Know of any *working* Ring Mod layouts?

[Mark Hammer]

Once again....

ANY modulated effect, be it vibrato, tremolo, chorus, flanger, or phase shifter, can be made to sound ring-modulator-ish once the modulation rate moves from the sub-audio (20hz and less) range into the audio range (above 20hz sweep rate).

If you already have any modulation pedal you don't mind modding, and if the LFO it contains is one of the standard 2 op-amp types, you can up the modulation rate by dropping the value of the timing capacitor in the LFO.  Staed more simply, if you look at the two op-amps forming the sweep generator, one of them will be what is called the "integrator'", and will have simply a capacitor in its feedback loop, but not a resistor.  Reducing the value of this cap will alter the sweep range proportionally.  So, if the cap is currently .1uf and the pedal currently sweeps from 10 to .1hz (10 times a second to once every 10 seconds), reducing the cap to .033u will change the range such that it will now sweep from roughly 30 times a second to once every 3.3 seconds.

The easiest way to do the mod is to stick the second cap value in series with the existing one, and use a SPDT toggle wired with the centre lug of the togle going to the point where the two caps are joined and each side lug going to the other end of one of the caps.  This will result in one or the other cap being effectively cancelled and replaced with the other, but in a pop-free manner.

Please note that "classic" ring modulation tended to involve pure waveforms generated electronically, not complex waveforms generated mechanically (such as by a guitar).  The result is that simply modulating a straight guitar signal doesn't sound nearly as good as the "classic" stuff.  Why?  Because once you add all those sums and differences of harmonics into the mix (and especially with chords or multiple notes) it starts to turn into noise.  A simple, and recommended fix is to do what you can to "round off" the guitar signal and strip it of harmonic content before modulating.

So, say you had a phase-shifter you wanted to use for high speed modulation.  Instead of using a SPDT switch to select between rate caps, use a DPDT switch to simultaneously switch rate caps and also switch in an additional capacitor or other lowpass filter to trim much of the high end at the input of the circuit.

[octafish]

Hmmm that layout and the schematic on your website look very tempting, and the CD4066 is a lot cheaper and easier to find than the AD633. Should be simple enough to add an external imput that will bypass the 555 circuit.  Does the oscillator leak through at all? My passive ring is a noisy beast but fun so I am looking for a cleaner modulator and 90c at DSE (for the cd4066) is a lot more tempting than 5 or 6 $US online mail order for an AD633 or 1495.