AM4012 Low Pass Filter

12 HP | AM4012 Low Pass Filter | User Manual (PDF) | Modular Grid | You Tube

This 12HP module is a re-imagining of the ARP 4012 low-pass filter constructed around a traditional “Moog” transistor ladder. It has a wide cutoff range between 0 - 35kHz and goes into self oscillation across the frequency range.

The 4012 module first appeared in the ARP 2600 synthesizer in 1971, and it is a refinement of the 1006 filter in the 2500 Modular synthesizer.

DESCRIPTION The AM4012 has been engineered with additional features to provide the best ARP  style voltage controlled filter in Eurorack. Additional features include:

• Voltage controlled resonance 
• Optional Q compensation
• Input resistors are 5% carbon film

External voltage control of resonance enables more control over the sound of the filter in realtime, whilst the Q compensation averts the drop out of the audio signal at high Q settings. 

CONNECTIONS There are seven 3.5 mm jack sockets on the base of the anodised aluminium front panel:

• SIGN IN 1 - 3 - Audio inputs with individual level control
• KYBD - 1/V octave CV input for filter cutoff, designed for keyboard pitch input
• FMOD1 and 2 - CV input for frequency ciutoff modulation
• QMOD - CV input for resonance modulation
• OUTPUT - Audio signal output

There are slide potentiometers for adjusting frequency (FM1 and FM2) and resonance modulation and rotary potentiometers for adjusting frequency cutoff and resonance. 

The module comes with a set of M3 mounting screws and washers, and a standard 10 to 16-way Doepfer power cable.

PRODUCTION STATUS: IN DEVELOPMENT