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

[Paul Birkeland]

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.

[aroide]

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.

[fullheadofnothing]

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.

[John Swenson]

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.

[Yoder]

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.

[aroide]

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.

[rburrows]

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.

[dw]

Has anyone tried Linux on a recent mac with usb 3.0?
If not, I will try it in several days.

Thanks,
Dave

[aroide]

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.

[Grainger49]

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.

[John Swenson]

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 really want to get to the bottom of this. As I mentioned earlier it's tough to try and work through this without knowing what the distortion is. Is there any way at all you can make a recording of the distortion so I can analyze it and try and see what is happening? At this point I'll take anything, use a voice recorder function on your phone to record it, the mic input of a laptop, anything you have on hand. If you have a choice record at a high sample rate if possible.

Thanks,

John S.

Once I have a clue as to what the distortion is I can start trying to figure out what is causing that distortion.

[John Swenson]

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.

Hi Grainger,
could you give me some details of the sequence of events that causes the problems for you? What input are you using? What sequence of powering on or off the CD player and DAC is happening? Have you been listening to another input?

Really helpful would be things like: I do A then B it works fine, but when I do A C then B it doesn't.

Thanks,

John S.

[Grainger49]

Yes John, It happens after listening for a while and when I close the tray (Philips DVD 963SA using SPDIF output) it sounds very odd.  I'll see if I can just open/close the same CD until I get the noise.  I have a recorder on my phone, but it is very low quality.

I have also ordered a TOSlink long enough to go to an OPPO CD/DVD player.  Once that arrives I will see if it happens there.

[aroide]

John,

I switched to using an older laptop (Ivybridge based) to work around the issue.  The DAC really shines through USB vs toslink and I didn't want to compromise.  When I get a chance, I'll hook my 2014 mac min back up and record the sound.

The distorted sound only happens for my using Audirvana.  I get that sound for a few seconds and the DAC no longer is recognized.  Audirvana uses integer mode of USB audio 2.0 and may be unique.  If I try and drive the DAC from the OS X system sound, I get NO SOUND at all and within 2 secs the BH DAC disappears as a device.  So the distortion may or may not give you a clue.

What I really want to do is to bring my DAC to work and get some traces on a USB gen 2 protocol analyzer.  If I can get some traces, are those useful to you?  I know for my team, its hard to use a trace without firmware source and driver source.

Tony

[Grainger49]

It hasn't happened to me again.  I got the TOSlink and haven't gotten it fished behind my cabinets yet.  There is not much room to work with.  It will not reach around the front it isn't long enough.

It might not have happened again since I haven't listened more than a couple of hours since it happened.  I'll try turning the system on, putting the CD on repeat and give it 4 hours to see.  It very well might be the Philips.