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Re: EDP Feedback pedals...

At 12:39 PM -0700 5/16/98, Andre LaFosse wrote:

>Feedback is linked to cycles; i.e. if you have a 20-second loop which
>consists of one cycle, you won't hear feedback changes until that
>20-second loop has come around to the start point again.  However, if
>you have a 20-second loop built off of ten distinct 2-second loops,
>you'll hear an audible change in feedback every two seconds.

Actually, this isn't right. Feedback works over the whole loop, not the
cycles. If you have a 20 second loop that consists of a single 20 second
cycle, or a 20 second loop that consists of 10 2-second cycles, the effect
of feedback is the same. It wouldn't really be feedback if it did
otherwise. The feedback level is applied after the loop audio output, and
before the loop audio is mixed back into delay line, so a given bit of
audio still has to wait 20 seconds before it is heard again with the
feedback setting applied. The feedback structure looks a little bit like
this crude ascii drawing:

                  ______________|feedback |__________
                  |             | level   |          |
                  |             |---------|          |
                  |                                  |
 input => ------>(x)--->|=========================|------> output
                               delay line

the idea of cycles and loops (were a cycle is a subset of the loop) is
another sort of abstraction, and I'm not even very sure how best to put it
into the picture above. This is dumb, but maybe it works:

Think of the path above as a train track that goes around in a circle. Your
loop would then be the train following the track, with the front end of the
train just reaching the back. Each cycle would be a car in the train. Doing
a multiply or insert adds cars to the train and makes the track longer to
let it fit. Now, if a given car (cycle) is at the feedback level station
when you adjust the feedback, it still has to go all the way around the
whole track to get to the output.

>Building loops this way is interesting; not only can you hear feedback
>results much more quickly, but you can also set up a hidden rhythmic
>foundation for a seemingly rubato loop.  In other words, if you've got a
>loop that's built off of several different cycles from the start, then
>you can insert, multiply, and otherwise cut-and-paste the thing to
>produce highly rhythmically precise effects by working within the
>underlying seperate cycles.  It's like painting over a brick wall, and
>then adding, subtracting, or re-arranging different bricks once the
>basic picture has already been laid down.

You're absolutely right about this part. Insert and multiply offer tons of
interesting possibilities for composing loops on the fly.


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