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Reverse delay?

is it possible to continuously reverse play a buffer while recording to it simultaneously, like a reverse delay effect? sorry if this is a dumb question!

thanks
-bl

Hrmm - it couldn’t be instantaneous without having the ER301 linked to a flux capacitor.

I’m not near my modular, so I’m unsure of the audible result - but you could have a looper recording to a buffer shared with a sample player, and have the speed set to -1 on the sample player.

Or, same idea with the grain using a saw wave with negative gain so the position head is running from end to start.

The trigger of the grain could essentially be the “taps”.

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hah yeah, i didnt say instantaneous, just continuous. the length of the buffer…
thanks for the suggestion i will try it out

tried it out and works pretty good (Looper and sample player method). only thing is i get some clicks sometimes, not sure if there’s anything that can be done to minimize that, but happy i was able to get this working.
check this vid, im using a 5 sec buffer here. you can hear some occasional clicks im talking about

This is a hip idea. Funny I was watching @DivKid’s video on the 4MS DLD a bit earlier and it kind of got me thinking about reverse delays. And then later I see you have the ER-301 doing something like that. Nice!

I didn’t really notice the clicks so much. Maybe I was too engrossed in the hypnotic pattern you made, @bjlogic. :slight_smile:

Did you have any crossfade dialed in on the sample player? If not maybe that would help? Might be clicking when it transitions back to the start (in your case end) of the buffer? Just a thought.

I bet it is clicking when the play head crosses paths with the record head. They are going in the opposite directions after all. A looping record buffer does not create clicks at the start/end of the buffer. There is nothing special about the start or end of a circular buffer.

Makes sense. Thinking about the buffer as circular is a good metaphor for helping understand. I’ve always mentally envisioned it as linear!

In Sandman Pro, we implemented the reverse delay by using a windowed multi-tap buffer. The algorithm is likely very similar to the Pitch Delay unit in the 301.

For solid, click-free reverse operation, we’ll likely have to wait for the SDK.

One alternative that I can’t test at the moment would be to use the Manual Grains unit with a shared buffer. Attach an oscillator to the manual trigger to trigger the grains at a constant rate. Have the grains set to play in reverse. Use a sawtooth to traverse the buffer’s start point.

It’d be a fragile patch, but if it works the way I’m thinking then it should be capable of some pretty cool effects.

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Try this one out as a starting point:
weirdGrain.lua (16.2 KB)

I’d give it a better name, but it didn’t end up being a very traditional reverse delay. For fun, change the playback speed of the grain.
A Gate on G1 will resync the looper and the buffer phasor.

EDIT: First attempt was terrible. I uploaded a new one:
weirdGrain.lua (16.2 KB)

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Thanks for sharing! I was having some fun tweaking around with this. Here’s something to try from your starting point #2.

In manual grains, set
Speed: +1.0

In the saw osc controlling the grains “Start” param, set it’s frequency to min (0.027).
Add a modulator to f0 of this saw osc.
Insert an offset in it’s modulator chain, setting 0.1
Set the gain of the modulation chain for f0 in the saw to -12
This turns the ramp up into a ramp down.

The start param of manual grains now moves top to bottom (roughly 1s per cycle)

I think it sounds more like a traditional reverse delay?

For fun, go into the sample player and bring the dub down a bit (say 0.8) - equivalent to turning up the feedback parameter on a delay unit.

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I really like recording to the buffer using the looper and then playing the buffer back in reverse with the sample player, but I still haven’t figured out a way to get rid of the click. Any other option ideas how to get the same thing but with out a click? I know it may not be possible because of the nature of what’s happening but I still believe there must be a way. Just a short ms fade in fade out somehow maybe. But when I try applying it in the unit it doesn’t help.

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I’d like to know too.
Is it impossible to avoid it in principle?

maybe, although in the past i know ive used guitar pedals that have had reverse delays with no apparent click. it was a long time ago though i dont remember exactly which ones.

I have been thinking about clicks recently, due to experiencing them when retriggering samples. They are caused by a sharp change in a signal. A classic way to smooth out fast signals is a slew limiter. Now the problem is that your audio probably has fast changes (like a square wave). It seems like if the software could predict when a click would happen, like when the record head and play head were overlapping, it could very briefly engage a slew limiter. I don’t know how well this would actually work in practice, and I don’t know how you would implement it in this situation, but I can think of how to do it with sample retriggering. I might give it a shot but the clicks usually don’t bother me. Sometimes they are nice into effects.

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