[LAU] another cpu question

[Len Ovens]

On Sat, 13 Sep 2014, Ede Wolf wrote:

> it is kind of live use. But not on stage, but in my humble homestudio. So I 
> do not have to be mobile, but I am not arranging, I am just playing live - 
> that is, enjoy turning a lot of knobs without any real clue. And if it sounds 
> crap for a given day, I at least do enjoy all the blinking lights.
>
> The card is an old RME Hammerfall (not even DSP), and I'll be using X with a 
> standard distro. Gentoo or Arch - or maybe KX, if they really should drop 
> ubuntu as a base, as I've read somewhere. Depending on the software I'll be 
> using in the end.
>
> So we are talking about a simple desktop PC in a tower case with an 21" CRT 
> Monitor.

That answers a lot. As you already have the IF, it is worth while (money 
wise) putting this together. It seems you have most of the parts.

> About multitrack: Being able to run 32 effects (8 Tracks x 4) would be great, 
> 16 tracks perfect, but my budget is not infinite and I doubt I'll really use 
> 16 Tracks at once. And most likely not really reverb on all tracks, that is 
> just the worst case to find out a proper CPU.

As your audio IF is PCI (? I am guessing) you need to start by making sure 
that you can get a MB with PCI slots in it for your chosen CPU. Any of the 
server class MB I looked at (aside from costing too much) had only PCIe 
slots. In my case I did not look for just one PCI slot either, but looked 
for the most I could get, which happened to be 3. I did this because I 
wanted PCI slots that did not share IRQ with something else and some MB 
with one PCI slot will put it on IRQ16 with three or four other things. 
However, even though there are many things list as such on my new mother 
board, the new hw seems to also be able to rout the IRQs else too. (PCIe 
seems to have soft IRQs) So I may have been more rigorous than I needed to 
be.

> Maybe I'll try to control some of the effects via Midi - I do own an old 
> Doepfer Drehbank controller, but not sure, wether I'll have the patience to 
> program it before winter. Maybe handy for the EQ. But it's also occupied for 
> the microwave II.
> However, EQing with a mouse is a PITA and something I will have to solve 
> sooner or later. Way worse then setting up reverb or delay. imho.

If you already have an external mixer do you need EQ in the box? Mixbus 
seems to be able to handle EQ per channel as well as some other per 
channel effects on older hw ok... but cpu use is known to be high.

> This box will just be plugged into the inserts of my mixer - therefore the 
> ideal of 16tracks - which I suppose will be cheaper and better to use than 
> buying a couple of multieffects. I do not have any more ADDA convertes 
> anyway. And for my lousy ears, the quality of named plugins is more than 
> adequate.

So 16 channels. probably with jack at 64/2, but maybe lower. Though for 
just playing around do you actually have more inputs than a few? For 
example, I have 6 inputs (I could have two more with resampling) I record 
with. I have done projects up to 14 or so tracks, but have never used more 
than two input channels. But then I mixdown in SW. I too would like 
faders/knobs over mouse, but have chosen instead to work on a control 
surface.

> So it's basically -> jack-in->effect1-effect2-effect3-effect4->jack-out with 
> 16 permanent physical connections bewteen soundcard and mixer. Though not all 
> of them will be used at once.

Controling a number of separate racks of effects with an external midi 
controler will take some internal glue of some sort. PD, midifiltering or 
something.

> The price limit is a bit difficult as prices are varying between countries. 
> As I've said, an upper class intel i5 or AMD is about what I am thinking of, 
> until general consesus is, that there is no way to accomplish this with 
> standard, upper class (as opposed to high end) PCs.
> Then maybe I'll wait a little more and save some money.
> But, as you mentioned, I do remeber running softwareeffects, even not really 
> in parallel, way back on an 2GHz AMD 3200 in decent quality even on WIndows, 
> so a modern multicore, I would suspect, should be able to run a couple of 
> them. Just which would be the best bet.
>

> For hardware devices: Behringer is out of discussion. As is Alesis. I do have

No worries, if you already have most of it, why buy more?

> So again - are plugins really FPU heavy? Or would it be more important to 
> have feature X, like AVX or SSE27 or so? Unfortunately I am not really into 
> this recent hardware stuff and all the latest buzzwords.

Ya, I find the same. there are two things I look for:

Auto speed changes are bad, but generally can be turned off.

Anything that can take processing time away from my RT thread, HT, some 
styles of on chip video (some older AMD had this), Some HW MB monitoring 
for heat etc. can effectively (so far as the OS is concerned) make for 
very long cpu clocks.

> And I usually do not trust benchmarks, but that's all I have and the FX 
> series did quite well in some so called media benchmarks, like rendering, 
> however, I am not sure whether this can be tranferred to running multiple 
> audio effects without problems. AS maybe rendering is just two fast threads 
> instead of 16 medium ones. Dunno.

There is a big difference between throughput and lowlatency. HT will help 
throughput and things like video rendering. RT/lowlatency is about 
schedualing rather than speed.

> The price advantage for the AMD would probably be eaten up by the more 
> expensive colling - I prefer it rather quiet - and the higher energy bill.

The only CPU I know of that comes no-fan OOTB is the atom. Both the Intel 
Core (i3, i5, i7) and the AMD will need cooling. Both cost more to add no 
fan cooling to (read aftermarket).

> But if it would be the more adequate CPU for this very workload, I would go 
> that route.  i7 are all HT, so that would leave the i5 as only other option.

In my experience (limited), I have found that HT is only an issue with 
jack latency below 64/2. On my old P4, I could do pretty good down to 64/2 
with HT on, but could go down to 16/2 with it off. For your use you may 
find 64/2 (or higher) works just fine and that the extra processing power 
is worth while. If you have an old MB around that can do 2 channels you 
could try it out first, see if the delay is too much.

--
Len Ovens
www.ovenwerks.net