3280 and AD533 availability, EN frequency shifter

[Debby and Gene Stopp]

I built the EN frequency shifter about ten years ago. I built it exactly as
published, with no deviations either in parts used or in circuitry (a rare
thing for me). It is truly a fantastic module. It's easy to get very drastic
"blow your mind" effects out of it. The multipliers I used were either 533's
or 633's (or something like that, I don't actually remember) which I bought
from Hamilton via phone order and personal visit to their will-call desk.
They were something like $30 apiece, and the circuit uses four of them. I'm
not sure what's available these days. Hopefully somebody can answer that one
for you.

But I can talk about the circuit - it shifts all of the harmonics in an
input signal by the same number of hertz, rather than the same interval like
a pitch shifter. This means that an input having harmonics at 440 Hz, 880
Hz, 1760 Hz, etc., with a shift oscillator frequency of 5 Hz, will produce
an output of 445 Hz, 885 Hz, 1765 Hz, etc. The resulting harmonics are no
longer integer ratio relations to each other, producing what can best be
described as a strange inharmonic sound. Of course small shift amounts have
a subtle effect and large shift amounts are more drastic. However, unlike a
ring modulator, the original sound is still fairly recognizeable yet
strangely warped. You can actually get the same effect with an FM radio with
analog tuning - I'm not sure what the mechanism at work in this case is (I
never got familiar with FM radio circuits), but it's definitely the same
effect. Radio nerds refer to it as single sideband modulation - maybe
somebody else can explain how a radio does it. The radio I use is an old
Fisher tube receiver, so I don't know if just any radio can do it. You have
to tune slightly off-station with no squelch to get the effect.

The effect is used sometimes in sci-fi movies, usually on speech to get
alien voices. It's not very common. I think I heard it once very briefly in
one of the Star Wars movies. Also an old episode of the Outer Limits from
the early 60's (the pilot episode, called "The Galaxy Being") features a
frequency-shifted alien voice quite prominently through the whole show. The
EN circuit does this perfectly.

Hey this makes me want to go fire it up again....

- Gene


----- Original Message -----
From: "Paul R. Higgins" <higg0008 at tc.umn.edu>
To: <synth-diy at node12b53.a2000.nl>
Sent: Monday, May 01, 2000 4:55 PM
Subject: 3280 and AD533 availability, EN frequency shifter


> Does anyone know what the current status is on the availibility of the
3280 OTA?
> My Digi-Key catalog claims that they still carry it, but people on the
list have
> said otherwise.
>
> I was also looking at the frequency shifter in the EN Builder's Guide and
I had
> a couple of questions that I knew the DIYers would have answers to.
>
> 1)  The dumb question first: what the heck does a frequency shifter do,
and what
> is it useful for?  I know it's not the same as a pitch transposer, but
that's
> all I know.
>
> 2)  Can you still get the AD533 analog multiplier used in the EN frequency
> shifter?  If not, is there a substitution available?
>
> Thanks,
> -PRH
>
> _____________________________________________
> Paul Higgins
> email: higg0008 at tc.umn.edu
> University College, University of Minnesota
> _____________________________________________
>
>