Issues with ALIX / Voyage MPD

[Natural Sound]

I finally got around to hooking up my Bottlehead DAC and I'm having problems with the DAC detecting the correct sample rate. Please keep in mind that my system has been working flawlessly for a couple of years with all sample rates using a Micromega MyDAC.

It should also be noted that I've tried several boot up and USB connection sequences. MPD likes to see the DAC as being present during boot up or its not happy.

Here are the details.
44.1 and 88.2 and 176 files play fine
96 files show 88.2 and sound slow
192 files show as 176 and sound slow

Hardware PC Engines ALIX, USB Cable, supplied Supra. Also tried two other cables and Bottlehead DAC.
Software: Voyage Linux MPD Version: 0.9.5 (latest version)

aplay -l
**** List of PLAYBACK Hardware Devices ****
card 0: BHDACV1 [XMOS Bottlehead DAC BHDACV1], device 0: USB Audio [USB Audio]
  Subdevices: 0/1
  Subdevice #0: subdevice #0

mpd.conf
audio_output {
        type            "alsa"
        name            "Bottlehead DAC"
        device          "hw:0,0"        #optional
#       format          "44100:16:2"     optional
#       mixer_device    "default"        optional
#       mixer_control   "PCM"            optional
#       mixer_index     "0"              optional
dsd_usb         "yes"
}

NOTE: I tried to # out dsd_usb         "yes" then restarting MPD and it didn't make any difference.

Here is an example of a 96 bitstream that the Bottlehead DAC sees as 88.2.

# cat /proc/asound/card0/pcm0p/sub0/hw_params
access: RW_INTERLEAVED
format: S32_LE
subformat: STD
channels: 2
rate: 96000 (96000/1)
period_size: 12000
buffer_size: 48000

Here is an example of a 192 bitstream that the Bottlehead DAC sees as 176.

# cat /proc/asound/card0/pcm0p/sub0/hw_params
access: RW_INTERLEAVED
format: S32_LE
subformat: STD
channels: 2
rate: 192000 (192000/1)
period_size: 24000
buffer_size: 96000

If there are any Linux guru's out there that can help I'd appreciate it.

[denti alligator]

When this gets resolved (which I'm sure it will soon), I'd love to hear how the Bottlehead DAC compares to the MyDAC (which I also have).

[John Swenson]

Could you please post the contents of the stream0 file while playing a 48 family file. It will most likely be at:
/proc/asound/card0/stream0

this is assuming the BH DAC is card0.

On MY system at
/proc/asound
is a BHDACV1   directory, this takes you right there.

Is there any way you can test this over S/PDIF (optical or coax)? I would like to determine if it is a USB interface issue or not.

If you are using mpd could you try shutting down mpd and trying directly with aplay?

If you have a wave file that has a 48 family sample rate you can play it direct with:

aplay -D hw:0,0 <wave_file_name>

(this is assuming card0)

You can also try:
aplay -D plughw:0,0 <wave_file_name>

Thanks,

John S.

[debk]

I am having a similar problem with my Mac mini.  I have a 192 flac file which the DAC is showing as 176 and plays wrong.
The weird thing is that the first time I played the file it played correct and then I switched to a file with a different sample rate and when I came back to the 193 file it was showing a 176.  I am using hte supra cabke and Jriver for mac as the the media player.  I restarted the computer and still get the 192 file playing at 176

Debra

[dw]

I noticed this one or twice when I was first using the DAC. Now I can't repeat it and I'm switching between  352, 176, 48, 44. I've done probably 20 combinations with these. This is on a mac with amarra.

-Dave

[Doc B.]

Just want to assure you folks that we are on this. I will be working on reproducing the issue in the lab today.

[Doc B.]

When I got in to the office we reproduced a facsimile of the issues reported here on my Mac Mini. What we did was take a DAC that had been running properly on all sample rates for an hour or two on USB. I powered it down and disconnected the USB cable. Then I switched the selector to SPDIF. Then I powered it back up and plugged in the USB cable. The Mini was left on, with Amarra  running (not playing music, just open) the whole time.

With the DAC still switched to SPDIF, the DAC display read 44.1. When I switched it to USB it read 352k. Audio MIDI settings on the Mac showed 384k. Playing any 48K multiple sample rate would only run at a multiple of 44.1K -  i.e., 96K ran at 88.2k, 192K at 176K, 48K at 44.1K, etc.

Solution:

So I unplugged the USB cable from the DAC, powered it down.
Shut down the Mac.
Made sure DAC was set to USB.
Connected USB cable to DAC.
Powered DAC up.
Booted up Mac.

DAC shows 384K, or whatever the last Audio MIDI setting was, and functions properly.

Please try this exact undo/redo sequence and let us know if it resolves the issue. I'm afraid I don't have a Linux box here, but I'm sure John is working to reproduce the issue on a Linux box.

[Grainger49]

Guys,

You don't get this kind of service if you buy a DAC from Wadia, Music Fidelity, Sim Audio, Elgar, Manley (sorry Eveanna), PS Audio or any of the other guys.

There is a reason to be here and this is it!

[fullheadofnothing]

Just to add a few notes about the reboot procedure:

The DAC was displaying 44.1 when powered up while the computer was off, and during the first phase of the computer's booting. When the Mac was about 3/4 way through loading the kernel, the display switched to 384. This computer is set up to automatically boot into the sole user account. As the account loaded (i.e. Finder was showing, but not yet interactive) the sample rate displayed changed to 48, which is where Dan had left Audio MIDI Setup before the shutdown. As stated before, from here on out the DAC behaved normally.

[Doc B.]

For the sake of completeness I should also add that I used Amarra 2.4.3 for this test. I had been using the latest version and it works great, except for the fact that I had to reboot Amarra every time I switched to a different DAC as I checked them out. 2.4.3 seems to be able to handle hot switching the DACs - something that nobody but me is gonna be doing.

[Doc B.]

OK, more data -

We were able to reproduce the issue on another DAC. We did exactly the same sequence to refresh it. This time it did not take.

So we left the Mac booted up, and powered down and disconnected the DAC. We waited 12 minutes, then powered up the DAC and connected the cable. Problem solved, the display went right to 384 as expected.

This would tend to indicate that there is something either in the DAC or the Mac that needs a little time to reset.

[John Swenson]

I really want to find out if anybody has this issue with S/PDIF (optical or coax).

Also it might be related to temperature inside the DAC case. Does it only happen when the DAC has been running for several hours?

Does it happen right after power up, or does the DAC work fine for awhile, then when you change rates it gets it wrong?

I cannot make this happen on mine,
some differences are: I don't have a Mac but I do have windows and several linuxes. My Dac is not in the official case, it is screwed into a piece of plywood, thus might be running cooler than when in a case.

The sequence of numbers on the display is normal. If the DAC is on before the computer it will show 44.1. During the boot of the computer when DAC first connects to the OS it gets set to its maximum rate, then when boot is finished and applications start up it will show the rate of the application.

When the selector switch is set to S/PDIF the USB receiver is still active and can connect to your computer, the switch is basically switching between the output of the two receivers.



Thanks,

John S.

[fullheadofnothing]

Since we have been encountering this issue during the burn-in cycle, they have generally been warmed up. We may have seen it on a cooled unit, but I am not sure either way.

When the DAC was glitching on USB, we plugged TOSLINK in from a BluRay player (TOSLINK is dead on that computer) and were able to get 44.1 and 48 to display properly. We did not try the coax but we can if that would be useful. When switched back to USB, only the 44.1 derived rates were working.

The problem will manifest immediately when the issue is present. It seems that once it is running OK, it stays fine, but this has not been extensively tested.

Also, during our last test, when we did a full shutdown/start-up but it didn't resolve the issue, the display showed 352 when the OS loaded.

[dw]

For me it seemed like it happened in the first 24 hours of being powered up. Perhaps, even the
first 6 hours. Since then I've left it powered up continuously for 3 days and have not seen the issue.

Thanks,
Dave

[Doc B.]

The sample rate input switch glitch seems to happen right at startup on USB for us here. We have not seen it happen with SPDIF or TOSLINK. We have seen an SPDIF connection quit a couple times - not a sample rate glitch, but a no play situation. We aren't sure if that is source related or not, and it seems that it is easily reset with a disconnect/reconnect of the power to the DAC. We have not seen any odd behavior with TOSLINK.

We are letting one DAC cool down now, to see if we can reproduce the glitch on a cold DAC.