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Focusrite scarlett 2i2

Hi! I get a problem qjack's software! I bought this Usb'soundcard and I get 42 mm of latency to playing very well! When i try to get fewer latency, xruns running! How can I get better performance??? Pleaseee helppp meeee!!!!
1024 48000 2 - spec qjack
6000 dual core 4 ddr2 - spec computer

Image icon j.jpg76.64 KB
Image icon j2.jpg106.18 KB
rncbc's picture

for usb devices the best compromise you should get is:

sample rate (-r): 48000
frames/period (-p): 128
periods/buffer (-n): 3

these settings makes for a static i/o latency of 8 ms, which is pretty good and enough for most setups.

if you still get systematic xruns with the above, then you may start looking at the hardware itself or the device driver configuration (kernel/alsa module params, nrpacks, whatever).

please note that i don't know nothing about this device, so the are only wild tips.

also, if all else still falls short, consider a better tuned kernel eg. threadirqs boot option or preempt_rt patch + rtirq w/usb on top priority


Tnxxxx for reply me! So I tried to change it! But now qjack dont' run neither! (You can see screen above) I tried Ubuntustudio also - rt-kernel of course - but latency is always at 38/35 mm!
I don't undestand why I get it! O_o... I thought to my motherbord's USB! Is it possible that if I get an USB 2.0 pci I'll get better latency?Thanxxxxx

rncbc's picture

why is it now hw:3 while before it was hw:1? are you sure you're dealing with same precise device to start with?

i guess you 're messing things up. make sure the focusrite is exactly the device identifier you set into "interface" setup/settings field. when in doubt, please use the [>] device selection drop down menu button. always ;)


Yes, it's the same! Because I have change usb's port...tnxxx

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