Re: [LAU] Sound quality of the Focusrite Scarlett 18i20 2nd Gen

On Sun, 8 Jan 2017 21:25:35 +0100, Johannes Kroll wrote:
>...which would mean that you if you listen to an input, you mix it with
>a copy of itself delayed by the buffer size. That would definately
>sound weird, and could explain Ralf's experience.

No, since on Linux I used Ardour and directly connected the stereo
track's outputs by jackd to playback_n. I didn't test any of the
18i20's inputs.

[rocketmouse@email-addr-hidden ~]$ pacman -Q ardour5 jack2
ardour5 5.5-1
jack2 1.9.10.r202.gf2ece24-1

On the iPad I used Cubasis 2 with a single stereo audio track and
directly connected Cubasis 2 to the Focusrite outputs.

The original WAV is ripped from Crowded House's CD "Woodface", track
5, "weather with you", a 44.1 KHz, 16 bit file and then imported by
Ardour at 44.1 KHz, 32 bit float and by Cubasis at 48 KHz, 24 bit.

>> Not just that, my focusrite sounds crappy when the outputs are "too
>> loud" in alsamixer. means over 80% its not usable. so maybe that is
>> an issue, Ralf?
>
>That's definately an issue with my 18i8 first-gen as well. When I set
>an output control to more than 0db, the output doesn't clip -- it
>integer-wraps, which causes really evil distortion. I confirmed that
>with an oscilloscope. I'm not sure whether this is a Linux driver
>issue, or bad design. It shouldn't be possible to turn volume up beyond
>the 0db setting if that causes such distortion.

> 0 dB related to what? The audio files were played with an output
< 0 dBFS and perhaps at max. 0 dBFS here. Does the Focusrite mixer
control the analog domain? Does it increase a digital signal that comes
from the DAW by the digital domain?

On Sun, 8 Jan 2017 21:46:40 +0100, Johannes Kroll wrote:
>First, look here:
>https://github.com/smilingthax/alsa-driver_scarlett/commit/7a77707b66ee476dbf2b87c18fde6a2ea4ded1ec?diff=split
>(This patch is now inside the mainline kernel; I did not write it)

It's neither part of the latest kernel supported by the rt project, nor
by the current mainline rc, https://www.kernel.org/ :

[rocketmouse@email-addr-hidden tmp]$ wget -q https://www.kernel.org/pub/linux/kernel/v4.x/linux-4.9.tar.gz
[rocketmouse@email-addr-hidden tmp]$ tar -xf linux-4.9.tar.gz
[rocketmouse@email-addr-hidden tmp]$ grep USB_ID -n linux-4.9/sound/usb/mixer.c
850: case USB_ID(0x0763, 0x2030): /* M-Audio Fast Track C400 */
851: case USB_ID(0x0763, 0x2031): /* M-Audio Fast Track C600 */
878: case USB_ID(0x0763, 0x2081): /* M-Audio Fast Track Ultra 8R */
879: case USB_ID(0x0763, 0x2080): /* M-Audio Fast Track Ultra */
898: case USB_ID(0x0471, 0x0101):
899: case USB_ID(0x0471, 0x0104):
900: case USB_ID(0x0471, 0x0105):
901: case USB_ID(0x0672, 0x1041):
915: case USB_ID(0x046d, 0x09a4):
925: case USB_ID(0x046d, 0x0807): /* Logitech Webcam C500 */
926: case USB_ID(0x046d, 0x0808):
927: case USB_ID(0x046d, 0x0809):
928: case USB_ID(0x046d, 0x0819): /* Logitech Webcam C210 */
929: case USB_ID(0x046d, 0x081b): /* HD Webcam c310 */
930: case USB_ID(0x046d, 0x081d): /* HD Webcam c510 */
931: case USB_ID(0x046d, 0x0825): /* HD Webcam c270 */
932: case USB_ID(0x046d, 0x0826): /* HD Webcam c525 */
933: case USB_ID(0x046d, 0x08ca): /* Logitech Quickcam Fusion */
934: case USB_ID(0x046d, 0x0991):
1503: case USB_ID(0x08bb, 0x2702):
1509: case USB_ID(0x1130, 0xf211):
[rocketmouse@email-addr-hidden tmp]$ ls -lh linux-4.9/sound/usb/sc*
ls: cannot access 'linux-4.9/sound/usb/sc*': No such file or directory
[rocketmouse@email-addr-hidden tmp]$ ls -lh linux-4.9/sound/usb/s*
-rw-r--r-- 1 rocketmouse rocketmouse 21K Dec 11 20:17 linux-4.9/sound/usb/stream.c
-rw-r--r-- 1 rocketmouse rocketmouse 286 Dec 11 20:17 linux-4.9/sound/usb/stream.h
[rocketmouse@email-addr-hidden tmp]$ wget -q https://cdn.kernel.org/pub/linux/kernel/v4.x/testing/linux-4.10-rc2.tar.xz
[rocketmouse@email-addr-hidden tmp]$ tar -xf linux-4.10-rc2.tar.xz
[rocketmouse@email-addr-hidden tmp]$ grep USB_ID -n linux-4.10-rc2/sound/usb/mixer.c
850: case USB_ID(0x0763, 0x2030): /* M-Audio Fast Track C400 */
851: case USB_ID(0x0763, 0x2031): /* M-Audio Fast Track C600 */
878: case USB_ID(0x0763, 0x2081): /* M-Audio Fast Track Ultra 8R */
879: case USB_ID(0x0763, 0x2080): /* M-Audio Fast Track Ultra */
898: case USB_ID(0x0471, 0x0101):
899: case USB_ID(0x0471, 0x0104):
900: case USB_ID(0x0471, 0x0105):
901: case USB_ID(0x0672, 0x1041):
915: case USB_ID(0x046d, 0x09a4):
925: case USB_ID(0x046d, 0x0807): /* Logitech Webcam C500 */
926: case USB_ID(0x046d, 0x0808):
927: case USB_ID(0x046d, 0x0809):
928: case USB_ID(0x046d, 0x0819): /* Logitech Webcam C210 */
929: case USB_ID(0x046d, 0x081b): /* HD Webcam c310 */
930: case USB_ID(0x046d, 0x081d): /* HD Webcam c510 */
931: case USB_ID(0x046d, 0x0825): /* HD Webcam c270 */
932: case USB_ID(0x046d, 0x0826): /* HD Webcam c525 */
933: case USB_ID(0x046d, 0x08ca): /* Logitech Quickcam Fusion */
934: case USB_ID(0x046d, 0x0991):
935: case USB_ID(0x046d, 0x09a2): /* QuickCam Communicate Deluxe/S7500 */
1504: case USB_ID(0x08bb, 0x2702):
1510: case USB_ID(0x1130, 0xf211):
[rocketmouse@email-addr-hidden tmp]$ ls -lh linux-4.10-rc2/sound/usb/sc*
ls: cannot access 'linux-4.10-rc2/sound/usb/sc*': No such file or directory
[rocketmouse@email-addr-hidden tmp]$ ls -lh linux-4.10-rc2/sound/usb/s*
-rw-r--r-- 1 rocketmouse rocketmouse 21K Jan 1 23:31 linux-4.10-rc2/sound/usb/stream.c
-rw-r--r-- 1 rocketmouse rocketmouse 286 Jan 1 23:31 linux-4.10-rc2/sound/usb/stream.h
[rocketmouse@email-addr-hidden tmp]$

Regards,
Ralf
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Received on Mon Jan 9 00:15:03 2017