Re: [Jack-Devel] speaker management
istvᮬ
On 12/10/2012 11:55 PM, IstvᮠKirᬹ wrote:
>
> Hi folks, ...
>
> I'm looking for a way to manage a club sound system, and instead of
> buying relative expensive dedicated hardware sound processors, (XTA,
> Xilica, .. etc) thought of buying sound cards and do the processing -
> delay, FIR filters, etc, - via software. This would add me room for
> additional functionality, remote control, etc, ...
that is surely feasible. but a pc based solution will always have more
downtime than a dedicated piece of hardware - there's so many more
things that can go wrong in a pc. if that's ok for the job at hand, by
all means go ahead, you will get a lot more capability and flexibility
for less money.
careful design can alleviate this:
underclock the box (by pinning the cpu governor to a frequency less than
the maximum).
put the system on a raid 1.
use SSDs rather than spinning disks: less heat, less power consumption,
waaaay faster, but also expensive. ok if you don't need massive storage
space, two 120GB ssds can be had for 200 € these days.
ensure good airflow, and make sure the rack it sits in isn't too hot.
use optical i/o to avoid static discharge damage and hum loops - hum
isn't audible in digital copper circuits until the signal completely
breaks down, but it's there and it lowers your safety margin.
strip down the linux system as much as possible.
> I was reading on the bruteFIR page, that it can work with Jack.
yes, it does. but there are other convolvers as well. i don't know how
low the latency of bruteFIR can be (does it do partitioned convolution
at all?), and that will be important the moment you have djs who do live
interaction. but fons' jconvolver is a good alternative, and it does not
add any latency above the jack period length that you'll always have.
> The goal would be to have
> deck's -> up to 4 digital sound channels, possibly AES -> Jack on
> linux -> DA Converters -> amplifiers -> speakers
>
> The hardware is expensive, so please share your opinion about this.
> Can the RME HDSPe MADI work smooth with jack and linux - a PCI express
> card?
> Or am I better off with some firewire soundcard, like the MOTU 828?
> [financially for sure]
i would recommend against a firewire interface for fixed installations.
firewire is very versatile if you want to use the hardware on different
computers, but it does come at a price: much more complicated tuning,
flimsy connectors, higher cpu load, possibly more problems with routine
kernel updates...
the cheapest option is an ADAT capable card such as the RME HDSP series
with a behringer ADA 8000 for eight channels analog in (for those who
work with vinyl) and eight analog outs (enough for four-point surround
plus two subs plus two monitor wedges or extra anteroom feeds). but
there are cheaper adat cards out there...
as to your question, older RME pcie cards work well with all features
supported, cutting edge ones like the MADI FX might not, but that
usually gets fixed pretty quickly as soon as people actually use them
and complain...
> How do I chain bruteFIR into Jack?
connecting software in jack is easy - get qjackctl and use the graphical
patchbay while you're learning and experimenting. then, once you have
decided what you setup will be, use the command line tool jack_connect
in a script to automatically set your system up when you boot.
while you're at it, you might want to try fons' zita-lrx crossover
between your tops and subs, it does linkwitz-riley and butterworth.
haven't used it in production yet, but a quick test suggests it does the
job nicely.
best
jörn
--
Jörn Nettingsmeier
Lortzingstr. 11, 45128 Essen, Tel. +49 177 7937487
Meister für Veranstaltungstechnik (Bühne/Studio)
Tonmeister VDT
http://stackingdwarves.net
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