On Sat, 31 Jan 2015, Peter O'Doherty wrote:
Many thanks Robert, Arnold and Len for your very helpful advice.
Up to now I have only been doing sound synthesis but want to start recording
and live processing of sound too, so I'll take your advice and get a usb
device.
Generally, I would take the laptop to the store where you will buy the USB
audio IF and try it in the store. This is the nice thing about about a
laptop :)
I am assuming that you already have jackd and qjackctl installed. I would
also install the lowlatency kernel.
If you have used qjackctl before but only with the default device... when
selecting the "Interface" use the > button not the v dropdown. You will
need this to find the USB device to start jack with. Many USB devices do
_not_ have mixer controls in ALSA, but rather have physical level knobs
on the unit itself. This is a good thing (IMO) as no software can change
your carefully set levels for you.
With a laptop, you will want to find out which USB plug is not shared with
anything internally (SD reader/camera/etc.) and use that for your audio
IF. Do not use the same USB with anything else (mouse/external drive/etc.)
I know this all sounds very picky, but computers are _not_ designed around
low latency audio... they are designed for high throughput.
One last thing: You may have to boot with WIFI turned off for clickless
audio for lower latencys. The choice is your's to run a higher latency and
monitors the input audio externally or do the work to get good low latency
performance to monitor via the audio IF out. Many of even the cheaper USB
audio IFs do allow mixing the input audio directly with the audio coming
from the computer for miintoring. This does mean not allowing the
recording program Ardour for example, to do the monitoring for you.
Really low latency is only really required for live use. That is using the
computer as a softsynth on stage with a keyboard controller or as an
effects unit (with guitarix for example). For recording a higher latency
can be very workable.
--
Len Ovens
www.ovenwerks.net
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