USB DAC with Tenor TE8802L - sound drops/crackels

Volumio Development Bug reports
1

Hi All,

I use a DAC8 from T+A and its not playing well under Linux including Volumio2. The audio output is very stutteriing… i guess something is frong with the audio buffer in the asynchron mode, which seem to underrun frequently.

I am keen that it can be adressed because the Teac UD-H01 seem to run ok under linux and also within volumio. I am not a Linux kernel guy but i digged out some infos in the Internet regarding this which might bring us to a solution. I also contacted T+A and they gave me a hint, which is unfortunatly not usable in an easy way.

1.) Here are the Infos from T+A:

They told me that this works well… aplay -D hw:2,0 -B 8000 -F 4 test.wav

I tested it and it played well till 192khz … the switch -B and -F are setting the Alsa “buffer_time” and “period_time”. Unfortunatly I can set these variables within the aplay but not for the whole alsa or start the mpd using those settings…
-> could one of the experts here make those variables configurable which could probably help for many USB DAC issues?

2.) I found a implemented USB AUdio FIX in the Forums which were created for the Teac UD-H01. Maybe we can add the USB device numbers of the T+A DAC8 or somehow genericly the device id’s of all Tenor 8802TL based systems to see if this works well?

here are the infos regarding this Fix…

lists.ubuntu.com/archives/kerne … 42304.html

stable.vger.kernel.narkive.com/C … dback-data

It really look like a problem of the internal Buffer Handling/Calculation and I would love if those issues for the Tenor receiver could be fixed in a general way since the manufaturer of this chipset did quit and is not supporting any of these products.

It would be really cool if somebody could pick this up and adress it within the volumio2 contect and maybe a generic linux kernel patch could be the result for this effort as well?

Here are the T+A DAC8 USB ID’s

[ 7218.315006] usb 1-1.5: New USB device found, idVendor=1852, idProduct=5034
[ 7218.324362] usb 1-1.5: New USB device strings: Mfr=1, Product=2, SerialNumber=0
[ 7218.334081] usb 1-1.5: Product: T+A USB Audio Device
[ 7218.341442] usb 1-1.5: Manufacturer: T+A elektroakustik
[ 7218.352696] input: T+A elektroakustik T+A USB Audio Device as /devices/platform/soc/3f980000.usb/usb1/1-1/1-1.5/1-1.5:1.0/0003:1852:5034.000/input/input0
[ 7218.372377] hid-generic 0003:1852:5034.0001: input,hidraw0: USB HID v1.00 Device [T+A elektroakustik T+A USB Audio Device] on usb-3f980000.usb-1.5/input0

kind regards,

–thomas

2

Dear Volumio Team,

actually I were able to fix this issue with a kernel patch. At a later time I will provide this patch to the mainline kernel sources… but this will probably take some time…

Is there a way that i could already provide this patch to your volumio (specific) kernel sources?

Also other user of this Tenor Chip (8802tl) should reply if they recognise this issue and then maybe I could add these devices to this fix as well…

Please note that the this excludes the popular Teac UD-H01 … because this device is already fixed in the linux kernel and should work properly.

kind regards,

–thomas

3

Dear Thomas, very nice work indeed!
I think the easier way to include your fix would be a manual overwrite of the incriminated module, if that’s possible. Since we use mainline pi kernel, we don’t recompile it.
Does it affect a particular module or it’s something that requires a full kernel swap (and this will bring loooot of troubles with compatibility checking…).

I’m very interested, let me know

Michelangelo

PS: Which version of Volumio are you using?

4

Dear Michelangelo,

I dont want to sound too cheesy, but first thx a lot for all the great work you and the community has done on this project!!! I really enjoy it, especially Volumio2 is a real pleasure!

I did dig though this module topic and I think it could be done by patchin the snd-usb-audio module. I could try to build locally a kernal with exact the version u use in your volumio 2 releases … test it here and then provide this module to you…

Lets cross fingers if this can work…the kernel is checking those module dependencies very hard…

In the future a real fix will be supplied via the mainline … i am already in contact with those guys to push it in there…

kind regards here from berlin!

–thomas

5

Danke Thomas!
I think a good solution would be having both snd usb modules, and add an option (rpi-only) to switch one accordingly to the situation needed (by renaming them and rebooting).
So thank you very much for the effort… Let me know and we’ll add this !

6

Hi there,

I could not find any further comments on this topic, so I hope there will be some response. I am trying to use a roonbridge with “dietpi” on my raspberrie Pi 3. All seems to be working well, exept for the sound drops/crackles as reported in this topic. I also use the TA Dac 8 with the Tenor USB chip. I am not an expert on linux/alsa at all, so I whas hoping there is an easy solution to the problem?

Thx,

Peter