speaker popping

[orgnyst6226]

Hello,
I've got some popping/crackling sounds under heavy load and I'm having trouble getting it toned down.
Here is the hardware spec.
i7core - Intel
24 gig ram
RME fireface 800
Mackie SRM 450's and Mackie SWA 1501 sub woofer.
Got the PAB Extended installed with Cathedral Acoustics
Been monitoring the load on the CPU and it does not pass 77% with full crescendo
I have the polyphony set to 4500 under the organ settings and 6000 under the general settings.
I'm baffled because the CPU never maxes out which is usually the cause of this problem and the total ram used is just under 18 gig. Is it possible that I'm pushing too many voices thru to few speakers?
Thoughts or suggestions would be greatly appreciated.
Thanks
Steve

[B. Milan]

Hello Steve,

The organ settings polyphony will always override the General settings polyphony management unless you have a value of 0 in the Organ settings in which case the General settings would then take effect.

I would say one of two things are happening, either your polyphony is set too high in which case just try lowering it until the popping is gone. Or you have audio overload (clipping) in which case you can simply turn down the audio output levels until the popping is gone.

77% load on the processor *should* be OK but depending on your OS settings this may be a little too high. Lowering the polyphony settings should lower this value. I would say that 4500 is probably too high for the i7, if you run the polyphony testing organ you should be able to try and determine that most acceptable polyphony for your computer.

However my guess would be that your audio output just needs to be turned down and that you are experiencing audio distortion. You should be able to view the RME control panel meters which should be in (or near) the red if clipping is occurring.

I hope that helps.

[orgnyst6226]

Hi Brett,

For the record - and hopefully to assist others, I played with various settings in the RME control panel and also ran their "digicheck" software. I was able to eliminate the speaker popping by doing the following:
1. Limit Bandwidth setting - I only use the first eight analog channels, so essentially turning off the SPDIF and ADAT which I do not use allowed the unit to maximize the bandwidth just for the 1-8 analog channels and allocate nothing to the SPDIF and ADAT.
2. I also increased the buffer size from 256 to 512

I also decreased the polyphony from 4500 down to 4000, however, after success with the RME settings I increased the polyphony back to 4500 and still no crackling or popping sounds. Success!!

The PAB organ will most likely be the largest I ever install - I think if I can run that, I should have no problems running the Paramount 320 - 330 or 440.
BTW, the m-audio 1010lt is great, however, the RME fireface is nothing less than WOW!!!
I highly recommend it.

Oh, noticed something else - after making the adjustments to the RME I noticed that the load on the processor decreased from 77% to the high 60's - not sure if that should really make sense - or perhaps I did not have the same number of stops pulled.
Thanks again Brett for all your guidance
Steve

[B. Milan]

Hello Steve,

Thanks, glad to hear you managed to get it sorted then.

[mdyde]

Hello Steve,

Oh, noticed something else - after making the adjustments to the RME I noticed that the load on the processor decreased from 77% to the high 60's - not sure if that should really make sense

That's probably be due to having increased the audio buffer size from 256 to 512. Larger buffer sizes put less load on the processors and reduce the likelihood of buffer underruns (audio glitches) - see also the 'performance tuning' section in the Hauptwerk user guide for more details.