[sdiy] Delays: how?

[Seb Francis]

harrybissell wrote:

> > >Old reel to reel tape deck (I'm sure you can pick one up pretty easily),
> > re-fitted with a variable speed motor, and a continuous loop of tape.  Vary
> > the tape speed for the delay time, vary the erase head current for the
> > feedback control.
>
> no no NO !!!  You run the erase head FULL at all times... or not at all
> (for sound on sound)...
>
> You get the decaying repeat by feeding back a portion of the signal from
> the play head preamp to the record preamp.
>

<thinking mode on>
makes sense!  some kind of processing (e.g. EQ) in the feedback path would also be interesting

I've had it in the back of my mind to build a tape delay for a while, but not really started to seriously think about it yet.  I've got an Eventide which does all kinds of delay+pitch shifter stuff, but I just plain like the sound of analog stuff .. I've always wanted a Roland Space Echo.  The Schober Reverbatape looks pretty cool too!


> Three head reel to reel machines can usually do echo with no modification
> ... as is. Feedback from the play head to the record head and you're there.
>

yeah, seems like the more playback heads the better for multi tap delays.  perhaps 12 would be a nice musical number to have :)

BTW, how easy is it to vary the speed of the tape transport?

Seb [feeling inspired to go searching in some junk shops for old tape decks]