AM 8014 Module - Ring Modulator
Overview This is a replica
of the ARP 2600 Ring Modulator and Noise Source built into a single FracRac module, using an Oakley Sound 4014 PCB for the Ring Modulator and an Analog Metropolis designed ARP 4022 Noise Source PCB.
A Ring Modulator performs a
variation of amplitude modulation in which two input signals are multiplied creating an output that contains the sum and difference of the input signals (called sidebands), but without the original input signals themselves. The result
is a very strange clanging, bell-like sound that can only be created with a ring modulator. Useful for producing gong sounds, bell sounds, and many strange sounds having no description. (yeah right!)
Original Ring Modulator Circuit
The original design first appeared in the ARP2500 in 1970 as the 4005 Modulator and VCA. ARP created a potted sub module called the 4014 which contains the majority of the electronics needed for a Ring Modulator. This module was re-used in the infamous ARP2600, but not within any later ARP synthesizers due to its relative high cost.
Original Noise Circuit
ARP designed a noise circuit in the ARP 2500, which I cloned a few year ago, as the AM4016. This ARP circuit forms the basis for the 4022 Noise Circuit in the ARP 2600 and I have created a dedicated PCB (AM4022) to replicate this design. The Noise Source uses the traditional transistor in avalanche mode to create white noise which is then amplified by an Op Amp and then filtered to provide a spectral range of noise from white through pink to red. The COLOUR potentiometer adjust this spectrum, and there is a level control pot too.
AM8014 Module For my FracRac ARP 2600 synthesizer I wanted to recreate as many of the special modules as possible as well as the standard VCO, VCF, ADSR, VCA. For the Ring Modulator I was in luck as Tony at Oakley Sound
designed an updated version of the 4014 in early 2009, so I have used his excellent design and PCB for half of this module. More details are here
This still leaves some panel space and 3 jack sockets. So I recreated the ARP 4022 Noise Module onto a new PCB, a complete replication with the addition of a LED level circuit
so the overall volume of Noise can be seen, as well as when there is low random noise.
The module has the following front panel controls:
Ring Modulator: X-Level, Y-Level
Ring Modulator: AC/DC X Input, AC/DC Y Input
Noise Source: Colour - colour of the noise
Noise Source: N-Level - noise level
Noise Source: LED - Noise Source Level
There are six 3.5mm jack sockets mounted on the left hand side of the panel, these are:
Ring Modulator: X Signal Input, Y Signal Input, Output
Noise Source: Mix Output 1, 2, White
Front Panel The front panel is a 3" wide FracRac with Alpha potentiometers and push fit mixer style knobs.