[moodyalex]

Bonjour everyone,

First, please excuse me for sometimes misusing English, as i'm french and also for being a learner !

I've recently set up an audio rig with: MacBook pro running lion, audirvana plus and fidelia (trial for now), a Mav-audio TubeMagic D1 plus (up to 24/96 in USB, 24/192 for optical/spdif) and akg k701.

here's my problem :
With every configuration, USB input can't handle 24/96, whereas 24 / 41 or 48 is ok, and 16/96 is ok (when i set 24/96 for the input in Audi midi set up, the dac doesn't "boot" and no music can be played).
When players are set to automatic control of bit/rate, they lower bit depth from 24 to 16bit.
The spdif work fine up to 24/96 using the optical out from the macbookpro, but with sound limitation from not bypassing coreaudio.

i browsed the internet forums and i've got the impression that it might be kind of a saturation of USB bus.
The tenor 7022l (interface used by the dac) datasheet says:
- it is USB 2.0 audio class 1 FULL SPEED
- "Due to 12Mbps bandwidth limitation of the USB full speed operation, only one I2S input or output can be set for 24bit/96KHz application, under this condition, for simultaneous multiple-channel applications, rest of I2S interfaces has to be configured at the combination of 16-bit / 48KHz, 16-bit/96KHz and even lower resolution/sampling rate. In the application of USB internet telephony, lower resolution and sampling rate are needed."

When i look into "system profiler" then USB i see all USB bus. MacBook pro has only 2 USB ports. No matter which port i choose :
- maverick appears as USB full SPEED (not high SPEED) with 12mbps : So normal as i understand.
- it is always a shared USB bus (with iSight or internal keyboard or trackpad). Disabling iSight with isight disabler didn't make any change.


is it possible that, by being shared, USB bus is limiting bandwidth , leading to incapacity of habing full 24/96 ?

Do you have an advice ?

Thanks a lot, for this and for being such a great resource through this Forum!

Alex

 

[moodyalex]

If anybody's interested (not even someone ? )
With help from GFEC (who's manufacturing the tenor 7022l interface) I think we found the answer.

For audio interfaces ( input and output or D to A and A to digital, like in recording interfaces) USB full speed have limitations :
- 2 Inputs and 0 Outputs at 24Bit / 96kHz
- 0 Inputs and 2 Outputs at 24Bit / 96kHz
- 4 Inputs and 2 Outputs at 24Bit / 44.1 or 48kHz
- 2 Inputs and 4 Outputs at 24Bit / 44.1 or 48kHz
- 4 Inputs and 4 Outputs at 16Bit / 44.1 or
- 4 Inputs and 4 Outputs with every other sample rate up to 16Bit/44.1kHz.

THe problem is, since os x 10.6, some audio DAC, though only having output capacity (d to a), are wrongly recognized as having both input and output. That's why I see both in and out in "audio midi settings"!!

Then the player, in hog mode, matching depth qnd rates to file played, try to equalize input and output.... Leading to 24/96 +24/96 = USB full speed saturation!!!

The same problem apparently occured with udac2 users!

 

[etys rule]

Thanks for posting this and following up. I, too, just received the Maverick D1 + and found the same thing happening. No sound when connected via USB. I had the midi settings maxed at 24/96, but they were 2 in and 2 out. Obviously that won't work, so I swapped to optical and there was no problem.
 

 

[moodyalex]

You're welcome!
The problem is that using optical you can't bypass coreaudio and benefit from integer mode in audirvana, etc
Which os x are you using ?
When you go to audio and midi settings, can you see output and input (with 2 sources: external and spdif) ?
Can you try to set the input at 24/48 or 16/96 and see if it works using USB ?

 

[moodyalex]

I told Ryan from mav audio. He's working on it to understand and maybe solve our problem!

 

[moodyalex]

I found a solution!! I'm waiting for ryan's answer to confirm but it works !
I just used the USB descriptor he gave me and unable some tenor 7022l settings. Now Mac os recognize only an output and 24/96 works fine!
Ask me in pm if you want the descriptor (working only in windows)

 

[mkrzych]

I found a solution!! I'm waiting for ryan's answer to confirm but it works !
I just used the USB descriptor he gave me and unable some tenor 7022l settings. Now Mac os recognize only an output and 24/96 works fine!
Ask me in pm if you want the descriptor (working only in windows)

Hello,
I have similar maybe problem on Mac OSX now with my DAC. Do you have any information how to fix it on Mac OSX? What and how to find this descriptor? I can see 2in/2out as well on my Mac for TENOR chip, so it there any solution to fix it and disable input?
 
Thanks a lot for any help.

 

[junkscience]

The solution to the problem in connecting an external DAC (e.g., a Maverick Tube Magic, other external DAC) to a MacBook Pro Mac OS X  to pass the high resolution (hi rez) file at 24/96 audio out via the USB to the DAC:
 
"The trick is to set 24/96 for output, but 16/96 for input. It seems that OS X reserves the bandwidth on the UBS chain for input, even though the DAC will never use it"
http://www.head-fi.org/t/590961/96-khz-24bit-integer-output-via-usb-to-burson-ha-160d-on-latest-os-x-not-working-solved
 
Step 1: Audio MIDI Setup > Window > Show Audio Window
Step 2: Select the ***Connected*** USB DAC in left hand column (e.g, Maverick Audio ...)
Step 3: Select "Input" and set "Format" to "2 channel 16 bit integer" -- (this is the obscure non-intuitive step)
Step 4: Select "output" and set "Format" to **** 2 channel 24 bit integer"  **** -- (this is the goal)
 

 

 

[junkscience]

RE: connecting an external DAC:
A few more pearls here:
http://www.audioasylum.com/cgi/t.mpl?f=pcaudio&m=143708