[sdiy] Build a Tape Flanger?

[James Husted]

on 8/30/01 8:28 AM, Glen at mclilith at ezwv.com wrote:

> At 02:15 AM 8/30/01 , Scott Gravenhorst wrote:
>> I've always wondered:  Once one reel down is momentarily slowed,
>> how did they 'resynch' the decks so that the difference is
>> eliminated again?  Drag a finger on the other one?  Sounds
>> difficult.  Pardon my naivete...
> 
> If I understand it correctly, they would first slow one deck, and then slow
> the other one. This process was repeated over and over, for as long as they
> needed the flanging effect. If they needed to perfectly synch the sound, or
> eliminate the flanging effect, it would always be simple to fade down the
> volume of one of the decks, leaving only one of them audible.
> 
> Yes, this does sound difficult, but I believe this was how it was done
> before purpose-built "flangers" were invented.
> 
> 
> Later,
> Glen
> 
Actually the decks were in record mode and monitoring off the tape. The
outputs were then mixed together. The slowed deck would snap back to time
immediately once the finger was removed. The final recording was done on
another deck. It was basically a reel-time operation (pun intended!) You
need three decks to pull it off. Signal parallel to two decks on record,
monitor off the tape (you need two decks to match the delay off the playback
heads), mix these together and record the result to the last deck. This way
you can selectively flange any track of a multi-track recording (as long as
you had at least two decks of the same type (the flanging decks). This was
usually done at final mixdown so the final deck could be a cheaper stereo
master deck. So nowadays, by two tape decks do the flanging with them, and
do the final mix back on your computer. Then time shift the flanged track
back so it's in sync with the other non-flanged tracks. You can easily
veri-speed many older decks. I have done this mod to some older Sony decks
(love stereo tape echo). Just look and see if the deck has a 50Hz/60Hz power
selection switch on it. If it doesn't, chances are the motors are DC. Open
it up an chances you'll find a PCB near the capstan motor that has two
trimpots on it (usually painted to fix their settings). Put a switch around
one of them to a remote pot of the same value and viola!, vari-pitch
recorder. I have a Sony deck that I can bring from 7.5 to dead stop. Works
great. For the flanger, the effect would only happen in a *very* small
range. The finger method works much better.
-James
-- 
James Husted
The ErsatZ Planet
james at ersatzplanet.com
www.ersatzplanet.com