Hello,

I recently purchased a Focusrite Scarlett 4i4 external USB audio card. I am very happy about the audio quality, and recordings are very noiseless.

Unfortunately, during playback, I have a very annoying random click (a sound similar to a elecrostatic discharge, very short and high pitch) every second or so.
That happens :

• with every output, both headphone and speakers,
• on both audio recorded on disk (SSD and HDD) and on live input,
• with either PulseAudio and Jack.
• sometimes louder than others, and sometimes more to the left or to the right

I do not have that issue with my other devices (internal soundcard or graphic card HDMI). I also don't have the issue on Windows. The card is dead silent with no audio playback.

I tried a few things including increasing buffer and periods in Jack, or booting with usbcore.autosuspend=-1, but I can't seem to solve the issue on my own.

I have no idea what to try next (except maybe boot a live CD of some other Linux distro dedicated to music creation). Do you have some?

Thanks.

I would contact the official support.

Thanks. I might end up doing that, but the card is not officially supported on Linux. I have read multiple comments of people who got it working though.


I just tried Ubuntu Studio 19.10 and I have the same issue :S

I guess it is hardware related (power supply), that's why I told you to contact the official support. But obviously it is just a thought.

Hi djib,

I have the same device Focusrite Scarlett 4i4 3rd gen and I have the same issue: random, slightly clicks during playback on Linux.
From my tests:
- it happens on Linux regardless of the machine, kernel 4 or 5, even 5.6 (1)
- no issue with a native Windows running official drivers (2)
- the issue happens also with a Windows running official drivers as a Vagrant libvirt guest of a Linux machine (3)

I started checking the USB URB isosynchronous frames. From what I see, native Windows (2) has shorter URB frames than (1) and (3):
at 48 kHz:
(2) each URB is composed of 16 packets of 6 samples of 4 channels with 32 bits resolution
(1) and (3) each URB is composed of 32 packets of 6 samples of 4 channels with 32 bits resolution

Unfortunately, the current Alsa driver does not allow to change the number of packets (was the case with nrpacks option before implementing automatic length guess that works well most of the time).

I'm not a USB Guru, just learning from what I see and some resources.
Not sure, if the URB length that is too large can affect the audio on the sound device, may be a really short buffer that does not support packets of this length?

=> I will check if I can limit the packet number with a quirck on the USB audio driver and tell you if it improves things.

Cheers,

Hi pan64,
Thanks for you suggestion.
The device is self powered by USB 3 (no external power supply possible on this model) and works well with Windows on the same machine so it would be quite difficult to make the official support understand that since Linux is not supported but the intended OS Windows works.

Thanks for the feedback.

I ended up sending the device back Too bad because I really liked the sound.
I am considering purchasing a ConnectAUDIO2/4 which seems to be one of the only USB cards with official linux support.