Unexpected noise in audio-driven x-fade mux

Antimon

I tried to do a kind of waveshaper using a mux, but a weird noise (sounds a bit like radio interference) appears on some keypresses. I can't connect the noise to any specific note, it seems rather to be connected to which voice is playing. Try the attached patch, press the same note repeatedly and you will sometimes hear the noise, sometimes not. Does anyone know what's going on?

/Stefan

sbt_mux_shaper.pch2

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Blue Hell · Posted: Sat Aug 25, 2007 8:24 am Post subject:

It looks like some sort of internal calculation overflow. When I reduce the voice count to 3 the bad is gone ... I tried adding attenuators before all eight mux inputs, I can then raise the voice count again (but not to eleven anymore due to increased complexity).

Antimon · Posted: Sat Aug 25, 2007 8:31 am Post subject:

OK, thanks Very Happy

I'll try that out!

/Stefan

Antimon · Posted: Sat Aug 25, 2007 2:33 pm Post subject:

This has got to be a bug. I made a simpler patch, with an LFO patched through a 4 to 1 switch. Try pressing the same key repeatedly. Every now and then you will get a tone with noise.

If you agree - maybe this thread could be moved to the bug forum?

/Stefan

sbt_switch_bug.pch2

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ian-s · Posted: Sat Aug 25, 2007 3:02 pm Post subject:

Can't duplicate here. Sounds fine after at least 100 key presses.

Might depend on lfo phase, which is random every time patch is loaded. I tried several loads and can't detect anything but the sine tone.

I do get mystery noises sometimes when the G2 has been running for several days.

Antimon · Posted: Sat Aug 25, 2007 3:08 pm Post subject:

Ooh - one of those not reliably reproducible thingies. I hate those. I liked my waveshaper Sad

Blue Hell - by attenuators a think you mean a 1-1 mixer, right? If I add those it works, but memory rises above 50% Sad

Oh well, I can always edit in lfos and whatever as I please, instead of using those switches.

/Stefan

Blue Hell · Posted: Sat Aug 25, 2007 3:19 pm Post subject:

Blue Hell · Posted: Sat Aug 25, 2007 3:21 pm Post subject:

Antimon · Posted: Sun Aug 26, 2007 2:40 pm Post subject:

Thanks.

Messed around some more. I thought that the villain maybe was the set of switches, so I changed from switches to 2-1 mixers instead (attached) - still the same problem.

It's a really weird noise. Not pure distortion, more like an interference of some kind.

Then I switched from 2-1 mixers to 4-1 (also attached), and moved the constant from chain to attenuated inputs, and then it's ok. More or less what I wanted from the start (the switches were a clumsy solution anyway), and within 8 voice territory.

It's like you say, something happens when sound is taken from a control signal that is mixed too high.

Also, I wonder why the x-fade mux outputs a blue cable when it is controlled by a red.

/Stefan

sbt_mux_shaper2.pch2

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sbt_mux_shaper2.pch2

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4-1 mixer with no chain