On Sat, 13 Sep 2014, Ede Wolf wrote:
I may be putting together a box dedicated just to act as a multitrack effects
unit - without planning any recording. The effects stack will for most
My guess is that this will be used live then? So you must have an audio
interface in mind and a channel count. I am guessing that this will end up
rackmount with a MB that has PCI(e) slots? Will it have a gui screen? or
be run via MIDI/OSC/custom control surface? (I would recomend something
sort of standard as it may be nice to have a MIDI control surface on a
desk particularly for EQ use... though a touch notepad Interface might
work too)
channels most likely look like this: reverb, delay, EQ and maybe one of
flanger, chorus or rather seldomly compression. Anyway, just the classics,
planning so far to only to install the calf and invada lv2 packages. Though I
am open for recommendations here, too. And of course I am looking for a
suitable effects host/rack.
Because you have (I would guess) a set number of channels you have the
option of looking at either a multitrack mixer such as non-mixer or a set
of stereo racks. I would put all the possible effects in line but have the
ones not used bypassed... at least I would try that. This is so that it is
easy to set up a midi controller. I suppose I should also ask if you are
going to do any of your own coding to glue this together. You will
probably at least need some shell scripts to set things up unless you will
have some sort of UI that will allow manually setting this up every time.
Another question... Will X run? Or will you be running all CLI?
However, I do suppose, the reverb will be the most cpu consuming item and I
am wondering, what feature an a cpu should I be primarily looking for? I
guess, for effects, especially reverb, the floating point performance will be
paramount?
Without a track count, it is hard to know. multitrack could be 4 or 24
tracks. Even then, it would be hard to tell as I have found changing
parameters within a plugin can change cpu use of that plugin. Of course
knowing what latency your IF is capable of and the latency you intend to
use is important too. It would be pretty easy to say that a dual xeon
board would handle it, but then one of the new 8 core atom boards may work
just as well... note: I don't know how far a single audio chain can be
split over cores.
WRT reverb: Do you really want each track to have it's own reverb? Having
one reverb (or two) service a number of tracks through sends is not only
done to conserve CPU cycles. It also lets the sounds be in the same virual
acoustic space. However, setting up the sasme reverb 5 times does allow
each track to be dealt with separately.
Another question: will you be mixing the outputs? (sometimes, never)
As HT generally has a bad reputation for audio, currently, the AMD FX-8350 is
on top of my list, as the floating point preformance is said to be rather
good and lots of cores should be ideal for running lots of effects in
parallel - though unfortunately not every core does have its on FPU. As it is
not going to run 24/7, the insane energy consumption is somewhat acceptable.
But, beeing no coder, I may be completely off track with my conceptions here,
so I am asking for some more insight or alternative recommendations, maybe
even with a short reasoning
What parts do you already have? What is your budget? What is your reason
for wanting to do this in a computer rather than just buying something
that has these things. By the time you buy the interface ($500 for 8 i/o),
case, MB, CPU, memory, PS, HD, midi controller and PCIe card for the audio
IF... you are getting close to the $2000 mark already. (this is noting
that you said this is a one use box) You can buy a digital mixer with 16
channels already. You have said that there is not some effect that you
want in particular, but generic effects.
Look at:
http://www.allen-heath.com/ahproducts/qu-16/ ~$2100
http://www.behringer.com/EN/Products/X32-RACK.aspx ~$1200 (Sweetwater)
I am sure there are others too.
This is not to say your project is not valid. I am just trying to make
sure you have some perspective. BTW, the units I pointed out do not use
one fast CPU, but a number of ARM and DSP units. If you already have most
of the parts on hand... particularly if you have a spare computer even
with only two inputs. I would try it out with that for two tracks so you
have an idea of what sw is around. You can try more tracks than two by
just setting them up, as jack does not care if inputs are physical or not.
Playing back *.wav files does not take much cpu.
I was able to do quite a lot with just an old P4 even at low latency, The
new i5 already makes audio use much less cpu. (even with jack set 16/2)
All of todays CPUs are beyond yesterdays super chips.
--
Len Ovens
www.ovenwerks.net
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