Cave Troll

What it does

A ring modulator multiplies two signals together instead of mixing them, so what comes out is the sum and the difference of their frequencies rather than either of the things you fed it. That is the clangy, bell-like, atonal sound people build these for. Doing it passively means no chip and no supply, just transformers and a diode ring, and it also means the circuit loses level on the way through, so it wants a strong signal.

That is not really what I am getting out of it. On my bench it passively mixes the two inputs and maybe colors them a little, and that is about as far as it goes. I think the honest answer is that I do not have the right gear to drive it properly. A passive circuit wants a hot signal and a proper carrier, and I have been feeding it what I have.

So I am selling it as what it is and not as what the schematic says it should be. If you have the rig for it, it may well do the full clanging thing, and people who have that gear tell me it is a lot of fun. I cannot promise you that from here.

Swap the two inputs around and see what happens. That is the first thing I would do with it.

One of a kind. When it is gone it is gone.

Demo

Controls

Top jack

An input.

Middle jack

The other input.

Bottom jack

The output. This is the one that goes to your amp. The name is on the face but the jacks are not lettered, so it is worth writing down somewhere.

Nothing else

No knobs, no footswitch, no lamp and no power. There is nothing to set. What you get out of it depends entirely on what you put into it.