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
