Strange clicks/spikes/glitches

Today I noticed (for the first time) strange clicks when playing the shruthi (yellow magic). This is clearly visible in the recorded waveform (see attached pic). Sample-file (aif)

I wonder whether this is caused by the shruthi or coming from elsewhere, in particular as I haven’t noticed this before. I got an Akai MAX49 masterkeyboard 2 days ago and hooked the shruthi to the Mido out (was using an Unitor 8 before), but can’t really think that this could be related to the clicks…

Any ideas as to whether this is a shruthi hardware/assembly issue or caused externally are greatly appreciated!

Edit: after the initial panic subsided and some more fiddling around, it appears these interferences are caused elsewhere - computer and/or audio-interface related… at least I experienced the same when switching to the slim phatty, later on it seemed to have disappeared again(?!) So I guess I have to keep experimenting…

These are exactly one sample deep, and they are 1536 samples (1024 + 512) apart. When it’s only one sample deep and involves powers of two or sums of 2 power of twos (which are typical system buffer sizes for historical reasons), there’s a good chance it’s a digital problem. A glitch on the Shruthi-1 side would be “smeared” over adjacent samples by the analog signal processing chain, the soundcard’s amp, etc.

Driver bug; system buffer underflow, etc…

I got some like that on my FA-66 when I’m recording in Audacity under heavy CPU load.

You mention a soundcard / pc. Have you tried changing the latency? Especially the input, as it being recorded I don’t think it would be the output.

Thanks a lot!

@pichenettes: very convincing analysis, merci! Will try to figure out what’s happening on the hackintosh side, in particular as this seems to come and go randomly…

@Dunk: yes, I tried different buffer settings, but it seems unrelated - the clicks continued even after I increased the buffer way beyond the theshold at which the normal glitches come in.

@nordlead: You may find this elderly but still valid feature I wrote way back in 2003 entitled Eliminating PC Audio Glitches useful, since it includes various screenshots showing glitches.

A useful and more recent tool is the freeware DPC Latency Checker utility, which I discussed in this 2008 PC Notes column, since it may help you track down another driver or settings that causes these interruptions.

Hope they help!