Audiophiles: iTunes Equalizer making Static, Noise, Distortion

Hello,

Replaced a 2012 MBP with a late 2015 iMac and the Equalizer in iTunes now generates noise. I have a very good desktop audio system and have isolated it to the EQ. I'm using an external DAC so it's in the USB output. Anyone else experience this? Or know if the EQ occurs in the digital domain (likely) and not a round of D/A and A/D conversion. I'm guessing the hardware was cheapened. Really unhappy about it as a solid and clean system-wide equalizer is a unicorn but at least iTunes has (had) a good one. And yes, I have Boom 2.

Thanks!

iMac with Retina 5K display, OS X El Capitan (10.11.1)

Posted on Dec 7, 2015 8:23 AM

19 replies

Dec 11, 2015 3:16 PM in response to SVO

if you have not already, there are some audio-related settings stored in PRAM, so do a PRAM reset

How to Reset NVRAM on your Mac - Apple Support (I guess it's called "NVRAM" now.)

And to reset the USB ports, do an SMC reset, which for an iMac is just unplugging it from power

Shut down the computer.

Unplug the power cord.

Wait fifteen seconds.

Attach the power cord.

Wait five seconds, then press the power button to turn on the computer.

If you have an external drive that can be erased, try installing a fresh install of OS X on it and boot from it. I actually use an SDXC card in my Mac's high-speed SD card slot as a startup disk for testing software (surprisingly fast). You said the DAC has no driver software, but you may have other driver software or background process installed that is causing this interference. Try using the DAC on a system without any third-party software. When you do this, you should disconnect ALL other external devices, except standard keyboard/mouse (if used). If the test startup disk is on an external drive, that obviously needs to stay connected.

SVO Author

Level 1

8 points

Dec 11, 2015 5:00 PM in response to Kenichi Watanabe

Did the PRAM reset and SMC reset- no change.

The iMac is brand new and still I wiped the drive, reinstalled El Capitan and then moved over all my applications and files.

All my songs are in Apple Lossless and I have a large photo collection so reinstalling my 750GB of data is not something to take lightly.

I just used the DAC on a system without 3rd party software- the iPad. Problem disappears

Decided to install Fidelia player (iTunes alternative) and see what happened- issue disappears. So that would imply to me that it is in the OS X audio drivers, rather than hardware, but I'm no expert. Also, Soundcheck seems to make it a bit worse. I can use third-party MIdi plugins for EQ with Fidelia (although these are often not stable in my prior expereince).

Thanks Kenichi

Dec 30, 2015 9:36 AM in response to SVO

The iMac is brand new and still I wiped the drive, reinstalled El Capitan and then moved over all my applications and files.

It's the "moved over all my applications" part that you want to rule out as a possible cause. I'm not saying you should wipe your data and reinstall a fresh OS X system. Use an alternate test system (with the same hardware) with the latest OS X, that does not have any third-party software. Using the iPad is not helpful, because that is completely different hardware. You're not trying to prove the problem is on the iMac; it is obviously a problem on the iMac. The goal is to isolate the problem on the iMac, and hopefully eliminate it. One step is to rule out third-party software as the cause.

NOTE: You can use Disk Utility to create (add) a small partition to the internal drive, and you can install your clean test system there, if you don't have an external drive (or sufficiently large SD card) that you can use for the test startup disk. I didn't suggest that, because there is a small risk to existing data. I prefer to use my SDXC card and start up from it for testing, because that leaves my day-to-day system on my Mac's internal drive alone.

Decided to install Fidelia player (iTunes alternative) and see what happened- issue disappears.

That's good. It probably means your iMac's hardware is ruled out as the cause. As a test, what happens if you use QuickTime Player to play a song? And it would be good to know if iTunes on a test system with no third-party software installed still has this problem.

SVO Author

Level 1

8 points

Dec 30, 2015 11:16 AM in response to Kenichi Watanabe

Kenichi- Great advice. Partitioned drive and installed clean OS X and no problem. So I went digging for anything audio related (again) and found an old plugin. Dumped to trash, emptied and much better. I only have the distortion now with a few tracks with huge dynamic range with EQ engaged. Seems like there may be a slight problem in iTunes Equalizer and the plugin was doing some EQ that magnified the problem several fold. As I said, I have a very high resolution desktop audio system and all my tracks are ALC so I would tend to notice problems that escape 99%+ of users.

I had previously looked for any old stray items like that to delete before I migrated to the new computer (found several) but that one I missed somehow. No idea why it did not interfere with the same version of OS X/iTunes on old 2012 Macbook Pro while it conflicted on new iMac. Thanks a ton.

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Audiophiles: iTunes Equalizer making Static, Noise, Distortion