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

[aroide]

I just received my DAC and I have an issue.  I've already worked through the startup sequence and sample rate glitch protocols, and I do not have issues there.

I'm driving from USB and my DAC sounds clipped and nasty.  I can get sounds for a few seconds, then the DAC is dumped from my mac mini (latest version) as a device.  This happens consistently and also happens from my apple laptop running different software.  Same issue every time.

More info:  sample rate displays correctly always and I've tried 44.1 files.  I might have tried others but I can't recall.  DAC power is clean as a whistle driven from a PS audio regenerator.  DAC is driving a BeePre.  My old DAC worked fantastic in this exact same setup.  I tried both audirvana and mac mini audio output... same major sound quality issue.  I don't have a reliable SPDIF or coax source to try.  But I'll try and figure something out there.

Did I get a bad DAC?

Tony

[Doc B.]

This is not a situation that we have heard of before, so it might be worth checking out the other inputs to see if we can narrow down the possibilities. Can you try running TOSLINK out from the Mac Mini?

[aroide]

OK updated my thread saying toslink didn't work.  I had the switch backwards...

toslink 44.1 does work and sounds fine.   USB is not usable on several macs with different usb cables and sources (audirvana 2.0, 1.5, and system output).  All USB is clipped, distorted, and not listenable.

I have other xmos 2.0 USB dacs on these same systems that work just fine.

[John Swenson]

So you hear badly distorted music (but still recognizable as music) for a few seconds then it goes away (ie goes silent) and stays silent until what happens? I'm just trying to get a good understanding on what you are experiencing. Does the display keep on showing the correct sample rate when it stops?

The badly distorted but recognizable music sounds like the DAC is getting fed the wrong format. The USB interface on this DAC only supports S32_LE (32bit integer) format. If somehow the software is sending something else it would sound the way you describe. The software (player and or OS) is responsible for adding the zeros to convert 16bit or 24 bit to 32 bit. There might be something in either the player or OS configuration that is forcing a different format.  (usually the software asks the DAC what it supports and automatically does the conversion, but some software allows that to be over-ridden)

I don't know Macs so I can't advise where to look for this, someone else will have to give advise on that.

John S.

[aroide]

Hi John,

So I have 2 different behaviors using USB.  The first is that I hear some audio, but it sounds like it is digitally clipped... I'm familiar with that sound from my music work.  It is recognizable as music, but it sounds like 50% or so of the samples are clipped.  I get this sound for about 2 seconds and then the USB device no longer appears on my computer.  To get it back I need to power cycle the DAC.  That happens with a latest mac mini running Audirvana 2.x.

2nd behavior is when using the DAC as the normal output of the mac.  In that case I can select the DAC, but when I try and send any audio, I get no sound and IMMEDIATELY the DAC disappears as a device.  power cycle again brings it back.  This happens on 2 different macs and with audirvana 1.5. 

In all cases, the macs have USB 3 ports.  As macs are basically unix, I'm assuming there is a log file I can get to see when the DAC disappears.  But I suspect that it is on the DAC side because of the audirvana behavior... it keeps playing as if the DAC is still there.  On the mac audio side, the mac sees it disappear and then switches over to internal audio as a default.  Maybe some firmware programming went wonky?

I have tried switches in audirvana to force 24 vs 32 bit mode, turn on direct mode, disable integer mode.  In the 24/32 case no behavior change.  In the others I get no audio at all.

My other XMOS dacs are all fine on the same equipment.  I'm not sure if you are using XMOS firmware or something special for the USB async receiver side.  But it is unusable for me in any USB configuration.

Tony

[Doc B.]

Hi Tony,

Sorry that you are struggling with the DAC. I think the thing to do at this point is for us to issue a call tag and bring it back here for a look see, and get you up and running ASAP.

[aroide]

Thanks much.  The DAC sounds FANTASTIC with my toslink test.  It is immediately a dramatic improvement in detail and musicality.  I would LOVE to have it happily creating music.  Let me know what the process is.  I have all the original packaging and can send it soon.

My BeePre is lonely :-)

Tony

[Doc B.]

Hi Tony,

Sorry to take so long to get to your DAC, it's been a very busy week. I ran it in our testing setup this morning, along with the four DACs we are shipping out today. I took the most difficult approach I could to try to get it to fail, which is to hot plug to USB with Amarra up and running on the computer. The Mac found the DAC immediately and played all sample rates without distortion. Josh just also tested it on a Win 7 desktop with no issues.

So I guess we will need to figure out what the issue is between the DAC and your computers. We haven't seen what you have described with a Mac ever, but we have seen a similar issue with very new Laptops running Win 8.1. In those cases it had to do with the USB settings in the BIOS, and was solved by disabling booting from USB. Don't know if that is possible on a Mac and I don't have the latest Mac Mini with which to test.

Next we will try loading a trial of Audirvana to see if anything changes.

[dw]

Has anyone else tried the BH DAC on usb 3? I've read that usb 2 and 3 are supposed to be compatible but
also that some people have trouble when plugging usb 2.0 devices into usb 3.0 ports.

-Dave

[John Swenson]

Has anyone else tried the BH DAC on usb 3? I've read that usb 2 and 3 are supposed to be compatible but
also that some people have trouble when plugging usb 2.0 devices into usb 3.0 ports.

-Dave

Yes I have tried it on a USB3 port and it works fine on one computer and has some problems on another. The correlation seems to be not whether it is USB3, but whether the motherboard uses UEFI (modern BIOS replacement). Some manufacturer's UEFI seem to have an issue. Since newer motherboards are the ones that seem to have USB3 and UEFI it's sometimes hard to tell what is really responsible, the USB3 or the UEFI.

I have a laptop which does NOT have UEFI but does have both USB 2.0 and 3.0 ports, the DAC works fine on both types of ports. I have a desktop that has UEFI, 2.0 and 3.0 ports, all of them have problems. This tends to point to it being a UEFI problem rather than a USB3.0 problem.

The UEFI problem seems to be taken care of by turning off all UEFI USB boot options. The UEFI is supposed to hand over control of all devices to the OS when it starts, it looks like some UEFIs don't completely do that. If the UEFI never talks to USB it doesn't matter.

John S.

[dw]

Thanks for the explanation, John.

[aroide]

thanks Doc!

I'm very curious to see what Audirvana on a mac with USB 3.0 does.  All my macs are now newer and have USB 3.0.  I know Audirvana takes low level control of USB so it can enable 'sonically good' modes like integer (vs normally floating point approximations are used for data).  I tried combos of enabling/disabling features, but nothing worked. 

My listening room mac is a 2014 mac mini running latest version of Yosemite OS X.  All ports on all my macs are USB 3.0.

I was digging and found some issues with XMOS 2 and USB 3 macs (the Shiit DAC mostly).  The solution is to put a USB 2.0 hub between mac and DAC.  I have a 2.0 hub if that turns out to be the workaround.

[fullheadofnothing]

I realized that my wife's computer is newer than mine, so I checked and it does have USB 3.0 ports. I tried it and the DAC works fine. The computer is a Mid-2012 13-inch MacBook Pro running OSX 10.9.5. Listened for 15 minutes on iTunes 12.1.0.50 before installing the Audirvana demo. Still works fine. Tried both USB ports as well.

Did you ever try just using iTunes, or was all testing done with the same software?

[aroide]

I tried native mac audio and audirvana.  So I must have one of the unstable combos, or maybe latest USB silicon and driver are different?  My systems are 2014 and the latest 2015 Broadwell-based macbook pro (kick a$$ machine).

I can put a usb 2.0 hub in the chain.  This should eliminate any USB 3.0 port issues.  3.0 can downgrade to 2.0 data rates, but the HW protocol is still 3.0.  A 2.0 hub eliminates that issue (assuming the hub is stable talking to a 3.0 port on the mac.

[Doc B.]

Sorry to say we don't have a more recent Mac around to try. Our not being able to recreate the issue does seem to point to it having to do with some change made in the more recent models. The other remaining possibility is the OS, as I don't think we have tried it with the latest version.

My son has a newer Macbook. I will ask to try a DAC on that when I see him next, which might be a week or two away.