clipping sound on new iMac when Logix X is running

The Art Of Sound wrote:

My client who has this issue, reported the same snap, crackle and pop problem. (Hereafter known as the "Rice Crispies" effect.... 🙂) via everything from Radium (a 3rd party radio app) to Virtual DJ.. and from editors such as Sound Studio and Fission to games such as Bioshock and COD which kind of rules out CoreAudio itself I suspect....as the single cause of the issue.

Doesn't everything go through Core Audio... as far as I know it's inescapable.

Doesn't everything go through Core Audio... as far as I know it's inescapable.

That's true...... I was just doing some reading up on Core Audio and found that even if you use different methods of sending Audio out.. you still have to, at some point, go through Core Audio....

The Art Of Sound wrote:

Doesn't everything go through Core Audio... as far as I know it's inescapable.

That's true...... I was just doing some reading up on Core Audio and found that even if you use different methods of sending Audio out.. you still have to, at some point, go through Core Audio....

Right, as you mention, there are different ways to access core audio, possibly relating to the priority of the task.

Back in the day, before operating systems took over complete control, a manufacturer could write drivers that accessed hardware directly. The Good: Very high transfer rates and excellent timing, The Bad: A poorly written driver could take the system down.

Deadphish42 wrote:

Hi Guy's

you still have to, at some point, go through Core Audio....

So does that indicate firmware fix?🙂 or hardware?😠 or we still can't be sure?😕

Thanks,

DeadPhish

I've always though this would be a firmware fix.

Art mentioned that recent Mac Mini owners with Fusion drives were not reporting audio problems but Mini's will be using a different firmware that reflects their hardware configuration.

You mentioned the problem showed up right away in Garageband.. can you run a quick test?

Load Garageband, load whatever samples or GB project that causes the noise.

With GB playing, minimize GB so there's no graphic movement going on, does the noise change? With GB still playing open Activity Monitor and see if there's anything using a big chunk of CPU.

Just an idea, if you ran a linux live cd (Like ubuntu etc.), or boot camp with a windows installation, it would be interesting to see if the audio crackled in that environment. As it could possibly be related to the fusion drive who's not to say this is something physical going on, like interference, so would show up in either OS's.

Also, the noise is definetly in the signal chain, and not a physical sound emanating from the iMac's internals (or casing), correct? I ask as there was an issue with the Fusion drive and case noise a while back.

Since we're great at speculating.. (indeed, it's my second hobby).

It could be something as simple as the built-in-interface of the Fusion drive placing a load on the bus or using an abundance of bandwidth.

No, the volume of the crackling is dependent on the system volume. Also there was a post earlier regarding graphics, minimizing etc and I do think that the problem is worse when the machine has more user inputs.

It still happens when idling i.e. I had something playing through iTunes when I was doing something else in the same room where the popping happened every 5 or so seconds. When I sat down to browse the web, the popping would happen >1 per second.

At this stage it's all speculation, would be great if any SSD only users can post if they have the issue.

Also regarding a certain batch/region it could be true regarding the batch but I'm based in the UK and the OP in So Cal so no regional correlation.

Hi all

Just got my new Imac last night specifically for DAW and Logic Pro x, wish I had seen these postings before purchase...

My imac

21 inch

3.1 core i7

1TB Fusion

16GB

Nvidia video chip

Focusrite 2i4

And YES had the popping through the internal speakers and audio interface on the demo track of LPX. When I changed the io buffer to 256k it did disappear from LPX but I was only running a drummer track. This was after changing gain and chan settings with no initial improvement. First I thought it was the external interface but when I just used the on board sound it was still there. But changing the buffer did work last night. Will spend more time tonight.

Other audio apps sounded ok such as online radio and sound from YouTube or safari.

Really do hope this will be resolved without returning the computer as it's been a fairly big investment for all the kit so far.

Ok well will wait and see what mavericks will do and will contact UK apple support if the popping has not been solved from upping the buffer size

Waiting in anticipation and thank

Clandestyne

Ok so really strange.

I've been using Chrome exclusively and didn't even think to try Safari/Firefox.

With Chrome completely shutdown there is no crackling/popping or any interfernce playing the same URL from youtube! I've plugged the iMac into my Hart Evo1 in the lounge and it's even more obvious with Chrome. Tried B&W headphones and that also shows clipping with Chrome content + slight when chrome running in the background.

Now I'm not sure whether to send it back or not. Any other test I could do? I'm not an audio engineer so don't have logic x etc

Thanks.

Babw,

The thing is.. there are several other reasons why 'clipping' could occur (This, in itself is not an uncommon issue) and not just the problem that seems to have been identified by others here.. (The Fusion Drive and 2013 iMacs) and it is all too easy to think/believe you have the same issue as others simply based on the fact you have the same hardware and you hear pops and clicks.. when in fact it could be the same sort of problem but with an entirely different cause....

What I would suggest you do is shut down Chrome completely and test with iTunes and the built in Audio Output (as others have tried and reported back on) and if you don't hear the "Rice Crispies" effect then the likelyhood is your iMac, for whatever reason.. doesn't have this issue... and your issue is being cause by something else... In your case, your Chrome installation... if when running Chrome is the only time you hear the pops and clicks.

Babw wrote:

Tried B&W headphones and that also shows clipping with Chrome content + slight when chrome running in the background.

Clipping is not the same as static and pops. Clipping is a signal overload (distortion) as when an amplifier preamp or amp section is driven so hard that it clips off the top of the signal/waveform when viewed on an oscilloscope.

If you want to test it follow one of the procedures Deadphish used, such as loading some samples into Garageband.