Please note: This is not a guitar effect where you can "plug in your guitar and get a sound out". Extra circuity is absolutely essential, either directly wired, or as parts of other equipment. If you need to ask how to use it, then it's not for you.

Four quadrant multipliers have more or less replaced ring modulators in synthesizers, even though they still bear the label "ring modulator". The distortion in these is lower than that of a true diode ring modulator, because the diode voltage drops have been eliminated. This leads to better specifications, though in a noise maker, this is not always desirable.

For years I have been building various four quadrant modulators, and have been satisfied with none of them. Not one of them had the raw sonic beauty of the traditional ring modulators I made when I was first starting out in synthesizer building.

For that reason I present here the "Real Ring Modulator", a traditional diode and transformer ring modulator. Each is hand assembled using matched germanium diodes and a pair of brand new 3k impedance transformers. Some RRMs used diodes from a computer from 1969, but due to the huge demand for these modulators, I have used up my stocks and may now use brand new germanium diodes as needed. The sound remains the same.

Bare printed circuit boards and kits will not be available - just the assembled ring modulator units. They are passive devices, and can be used as is, or integrated into more complex projects.

Carrier suppression is good, but not complete, so a compressor-expander could help if better suppression is required.

The schematic of Real Ring Modulator. Above is the standard diagram used for a ring modulator, if for no other reason than it is easier to work out what is going on by looking at it. Below the diode ring has been "unfolded" to make it clear that it is a diode ring, not a diode bridge.

Construction

Wiring the ring modulator. The center input is the carrier input. In and out are interchangeable.

The only "assembly" needed is to connect the board to input and output jacks.

Notes:

• PCB info: 0.6" x 2.3" with 3mm mounting holes 0.15" in from the corners.
• Please email me if you find any errors.

If anyone is interested in buying these units, please. Check the PCBs for Sale page to see if I have any in stock.

Can't find the parts? See the parts FAQ to see if I've already answered the question. Also see the CGS Synth discussion group.
 

Article, art & design copyright 2004 by Ken Stone

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