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 Forum index » Clavia Nord Modular » G2 Patches - Experimental
Loop delay
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Burp



Joined: Dec 18, 2006
Posts: 31
Location: Utrecht - NL
G2 patch files: 7

PostPosted: Mon Apr 09, 2007 12:48 pm    Post subject:  Loop delay
Subject description: trying to make a loop delay (not clocked)
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Hello there,

I'm learning a lot reading all kinds of threads here! Thank you all!

But i'm stucked with patching...

I'm trying (inspired by the elastic audio / loopers and so from tim which ar great!!) to make a loop delay.

A loop delay without fixed length and without syncing to midi clock.

A button will start the recording,
another button will end the recording and start playback (and sets the length of the loop).

I'm trying this by keeping a LFO tracking the timing of the delay and with some S&H's keeping the start and end points. The idea is to constantly add the length of the loop to the pointer (and subtracting maximum value if reached it) and so restarting the loop over and over.

But i come some problems:
- first: i can't set the LFO's to perfectly match the delay's length, so the whole thing drifts.
- it seems the length is ok, but it starts at wrong place.

Any ideas? Or maybe a totaly different approach?

Thanks
-Jan


loop delay.pch2
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Tim Kleinert



Joined: Mar 12, 2004
Posts: 1041
Location: Zürich, Switzerland
Audio files: 6
G2 patch files: 213

PostPosted: Mon Apr 09, 2007 2:50 pm    Post subject: Reply with quote  Mark this post and the followings unread

Your approach is basically correct.

However, it isn't possible to perfectly phase-lock an LFO to the delay time by itself. It always drifts after a few minutes or so. So the only way to do it is to time-stamp the beginning of the sampling within the delay loop. I do this by injecting a max headroom (+256 Clavia units) but very short (a few samples) click into the loop. (The audio headroom is reduced to make sure that it doesn't approach the max) This click is detected afterwards and used to resync the readout LFO. Hence it is necessary to empty the whole delay line loop everytime you capture audio, because otherwise there might by chance be two clicks in the loop (the new one and an old one), making the patch malfunction. Yes, It's a fiddly kludge, but the only one that works reliably.

Here's a patch that does what you want. It captures audio as long as the "capture" button is pressed (but not more than 2,7 secs, obviously), and loops it as soon as the button is released. I colored and named the function groups to help elucidate what goes on. Hope it helps.

best,
tim


SimpleLooper TK.pch2
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Burp



Joined: Dec 18, 2006
Posts: 31
Location: Utrecht - NL
G2 patch files: 7

PostPosted: Tue Apr 10, 2007 4:12 am    Post subject: Reply with quote  Mark this post and the followings unread

Hi Tim,

Great! Thanks for your help. It works perfect.
It is indeed a bit of a workaround, but timing is good.

Just some questions, is the calibrating (readout LFO) to avoid hearing the timestamp?

The only thing now is that i like to start the loop immediately after releasing the capture button. Now it waits till, i think, the timestamp comes by again (when from the start the whole 2.7s are passed).

I'll try for that later.

Thanks,
-Jan

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Fozzie



Joined: Jun 04, 2004
Posts: 875
Location: Near Wageningen, the Netherlands
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G2 patch files: 49

PostPosted: Tue Apr 10, 2007 11:34 am    Post subject: Reply with quote  Mark this post and the followings unread

Hey Tim, thanks for the looper for dummies patch, it helps me to finally understand a bit of your fantastic looper patches (I was puzzling again over them in the last few days).
Question though: is it really necessary to have the separate readout and loop lfo's? It seems to me the readout lfo is used with the phase setting to get the sync signal at the restart of the loop, but this could be done just with one lfo and a s/h, right? Can't check right now myself.

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Tim Kleinert



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PostPosted: Tue Apr 10, 2007 3:54 pm    Post subject: Reply with quote  Mark this post and the followings unread

The Loop LFO is necessary to establish the exact time intervals of the loop.
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Tim Kleinert



Joined: Mar 12, 2004
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G2 patch files: 213

PostPosted: Tue Apr 10, 2007 3:57 pm    Post subject: Reply with quote  Mark this post and the followings unread

Burp wrote:

The only thing now is that i like to start the loop immediately after releasing the capture button. Now it waits till, i think, the timestamp comes by again (when from the start the whole 2.7s are passed).


You can unplug the yellow cable running into the AM input of the Envelope (below the delay module). That should do the job.

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Burp



Joined: Dec 18, 2006
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G2 patch files: 7

PostPosted: Wed Apr 11, 2007 5:29 am    Post subject: Reply with quote  Mark this post and the followings unread

tim wrote:
Burp wrote:

The only thing now is that i like to start the loop immediately after releasing the capture button. Now it waits till, i think, the timestamp comes by again (when from the start the whole 2.7s are passed).


You can unplug the yellow cable running into the AM input of the Envelope (below the delay module). That should do the job.



Yes it works. Thanks!

Now i have to keep my timing good Wink

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