Bifrost (C-Media 6631a)

[Jud]

Playing with a new DAC (just PCBs on a bit of plywood for now) in my main system, so moved my Bifrost (CM6631a output chip) upstairs to the desktop system with XXHE.  Win7 will only run WASAPI push (Event style) with the Thesycon driver, so XXHE only sees the DAC if the Win audio driver is running.  No minimized OS, no Ultimate XTweaks, etc.

Any suggested workaround, or should I put the Audioquest Dragonfly back in the system?

[PeterSt]

Hi Jud,

First off, congrats with your homebrew doing something !

So, what's up with your Bitfrost now ? hard to tell ...
Since it should be "capable" of KS just the same through the Thesycon driver, to me it looks like the Driver Config Files are not "correct". Don't ask me how that can be, but it has to be something like that. I think it can also be a wrong install of the Drivers for whatever reason. If so, it may be hard to solve for you without the help of up to Thesycon  themselves. But maybe Schiit has some knowledge too.

What you also can try is tick that box "Contains Diacritical Marks" (similar) in XXHE Settings. Don't forget to untick it when it doesn't help.

It could be an idea to try Foobar with KS. If that works it should be XXHE and we must see further what to do to sort it out.

Peter

[Jud]

Hi Peter,

Thanks!  I can't really claim that it is "homebrew," I just soldered a couple of connections to a transformer and an IEC inlet.  The rest is PCBs made by someone else with the usual plastic "push and click" connectors to run the wires between boards.  The nice thing is it will accept 352.8/384 sample rates through async USB, which is the same rate at which the D/A conversion is done, so no in-DAC sample rate conversion necessary.  (Guess where I got that idea.)  I plan to replace the point-to-point wiring with better stuff and get two wooden chassis for the boards eventually.  Looking forward to making some room to install Boot Camp on my MacBook Pro and running it with XXHE.  Maybe not the ideal environment for XXHE, but still it will be interesting to be able to hear Arc Prediction without a DAC chip's SRC layered on top of it.

Now the Bifrost - From what I read last night, it does seem to me that the behavior I got is what's expected from the Thesycon driver for the CM6631a.  There are multiple other reports on the Web that these drivers don't allow kernel streaming, just WASAPI push/Event style.  I'm as certain as I can be (i.e., one can never be absolutely sure, but if I had to bet...) that the driver installed as it was supposed to.  I also have Win8 on the same computer, and everything about the driver installation and result is identical there - the Bifrost identification in Win sound properties includes "Speakers," and there's no other entry available for the device.

Forgive my ignorance but does ASIO roughly or exactly equal kernel streaming in Windows?  'Cause I've read that ASIO4All works with the CM6631a chip.  On the other hand, what I've read about ASIO4All leaves me thinking that may not be the solution I'm looking for.

[Jud]

A snippet from the Web that may help:

Other sources: the latest version of the driver is a unified version for the CM6631 and CM6631A devices, thus available from other manufacturers using either the 6631 or 6631A part (likely they all offer the same versions. some manufacturer may be faster than others in offering newer versions):

•Emotiva [link]
•MHDT Labs [link]
•Schiit [link]
I tried the Emotiva provided driver and it works. Here is a screen shot:



FIRMWARE

There are two versions of the firmware as discussed here [link] and here [link]. However, these versions seem to be related to the SPDIF features of the chip. For this board, which only supports I2S, I don’t think these versions of the firmware matters. Note: according the tdtsai [diyaudio], the developer for the driver s/w, the firmware for the CM6631 is not compatible for the CM6631A.

•Firmware 0101 PID 0×0319 can output to SPDIF via CMedia ASIO, but it will never passthrough DTS and AC3. I2S and SPDIF-Out work simultaneously
•Firmware 0108 PID 0×0314, using current drivers, will not output to SPDIF via ASIO, but it can passthrough DTS and AC3 correctly. I2S and SPDIF-Out are reported as different devices (so one output at a time depending on which one you choose)

[Jud]

Forgive my ignorance but does ASIO roughly or exactly equal kernel streaming in Windows?  'Cause I've read that ASIO4All works with the CM6631a chip.  On the other hand, what I've read about ASIO4All leaves me thinking that may not be the solution I'm looking for.

Never mind re ASIO.  "Direct kernel streaming" or more recently avstream, it appears.

[PeterSt]

I don't quite understand your latter post, but anyway :

ASIO4ALL would work if only XXHighEnd supported ASIO, which it does not.
Otherwise ASIO goes around KS streaming. So when KS does not work, ASIO still can (but not for XXHE).

[Jud]

I don't quite understand your latter post

Likely a result of my reading stuff like this too quickly in an attempt to gain a rudimentary understanding of what "kernel streaming" is on Win 7:

https://en.wikipedia.org/wiki/Windows_legacy_audio_components  (see the Kernel Streaming section)

So when (if?) XXHE is using something other than WASAPI in Win7, what is it using, if that's something you want to talk about?

[PeterSt]

Ehm, Kernel Streaming.

Sorry to come across confusing, but that's really the sheer answer.

Also read this (quote) from your WikiPedia link :

WASAPI Exclusive mode bypasses the mixer, as does using third-party audio APIs like OpenAL or ASIO, which still have direct access to the hardware.[14]

So, this tells (you) that ASIO is just another method (and not part of Windows) to get to the audio hardware.
XXHE never supported it because it sounds like sh*t, actually just like WASAPI doesn't sound the best. It's only that XXHE started it's life with WASAPI (and over a year earlier than any other player) - which is why WASAPI is supported. But I think if I removed it, nobody would complain (not that this is your subject by any means).

Peter

[Jud]

Ehm, Kernel Streaming.

Sorry to come across confusing, but that's really the sheer answer.

Peter

Not confusing, actually it gives me the chance to explain one of my previous comments: It appeared to me (whether correctly or not) from the Wikipedia article and other references that AVstream was the name for an improved MS kernel streaming driver in XP and later.

So getting back a little on topic:

Any chance of the Thesycon drivers from another company working (Emotiva and one other were mentioned in that snippet I quoted above)  or best not to take the risk?

And if not that, then I can try the diacritical mark checkbox; failing that, it's probably back to the Dragonfly while I or someone else contacts Schiit/Thesycon, I suppose.

[Jud]

Just to close the loop on this one -

Looked through everyone else's CM6631a drivers, including the ones Crystal Media offered on its own site.  They were exactly the same as those from Schiit.  I just didn't feel up to taking the time to try to persuade CM and/or Thesycon to change the drivers, so the Dragonfly is back.

[PeterSt]

Thanks for the feedback Jud. I lacked further answers anyway ...
(but still I am positive that it should be able to work and it is about Init settings which come along with the drivers - but you can't change them yourself because you will be beaten by Windows complaints about the signed drivers. At least that is what I think).