AM8047 UAF

ARP Universal Active Filter

This module is a replica of the ARP 1047 Multi Mode FIlter and Resonator from the ARP 2500. This 2-pole filter has Low, Band and High pass modes, along with voltage controlled resonance

The VCF has variable Frequency Cutoff and 2x voltage control inputs and pots for Frequency Modulation. There are 2x audio inputs with variable control and 2x audio output. Resonance has a front panel control plus a CV input and level pot. The module has a mixture of slide and rotary potentiometers and there are slide switches to limit the filter and to select filter mode at the two audio outputs. There is a LED to monitor the audio ouput.

Detailed Description
This 21 HP wide module has at its core a 2-pole (12dB/octave) traditional state variable filter using transconductance amplifiers built from transistor arrays (rather than OTA chips) plus fast slew Op Amps. This accurate replica uses the same ARP circuit design as in the ARP 1047 but I have upgraded the design with modern components. The filter has 4 modes:

Low Pass
Band Pass
High Pass
Notch

To conserve panel space there are 2x signal outputs which can select from the 4x filter modes. The Keyboard Percussion feature of the original ARP 1047 has also been excluded as there simply is not enough front panel space! However an additional small module will provide these features in the future, for any VCF that has high resonance capabilities. This AM8048 module is patched in via an audio signal input and a Fequency CV input, and uses the Gate and Keyboard CV signals on the Doepfer bus to generate percussive “ringing” resonance effects.

Technical Specifications

Potentiometers:
Cutoff Frequency Coarse and Fine
Resonance and Q CV Level
2x Audio Signal Levels
2x CV Modulation levels

Connections [3.5mm jack]:
Signal A, Signal B
CV Input 1, CV Input 2, Q CV Input
Audio Signal Output

Switches:
2-way slide switch to select Normal or Limiter Mode
2-way slide switch to select HP or LP output
2-way slide switch to selecet BP or Notch output

Indicators:
1x Green 3 mm LED to indicate Audio Output Level

Power:
Standard Doepfer 16 way cable to 16 pin power bus

Front panel:
Machined out of 2mm aluminium and colour printed

Dimensions:
21HP width, standard 128.5 mm EuroRack height, 25 mm depth

Module Package Contents:
1x AM8047 EuroRack Module
4x Doepfer compatible 3mm diameter mounting screws
1x 300mm Doepfer compatible power lead
Unique holographic serial number
12 month warranty covering product defects