Looking for exciter schematics

[Sean Costello]

The Dark force of dance wrote:

> As best as I can figure it, the audio in the selected frequency band 2
> quadrant multiplies with the original signal causing harmonic spikes. The
> irony of this is that this should, in theory, provide similar enhancement
> properties you can get with a good valve pre-amp. (Note here Eric. I said
> "Similar" not the same.)

Are you sure it is using amplitude modulation?  With the 13600 circuit
you describe, maybe it is controlling a lowpass or allpass filter with
the input frequency.  FMing an allpass filter would seem to be a great
way to produce lots of harmonics.

> I noted recently also that Vesta made an almost identical clone to the
> Aphex type C box. The principal is probably well established now. I just
> wish I could find an actual circus to the Aphex type from which I could
> work. If anyone has such a circuit kicking round in their archive, I'll
> swap you three chickens and a goat for it.

If the circuit was patented after 1974 or so, you should be able to find
it at http://www.patents.ibm.com.  I did a search for "Aphex" last
night, but all of the patents seemed too recent.  Did Aphex have a
different corporate name in the past?

Sean Costello