[LAU] Crackles in audio - how to troubleshoot ? Tim's TEST RESULTS:

termtech termtech at rogers.com
Thu Aug 25 22:19:17 UTC 2016

On Thursday, August 25, 2016 3:20:40 PM EDT jonetsu at teksavvy.com wrote:
> Hello,
> Suddenly the audio started crackling.  I was listening to a youtube
> tutorial (firefox) and it started.  Bitwig and Renoise were running but
> not playing anything.  I looked at  the log files (syslog, kern) nothing
> relevant.  Card is 10101LT.
> jackd runs at about 10.3ms latency (last time I checked using
> jack_iodelay), so it run as:
> /usr/bin/jackd --sync -T -P95 -ndefault -dalsa -dhw:M1010LT -r44100
> -p128 -n2
> scaling_gouvernor all set to performance.  Interrupt prio looks OK:
>   436 FF      90   - 130  1.6 S    irq/18-snd_ice1
>    47 FF      50   -  90  0.0 S    irq/9-acpi
> limits audio.conf is:
> @audio   -  rtprio     95
> @audio   -  memlock    unlimited
> Interrupts servicing for all 4 CPUs (i5) :
>   0:  IR-IO-APIC-edge      i8042
>   4:  IR-IO-APIC-edge
>   8:  IR-IO-APIC-edge      rtc0
>   9:  IR-IO-APIC-fasteoi   acpi
>  12:  IR-IO-APIC-edge      i8042
>  18:  IR-IO-APIC-fasteoi   snd_ice1712
> jackd and pulse processes:
>  /usr/bin/pulseaudio --start --log-target=syslog
>  [pulseaudio] <defunct>
>  /usr/bin/jackd -T -ndefault --sync -T -P95 -ndefault -dalsa
>  -dhw:M1010LT -r44100 -p128 -n2
> The pa zombie was there way before the crackling started.  Not sure if
> this is related.
> The pulseaudio jackd sink is active and can be seen in qjackctl.
> So it seems OK.  But the audio is full of crackles.  In firefox, as
> well as Bitwig and Renoise when now something is played.  Of course,
> when the machine was started some audio was played in both Bitwig and
> Renoise and it was fine.  Then I watched a youtube tutorial and bam,
> after maybe 15 minutes, all audio output is full of crackling.
> Since the log files shows nothing.  How is troubleshooting information
> gathered ?  There should be some SW system component that can be
> probed, somwthing that could be observed.  - or is it that the 1010LT
> is going awry ?  Can this happen at all ?
> Thanks for suggestions and comments !
> Cheers.

Hi, this is very, very ironic for me.
Is this a new or replacement PC?

I hope the following helps provide at least one answer for others having 
 these problems:

My new i5 Acer M3910 PC is doing the same thing with my 1010LT.
Right from day one. Digital noise, crackles, and pops, on the analog output.

This is in BOTH Linux and Windows 7. The same noises in each.

To be sure, I reinstalled the card on the older PC from which it came,
 and it is fine. I also installed a SBLive! PCI card on the new PC and 
 it is fine. Seems this 1010LT doesn't like this new PC.

I have noticed many people complaining about such noises,
 especially the clicks and pops. But as you know this can be muddy 
 territory, with several different causes that are hard to pin down.

So, being heavily involved with these ice1712 cards
 (I helped with mudita24 mixer), I have some test results
 that should interest owners of this card:

Go to this site:
 and input a high frequency of say 15000Hz, so that you don't
 hear the tone so much as any noise that may accompany it.
Or, if so desired, use Jack and a tone generator plugin.

On this new PC I get really horrible digital noise, clicks and pops.
The digital noise, oddly, is worse with higher frequency test tones.
>From listening carefully to the noise, it seems something to do 
 with the PCI bus timing or voltage, or poor digital shielding such that 
 noise is getting into the D/A converters before conversion to analog.

This 1010LT card is revision 'C', the last and latest revision.

I tried everything. Turned off SpeedStep, adjusted Jack buffer size etc.

This PC's BIOS is not very friendly, it is a so-called 'locked BIOS'
 where you don't have much in the way of critical timing parameters.


So, today I brought the card to my dealer and we tried it on
 another i5 PC, having a much better Asus MB.

Result: Perfect behaviour. Even at the lowest power saving settings,
 on that test-tone website the card only made a couple of pops but 
 no digital noise. I would expect a couple of pops here and there 
 at these settings, so I concluded the card is fine there.

Conclusion: My dealer is replacing this Acer MB with the better one.

Believe me if there was something I could do to make it work
 I would do it and report back. I was contemplating replacing the 
 electrolytic capacitors on the card just in case. You'd be surprised just
 how weak caps can be, allowing digital ripple on supply lines etc.
It's possible that may help.
But given that the card works OK elsewhere, and I don't want to waste
 any more time on this, I am just going for the replacement PC instead.


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