New DAC has distorted/clipped audio w/new Mac and OS 10.10

Had I been able to create the failure mode, my first plan to resolve it was to try setting up a firmware password:

http://apple.stackexchange.com/questions/97157/preventing-booting-from-external-media

The reason behind my thinking here is that the problem on Windows 8 has been related to the USB boot option in the BIOS, so the closest I could find to disabling that on a Mac was this. No idea if it will work or not, but if dropping the USB3  to USB 2 via a hub doesn't work, it might be something to try.

I just slapped a label on your box, so you should see it in a few days. Please update the thread if you figure anything out.

 
I found the same problem as decribed in this thread when I tried a mac pro cyclinder with usb 3.0 ports.
I used AudioGate as the player. A few seconds after AudioGate plyas a song, the DAC disappears from the list of devices seen
in the audio/midi window. I don't recall any sound coming from the DAC. Rebooting the DAC brings it back as a device.
I have not tried any workarounds. I'm running OSX 10.10.2.

-Dave
 
Here is something to try (when my dac arrives I will try this).  Several people have reported issues when vt-d is enabled.  Here is something I found on disabling vt-d and seeing what happens:

The fix is to disable VT-d by entering the following command in Terminal, then restarting the Mac:

sudo nvram boot-args="dart=0x0"

This change is reversible by deleting the boot-args parameter in nvram, which you can do by entering the following command, then restarting:

sudo nvram -d boot-args

Comment added by Joshua Harris:
Caveat emptor, this solution could cause issues if your startup drive is an SSD. Please research carefully before applying this method to a computer with an SSD.
 
I'm experiencing similar issues with a 2014 Macbook Pro Retina with USB 3 ports. Toslink output from the computer is fine, but with USB:

  • with Midi Settings at 44.1 khz, 24-bit, the DAC plays garbled music for a few seconds then becomes unrecognized by the computer, requiring a DAC restart.
  • with same Midi Settings but using Aroide's system tweak above, the DAC plays for about 30 seconds, still garbled but less so, before the DAC becomes unrecognized. Resetting the tweak restores the original behavior.
  • on an older Macbook Pro from 2009 it plays with no problems
 
There are 8 models of 2014 MacBook Pros with Retina. Can you be more specific? Also what player? What OS?

••••••••••

Has anyone tried the USB 2 hub trick yet? Does it work?

Has anyone tried the firmware password?

Are any of you still covered under AppleCare on these machines? Has anyone placed a call in?
 
More specifically, my device is:

MacBook Pro (Retina, 15-inch, Mid 2014)
https://support.apple.com/kb/SP704?viewlocale=en_US&locale=en_US

running OS X Yosemite 10.10.2 (14C109)

Players are Plex, iTunes, Spotify (same as on the 2009 machine)
 
Several of the machines listed here are old enough that they didn't come with 10.10 installed. It looks like it's pretty simple to roll back if you have TimeMachine backups from before your "upgrade." Anyone care to try?
 
I don't want to volunteer my machine for the roll back as its really my day-to-day work machine. I have an older mac pro with usb 2.0
that works fine with the dac and that machine has the audio duties.

I did some searching on the internet a while back and there are a lot of reports of dacs having trouble with usb 3.0. This is across various platforms,
not just recent macs. The most common workaround is the usb 2.0 hub. I haven't searched enough to find a dac manufacturer that "fixed" the
usb 3.0 issues. I believe I have seen reports of some dacs working on usb 3.0 while others did not for the same platform. At some point I could try my
4+ year old emu dac with the modern usb 3.0 mac pro I have.

I don't know if the fault lies in the host or the dac. I'm wondering if the dac has disconnected from the host has the dac "crashed". If it has, is there a way to
use a logic analyzer or some other hardware device to see where it crashed or what led up to the disconnect? I'm sure John does this all the time in his
development.

I don't think this is too serious as long as the usb 2.0 hub workaround works. I love the dac and am very happy with the sound.

-Dave
 
There are several options for fixing this. You have chosen one (using a different machine). That works for you, so great. It's the people who don't have that option that we are trying to find solutions for. So far, one solution seems to have not worked, and no other ones have been tried.

We know that it's the combination of 10.10 AND USB 3.0 that causes the issue*. That's why I'm suggesting rolling back for those that can with relative ease. Searching online shows that it is not just our hardware, but other hardware as well. The U in USB is universal; there is a hardware/OS implementation that removes the universality. This is a problem that Apple needs to fix. Do they know they need to fix it? That's why I'm encouraging people to contact Apple if they are still qualifying for the free phone support for a recent purchase; it gets the problem logged in their system.



*The USB 3.0 issues we have encountered on the Windows side have been limited to Windows8, and resolvable with a change in BIOS settings.
 
I received my DAC back and have been trying some things out:

- OSX 10.10.3 upgrade did not change behavior
- VT-d fix does not work (same behavior).
- USB2 hub does not work (same behavior).

This might be an XMOS firmware issue or a combo of a firmware behavior and new USB3 chipset/driver.  My other DAC has an XMOS front-end and works fantastic with same exact mac and SW to its max of 384Khz.  It probably will take a debug version of XMOS firmware and a USB3 protocol analyzer to figure this one out.

I'm going to have to either resurrect a VERY old mac mini (the first one ever) or switch to toslink until something is figured out.  But that limits some of my 24/192 source.  Crap.

Does XMOS provide a OS X driver?  Everyone says one isn't needed, but maybe adding their driver fixes the issue.  I believe that only licensed developers can get access to those kinds of things.

 
I don't believe it's an Xmos issue at all, but I'm happy to leave a support ticket on our account to see if they have heard anything from other developers.  A web search shows that there were some Xmos/USB3 issues around 2010, but they were resolved rather quickly.  Josh mentioned that there was a Windows 8/USB3 error, but it's just a Windows 8 and USB booting error, as the error presented itself on both my USB 2.0 and USB 3.0 jacks (I'm in an odd situation where I have a Windows 8 machine that has both jacks).

USB 3.0 is supposed to be backwards compatible, and it looks like it isn't on Apple products.  This is something that needs to be addressed with Apple.

I'd be curious if anybody is willing to try the firmware password, as that solved the issue on the Windows 8 end, and may prove successful on the newest Macs as well.
 
what is the firmware password?  I'm game (and tech savvy).  I was going to wipe and downgrade my system to 10.9 anyways so if I brick it, no big deal.
 
See this message:
http://bottlehead.com/smf/index.php?topic=7699.msg74852#msg74852

Also, you probably can't take your 2015 box to 10.9; Apple has never supported installing an OS older than the machine. Rolling back the OS at all became much harder once they went to installing the OS through the App Store; looking around it seems like the easy way to do it now is if there's a backup of the old system on your backup drive.

Your 2015 machine has to be within the 90day free phone support since it went on sale in March, so you really, really, really should try calling them about this issue. The software developers will only work on the problem if they know it's a problem. It's up to the users to tell them the problem is there.
 
It would help trying to figure out what is going on if someone who has the problem could record the output of the DAC. Not a microphone recording the sound from a speaker, but directly connecting the output of the DAC into the line input of something that can record it, It would really be great if you could record a sine or triangle wave at say something like 400HZ.

It doesn't really matter what the recording device is ( a line jack on a laptop, a separate audio box with line input etc). It is important to make sure that the level of the recording is set so the signal is not overloading the input. The sample rate doesn't matter.

It would be nice if the file format is something I can read on non-macs, such as flac or wav.

There are lots of things I can do to try and debug this, but I don't have any Macs. So in order to debug It I need to have a computer that has the problem. I'm going to have to let you Mac people figure out what causes the issue.

A recording of the distorterd signal will let me know what is happening, which might give a hint as to where it is happening, in the computer or in the DAC.

There are many ways a digital audio signal can be "distorted", without looking at the signal I can't even make a guess as to which it might be.

The XMOS interface is running 32 bit little endian integer, the MAC software is supposed to query the DAC for this information and make sure it sends this format to the DAC. If it is not actually sending this format (for example if it is sending big endian or float) you would get a highly distorted sound. Is there anyone that is familiar enough with MACs to find out what the actual format is that is being sent to the DAC? I know how to do this in Linux but not MACs.



BTW I'm on vacation for another week and a half, so I can't do anything about it right now, but I can read the info on what is happening And maybe make some suggestions.

Thanks,

John S.

 
I skimmed the various posts and did not see any mention of the Audio Midi Setup. Maybe one needs to set the AMS output to the BH DAC to 2-channel 32-bit float. I am running my iMac 5K into an older e-Mu 0404 and have had zero problems. On different machines around the house, sometimes my audio component will not handshake with other hardware. It is always fixed by going into the AMS and defining a different sample rate.

There had been issues with one macmini that distorted the sound and the picture (am running HDMI into amp). The easy fix was to change the sample rate via AMS. Sometimes had to reboot the browser when viewing Web content. Since rolling the mini back to Snow Leopard, the problem has ceased. But, when I change from computer output to TV the amp will not do a handshake. Again, I have to go into AMS and change the bit rate.
 
I also have no problems with latest Yosemite, USB3 on a 2014 mac mini and 2015 macbook pro with my Gustard X10 XMOS DAC.  No issues with my HRT micro streamer DAC (not XMOS-based).  So far my only issue has been with the BH DAC.
 
I tried turning on the firmware password. This produced the same result as the "disable VT-d" trick: instead of 5 seconds of extremely garbled output, I got about 30 seconds of intelligible music with digital pops and ticks before going unrecognized.
 
Has anyone tried Linux on a recent mac with usb 3.0?
If not, I will try it in several days.

Thanks,
Dave
 
I tried to downgrade my 2014 mac mini to Mavericks, but I can't.  It was shipped with 10.10 Yosemite and you can't downgrade to anything earlier than what a mac was shipped with.  I didn't know that.  All the info you need to know is here: https://support.apple.com/en-us/HT204319

When I did have USB working on an older mac, USB audio was subtley better than toslink.  I prefer USB.

So until this gets resolved, I'm choosing between toslink or using an older laptop for my music source.
 
I have experienced this sound in the last week a couple of times.  It is always when I start a new CD.  I found that switching inputs and back solves this problem.  So I'm just careful at the start of a disk.  Since I'm at the DAC to put in a new disk it is pretty minor.

It is the DAC as the analog outputs are fine.  But it might be some anomaly with my CD player at the start of a disk.
 
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