Aug Loop: The Zipper Noise syndrome

[pboy]

I noticed that when adjusting continuous parameters as Feedback, Input, Dry/Effect level Augustus Loop creates a nasty zipper-like noise.

I thought I should flag for this issue since I recently discovered the same problem with EchoBoy and had it confirmed from SoundToys that this actually is a bug (bad coding solution somewhere). SoundToys has implemented a smoothing crossfade but unfortunately this is being skipped when the system reaches a higher CPU load level, in my case at 55% of this 2.7 GHz 2 core i7 MBP.

Ok, back to Augustus Loop now. With Augustus Loop this zipper noise happens even at the lowest CPU load, so one might guess there is no crossfading at all to smooth out value sweeps?

Bottom line: Can we have that, please?

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Tip for user workaround:

One can partly work a round the Zipper NOise syndrome by not controling the plugin's own parameters but rather assign faders etc of a host application and then set up a similar signal routing in the host. Like for example: instead of controlling AL's Feedback parameter one might slap AL, set to "Feedback = 0", over a wet effect loop of the host's and simply send back return signal into that loop to achieve the function "increased Feedback".

[os]

The Input Level does already have a smoothing crossfade, so I'm surprised if you're noticing problems with that.

To be honest, I'm surprised you're noticing problems at all. I've been using AL myself for years and never noticed any zipper noise. But I could certainly smooth things out in a future upgrade.

What processing buffer size are you using, by the way?

[pboy]

The Input Level does already have a smoothing crossfade, so I'm surprised if you're noticing problems with that.

Well, I have not researched it deeply enough to tell exactly how much each one of the four simultaneously MIDI controlled parameters is adding to the noise. I might very well be that the Input Level parameter in particular is not guilty here.

To be honest, I'm surprised you're noticing problems at all. I've been using AL myself for years and never noticed any zipper noise. But I could certainly smooth things out in a future upgrade.

I'm surprised as well, being a long-time AL fan (+ Oomingmak + CFLS). But in the past I have not controlled as many AL parameters by the same external CC#, so this is the new factor in the calculation ("wink-wink?").

I was using one external MIDI CC# expression pedal to simultaneously control
1) Input Level
2) Dry
3) Effect
4) Feedback (global)

What processing buffer size are you using, by the way?

256, which is a drag really. I like 128 better but Bidule can't handle that as well as I've gotten used to from using Mainstage lately. But I prefer Bidule anyway because of the freedom in signal addressing it offers.

[os]

Ouch, 256 is pretty high, and is going to make these kinds of problems worse than they need be.

That said, there are definitely things I can do to improve the situation, but it's not a quick job.

[pboy]

To a certain extend you can work around this issue by setting up the signal routing in the host mixer and controlling them instead of directly controlling the plugin's parameters.