A-133 is a special dual voltage controlled amplifier that enables both positive and negative amplifications. Negative amplification means in this context that the signal is inverted. The main application of the module is the processing of control voltages, e.g. ADSR or LFO but the module can be used also for audio applications.

The amplification range is about -2.5....0....+2.5 (other amplification ranges for small additional charges, e.g. -1...+1 or -5...+5). Amplification can be adjusted manually (Man control) and by an external control voltage with attenuator (CV). The present amplification is displayed with two LEDs: one for positive and one for negative amplifications (not a signal display but amplification diplay, similar to A-134).

The overall amplification of the A-133 is defined by the resistors R18 (upper unit) and R32 (lower unit). The factory value is 270k for both. Lowering the value of the resistor reduces the amplification of the unit in question, increasing the value of the resistor increase the amplification of the unit in question. For example 100k (exact value 108k) reduces the amplification range to about -1 ... +1 (instead of -2.5 ... +2.5), 560k (exact value 2*270k = 540) increases the amplification range to about -5 ... +5.

Dimensions
8 HP
50 mm deep

Current draw
30 mA +12V
20 mA -12V