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Re: sync-ing non-midi loopers/ cheap stereo loopers???



At 9:24 PM -0800 12/9/99, Jax1723@aol.com wrote:
>I was wondering:
>Say you had two non-midi loopers (headrush A and headrush B).   Would it 
>be
>possible to open them up, disconnect the footswitches in A; then hook up 
>the
>footswitches in B to both units (i.e., one set of footswitches for two
>units)?  The $64000 question is: Since both loops are starting/ending at 
>the
>same time, would they stay in sync or IS THERE SOMETHING INTERNAL THAT 
>WOULD
>CAUSE THE LOOPS TO FLUCTUATE?

no, they won't stay in sync. You have some crystal oscillator clocking the
system logic of your headrushes. It is pretty much impossible for two clock
oscillators to have exactly the same frequency. They will be within some
tolerance, so they will be close, but not exact. Clock oscillator
frequencies will also drift a bit with temperature, age, and the tolerance
of the load caps on the crystal. If you have no feedback mechanism to keep
the clocks synchronized with each other, they will drift from each other.

This means, you'll record two loops that will start off together. As they
loop, the slight differences will cause the loops to slowly drift apart,
causing phase problems, then flamming, then just odd rhythms. Sometimes
this can be obvious very quickly, sometimes slow. Just depends on the
natural random variance between the clocks on the two headrushes.

This is the whole point of why midi sync exists. Pretty much any device
that is expected to continue running and staying together with other
devices uses it. (jamman and echoplex are two loopers that do.) Before midi
there were similar control voltage methods that did the same thing on older
synth/sequencers. Midi sync has limited precision, so on the Echoplex we
took this idea a step farther with BrotherSync. This actually synchronizes
the sample clocks of two or more echoplexes together, so they stay
perfectly in sync. It uses a sort of pll-like feedback system that can
change the frequencies of the clocks in each unit by small amount,
correcting for any error difference between them. Once they find
equilibrium, they stay there. So two echoplexes can stay locked together
very well. I think you can do this in a more limited fashion with midi sync
on a jamman, although then one unit will have to be slave to the other.

If this is what you wanted to do, you got the wrong product. Headrush
doesn't have any sync features, it's just a simple pedal not intended for
such use.

kim

______________________________________________________________________
Kim Flint                   | Looper's Delight
kflint@annihilist.com       | http://www.annihilist.com/loop/loop.html
http://www.annihilist.com/  |