DIY tape echo -- possible?

Rene Schmitz uzs159 at uni-bonn.de
Mon Jan 19 13:47:25 CET 1998


At 04:43 18.01.1998 +0000, you wrote:
>I've been working on setting my reel to reel tape
>recorder to work as an echo. This ofcourse involves
>getting the unit to play and record at the time,
>the echo delay based on either the physical space between
>the two heads and the playback speed. OK.
>
>My problem... My reel to reel only has two heads,
>erase & play/record. I've sucessfully hacked on an old
>walkman playback head, but it only doubles the function
>of the other head (either both playback or both record.)
>I've tried to alter the electronics so that it would do
>both simultaneously, but with no luck.

Its interesting that you say that, since I made similar experiments,
walkman playbackheads and all that. I made it in the following manner,
useing TWO (almost identical) reel2reels one for playback one for record.
The tape runs from the record mode machine to the playback machine.
>From what you say, (and what I know of tapemachine circuitry) the record,
and the playback
is not seperate circuits, it is cleverly switched circuits in most case, i.e. 
the play head amplifier is used as input amplifier for record.

>What I want to know is, how hard would it be to build a
>circuit that'd translate audio to/from the three tape heads,
>so that I can detach all three heads from the current circuit
>and run the new output straight to a jack. I'm really looking
>for the simplest circuit that'll do this.

I don't think that this will be possible.
But while you already hacked into a walkman, try using it as a seperate
playback unit, 
leave the reel2reel as it is and access the delayed signal with the
playbackhead connected to 
the walkman circuitry. (Or go for a seperate little (mic) amplifier, I have
circuits for 
playback amps with proper equalization, which use specialized ICs, if you
want them I could email them)
Feed the signal of the output amp back into the recording machine via a
small mixer.
And of course into your output jack.

In an asciimatic it would look like this 

(E)   (P/R)    (P)
--------------------------- <-tape

E being the erase, P/R the play/rec head of the r2r and P the seperate
playback head.

Hope this helps !

Rene

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