Stereo tap delay

[Afro88]

I've been playing around with some stereo tap style filter delays lately, but I can't figure out one thing - panning. Is there a way (like the Waves Supertap plug) to have each tap pan slightly in one direction each tap? Like have something in the feedback path that sends the signal more and more to the left or right every tap? And here's the tricky part - when the taps hit hard left or hard right, come back again?

In the supertap plugin, it's called "rotation", it's on the feedback parameter, as well as each tap (although with each tap it simply acts as a static panning control). Rotation on the feedback doesn't simply pan all the feedback audio. If you send say a short burst of noise to it, the noise will delay and feeback, panning slowly left (or right depending on a -/+ rotation value). Now, when you send another burst of noise, it starts in the centre and starts panning left (or right) while the old noise continues it's panning circle.

I'm stumped . I tried sending a little bit of one tap's signal to the other, but that's just cross feedback and doesn't give me the desired effect. Any ideas?

Here's the delay patch I'm working on:

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st 2tap dub dlay.pch2
Description:	Rotation??	Download (listen)
Filename:	st 2tap dub dlay.pch2
Filesize:	2.11 KB
Downloaded:	1887 Time(s)

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[jksuperstar]

I think you'd have to brute force it...to keep the two audio "circles" seperate. But this method means your effect has...polyphony

By doubling what you had, subsequent audio "streams" could be handled seperately. Here, I added (to your 2tap) a panning mechanism. Right now, it will pan both taps together. If you change the "level converter" down near the panning lfo, it will seperate the 2taps into opposite speakers.

At the top, I used a flop to alternatively select which set of delays you are using. The keyboard gate controls it, so every time you lift your fingers of the keys, it gets ready to switch (watch the Flop's LED in the editor). You could also use a threshold compare on an audio signal to control this switch, so every time the audio dropped below thres, the next time it got loud it would be sent to the other set of delays.

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st-twin-2tap-dlay.pch2
Description:	Twin 2tap delay, with alternating input and panning output	Download (listen)
Filename:	st-twin-2tap-dlay.pch2
Filesize:	4.03 KB
Downloaded:	2151 Time(s)

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[Afro88]

Thanks jk

That works quite well with the lfo's turned down to sub ranges, exactly the sort of effect I was looking for. However, now there's 4 sets of filters, overdrives etc. to control live.. could make it much more interesting though.

Your patch gives me some good ideas, I'm gonna have a play around and see if I come up with something...

[Afro88]

Ok, I figured it would be something in the feedback path that does the panning, so I tried patching the pans you used into the feedback loop with the thought that it might pan the sound further and further left with each tap. This didn't work but replacing the pans with crossfade modules with only 1 input used for each (left and right respectively) and it worked!

The patch here is a simplified stereo 1 tap - with rotation! However it only pans one way (either left or right) and doesn't come back the other way. I tried attaching an lfo to the pan control to modulate it, making the panning go in both directions but it's just not right. The thing I like about the waves 2tap is that you can play one sound, then a second later play another and they chase each other around the stereo field perfectly.

I had a closer listen to the waves 2tap delay and it sounds like there's some kind of phase thing going on once the sound reaches hard right to send it back to the left. I've posted an mp3 of this as well as the new patch . Thanks for your help jk, have you (or anyone else) got any ideas for this conundrum?

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simple rotdel.pch2
Description:	Rotation delay	Download (listen)
Filename:	simple rotdel.pch2
Filesize:	1.42 KB
Downloaded:	1851 Time(s)

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[ian-s]

That was a good challenge. You got the ‘change phase when reversing’ right. Took me a long while but I think this patch does what you want. Just two stock delays with feedback and cross feedback. One of the cross feedbacks is inverted and its gain determines the rotation speed.

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rotateDelay.pch2
Description:	rotating stereo delay effect	Download (listen)
Filename:	rotateDelay.pch2
Filesize:	1.14 KB
Downloaded:	1984 Time(s)

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[Afro88]

I am not worthy!! You're a genius! I have no doubt that that's exactly how it's done in the plugin. So simple but such a cool effect! It actually sounds like it swirls around your head - with 13.2 dsp cycles!

Well, I played around with it for a bit and unfortunately there seemed to be a problem At first it was that the rotation wasn't even, and I soon realised that by setting the inverted cross feedback and the normal feeback to the same level on each mixer, the panning becomes exactly even. alright!

However, eventually very high frequencies creep in and start a feedback loop which should be impossible because the inverted signal should cancel out the non inverted. At this point I thought some kind of dc offset could be causing it to clip, so after moving a few things around to figure out a solution with high pass filters, it started working flawlessly, even without the filters. Weird.

Then it hits me - calculation order! Thank god Clavia introduced the new calculation order feature! By putting each delay right next to each other, they are calculated at the same time (or at least as close to it as needed). This means that both waves are exactly in sync and there's no room for a feedback loop to start because they truly do cancel each other out!

So yeah, here's the same patch but with the modules in the correct order. Sorry if I'm getting a little excited, it's just that I've never considered calculation order in patches before and it's exciting to see how useful it can be! Real low level stuff .

Change the first knob of each mixer together to change rotation speed. Keep the levels the same for symmetrical rotation, and different for assymetric. Invert the inversion (hehe) of the first input on each mixer to change the direction of the rotation.

Oh, and thanks very much to g2ian for the patch!

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rotateDelay-3.pch2
Description:	Delay with rotation using phase inverted cross feedback	Download (listen)
Filename:	rotateDelay-3.pch2
Filesize:	1.14 KB
Downloaded:	1813 Time(s)

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[ian-s]

I like this a lot as well. I have not seen anything like it before.
Thanks for bringing it up, and debugging my first attempt. I’m sure someone could come up with a single rotation speed control mod, but I like some of the asymmetric effects.

[Afro88]

Done - http://electro-music.com/forum/post-25033.html#25033