On Tue, 01 Nov 2016 00:24:16 -0400 termtech <termtech@xxxxxxxxxx> wrote: > Yeah nice one but I doubt heat related - more like voltage drop spike > related, more activity on the power rails causing more spikes causing > the audio card to glitch. > > In the original thread we talked about weak capacitors on the sound card. > > I was seriously contemplating that possibility once again today, > until I managed to capture the sound and analyze it : > > https://dl.dropboxusercontent.com/u/53315356/Test_tone_passthru_noise.ogg > > It is a recording of a hardware audio sine generator (my keyboard), > input to the Delta1010, recorded as it is being passed through to an > audio output via Jack. What you hear is what I hear out of that output. > > Hey all you digital audio experts! > Listen to the recording, be patient and watch how the distortion slowly > drifts in then out. Open it in Audacity or something, and notice the spikes. > > Seems to me, that you can tell by the distortion's overtones which slowly > rise in spectrum then disappear, that this /resembles/ a textbook case of > some read pointer 'meeting up with' and passing some write pointer and > when they meet there is distortion. > In other words they are at slightly different /rates/. > > Do you hear what I mean about being easily recognizable as a sync problem? > > But how? And why core related? > I mean... I'll have to check chip docs but the card may have separate > read and write sample rates... > But no, look closely at the spikes in the wave in Audacity. It appears some > buffer is 'starting' too early or too late - like the buffer is suddenly > being switched in the middle of a wave and it is that switching time > that is varying. > > So maybe not a /soundcard/ clock rate problem but something is not filling > the buffers at the right time? Again - core synchronization? > > Also, aside from the drifting noise, notice the slight glitches in the sound > that are pervasive throughout. > /That/ is what I hear even with simple playback of test tones on websites! > You can hear the clock rates jumping around slightly. Yes, I know this is > /usually/ caused by Speed Step, Hyper Threading and so on, but the > fscking thing does it with all such setting turned off. On the other PC too. > > Only choosing TWO (or one) cores instead of FOUR stops all these noises. > > Thanks for listening. Whaddya think? > Tim. As a matter of interest, have you got access to a USB sound unit? If so does that exhibit the same problem? The reason I ask is that I have a Novatech nspire laptop with a quad core i5, and have no issues at all using it with a KA 6 - indeed I used it on last year's LAC where it was running for an hour and a half. At that time it wasn't even running an RT kernel. -- Will J Godfrey http://www.musically.me.uk Say you have a poem and I have a tune. Exchange them and we can both have a poem, a tune, and a song. _______________________________________________ Linux-audio-user mailing list Linux-audio-user@xxxxxxxxxxxxxxxxxxxx http://lists.linuxaudio.org/listinfo/linux-audio-user
