AM1031 Multi Purpose Filter

14 HP | AM1031 Multipurpose Filter | User Manual (PDF) | ModularGrid | You Tube

OVERVIEW This 14HP module is a re-imagining of the ARP 1031 Dual Multi Purpose filter that was announced in 1970 as part of the 2500 analog modular synthesizer. The module never made it into production, but it has now been recreated as the AM1031 module.

DESCRIPTION The AM1031 takes inspiration from the Aries 327 state variable filter module which Dennis Colin designed around late 1975. It has the same name (Multipurpose FIlter), and the five filter modes, that were planned for the ARP 1031, which Dennis would have designed at ARP in 1970.

The module has these filter modes:

• Separate High Pass, Band Pass and Low Pass
• In addition, either a Notch or Peak output

 A peak filter is a frequency filter that passes a narrow band of frequencies and stops all other frequencies. In essence, a very narrow band pass filter, the opposite of a notch filter.

The filter delivers high Q without self oscillation and is an advanced version of the ARP 1047 circuit. Dennis carefully designed a new dynamic Q limiting circuit to ensure the filter remains controlled at high Q values, as well as voltage controlled resonance. This is a beautiful sounding filter and a homage to the genius of Dennis Colin and Triangulum Research in the USA for sharing the Aries schematics.  

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CONNECTIONS There are ten 3.5 mm jack sockets on the anodised aluminium front panel:

• SIG IN 1 & 2 - Audio inputs with individual level control
• KYBD - 1/V octave CV input for filter cutoff, designed for keyboard pitch input
• FMOD1 & FMOD2  - CV input for frequency cutoff modulation
• QMOD - CV input for resonance modulation
• OUTPUTS - Audio outputs of the filter HP, BP, LP, Peak/Notch

There are rotary potentiometers for adjusting signal levels, frequency and resonance, and slide potentiometers for controlling frequency and Q modulation.

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

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MODULE STATUS: IN PRODUCTION