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

The Doepfer A-105-2 is a CV-controllable lowpass filter with 24dB that is based on the formidable sound of its predecessor A-105.

The sound of the SSM2044 chip in the A-105 filter lives on in the A-105-2 and is the salvation for all those who cannot do without the sound of the established A-105 module. Instead of the SSM2044, which is no longer available at acceptable prices, its successor SSI2144 is used. Soundwise we are talking about the fabulous qualities of devices like Korg Monopoly and Polysix, PPG Wave 2.2 and 2.3, Fairlight II or EMu SP-1200. The outstanding feature of the filter sound of the SSM2044 is the "True open loop design", which stands for a special sonority, which is appreciated everywhere in the synthesizer world.
The A-105-2 has controls for input volume, as well as cutoff, resonance. Of the two audio inputs, input 1 can also be adjusted by knob, with the double CV sockets for controlling the cutoff frequency, the second CV input (FCV2) is equipped with an attenuator, as is the CV input for controlling the resonance (QCV). In total, 2 audio inputs (Input 1/2) and 3 CV inputs (FCV 1/2, QCV) are available.
While the features of A-105-2 and its predecessor largely overlap except for the additional second audio input, the newer module is slimmer and operates on 4HP instead of 8HP. This is accompanied by a change in the arrangement of the controls, which, however, should not negatively affect the filter experience.

Features:

• CV-controllable 24dB lowpass filter based on the SSI2144 chip
• Resonance masters self-oscillation
• Potentiometers for cutoff, resonance and input level
• 2 audio inputs (Input 1/2)
• 3 CV inputs (FCV 1/2, QCV)
• 2 attenuators for FCV2 and QCV
• Frequency range approx. from 15 Hz to 15 KHz
• The signals at both inputs are mixed before they pass the filter