Popping with Key Tracker -> LFO -> Mixer Volume


Using a Key Tracker to trigger a one-shot LFO results in a popping sound for a few milliseconds when triggered.

6853 Key Tracker - LFO.png

Steps to Reproduce:

  • Create an LFO with a one-shot envelope that controls the Mixer Volume.
  • Create a Key Tracker that resets the LFO to zero.

Here’s a repro project, just press play:

6854 Bug-Key Tracker-LFO-Popping.xrns

Expected Result:

The LFO->Mixer Volume should be set before the note can be heard.

Actual Result:

The Mixer Volume stays at the previous LFO value for a few milliseconds resulting in a popping sound.

Additional Information:

  • I’ve tried working around this using a Formula in place of the LFO, but had the same popping.
  • I’m trying to use the LFO to cycle through samples of different pulsewidths, so I’m also using a Hydra to control multiple effect channel volumes.

This is likely caused by the “smoothing” that Renoise’s volume modulation has. I’ve run into this problem a few times, and I’ve found the gate device can be a decent substitute.

It’s not perfect, there’s still a tiny pop, but it’s a good temporary solution.

Skolskoly, you diabolical… I had a feeling that it might be due to smoothing somewhere in the chain. Your suggestion worked great, but I wasn’t satisfied using a a filter that does the extra work of analyzing audio, so I tried using a Gainer always set to -INFdb , and simply toggling it On/Off… This appears to be instant, and does exactly what I needed.

Thanks for pointing me in the right direction. :slight_smile:



This is a very easy fix, just make the last step fall back down to -inf.

Thanks for the suggestion, but that doesn’t work in a real song since the notes may not last the full length of the LFO curve.

For my purposes, using the curve to control the ON/OFF state of a pre-muted Gain device works flawlessly. :slight_smile:

Maybe keytracker device should have “lookahead”, too?

An option to disable volume smoothing on the instrument (or song) would also help in my case.

I’m not shure in which way you want to use this, but an immediate change to the volume bar is never any good.

Is there perhaps a better way to achieve the result you need perhaps?

Will this do it?

An other way to smooth out the abrupt changes is to use a formula device with the inertia preset. You can use it on every slider, but it will only delay the transition from one position to the other, so in your example it wouldn’t have worked if you want the slow attack.

I didn’t want to bog down the bug report with the particulars of what I’m trying to accomplish, so I posted the simplest demonstration possible to recreate my problem, but I suppose I need to clarify.

My Use Case:

I’m creating an instrument that simulates the NES sound chip. One of the features is to abruptly (in a single sample) change the Duty Cycle in quick succession to create a “plucky” sound you might remember from old NES games. So in my case, any smoothing ruins the effect. The way I’ve accomplished this is with the following structure:

Each Duty Cycle sample gets its own Effect Chain with a Formula Device and a completely muted Gain Device. The Formula Device takes a “Duty Cycle” input and determines if it’s the correct Duty Cycle sample for the job, then toggles it’s pre-muted Gain Device accordingly.

I then have a Dummy Effect Channel which uses a Key Tracker -> LFO -> Hydra to set all of the Duty Cycle Formula Devices.

Originally, my Formula Devices were setting their own Effect Channel Volume, but this caused the popping problem due to the inherent volume smoothing. Using pre-muted Gain devices solves that and I’m now perfectly happy with the result. :slight_smile:

A benefit of this approach is that it leaves me with a single Modulation channel, which I can conveniently use for various envelopes that are unaffected by Duty Cycle. :wink:

Ah, that was not at all what i had in mind. :stuck_out_tongue:

Glad you’ve solved it and i hope you’ll post it in the Downloads later. :slight_smile:

I’m not so shure this technically can be called a bug though, it has always been like this as far as i can remember, big sudden changes to just about any DSP introduces clicks.

Haha, just as soon as I perfect it! :wink: