Re: [LAU] Dual Delta Setup

On Sat, December 29, 2012 3:43 am, Ben Bell wrote:
> Hi all,
>
> Having recently acquired a second Delta 1010 for my setup I've been trying
> to run the two in tandem using the alsa Multi hack. I'm getting the xruns
> that I understand are expected but harmless[1] but I'm also getting some
> audible ones, which are obviously more of a problem. They're synched via
> the
> S/PDIF link and running either card on its own seems pretty solid.
>
> I've seen on various mailing lists people talking about digging into this
> but not found any conclusions. Is anyone here running dual Delta 1010s
> who can double check I'm running the latest recommended settings?
>
> I'm on a dual core 2.3GHz Athlon (4450e), running linux 3.2.0-2-rt with
> cpu scaling disabled, and the cards have exclusive use of IRQs 17 and 18.
> Jack is running at 44.1KHz with 6 frames and 64 periods, audio IRQs at
> rtprio 85 and Jack at rtprio 82.
>
> bjb
>
>
> [1] http://www.jrigg.co.uk/linuxaudio/ice1712multi.html

This page you mentioned lists RT kernels as a possible problem and
suggests using a kernel without the RT patch, but with preempt (a
lowlatency kernel) as the best way to go. I also suspect the latency may
need to be a bit higher with two cards, but I have not tested that.

Remember that John Rigg's setup has/had a hard wired clock setup (he seems
to have removed the link that shows it). He installed high quality clocks
in the PC case and wired them in place of the D1010 PCI board clock. So
all three of his D1010s were hard synced without using wordclock or
s/pdif. (he also used off board voltage regulation... in anycase his was
not an "out of the box" setup)

As with all Jackd projects, you need to analyze your latency needs for the
part of the project you are working on. For example, I use a low latency
for tracking (jackd started with -p64 on my old P4) and try to track
without effects and mute tracks I don't need to hear to do a track. Then I
increase the latency for mixdown and add whatever effects I want/need to
make it sound right. Some musicians need some effects to get the feel for
what they are playing, so each project is different.

In your case, I would recommend a higher latency if recording a live
performance (where you need lots of inputs) with all monitoring done
before the signal gets to the D1010 inputs. This would also be true if
recording "live in the studio". I would use only one D1010 for doing
single tracks with the lower latency (I find I rarely need more than two
tracks at a time, but I have no drums to record). That is, only use the
two D1010s synced when you need it and accept their limitations. The idea
of one setup works for everything leads to frustration ... at least with
what I have to work with.

-- 
Len Ovens
www.OvenWerks.net
_______________________________________________
Linux-audio-user mailing list
Linux-audio-user@email-addr-hidden
http://lists.linuxaudio.org/listinfo/linux-audio-user