Source of unknown crackling

[bassberry]

An electronic “crackle” ruins an otherwise fine track. I’ve spent hours trying to troubleshoot this and, so far, it’s winning. I don’t know what to do as a next step to banish this demon from my system. Any ideas would be appreciated. I’m desperate!

Here's a link to where you can take a listen...

Forum

I’m not clipping anywhere during recording. I’ve found no pattern to when it shows up. It lasts only long enough to muck up the track and cause me extra work. I record with a 256 Sample Buffer.

I really need some direction about how best to troubleshooting this. Thanks! -steve

[TheJackAttack]

First steps to take:
Turn off any networking adapters. Increase the buffer sample size. Don't move the mouse at all when tracking if you can help it. Make sure all digital cables are connected and tight-sometimes the pins can get corroded so it's not a bad idea to pull the cable off and push it back on.

Now if none of the above works then you have to go step by step. Start at your interface. Unplug all inputs and record some tracks without connections. Do you still get the crackle? If so then it's in your interface or more likely the computer. Embedded video chips on motherboards are culprits for this type of thing as well as extraneous USB connections and unnecessary mouse movements.

If the interface/computer combo doesn't produce the crackle then connect one piece of gear and try again. Crackle? Swap the cables. Crackle? Continue adding gear until the crackle occurs or you have sussed it all out.

[boxcar]

i've heard that sound before.
i use to run two aardvark q-10 interfaces and the clocks would drop out of sync once in awhile and i would hear exactly the same thing on playback.(didn't hear it during recording).
could be a clock related problem.
i don't know but maybe threre's a clue there.

[Shadow_7]

That's not the crackle I'm used to via network adapters. Are you doing a lot of processing (multitracking) while recording? Network adapter, or cable across interfering sources has more of a click than the crunch that that seems to be. You might use a resource monitor and see if there's any peaks in resource usage that coincide with the crackle. Any usb/firewire interface while also using usb/firewire HDD to store the data? Could be a lot of things. My guess would be a resource bottleneck. But it could be a lot of things. Power issues? Filesystem commit interval? and tons of other potential candidates. Some of which depends on how consistent / regular the issue is, or how random.

[bassberry]

First, my rant... why is happening to me? Does every other Mac user (or PC user) deal with this kind of thing or is this payback for some sort of bad karma? I thought this stuff should be plug-and-play! Okay, I'm done. Thanks for your patience!

Thanks to each of you for priming the pump with some good ideas. It seems to be a good list of potential issues. I'm guessing the answer is going to be in there. That said, there are so many possibilities! Yikes! The good news is that I have a list that can help direct my next steps - whatever they may be. They have also sparked new thoughts and history I can share. Maybe the list can be narrowed somewhat!

Here’s a bit more history. This issue first showed up when I was using a different setup. I had a small board connected to the computer via USB. At the time, I was reading on forum posts that Apple had something funky going on with their USB connection. So, I purchased my current preamp and connected up using an optical cable. It appeared the problem was solved - but no.

Given that this has happened with two different preamp setups (connected by two different wiring types), I think I can rule out wires and external HW. That leaves a potential HW or SW issue with the Mac, an interface issue (I’m thinking the clock issue fits in here), some sort of incompatible software settings, or a seemingly random intrusion by something like Airport or an electrical surge.

Regarding the potential clock issue, is there any way to confirm this without purchasing a new piece of equipment. Is there any way to force the clocks to go out of sync just so that I can hear the effect? I have (what I thought was) a relatively simple setup - just my computer and a Art Digital MPA connected with an optical cable. Am I understanding that it doesn’t matter how simple it is - connect one piece of outboard hardware and the potential for clock issues exists?

I'm going to try to focus on some of the easier things to test so that I can narrow the list. In the mean time, I'd like to hear your thoughts about my observations above.

Thanks again!

[Shadow_7]

How many tracks? What's the specs of the PC? What OS / version of OS? How much RAM? A lot of software issues can be solved by doubling your RAM. Strange but true... Not really solved, but a lot less frequent. You could try an alternative OS (linux) and see if that cures your issues, therefor confirming software related, and not hardware per say. Lots of ways to troubleshoot. But until you rule this and that out, you still DON'T KNOW anything for certain.

[bassberry]

I'm recording one track at a time. I am simultaneously playing a scratch track (instead of a click). And, my memory is maxed out.

Here's my gear profile:
Cubase Studio 5
Art Digital MPA Preamp
AudioTechnica 3035
Oktava MK-012
AKG C1000
Adam-A7 Monitors
Velodyne sub-woofer
MacBook Pro
Model Identifier: MacBookPro3,1
Processor Name: Intel Core 2 Duo
Processor Speed: 2.4 GHz
Number Of Processors: 1
Total Number Of Cores: 2
L2 Cache: 4 MB
Memory: 4 GB
Bus Speed: 800 MHz

[Shadow_7]

RAM looks good, CPU good. You can probably rule out the interface and connection cable.

Is it just the one mic? Or every mic?

How many tracks are involved with your scratch track? 1, 2, 8+? Any special effects in place, reverb, distortion, ???

How many tracks total in the project? How long are the tracks in the project?

I'd start with trying other mics, if the same effect is happening on multiple mics, then it's probably not the mics. Making it probably computer / power supply / software related. Try recording with audacity and see if the mic(s) have the same issue. Put a PSU between the computer and the wall to stabilize power and rule that out. It could still be anything. It might not even be in your house, radio station? power sub-station? neighbor is a HAM radio enthusiast? Other neighbor is a CB maniac with a beefy system in their house? neighbor is a first responder (fire / police / ambulance)? Depending on how frequent the issue is. Neighbor has a microwave based internet connection? Neighbor is a cell tower? Could be lots of things.

[TheJackAttack]

There is no way that machine is maxed out-at least if it's operating system is a clean install.

The other problem I see immediately from your gear list is that you do not have an audio interface. The ART Digital MPA is designed to send the audio into an audio interface prior to it being seen by the computer. This would also give you the ability to direct monitor latency free.

[boxcar]

First, my rant... why is happening to me? Does every other Mac user (or PC user) deal with this kind of thing or is this payback for some sort of bad karma? I thought this stuff should be plug-and-play! Okay, I'm done. Thanks for your patience!

Thanks to each of you for priming the pump with some good ideas. It seems to be a good list of potential issues. I'm guessing the answer is going to be in there. That said, there are so many possibilities! Yikes! The good news is that I have a list that can help direct my next steps - whatever they may be. They have also sparked new thoughts and history I can share. Maybe the list can be narrowed somewhat!

Here’s a bit more history. This issue first showed up when I was using a different setup. I had a small board connected to the computer via USB. At the time, I was reading on forum posts that Apple had something funky going on with their USB connection. So, I purchased my current preamp and connected up using an optical cable. It appeared the problem was solved - but no.

Given that this has happened with two different preamp setups (connected by two different wiring types), I think I can rule out wires and external HW. That leaves a potential HW or SW issue with the Mac, an interface issue (I’m thinking the clock issue fits in here), some sort of incompatible software settings, or a seemingly random intrusion by something like Airport or an electrical surge.

Regarding the potential clock issue, is there any way to confirm this without purchasing a new piece of equipment. Is there any way to force the clocks to go out of sync just so that I can hear the effect? I have (what I thought was) a relatively simple setup - just my computer and a Art Digital MPA connected with an optical cable. Am I understanding that it doesn’t matter how simple it is - connect one piece of outboard hardware and the potential for clock issues exists?

I'm going to try to focus on some of the easier things to test so that I can narrow the list. In the mean time, I'd like to hear your thoughts about my observations above.

Thanks again!

just trying to add more clues here.i listened to it again and it's the exact same sound i heard with the aardvark interfaces. in my case, if you right clicked the aardvark tab in the control panel, you could see the two clocks running side by side.
sometimes one would be running at 44.1003.???? don't remenber the exact numbers.
and the other one would start to go 44.1008. or 9 or more.
when that happened, i would hear that exact sound.
i would reset them and it would stop.
can you change the clock speed in the mac to 48k or something other than 44.1 just to do some tests or is it like an onboard audio card. i don't quite get how your running the art into the computer.is it an audio card you bought or do the macs come with an onboard spdif jack.
if it's an aftermarket card with adat in or spdif, there should be a control panel where you can change clock speed and select master/slave.