Doepfer A-105-2 24dB Low Pass (SSI-Type) Filter

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.