RM4014: Ring Modulator Module

Constructional difficulty: Small module with some simple setting up

The regular 5U Oakley format design in standard black. The smaller knobs used in this design have a diameters of 19mm.

This is a vintage ring modulator design with bags of character. It is based on the classic 4014 sub-module which was used on the 2500 modular and 2600 semi-modular synthesisers. The design has a fully discrete core but uses two op-amps for input and output amplification.

A ring modulator has two main inputs, usually called X and Y, and one output. The output voltage is the product of the two input voltages. In other words it multiplies the two input signals together to produce a new and different sounding output. If you have two sine wave input signals then the output will have both the sum and difference frequencies. For example, if X is a 440Hz sinewave and Y a 40Hz, you would get a 480Hz and a 400Hz sinewave from the output. However, this is only really true in a perfect ring modulator... And this ring modulator is not that. Each input has its own differing non-linearities or imperfections. This greatly adds to the character of the resultant output.

The Oakley Ring Modulator features three rotary control pots. Each input has its own attenuator, and there's also a offset control for the Y input. In conjunction with the Y attenuator, this third pot effectively acts as a wet-dry control for the X input. But because of the non-linearities inherent in the design it also acts in more subtle ways.

You can also use the Oakley Ring Mod as a standard VCA. Just use the Y input as your CV input and X will be shaped accordingly.

Each input can be either direct coupled (DC) or high pass filtered (AC). The former allows DC and low frequency signals to be processed. While the latter provides a DC block to process only alternating frequencies. The standard panel design makes both types of input available with each having its own socket. However, you can use a one socket on each and then use a switch to select between the two modes if you prefer.

The issue 1 ring mod built into a 1U wide natural finish Schaeffer panel in standard 5U Oakley/MOTM format. Issue 3 boards are similar but feature an additional Synth.com power header

This is one of our smaller format PCBs. The module can be either built as a standard 5U Oakley panel design, a single width MU format, or as a smaller 3U Frac sized panel. The pots are Alpha/ALPS 16mm types with our special matching brackets. The pot spacing on this module is 1.45" (37mm).

The module accommodates either our standard Oakley/MOTM/Frac power header or a Synthesizers.com power header. The current draw is +40mA and -35mA when run from +/-15V with no signal output.

The PCB is 8.6cm (deep) x 9.7cm (height).

As with all Oakley projects the PCB is double sided with through plated holes, has tough solder mask both sides, and has bold component legending for ease of construction.

Sound Samples

The following sample set was obtained using the ring modulator with an Oakley VC-LFO as the modulator (Y-input). The first of the three sounds uses a stable sine output from an Oakley VCO as carrier whilst the VC-LFO's frequency is manually swept with the frequency pot - this shows the huge range of the VC-LFO's frequency pot. The second sample processes the output of two mixed saw VCOs and sweeps the frequency of the VC-LFO from high to low. The final sample uses the same two saw VCOs but triggers the VC-LFO with the gate thus each new note always fades up from nothing.

This time we have an Oakley VCO sine which feeds the carrier (X-input) and a VC-LFO triangle wave as the modulator (Y-input). The X x Y out is going to an SVF filter whose low pass output goes to the master VCA. The SVF and VCA are controlled by an ADSR and the whole thing is sequenced from a P3 via a midiDAC.


Click here for how to order.

Ring Mod issue 3 PCB .................................... 16GBP

Ring Mod pot bracket kit ................................. 0.75GBP

The Pot Bracket Kit contains three Alpha pot brackets.

All prices include VAT at UK rates. Shipping and postage is additional to these prices. See also the FAQ page.

Ready made modules are normally available from Krisp1.com.

Project Downloads

Ring Modulator issue 3 Builder's Guide

Ring Modulator issue 3 User Manual

Construction Guide Our handy guide to building Oakley DIY projects

Parts Guide Our handy guide to buying parts for Oakley DIY projects.

Schematics are available to purchasers of the PCB and will be sent via e-mail when the board(s) are shipped.

Front Panel database

A Schaeffer front panel can be made for the 5U high 1U module in either standard black or natural finish.

5U format 1U panel in traditional black

5U format 1U panel in natural silver

To read these files you will need a copy of 'Frontplatten designer' from Schaeffer. The program also features on-line ordering, so its now even easier to buy your panels from Scheaffer.

The company are based in Berlin in Germany and will send out panels to anywhere in the world. Delivery to the UK normally takes around ten days. For North American users you can also order your Schaeffer panels from Front Panel Express.

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Copyright: Tony Allgood.
Last revised: October 10, 2017.