Sometimes, rarely, C3 gives me just nasty, aliased buzzing after a while

I’m using C3 on a MS Surface 4 with plenty of spare RAM and SSD space, optimized as Brad’s suggestions, a Novation USB hub audio interface(combines a USB hub with audio interface), and the Novation’s custom ASIO drivers.

Every so often when changing songs in a setlist, my system goes from working perfectly to sounding like crap - every keypress on the midi controller creates a horrible “hissing” static sound instead of the expected instrument sound. It is not a constant hiss, but only occurs when a midi keypress event fires. It’s possible to hear what the sound should sound like through the hiss, if that makes sense, maybe 90% static + 10% tonal sound (at that SNR I can’t tell if the tone of the sound is at the correct pitch). Changing songs again doesn’t fix the problem, but quitting C3 and restarting it does. It’s very infrequent, perhaps once every four months of rehearsals, but I live in fear of it happening at a gig, particularly if a song begins with a keyboard intro.

I’m not saying it is C3’s fault - it could be the audio driver’s fault. It can happen when loading either Kontakt or Pianoteq, so I don’t think it is VSTi issue. Nothing else unusual happens, and it can happen towards the beginning or towards the end of a set, but always immediately after changing a song. The songs being loaded are not complex - just one VSTi for the top midi controller and one for the bottom controller. I think when it happens both controllers are affected, but I’m not 100% positive - will check for certain next time.

I realize this is very slim diagnostic info to go on but…any ideas?

I had that problem sometime ago, turned out to be my focusrite driver was dropping out. Updated new driver, no problem. Also check your USB cable to interface.

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Every time my rig starts screwing up a lot it’s because my laptop got unplugged. Minor glitches happen when other stuff is happening in the background. I run with a Surface Pro 4 and I have disabled all cameras and both internal sound drivers in BIOS, and when I perform I use airplane mode to disable Wi-Fi and Bluetooth as well. The glitches have disappeared.

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Yes, I had a lot of glitches before I applied Brad’s general de-glitching suggestions. The drivers for the built-in soundcard in particular seemed to cause spikes with the Surface.

But I forgot to update the interface’s drivers. I’ve done it now, and no issues since. We’ll see if that fixes it longer-term. Interesting idea about loose midi cables. I don’t think that’s it, but will be aware of it.

Random thing here for folks who use Pianoteq EP (in case anyone searches these forums): I used to have a real problem with Pianoteq CPU overloads causing crackles with specifically its electric pianos, but could not track down why. Finally figured it out: My sustain pedal was not an on/off type, but generates continuous midi messages when going down or up. Each Pianoteq electric piano voice, corresponding to a midi on event, requires significantly more CPU when generated with the sustain pedal at a different location. So if I pedaled while pressing a chord, each note on event with a different sustain pedal level required a lot more CPU power to sustain. It doesn’t make a lot of sense to me, but that was it. I defined a “velocity curve” for the damper pedal so it was either on or off, eliminating half-pedal events. I have had no problems with half-pedaling its acoustic pianos, but eliminating half pedaling on its EPs solved the CPU spiking completely.