AM8060 JP6 Filter


AM8060 Module

Overview  This module is a replica of the Roland Jupiter 6 voltage controlled filter which comprises two 2-pole State Variable  filters in series. The analog polysynth Jupiter 6 was launched in 1983 with 6 voices that used CEM3340 VCO’s . The AM8060 contains the same two SVF’s, with each of the 2-pole filters switchable into either Low Pass or High Pass mode providing three VCF modes (all with variable resonance but without self oscillation):

  • 24dB Low Pass Filter
  • 24dB High Pass Filter
  • 12dB Band Pass Filter

The filter has a more aggressive sound than a simple 4-pole OTA based filter as used in the Jupiter 8, along with a lot more flexibility in sounds. The AM8060 JP6 VCF EuroRack module was launched in late 2010 and immediately gained positive feedback from customers and in 2014 we revised the design with resonance control circuit improvements and in total 30 modules were manufactured.

A small number of modules used original JP6 buttons and SSM2164 chips, and were made in 2015/2015 and this version is called the AM8060SE.

EuroRack Module:   14HP wide
User Manual:              AM8060 User Manual V2

JP6 Buttons

Description  The circuit is based directly on the Roland Jupiter 6 filter and knowledge of the MKS80 REV04 which is configured as a single 24dB low pass filter. The audio signal level is buffered and reduced down before going to the filter core, and then boosted back up after the core. The core is two SVF’s that use one IR3109 chip, then another IR3109 enables control of resonance.

The response of each filter is switched between 12dB low or 12dB high pass, and when the filters are set to Low and High you get the 12dB Band Pass mode. The module has rotary potentiometers to control Cutoff Frequency and Resonance, as well as the level of 2x Frequency control voltages, 3x audio signal inputs. Our 2014 and 2019 modules retains the same resonance circuit as the original and therefore do not go into self-oscillation. Roland avoided this in the Jupiter 6, MKS80 and Alphas, as SVF’s are difficult to tame when in self oscillation.

There are six 3.5mm jack sockets on the right of the front panel; the filters’ audio output, 2x Frequency control voltages, and 3x audio inputs. The filter topology can be adjusted using two front panel locking push buttons with grey square caps. The filter has two 2-pole SVF filters in series, and the push buttons select from 3 filter modes, each sounding different:

  • 24dB Low Pass Filter – Switches Out
  • 24dB High Pass Filter – Switches In
  • 12dB Band Pass Filter – Only Upper or Lower Switch In

SDIY Option The original AM8060 could be built by customers from a blank PCB, and a second-hand Boss PH-2 Phaser, but the PCB’s are no longer available.

 

Sound Demos

Availability The AM8060SE was re-engineered in 2019 to use the fabulous sounding SSI2164 VCA chip. This provides an even better sound than the SSM2164’s I used in 2014/15 and avoids using valuable and increasingly rare IR3109 chips. The SSI2164 is superior in sound and footprint to the LM13700’s used in the System 80 Jove filter (which is a copy and rework of the AM8060). This new version of the AM8060SE uses original JP6 buttons and LED’s and is now skiff friendly at 35mm depth. The IC’s in this version are SMD to save PCB space, but overall the build is simpler with three PCB’s in total.

A production run of around 50x modules is taking place in 2019.

 

 

Copyright AMSynths 2019