage controlled mixer based on the VCAs are available.

Controls, In/Outputs and Functions of each VCA:

- Level (manual control of the VCA amplification), small rubberized knob (L1...L4)
- Control voltage input with associated attenuator (CV1...CV4), for the full VCA control range about 0...+5V control voltage are required (attenuator fully clockwise), for higher control voltages the attenuator is used, the attenuators are without knobs, just plastic shafts with white marker
- Signal Input
- Signal Output
- All inputs and outputs are DC coupled. Consequently the VCAs can be used to process both audio and control voltages (e.g. to control the level of LFOs or envelopes)
- The signal input is not equipped with an attenuator. But the VCAs can process all signals up to 15Vpp / -7.5...+7.5V without clipping. In case of higher levels an external attenuator is required (e.g. A-183-1).
- The available amplification range is 0...1, the maximal amplification is 1 (i.e. it "clips" and remains at 1 even if the control voltage goes beyond the value that corresponds to amplification 1)

Functions of the voltage controlled mixers:

- Two outputs ("Selected" and "All")
- Selected output: the ouput if a VCA is removed from this sum signal when a plug is inserted into the corresponding VCA output.
- All output: sum of all VCA outputs, regardless of inserted plugs into the VCA outputs
- The maximal amplification is about 0.6 to avoid clipping at the mixer outputs (otherwise the outputs may distort with 15Vpp signals at each signal input and full amplifications)

Special functions of the voltage controlled mixers (selectable by internal jumpers):

- Dual Stereo VCA: In this case the control unit of VCA1 (L1 + CV1) affects also VCA3 and the control unit of VCA2 (L2 + CV2) affects also VCA4, the control units of VCA2 and VCA4 are out of operation
- Quad VCA: In this case the control unit of VCA1 (L1 + CV1) affects all four VCAs. The control units of VCA2, VCA3 and VCA4 are out of operation. In this mode the module has the same function as module A-132-2. That's why module A-132-2 will be discontinued.
- Normalling of the signal inputs: by means of internal jumpers signal input 1 can be normalled to signal input 2, signal input 2 to signal input 3 and signal input 3 to signal input In 4. That way the same input signal can be distributed to four different channels by means of control voltages (e.g. quadrophonic distribution of audio signals). Suitable control voltage sources are e.g. A-144 (Morphing Controller) or A-143-9 (Quadrature LFO).

Notes: A-135-2 is a miniature version of the A-135-1. Behind a front panel with 8 HP only four linear VCAs (voltage controlled amplifiers) and a voltage controlled mixer based on the VCAs are available.

Controls, In/Outputs and Functions of each VCA:

Level (manual control of the VCA amplification), small rubberized knob (L1...L4)

Control voltage input with associated attenuator (CV1...CV4), for the full VCA control range about 0...+5V control voltage are required (attenuator fully clockwise), for higher control voltages the attenuator is used, the attenuators are without knobs, just plastic shafts with white marker

Signal Input

Signal Output

All inputs and outputs are DC coupled. Consequently the VCAs can be used to process both audio and control voltages (e.g. to control the level of LFOs or envelopes)

The signal input is not equipped with an attenuator. But the VCAs can process all signals up to 15Vpp / -7.5...+7.5V without clipping. In case of higher levels an external attenuator is required (e.g. A-183-1).

The available amplification range is 0...1, the maximal amplification is 1 (i.e. it "clips" and remains at 1 even if the control voltage goes beyond the value that corresponds to amplification 1)

Functions of the voltage controlled mixers:

two outputs ("Selected" and "All")

Selected output: the ouput if a VCA is removed from this sum signal when a plug is inserted into the corresponding VCA output.

All output: sum of all VCA outputs, regardless of inserted plugs into the VCA outputs

The maximal amplification is about 0.6 to avoid clipping at the mixer outputs (otherwise the outputs may distort with 15Vpp signals at each signal input and full amplifications)

Special functions of the voltage controlled mixer (selectable by internal jumpers)

Dual Stereo VCA: In this case the control unit of VCA1 (L1 + CV1) affects also VCA3 and the control unit of VCA2 (L2 + CV2) affects also VCA4. The control units of VCA3 (L3 + CV3) and VCA4 (L4 +CV4) are out of operation.

Quad VCA: In this case the control unit of VCA1 (L1 + CV1) affects all four VCAs. The control units of VCA2, VCA3 and VCA4 are out of operation. In this mode the module has the same function as module A-132-2. That's why module A-132-2 will be discontinued.

Normalling of the signal inputs: by means of internal jumpers signal input 1 can be normalled to signal input 2, signal input 2 to signal input 3 and signal input 3 to signal input In 4. That way the same input signal can be distributed to four different channels by means of control voltages (e.g. quadrophonic distribution of audio signals). Suitable control voltage sources are e.g. A-144 (Morphing Controller) or A-143-9 (Quadrature LFO).

Additional technical specification for each VCA (based on the specifications of the VCA circuits CEM3360/AS3360 used in the module):

Crosstalk between VCAs: typ. - 80dB

Signal attenuation at 0V CV: typ. -70dB

Total harmonic distortion: typ. 1%

Control voltage feedthrough: max. 15mV

Width: 8 HP / 40.3 mm
Depth: 45 mm (measured from the rear side of the front panel)
Current: +40mA (+12V) / -40mA (-12V)

Notes: Module A-135-5 is a combination of a voltage controlled polyphonic mixer and a polyphonic suboctave generator. It is made of 12 voltage controlled amplifiers (VCAs) which are arranged in form of a 4x3 matrix. Herewith up to three four-voice polyphonic signals (e.g. the outputs of three polyphonic VCOs A-111-4) can be mixed. The level of each of the three polyphonic channels (A, B, C) with four voices each can be controlled manually or by means of an external control voltage with associated attenuators.

In addition the module features four frequency dividers which derive the suboctaves from the four input signals of channel A. The suboctave signals are wired to the switching contacts of the sockets of channel B. As long as the sockets of channel B are not patched the suboctave signals of channel A are used as inputs for channel B. The suboctaves are symmetrical rectangle waves with half the frequency of the corresponding signal A. For example two polyphonic VCOs A-111-4) can be used and patched to the channels A and C. Channel B then provides the suboctaves of channel A.

As the module is fully DC coupled it can be used also for the mixing of control voltages in a polyphonic environment (e.g. for envelopes, LFOs or other control voltages).

The switching contacts of the 12 input sockets and the four outputs are internally connected to pin headers. That way the module can be internally pre-patched to other polyphonic modules (e.g. the four inputs A to an A-111-4, the four inputs C to another A-111-4 and the outputs to the polyphonic filter A-105-4). As the switching contacts of the sockets are used for the internal pre-patching the internal patch can be overridden by using the sockets at the front panel.

The module has these controls and in/outputs available:

Controls Lev.A, Lev.B, Lev.C: manual level adjustment of the channels A, B and C

Controls CV A, CV B, CV C: attenuators for the corresponding control voltage inputs

Sockets A1...4: inputs channel A

Sockets B1...4: inputs channel B (if the sockets are not patched the suboctave signals are used for the inputs B)

Sockets C1...4: inputs channel C

Sockets CV A. CV B, CV C: control voltage inputs for the channels A, B and C

Sockets Out 1...4: outputs

Dimensions
10 HP
55 mm deep

Notes: Module A-135-5 is a combination of a voltage controlled polyphonic mixer and a polyphonic suboctave generator.

Module A-135-5 is a combination of a voltage controlled polyphonic mixer and a polyphonic suboctave generator. It is made of 12 voltage-controlled amplifiers (VCAs) which are arranged in form of a 4x3 matrix. Herewith up to three four-voice polyphonic signals (e.g. the outputs of three polyphonic VCOs A-111-4) can be mixed. The level of each of the three polyphonic channels (A, B, C) with four voices each can be controlled manually or by means of an external control voltage with associated attenuators.

In addition, the module features four frequency dividers which derive the suboctaves from the four input signals of channel A. The suboctave signals are wired to the switching contacts of the sockets of channel B. As long as the sockets of channel B are not patched the suboctave signals of channel A are used as inputs for channel B. The suboctaves are symmetrical rectangle waves with half the frequency of the corresponding signal A. For example, two polyphonic VCOs A-111-4) can be used and patched to the channels A and C. Channel B then provides the suboctaves of channel A.

The switching contacts of the 12 input sockets and the four outputs are internally connected to pin headers. That way the module can be internally pre-patched to other polyphonic modules (e.g. the four inputs A to an A-111-4, the four inputs C to another A-111-4 and the outputs to the polyphonic filter A-105-4). As the switching contacts of the sockets are used for the internal pre-patching the internal patch can be overridden by using the sockets at the front panel.

Technical notes:

If required two or more modules can be cascaded when more than three polyphonic channels are required.

The max. overall amplification is less than 1 to avoid clipping (can be altered to amplification 1 by replacing resistors, but then clipping may occur)

The max. input levels without distortion are about 16Vpp (or -8V ... +8V for the processing of control signals)

The voltage range for each of the CV inputs is about 0...+5V (with corresponding attenuator control fully CW), higher control voltages (e.g. 0...+10V) can be adjusted by means of the attenuator control

The suboctave levels are about 5Vpp

The module should be used only with DC coupled VCO outputs (e.g. A-111-4, A-111-3). With AC coupled VCO outputs (e.g. A-110-1, A-110-2) a DC offset will occur at the outputs when the suboctave option is installed.

The document A135_5_INTERNAL explains the positions and functions of the internal pin headers and describes the cascading of two A-135-5

Notes: Module A-138 is a four channel mixer, which can be used with either control voltages or audio signals. Each of the four inputs has an attenuator, and there's a master attenuator, so that the mixer can be used at the end of the audio chain, i.e. it can be used to interface directly with an external mixer, amplifier, etc.

The A-138b has potentiometers with logarithmic response, so is especially suitable for audio signal mixing.

Notes: The A-138d primarily is used for crossfading between two modular signals. On the other hand you can used it for inserting stompboxes or other effects into your modular system. Both the inputs and the mix output are available twice, like a mini-multiples e.g. for using the input signal also for other applications, kind of like a Thru.

Crossfader: With the crossfading control CF you blend manually between the inputs In 1 and In 2. The Mute switch allows for muting one of the two signals, independent on the crossfader position.

Effect insert: The signal at input In1 is emitted at the FX Send output and can be attenuated with the Atten. control because the modular system works with much higher levels.

The effect unit's output is inserted to the FX Return input socket and its level can be boosted with the Amp. control. The processed signal is available at the bottom in 2 socket.

Use the CF control to blend between the original signal and the effect signal and to mute switch for quick muting e.g. of the effect return signal.

Notes: Module A-138m is a 4 x 4 matrix mixer with switches for unipolar/bipolar mode for each column. Unipolar means that the controls work as attenuators. Bipolar means that the controls work as polarizers. In this mode the amplification is zero in the middle position of the corresponding control. Turning the knob counterclockwise from the center position the signal is subtracted from the output sum with increasing amount (i.e. negative). Turning the knob clockwise from the center position the signal is added to the output sum with increasing amount. The module is DC-coupled and can be used for both audio and control voltage mixing.

By means of an internal jumper one can select if the four upper controls work as DC offset generators - provided that no patch cord is plugged into the upper input socket. If this feature is not required it can be deactivated by removing the jumper on top left of the pc board. The function is identical to the A-138a/b.

Dimensions
20 HP
20 mm deep

Current Draw
30 mA +12V
30 mA -12V

Notes: Module A-138n is a simple four channel mixer, which can be used with either control voltages or audio signals. Each of the four inputs has an attenuator available. The output is twice available (two sockets, hard-wired like a multiple).

The module is the slim version of module A-138a and offers nearly the same features. But the distances between the controls are smaller and rubberized small-sized knobs are used. In return the front panel has 4 HP only which is half the width of the A-138a. The module is primarily planned for applications where only limited space is available. The only functional difference compared to the A-138a is the missing attenuator for the (dual) output.

Width: 4HP / 20.0 mm
Depth: 30 mm (measured from the rear side of the front panel)
Current: +10mA (+12V) / -10mA (-12V)

Notes: Compact and simple four-input mixer module from Uncle Dieter. Linear pots make it suited to mixing CV signals but it can also handle audio. Mixed signal hard-wired to two sockets.

Supplier notes:
Module A-138n is a simple four channel mixer, which can be used with either control voltages or audio signals. Each of the four inputs has an attenuator available. The output is twice available (two sockets, hard-wired like a multiple).

HP : 4

Notes: A-138s is a simple but useful 4-in-2 mixing tool. It has four inputs available. Each input is equipped with an attenuator (Level) and a panning control that is used to distribute the signal to the left and right output. Beyond stereo mixing it is equally suited to create variable parallel routings. For example: Any of the four inputs may be routed in variable intensity to feed two filters.

You may regard the A-138s as a smaller version of the A-138m Matrix Mixer.

Inputs and outputs are DC coupled, i.e. the module can be used for the mixing of control signals too.

- 3U Eurorack module, 8 HP wide, 30 mm in depth
- Power consumption: 10 mA at +12 V and 10 mA at -12 V

Notes: A-138s is a simple but useful 4-in-2 mixing tool. It has four inputs available. Each input is equipped with an attenuator (Level) and a panning control that is used to distribute the signal to the left and right output. Beyond stereo mixing it is equally suited to create variable parallel routings. For example: Any of the four inputs may be routed in variable intensity to feed two filters.

You may regard the A-138s as a smaller version of the A-138m Matrix Mixer.

Inputs and outputs are DC coupled, i.e. the module can be used for the mixing of control signals too.

- 3U Eurorack module, 8 HP wide, 30 mm in depth
- Power consumption: 10 mA at +12 V and 10 mA at -12 V

Notes: Module A-140-2 contains two ADSR type envelope generators behind a front panel with 8 HP only.

Each ADSR provides these controls and in/outputs:

- LED (displays the envelope output)
- A: manual Attack control
- D: manual Decay control
- S: manual Sustain control
- R: manual Release control
- Gate Input
- Retrigger Input
- CVT Input with attenuator (CVT = CV Time)
- Envelope Output 1
- Envelope Output 2

The output voltage range for each envelope is 0 - 10V. The time range of Attack/Decay/Release is about 1ms to 30s.

By means of internal jumpers one can select which time parameters are controlled by the CVT input (e.g. D only or D+R or A+D+R) and in which direction (i.e. if an increasing CVT shortens or stretches the time parameter in question).

Socket CVT can be normalled to an internal fixed voltage (i.e. the switching contact is connected to an internal fixed voltage). That way it's possible to change all time parameters simultaneously by means of the CVT control.

Another jumper is used to set output 2 to normal or inverted envelope.

And another jumper is used for the normalling of Gate 2 to Gate 1 (i.e. ADSR#2 is also triggered by Gate 1).

Two more jumpers are used for the optional bus access to the gate signal of the bus for each ADSR. Changing the positions of the mentioned jumpers allows to modify the factory settings.

Notes: The module contains two ADSR type voltage controlled envelope generators with exponential curve shapes (charge/discharge curves of a capacitor) behind a front panel with 8 HP only.

Each ADSR provides these controls and in/outputs:

- LED (displays the envelope output)
- A: manual Attack control
- D: manual Decay control
- S: manual Sustain control
- R: manual Release control
- Gate Input
- Retrigger Input
- CVT Input with attenuator (CVT = CV Time)
- Envelope Output 1
- Envelope Output 2

The output voltage range for each envelope is 0 - 10V (10V = attack peak).

The time range of Attack/Decay/Release is about 1ms to 30s.

By means of internal jumpers one can select which time parameters are controlled by the CVT input (e.g. D only or D+R or A+D+R) and in which direction (i.e. if an increasing CVT shortens or stretches the time parameter in question).

Socket CVT can be normalled to an internal fixed voltage (i.e. the switching contact is connected to an internal fixed voltage). That way it's possible to change all time parameters simultaneously by means of the CVT control.

Another jumper is used to set output 2 to normal or inverted envelope.

And another jumper is used for the normalling of Gate 2 to Gate 1 (i.e. ADSR#2 is also triggered by Gate 1).

Two more jumpers are used for the optional bus access to the gate signal of the bus for each ADSR.

Notes: Module A-145 is a low frequency oscillator, which produces cyclical control voltages in a very wide range of frequencies.

Five waveforms are available: sawtooth, inverted sawtooth, triangle, sine and square wave. The LFO can be used as a modulation source for any number of modules - for instance modulating the pulse width or frequency of a VCO, modulation of the cut-off frequency of a VCF, or amplitude modulation with a VCA.

A three-way switch lets you select three frequency ranges, spanning from one cycle every several minutes at the lowest, to moderate audio frequency at the highest (about 4-5 kHz).

The LFO signal can also be synchronised, via the reset input.

Identical to the A-145-1, but only 4 HP wide and with additional LEDs for the square wave and the sawtooth signal.

Power consumption: 30mA at +12V and 20mA at -12V
Depth: 45mm
4 HP

Notes: Module A-145-4 is a simple quad LFO (Low Frequency Oscillator). Not a very "exciting" module, just a bread-and-butter device and a simple demon for work. Virtually in every modular system several LFOs are required for modulation purposes. The module contains four simple LFOs with the waveforms triangle and rectangle. A dual colour LED (red = positive / yellow = negative output voltage) indicates the triangle output of each LFO. The frequency range can be chosen for each LFO individually by means of a jumper between about 50 Hz ... 0.04 Hz (about 20 seconds, jumper removed) and about 2Hz ... 0.002 (about 8 minutes, jumper installed).

The module can be treated as a slimmed version of the quad LFO A-143-3 as it has similar features available. But the distances between the controls are smaller and rubberized small-sized knobs are used. In return the front panel has 4 HP only which is less than one third of the A-143-3. The module is primarily planned for applications where only limited space is available. The functional difference compared to the A-143-3 are the missing sawtooth outputs and frequency range switches.

Notes: Module A-145-4 is a simple quad LFO (Low Frequency Oscillator). Not a very "exciting" module, just a bread-and-butter device and a simple demon for work. Virtually in every modular system several LFOs are required for modulation purposes. The module contains four simple LFOs with the waveforms triangle and rectangle. A dual colour LED (red = positive / yellow = negative output voltage) indicates the triangle output of each LFO. The frequency range can be chosen for each LFO individually by means of a jumper between about 50 Hz ... 0.04 Hz (about 20 seconds, jumper removed) and about 2Hz ... 0.002 (about 8 minutes, jumper installed).

The module can be treated as a slimmed version of the quad LFO A-143-3 as it has similar features available. But the distances between the controls are smaller and rubberized small-sized knobs are used. In return the front panel has 4 HP only which is less than one third of the A-143-3. The module is primarily planned for applications where only limited space is available. The functional difference compared to the A-143-3 are the missing sawtooth outputs and frequency range switches.

Notes: Module A-147-2 is the successor of the VCLFO A-147 but offers much more features than the predecessor. The module is made of these sub-units:

- VCLFO: voltage controlled low frequency oscillator
- VCA: voltage controlled amplifier, switchable to voltage controlled polarizer
- VC delay unit: voltage controlled linear attack envelope (only one parameter: attack) for delayed LFO operation in combination with the VCA (e.g. delayed vibrato/tremolo)

LFO: The voltage controlled LFO has the waveforms Triangle, Sine, Sawtooth and Rectangle available and features a Reset/Sync input. Triangle/Sine and Rectangle are displayed by means of dual-colour LEDs (probably red/green), Sawtooth has a unicolor LED available (probably blue). The output levels are about -4V...+4V for Triangle, Sine and Rectangle. The Sawtooth level is about 0...+8V.

The CV control can be switched to attenuator or polarizer ("CV Mode" switch). In polarizer mode the CV inputs affects the frequency in the reverse manner when the CV control is left from the centre position. In the centre position CV has no effect and right from the centre the control works like a normal attenuator. The frequency range (without external CV) is from about 0,005 Hz (i.e. about 3 minutes per period) to 200 Hz (with external CV max. frequency about 1kHz). In addition a ultra-low mode can be activated by means of an internal jumper. When the ultra-low jumper is set a fixed voltage is connected to the switching contact of the "LFO CV" socket. In polarizer mode of the CV control that way extremely low frequencies (up to one hour period and more) are possible. For this a jumper has to be installed on the pin header JP6. In the factory a dummy jumper is installed on the pin header JP7 "Dummy". JP7 has no function and is used only for "parking" of the jumper. Simply remove the jumper from JP7 and plug it on JP6. JP6 is located behind the CV control.

VCA: This is a linear VCA that can be switched to "normal" VCA (i.e. kind of a voltage controlled attenuator) or voltage controlled polarizer ("VCA Mode" switch). In the "normal" VCA mode amplification +1 is achieved with about +5V control voltage. In polarizer mode the amplification ranges from about -0.5 (i.e. inverted signal with about 50% level) with 0V CV to +0.5 (i.e. non-inverted signal with about 50% level) with +5V CV. With about +2.5V CV the signal is suppressed. Details about the functioning of a voltage controlled polarizer can be found in the description of the module A-133. In this mode the VCA can be treated also a DC coupled ring modulator (similar to A-114).

The VCA of the A-147-2 has three sockets available: "In" (signal input), "Out" (signal output) and "CV" (control voltage input).

The Triangle Output of the LFO is normalled to the VCA signal input by means of the switching contact of the "VCA In" socket. If another LFO waveform (or any other signal) should be processed by the VCA the corresponding signal has to be patched to the "VCA In" socket. The VCA can be used also independently from the LFO and the Delay CV. In this case the VCA sockets In, Out and CV have to be patched accordingly. The VCA can be used also as waveshaper for the LFO signals (e.g. by patching VCA In and VCA CV to different LFO signals, if necessary via attenuator A-183-1 or offset generator/attenuator A-183-2).

Attack/Delay: The third sub-unit of the module is a simple, voltage controlled envelope generator that has only the parameter "Delay" (or Attack) available. This unit generates a linear increasing voltage that starts from 0V after each Delay Reset until it reaches about +5V. Then the voltage remains at +5V until the next Delay Reset occurs. The inclination or gradient is controlled by the manual Delay control and the Delay control voltage ("Delay CV" input). The waveform is linear, the control scale is exponential. The output voltage is displayed by a green LED and available at the "Delay Out" socket.

The manual Delay control ranges - without external "Delay CV" - from about 5ms (fully CW) up to 2 minutes (fully CCW). By means of an external voltage applied to the "Delay CV" socket this range can be extended. A rising CV shortens the delay time (behaviour like a VCO)!

The Delay output voltage ranges from about 0V to +5V. The rising edge of the gate, clock or trigger signal applied to the "Delay Reset" sockets resets the Delay output voltage to 0 V.

"Delay Out" is normalled to the VCA CV input by means of the switching contact of the "VCA CV" socket and consequently controls the Triangle level provided that no other patch is made. A typical example is the usage of a Gate signal (e.g. from a USB/Midi-to-CV/Gate interface) as Delay Reset. That way a delayed vibrato or tremolo can be realized if the VCA output is patched to the frequency CV input of a VCO (or VCF), or the CV input of a VCA.

Notes: Module A-147-4 is a dual voltage controlled LFO (Low Frequency Oscillator). Each LFO has the five waveforms triangle, sine, rising and falling sawtooth, as well as rectangle available. The rectangle output features manually adjustable pulsewidth and pulsewidth modulation by means of an external control voltage. The core waveform is triangle. The other waveforms are derived from triangle by means of waveform converters. The frequency of each LFO can be adjusted manually and modulated by means of an external control voltage with associated attenuator and polarity switch. By means of a jumper the basic frequency range of each LFO can selected: about 0.02 Hz (~ 50 seconds) ... 2.5kHz or about 0.0017 Hz(~ 600 seconds) ... 220Hz. That way each LFO can be used also as a VCO with a max. frequency of about 2.5kHz. Each LFO features a reset input which can be used to reset the triangle signal.

The module has these controls and in/outputs available:

Control F : manual control of the frequency, for each LFO the frequency range can be selected by means of a jumper from two values (see technical notes)

frequency coverage of control F in the high frequency range: about 0.075 Hz (~ 13 seconds) ... 1,4kHz

frequency coverage of control F in the low frequency range: about 0.007 Hz (~ 140 seconds) ... 125Hz

Control CV: attenuator for the signal applied to the CV socket, by means of a jumper a small positive voltage can be applied to the switching contact of the /CV/ socket, as long as no patch cable is connected to /CV/ socket the CV control then works as fine control for the frequency

Switch CV Pol.: polarity switch for the signal applied to the socket /CV/

Control PW/PM: combined control for manual and CV control of the rectangle pulsewidth:

when no patch cable is connected to socket /P/ the control is used to adjust the pulsewidth (PW) manually

when a patch cable is connected to socket /P/ the control works as attenuator for the external CV signal with a basic pulsewidth of 50:50.

Socket /CV/: frequency control voltage input, in the factory the module is adjusted so that the sensitivity of this input is exactly 1V/octave when the CV control is fully CW.

Socket /R/: reset input, according to the associated jumper the reset input is edge triggered or level controlled (see technical notes for details)

Socket /P/: pulsewidth control voltage input

Sockets with waveform symbol: output of the waveform in question (triangle, sine, rising and falling sawtooth, rectangle)

The output voltage ranges are about -5V ... +5V (10Vpp), except the rectangle output

For the rectangle output one can choose by means of a jumper if the range is about -5V ... +5V or 0...+10V.

LED: visual control of the LFO (triangle)

The inputs of the module are labelled with white characters on black background (in the text included into two slashes). The outputs are labelled with black characters.
Technical notes and special features:

The basic frequency range of each LFO can be selected by means of a jumper. The settings correspond to two different capacitor values for the VCO circuit. The relation between the two ranges is about 1:11. When the upper range is selected frequencies from about 0.02 Hz up to 2.5kHz can be generated. For the lower range the values are about 0.0017 Hz ... 220Hz. To obtain these full frequency ranges external control voltages are required. With the frequency control F only the frequencies mentioned above are possible.

Apart from that the range for the manual control F can be reduced to obtain a finer resolutuion. For this a jumper has to be removed. The range of control F is then reduced to about 1:4.5 only.

In the factory the starting voltage of the triangle output after a reset is adjusted to 0V, i.e. the triangle starts from 0V with the rising slope after a reset. By means of a trimming potentiometer the starting voltage can be adjusted to another value (e.g. to -5V).

Another jumper is used to set the reset behaviour to edge triggered or level controlled. When set to edge triggered the rising edge of reset signal is used for the reset (independent of the duration of the "high" state of the reset signal). When set to level controlled the triangle output remains at the starting voltage as long as the reset signal is "high". Only when the reset signal turns "low" the triangle starts.

Dimensions
8 HP
45 mm deep

Current Draw
80 mA +12V
70 mA -12V

Notes: Module A-148 (Dual S&H) has two identical sample & hold modules, designed to produce 'staircase' voltages. The signal present at the sample input is sampled at a rate set by the signal at the trigger input, and held at that voltage at the S&H output.

The exact shape of the staircase depends on the sort of waveform at the sample input: NOISE or RANDOM signals produce random patterns; an LFO produces rising or falling staircase patterns.

Two LEDs for each S&H indicate the voltage (positive or negative) of the sampled signal.

Notes: Module A-149-4 generates four triggered random voltages which meet the criteria choosen by several controls.

Manual controls for the criteria selection:
Octave range (manual control "Oct."): this parameter defines how many octaves are covered by the random voltages (0 ... +5V, with "Oct." control fully CCW only 0V are generated)
Grid (6 illuminated radio buttons): this parameter defines the grid of the random voltages:
Octaves (Oct)
Octaves + Quin (Quint)
Chords (Major or Minor chords)
Scale (Major or Minor scale)
Semitones
continuous (i.e. stepless)
Minor / Major (2 illuminated radio buttons): this parameter defines in case of chords or scales if they are minor or major. For all other grids this parameter has no meaning
Sixth / Seventh (2 illuminated separate buttons): these parameters defines if the sixth or seventh is added. Valid only if Oct, Quint, Chord or Scale is chosen as grid.

The output voltages follow the 1V/octave standard (i.e. 1/12 V voltage differenc per semitone) with exception of the Continuous mode. The voltages in this mode are totally random and do not follow the 1V/oct standard (i.e. not a multiple of 1/12V).
The generation of a new random voltage at the output (CV Out 1...4) is triggered by the rising edge of the signal applied to the corresponding trigger input (Trig. In 1...4). The trigger inputs are normalled top down. The minimum trigger level is +2.5V, the maximum level is +12V.

Applications:
random polyphonic structures (in combination with the polyphonic modules A-111-4, A-105-4, A-132-8, A-141-4 and e.g. A-157 as trigger source and A-173-1/2 for transposition of the polyphonic structures)
any application that requires several random voltages
four digital pseudo noise signals when higher trigger frequencies are used

Width: 4 HP / 20.0 mm
Depth: 50 mm (measured from the rear side of the front panel)
Current: +50A (+12V) / -10mA (-12V)

Notes: Module A-150-1 (Dual VCS) contains two separate voltage-controlled switches.

Each switch has a control voltage input, a common Out / Input, and two In / Outputs. The switches are bi-directional: they can work in both directions, so can connect one input to either of two outputs, or either of two inputs to one output. Voltages in the range -8V...+8V at the O/I resp. I/O sockets can be processed by the module.

Two LEDs show which in / output is active (i.e. which is connected to the common out / input).

Notes: Module A-150-8 contains eight manually/voltage controlled switches. Each of the eight switches has a manual control button (Man.), a control voltage input (CV), a common Out / Input (O/I), and two In / Outputs (I/O1, I/O2). The switches are bi-directional, i.e. they can work in both directions, so can connect one input to either of two outputs, or either of two inputs to one output. Two LEDs show which in / output is active (i.e. which is connected to the common out / input). In addition, the LEDs are used for the programming of the module:

For each unit the operating mode can be selected: Toggle or Level controlled. In Toggle mode the rising edge of the CV input or operating the manual control button changes the state of the switch. In Level mode the switch state is defined by the voltage applied to the CV input (low voltage = I/O1, high voltage = I/O2) or by the state of the manual control button (not pressed = I/O1, pressed = I/O2). The modes are programmed very easily: Operating the Toggle/Level button of the program section displays the current state of each switch with the LEDs: left LED on = Toggle mode, right LED on = Level mode. Operating the manual control button of the switch in question changes the toggle/level mode while the Toggle/Level button of the program section is operated. During the programming patched CV signals may have to be removed as the CV signals would interfere with the manual operating buttons during the programming process.

In addition, it's possible to define master/slave groups. In such a group the upper unit (= master) controls also the state of the following switches provided that they are defined as slaves. Master/slave programming is also very simple: Operating the Master/Slave button of the program section displays the current state of each switch with the LEDs: left LED on = Master, right LED on = Slave.

When all 8 units are defined as master all switches are independent from each other. If for example the sequence is MSSSMSMS the control unit of the first switch also controls the switches 2, 3 and 4. The control unit of switch 5 also controls the switch 6, and the control unit of switch 7 also controls the switch 8. The current states of the slave switches are overwritten by the state of the master switch.

Technical note: To protect the electronic switches in case of an unsuitable patch (e.g. connection of two outputs) a 1k protection resistor is inserted into the O/I line of each switch. If control voltages used for VCOs are switched this may cause a small voltage drop and lead to undesired audible detuning. For this application we recommend to insert a CV buffer between A-150-8 and the VCO(s), e.g. the Buffered Multiple A-180-3 or the Precision Adder A-185-2. Integrating the buffers into the module A-150-8 was not possible because this would ruin the bidirectionality of the switches.

Width: 12 HP / 60.6 mm
Depth: 55 mm (measured from the rear side of the front panel)
Current: +40mA (+12V) / -5mA (-12V)

Notes: Module A-151 (Quad Sequential Switch) is like an electronic four-position rotary switch.
It includes trigger and reset inputs, four in / outputs, and a common out / input. Each time a pulse is received at the trigger input socket, the common out / input is connected to the next in / output. After the fourth in / output, the next trigger makes it step back to the first again, and so on. A positive pulse at the reset input switches the out / input immediately back to the first in / output.
Voltages in the range -12V...+12V at the O/I resp. I/O sockets can be processed by the module (not only control voltages but also gate, trigger or clock signals provided that they are in the -12V...+12V range).
By means of a toggle switch the number of steps can be limited to 2, 3 or 4.
Four LEDs indicate the active in / output (ie. the on that is connected to the out / input at any particular time).

For more detailed information please look at the English user's manual: A151_man.pdf.

Similar modules:
A-150-1 Dual Voltage Controlled Switch
A-150-8 Octal Manual/Voltage Controlled Programmable Switches
A-152 Voltage Addressed Track&Hold / Switch (Multiplexer) / Digital Outputs

Technical notes:
To protect the electronic switches in case of an unsuitable patch (e.g. connection of two outputs) a 1k protection resistor is inserted into the O/I line. If control voltages used for VCOs are switched this may cause a small voltage drop and lead to undesired audible detuning. For this application we recommend to insert a CV buffer between A-151 and the VCO(s), e.g. the modules A-180-3, A-180-4 or the Precision Adder A-185-2. Integrating the buffer into the module A-151 is not possible because this would ruin the bidirectionality of the switches.
For modules manufactured before spring 2005 the voltage range at the in/outputs was limited to -8V...+8V. From spring 2005 the revised version of the module was available. With an additional switch the number of steps can be set to 2, 3 or 4 (thanks to Peter Grenader for this idea). Moreover the revised module allows to process voltages in the full A-100 voltage range (i.e. -12V...+12V). The limitation to -8V...+8V is no longer valid. The A-100 DIY page describes how to install this additional switch for the old version of A-151.

Width: 4 HP / 20.0 mm
Depth: 35 mm (measured from the rear side of the front panel)
Current: +20mA (+12V) / -10mA (-12V)

Notes: Module A-151 (Quad Sequential Switch) is like an electronic four-position rotary switch.

It includes trigger and reset inputs, four in/outputs, and a common out/input. Each time a pulse is received at the trigger input socket, the common out/input is connected to the next in/output. After the fourth in/output, the next trigger makes it step back to the first again, and so on. A positive pulse at the reset input switches the out/input immediately back to the first in/output. Voltages in the range -8V...+8V at the O/I resp. I/O sockets can be processed by the module.

Four LED's indicate the active in/output (ie. the one that is connected to the out/input at any particular time).

Notes: Module A-155-2 is a small, very compact designed analog sequencer with a lot of features. The sequence length is 8 steps. Each step has available a control for the adjustment of the control voltage for this step and an illuminated momentary switch (button). The buttons are used in the standard running mode to turn on/off the gate of the step in question (button illuminated = gate on, not illuminated = gate off). In combination with other controls at the bottom of the front panel the buttons are used for additional functions: depending on the position of the Program toggle switch the button Function is used to program the length of the sequence (switch position Limit), the running direction (switch position Direct.) or to call up the preset management (switch position Preset)

When function Direct (Direction) is selected these running modes are available:

Up

Down

2 x Up (each step is played twice with the normal tempo, not to be confused with Ratcheting x2, see below)

2 x Down (each step is played twice with the normal tempo, not to be confused with Ratcheting x2, see below)

Pendulum type 1 (start and end step are played twice)

2 x Pendulum type 1 (each step is played twice with the normal tempo, start and end step are played 4x)

Pendulum type 2 (start and end step are played once)

Random (Rnd)

When function Preset is selected the illuminated buttons are used to call up one of the 8 presets. In each preset these parameters are stored: active steps, running direction, length of the sequence, ratcheting. To call up one of the 8 stored presets one has to push and hold the button Function and then operate short-time one of the buttons 1 - 8 while the toggle switch Program is in position Preset. To store the present paramaters in one of the 8 presets the procedure is similar but one has to operate one of the buttons 1 - 8 for a longer time (approx 3 seconds).

Depending on the position of the Program toggle switch the Ratcheting button is used to program the ratcheting feature (x2, x3, x4) individually for each step of the sequence (toggle switch Program in position Rx2, Rx3 or Rx4). In case that at the step in question another ratcheting is already programmed (eg x2 or x3 when x4 is chosen) the other ratcheting is overwritten (kind of radio button function between the ratchetings x2, x3 and x4). Details about the ratcheting function are explained at the module A-160-5.

The button Start/Stop is used to start or stop the sequence manually. Button Reset sets the sequence to the first step. For this also the external input Reset can be used.

The module does not feature built in clock generator. Rather an external Clock signal is used. The positive edge of the incoming clock signal triggers the advance of the sequence to the next step.

The voltage range of the control voltage generated by the module can be switched to 3 different ranges by the toggle switch Range: 0 - +1V / 0 - +2V / 0 - +4V. The control voltage is available at socket CV. The voltage is not quantized. But there is an internal pin header available that outputs the data via Midi (note on/off from Midi note 36. Midi channel 1). It can be used to control a MIDI-to-CV interface if quantized control voltages are required, eg the planned Micro-CV-Interface A-190-9)

The Gate signal appears at socket Gate. The pulsewidth of the gate signal is defined by the pulsewidth of the clock signal provided that ratcheting is not active at the step in question.

Controls and displays:

1 - 8 (rotary controls): manual adjustment of the control voltage for each step

1 - 8 (illuminated momentary switches/buttons): manual gate setting for each step, also used for special functions in combination with other controls (setting of first/last step, running direction, ratcheting)

Range: toggle switch for selection of the control voltage range

Program: toggle switch for selection of a function in combination with the buttons Ratcheting and Function

Ratcheting: button for the programming of ratcheting in combination with the toggle switch Program

Function: button for the programming of sequence length (Limit) and running direction (Direct) as well as for the Preset management (Preset)

Sta/Stp: button for the manual control of Start and Stop, in running state the LED of this button displays the state of the Gate output (ie it flashes in the rhythm of the Gate output)

Reset : manual reset button

CV : control voltage output

Gate : gate output

Clock: clock input, the pulsewidth of the clocjk signal defines the pulsewidth gate signal

Reset: reset control input, reset type selectable via internal jumpers (eg positive edge triggers the jump to first step/positive leveltriggers the jump to first step and remains at first step as long as the reset input is high/waiting for the next positive edge of the clock signals before reset is carried out)

Notes: Module A-155-2 is a small, very compact designed analog sequencer with a lot of features. The sequence length is 8 steps. Each step has available a control for the adjustment of the control voltage for this step and an illuminated momentary switch (button). The buttons are used in the standard running mode to turn on/off the gate of the step in question (button illuminated = gate on, not illuminated = gate off). In combination with other controls at the bottom of the front panel the buttons are used for additional functions: depending on the position of the Program toggle switch the button Function is used to program the length of the sequence (switch position Limit), the running direction (switch position Direct.) or to call up the preset management (switch position Preset)

When function Direct (Direction) is selected these running modes are available:

Up

Down

2 x Up (each step is played twice with the normal tempo, not to be confused with Ratcheting x2, see below)

2 x Down (each step is played twice with the normal tempo, not to be confused with Ratcheting x2, see below)

Pendulum type 1 (start and end step are played twice)

2 x Pendulum type 1 (each step is played twice with the normal tempo, start and end step are played 4x)

Pendulum type 2 (start and end step are played once)

Random (Rnd)

When function Preset is selected the illuminated buttons are used to call up one of the 8 presets. In each preset these parameters are stored: active steps, running direction, length of the sequence, ratcheting. To call up one of the 8 stored presets one has to push and hold the button Function and then operate short-time one of the buttons 1 - 8 while the toggle switch Program is in position Preset. To store the present paramaters in one of the 8 presets the procedure is similar but one has to operate one of the buttons 1 - 8 for a longer time (approx 3 seconds).

Depending on the position of the Program toggle switch the Ratcheting button is used to program the ratcheting feature (x2, x3, x4) individually for each step of the sequence (toggle switch Program in position Rx2, Rx3 or Rx4). In case that at the step in question another ratcheting is already programmed (eg x2 or x3 when x4 is chosen) the other ratcheting is overwritten (kind of radio button function between the ratchetings x2, x3 and x4). Details about the ratcheting function are explained at the module A-160-5.

The button Start/Stop is used to start or stop the sequence manually. Button Reset sets the sequence to the first step. For this also the external input Reset can be used.

The module does not feature built in clock generator. Rather an external Clock signal is used. The positive edge of the incoming clock signal triggers the advance of the sequence to the next step.

The voltage range of the control voltage generated by the module can be switched to 3 different ranges by the toggle switch Range: 0 - +1V / 0 - +2V / 0 - +4V. The control voltage is available at socket CV. The voltage is not quantized. But there is an internal pin header available that outputs the data via Midi (note on/off from Midi note 36. Midi channel 1). It can be used to control a MIDI-to-CV interface if quantized control voltages are required, eg the planned Micro-CV-Interface A-190-9)

The Gate signal appears at socket Gate. The pulsewidth of the gate signal is defined by the pulsewidth of the clock signal provided that ratcheting is not active at the step in question.

Controls and displays:

1 - 8 (rotary controls): manual adjustment of the control voltage for each step

1 - 8 (illuminated momentary switches/buttons): manual gate setting for each step, also used for special functions in combination with other controls (setting of first/last step, running direction, ratcheting)

Range: toggle switch for selection of the control voltage range

Program: toggle switch for selection of a function in combination with the buttons Ratcheting and Function

Ratcheting: button for the programming of ratcheting in combination with the toggle switch Program

Function: button for the programming of sequence length (Limit) and running direction (Direct) as well as for the Preset management (Preset)

Sta/Stp: button for the manual control of Start and Stop, in running state the LED of this button displays the state of the Gate output (ie it flashes in the rhythm of the Gate output)

Reset : manual reset button

CV : control voltage output

Gate : gate output

Clock: clock input, the pulsewidth of the clocjk signal defines the pulsewidth gate signal

Reset: reset control input, reset type selectable via internal jumpers (eg positive edge triggers the jump to first step/positive leveltriggers the jump to first step and remains at first step as long as the reset input is high/waiting for the next positive edge of the clock signals before reset is carried out)

Notes: Module A-156 is a Dual Control Voltage Quantizer. A quantizer converts a continuous control voltage in the range 0...+10V into a stepped output voltage in the same voltage range (i.e. only certain voltages occur). Normally 1/12 V steps are used to obtain semitone steps. Quantizer 2 of the A-156 allows has more sophisticated quantizing modes like major scale (i.e. only voltages corresponding to the major scale), minor scale, major chord, minor chord, fundamental + fifth and addition of seventh or sixth when chords are selected. Only those voltages appear at the CV output which comply with the selection rule (e.g. minor chord with seventh). The mode setting of quantizer 2 is done with 3 switches (1-0-1 type with middle position). From the factory quantizer 1 is working in the semitone mode. But there is a jumper on the pc board that can be changed so that even quantizer 1 uses the same scale as quantizer 2.

For each quantizer the following in/outputs are available:

- Control voltage input (CV In): The input for the continuous voltage to be quantized
- Control voltage output (CV Out): The output of the quantized voltage
- Trigger input (Trig.In): If this jack is left open the quantizer is working permanently. If a rectangle voltage is applied quantisation happens only at the rising edge of the signal (e.g. from an LFO or MIDI-to-Sync interface). Thus the quantizing can be synchronized with other events
- Trigger output (Trig.Out): Whenever a quantisation happens (i.e. a new voltage is generated at the CV Out) a positive pulse occurs at this output. It may be used to trigger an envelope generator (ADSR) or for triggering other modules (sequential switch A-151, trigger divider/sequencer A-160/161, trigger delay A-162, ...). If none of these functions are used the jack is left open

On top of that the A-156 is provided with a common transpose CV input having an additive effect on both quantizers. This input is quantized in semitone steps. A typical application is the transposition of a sequence generated by the A-155 by a second control voltage (e.g. coming from the MIDI-CV interface A-190).

Typical applications:

- Quantizing the CV sequence generated by an A-155 (semitone, only major scale, only minor scale and so on)
- Quantizing the voltage coming from the Trautonium Manual / Ribbon Controller A-198, Theremin A-178 or Light-to-CV module A-179 to get accurate semitones or major/minor scale tones
- Arpeggio-like effects with LFO, random, noise, envelope generators as CV sources (for negative or symmetrical voltages an offset must be added, e.g. with the offset/attenuator module A-129-3, to obtain positive voltages for the A-156 input)

Width: 8 HP / 40.3 mm
Depth: 55 mm (measured from the rear side of the front panel)
Current: +50mA (+12V) / -10mA (-12V)