Intel iMac audio issue with all sound using USB DAC - RESOLVED

low.pfile · « **on:** 8 Sep 2010, 05:37 am »

My new 2010 iMac, a 27" 2.8GHZ Quad-core Intel i5 /8GB RAM/ OS 10.6. does not play nice with my Wavelength Brick USB DAC V2. The iMac was purchased new from Apple. I have used this DAC with my Apple G5 (Power PC with OS 10.4) for over 2 years, with much satisfaction and zero issues. The Brick V2 is a 16bit/44.1kHz DAC.

Connected to the Brick DAC, the iMac outputs audio, but it is essentially a distorted fluttering version of the song. Initially, I was listening to iTunes with the built-in speakers and the audio was normal. Therefore, iTunes is functioning normally. Furthermore, any audio (e.g. from internet streaming, web pages) also exhibit this fluttering playback sound when played back through the Brick DAC--iTunes is not the problem. I have contacted Gordon at Wavelength and this issue has not come up before--the Brick has been tested with 100s of computers.

Here is a recording (iPhone) of a familiar song streaming from Pandora on the iMac/Brick combo to demonstrate the issue. Audio [link]. The fluttering/distortion is identical with iTunes playback.

I swapped multiple USB cables(short, long, $cheapies, wireworld starlight) on the Brick/iMac system --this did not correct the issue. Each iMac USB port was tested as well resulting in no correction to the sound through the Brick. Also, I ran the hardware diagnostics (Apple install disc) and no problems found. My iMac is healthy--other than the potentially mis-implemented USB hub.

I wanted to confirm nothing was wrong with the Brick DAC so I configured other mac systems I had access to output USB audio through the Brick. I tested :

2008 Intel MacBook Pro unibody /2.8 Core 2 Duo(T9600)/OS 10.6:   Normal Sound
2006 Intel MacBook Pro/2.3 GHz Core 2 Duo(T7600) /OS 10.4:       Normal Sound
2005 G5 Power Mac Dual 2.3 PowerPC (970MP) /OS 10.4 (my original system):   Normal Sound

Other digital output is fine from my new iMac: Optical to a Monarchy NM24 DAC (Toslink, no USB input)

My next move was a consultation with the Apple Store genius bar, bringing along my iMac, Brick DAC and cables to demonstrate the issue (output to powered speakers). For his initial test he booted off of a "golden" boot disk on an external hard disk--distortion issue was still present. I convinced him to connect my DAC to the same model 27" iMac i5 on display--it had the same audio output problem. He had no idea other to say that the DAC and iMac are incompatible.

The latest test, (per Wavelength) was to put a USB 2.0 hub between the DAC and the iMac. I used a new powered Belkin USB 2.0 hub(480 Mbps). The distorted sound is still present exactly the same as without the hub.

Unfortunately, I don't have access to another USB DAC to test. Gordon stated that there are no other 16/44.1 Asynch DACs to compare to to validate the issue. But I would be happy to check any USB DAC at this point, to determine the DAC options to finalize my iMac based music system.

My plan to update my PPC system is not going as smoothly as expected. The idea was to continue to have a mac system for graphics/photo/CAD that also is an iTunes music server (when used as a dedicated music playback nothing else is running). I also wanted to test out the Pure Music application vs iTunes and that requires an Intel system. So either I find a fix for the Brick DAC, get an equivalent or better quality USB or FireWire DAC which works with my new iMac. I do not want to loose the sweet new iMac or run two computers.

Is anyone successfully using a 2010 iMac with any Asynch USB DAC?

Or know of similar USB audio output distortion issues with any newer mac?

Grazie,
ed

*** June 02, 2011 UPDATE:

Gordon determined that my Brick v2 DAC had old code which caused the distortion. The solution was a software update via ROM swap. He was correct, after the update, the wonderful sound is back in my system: iMac i5 > Brick v2 DAC > Modwright SWL 9.0 SE Sig > RWA Signature 30.2 LFP-V > Devore Nines

crusing through my audio demo/text tracks as I write this. YEAAAAHHH!

writeface · « **Reply #1 on:** 8 Sep 2010, 06:01 am »

I have been using W4s Dac2 (asynchronous )
with 2010 Mac mini. No issues.

ZLS · « **Reply #2 on:** 8 Sep 2010, 10:55 am »

Just spit-balling here.
Have you tried running your DAC through front row?
Turn off Itunes and see if that helps.
Another suggestion is to check the Midi Application to
make sure that it is properly configured to 16/44.1

Atlplasma · « **Reply #3 on:** 8 Sep 2010, 12:40 pm »

I'm assuming you're running the latest version of iTunes. If not, you might want to check for software updates.

There are also some setup and known issues described here: http://www.benchmarkmedia.com/wiki/index.php/ITunes-QuickTime_for_Mac_-_Setup_Guide

You might also want to download the demo version of Pure Music and see if it has any affect on your playback issues.

Steve

avta · « **Reply #4 on:** 8 Sep 2010, 02:19 pm »

I'm not sure you mentioned this but have you checked the Audio Midi settings to be sure that the settings match your input files ?

low.pfile · « **Reply #5 on:** 8 Sep 2010, 02:19 pm »

Thanks for the ideas people. I may have missed something very basic. But I am fairly confident the audio is set up properly--see Audio Midi setup window below (which has the same settings as the other macs I tested which had undistorted audio output.)

Latest software: my iMac is only 2 weeks old the software was the newest. But I have updated all Apple software this morning and now using iTunes 10--same results. There was no separate QuickTime update included. And the iMac tested in the Palo Alto Apple Store was very likely up to date as well.

Front Row: The same distortion is present playing a ripped CD.

Pure Music application:
This is the one of the things I am really looking forward to using on the iMac. I hesitate installing this now because I will not be able to make a comparison because of the distortion.

low.pfile · « **Reply #6 on:** 8 Sep 2010, 02:28 pm »

Additional details on my iMac:

System Version: Mac OS X 10.6.4
32-bit mode

QuickTime 10.0
iTunes 10.0

Atlplasma · « **Reply #7 on:** 8 Sep 2010, 02:37 pm »

Sorry you're not any closer to a solution. I using an fairly new Intel Mini as a server with a Pop Pulse 1796 DAC. I output over USB using an M2Tech HiFace converter. There are no audio issues. Do you have access to another DAC to determine if the Brick is indeed incompatible?

low.pfile · « **Reply #8 on:** 8 Sep 2010, 03:52 pm »

Atlplasma,
I am working on finding another USB DAC locally (SF Bay Area) to test.

Crimson · « **Reply #9 on:** 9 Sep 2010, 11:46 am »

Ed,

I've got the same exact machine on order and should have it tomorrow or Saturday. I also happen to still have my Brick v2 lying around. I'll also try it out with a Cosecant v3, as well as a few FireWire dacs. Give me a few days and I'll let you know how it works out.

low.pfile · « **Reply #10 on:** 9 Sep 2010, 12:48 pm »

Wow, what a coincidence! I'm sure you will be able to probe much deeper into the iMac than I can. I'll be waiting on tenterhooks, but take your time.

groovybassist · « **Reply #11 on:** 9 Sep 2010, 03:12 pm »

I would change the Audio Midi settings to 96k/24-bit to see if the problem still occurs. I had something similar happen (not quite as bad) when I started using my HRT Streamer II+ (an asynch USB DAC) with my 3-year-old iMac. I'm on a WIndows laptop now, but will start up the iMac and see if I can remember how I resolved it...

-Mike

low.pfile · « **Reply #12 on:** 9 Sep 2010, 03:18 pm »

Thanks for the suggestion Mike, no other sampling/bit rate options are available in Audio MIDI. just the 44.1k/16 that the V2 Brick DAC supports.

groovybassist · « **Reply #13 on:** 9 Sep 2010, 03:29 pm »

Well, I'm drawing a blank. The only settings available to me are 96/24 based on the DAC. I have a faint memory of having set the sample rate to 88.2 at one point per Gordon's website - he indcates he feels a multiple of 44.1 works better than 96; maybe I was able to do that on the Windows laptop I used to have running iTunes vs. the iMac I'm using now to stream.

low.pfile · « **Reply #14 on:** 9 Sep 2010, 03:36 pm »

Mike, there are two current versions of the Brick: V2 = 16/44, and V3 = 24/96. If you are referring to a Brick DAC then you must have a V3.

Fortunately, Crimson will be able to test the same V2 Brick DAC and iMac i5 combo that I have very soon, so we'll see...

cheers, ed

groovybassist · « **Reply #15 on:** 9 Sep 2010, 03:38 pm »

I've got an HRT Streamer II+, which is a 24/96 asynch USD DAC. Hope you get it worked out soon.

low.pfile · « **Reply #16 on:** 13 Sep 2010, 01:03 am »

I was able to test a Wyred 4 Sound DAC 2 for a short time with my iMac system. Thanks again Gokul(writeface) for coming over! After loading the USB drivers and a few restarts later, the W4S DAC showed up in the Audio Midi and undistorted sound was presented through my Devore Nines. Finally.

We each listened to a few songs we knew. Both Gokul and I thought the W4S DAC did not have a great synergy in my system. This wasn't really an evaluation of the W4S DAC, but it was obvious that it's high end seemed more extended than what we heard with the G5/Brick combo(and what I normally hear of my system) and very detailed. We thought the G5/Brick was more musical. Again, this was just a brief listening session.

So now I standby awaiting Crimson's findings with his new i5 iMac and DAC collection, including a Brick DAC v2.

low.pfile · « **Reply #17 on:** 28 Sep 2010, 01:57 am »

Update 2:

I didn't want to have to go down this road but, because of the iMac and Wavelength Brick V2 incompatibility, I'm looking at other USB or FW DAC options.

And BTW, Crimson also experienced the same audio distortion with his Brick V2 DAC and new 2010 iMac with both iTunes and Pure Music.

For the short term, I have a EE Minimax DAC on order and hope it comes close to the Brick. Picked up a Mullard 12AU7 for it. That could be the easy replacement, but if it doesn't cut it I will need to look for another DAC. My current connection is USB at 9ft due to it's location in my adjacent office. This distance may be a hurdle for some DACs (though not for the Brick/G5 server combo). The goal is to use the new iMac as the server.

I want to keep it around $1500. So my other consideration is a dB Audio Tranquility DAC. I only play 16/44 music, as my current library and music preferences do not warrant higher resolution capable DACs. A less preferable option, due to complexity, is getting a 2010 Mac Mini (dedicated music use) and keeping the Brick DAC, though that combo is not yet verified as trouble free. This is a more complicated solution since I listen to music in both my office and LR and the VNC/monitor connections.

Ed

Stu Pitt · « **Reply #18 on:** 28 Sep 2010, 02:21 am »

Ed,

Regarding having another Mac, it may not be as hard as it seems. There is a library sharing feature than you can use. What's on one computer can/will show up on the others by streaming. Haven't tried it myself, so no idea about specifics.

But I agree with the point that another new Mac may have the same problems as the current new Mac. It sucks that its not working out for you.

ZLS · « **Reply #19 on:** 28 Sep 2010, 11:38 am »

Quote from: low.pfile on 28 Sep 2010, 01:57 am

Update 2:

I didn't want to have to go down this road but, because of the iMac and Wavelength Brick V2 incompatibility, I'm looking at other USB or FW DAC options.

And BTW, Crimson also experienced the same audio distortion with his Brick V2 DAC and new 2010 iMac with both iTunes and Pure Music.

For the short term, I have a EE Minimax DAC on order and hope it comes close to the Brick. Picked up a Mullard 12AU7 for it. That could be the easy replacement, but if it doesn't cut it I will need to look for another DAC. My current connection is USB at 9ft due to it's location in my adjacent office. This distance may be a hurdle for some DACs (though not for the Brick/G5 server combo). The goal is to use the new iMac as the server.

I want to keep it around $1500. So my other consideration is a dB Audio Tranquility DAC. I only play 16/44 music, as my current library and music preferences do not warrant higher resolution capable DACs. A less preferable option, due to complexity, is getting a 2010 Mac Mini (dedicated music use) and keeping the Brick DAC, though that combo is not yet verified as trouble free. This is a more complicated solution since I listen to music in both my office and LR and the VNC/monitor connections.

Ed

Perhaps you may want to consider the Neko Dac http://www.nekoaudio.com/
I am using it with my Imac (running Pure Vinyl/Pure Music) and the sound is very Good.
It falls in your price range.