[sdiy] Automatic Double Tracking/ slapback device

[harry]

I did this in college...

You need three heads , erase/record/play.  Most cassette only have
two, unless you can find a rare one with a combo erase/record head.
I removed the erase head (but left it electriaclly connected, sometimes
they are part of the bias oscillator circuit)... moved the record head to
where the erase 'was'... and added a new playback head. At 1 7/8 ips
speed, and about 3/4" distance between heads, thats about a 1/2 second natural
delay.  Too much for doubling... thats echo for sure!

Tape speed can be varied with a pot on the motor in most decks... they
usually have a speed adjust resistor or pot in the servo speed mechanism.
Trace and hack... schematics help a lot !

Tape equilization varies with speed, so you will fvck up the eq. Thats why a lot

of echo units physically move the head (echoplex) or use multiple heads
(roland).

Its fun to play with...  BTW. Forget the endless loop tape. Just pop in a fresh
bulk erased C-90 and jam for 45 minutes at a time. Then later, pop that tape
into another machine and listen to the strange strange music of echo-only !

Erasing the tape / looping is a looser.

H^) harry


Jon Darby wrote:

> Howdy, everyone,
>     I was wondering how difficult it would be to modify a tape recorder to
> record an input signal directly before playing it back along with the
> original signal but slightly delayed to produce that Beatles double tracking
> effect? I can imagine it is possible to make an infinitely looping cassette
> tape by cutting a length of tapejust long enough to loop around the rollers
> and the tape-reading area and maybe held tight on the rollers by a small
> spring tensioned wheel in the middle. Am I dreaming or is this a possiblity?
> I would love to have the ability to speed up and slow down the delay while
> playing for whooping-effects on the synth, too. Can the motor speed of a
> cassette deck be harnessed and adjusted via potentiometer? I haven't torn
> apart a tape deck since I was a kid, so I think I'll pay a vist to the
> thrift store after work for a test specimen. Any known articles on this
> would be a great help! THank you!
>
> Your pal,
> Jon