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

Johannes Kroll j-kroll at gmx.de
Sun Jan 8 22:29:31 UTC 2017

On Sun, 8 Jan 2017 23:06:54 +0100
Ralf Mardorf <ralf.mardorf at alice-dsl.net> wrote:

> 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.

OK. Would still be interested in the comparison recordings you

> >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?

I'm referring to the ALSA mixer control, which goes up to +6db. 

> 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/ :

I've used the Scarlett on a stock Ubuntu kernel, Mint kernel, and the
AVL RT kernels. Mixer controls work on all of them, so I assumed the
patch would be in mainline by now. 

You can try applying this patch:

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