KVR Audio

Majken · Post by **Majken** » Mon Jul 04, 2005 9:17 am

I'm trying out an UAD-1 card but experienced some crackling noises. It only happens at very low latencies with high load on the UAD-1 card. However if i have a similar load on my CPU I get no crackling.

So if I run 2ms latency with 44.1kHz samplerate and have a 50% load on the UAD-1 it works just fine. However if I add more plugins and get up to 60-70% the audio starts crackling. If I raise the latency to 5-7ms I never get any crackle at all.

Now one would suspect that my computer is just not fast enough or whatever, but if I load some synths and such I can push my cpu beyond 50% without any crackle at 2ms. And while running the UAD-1 the only processing is the signal routing.

So anyone experienced anything similar? And can anyone run a quick test to see if you can confirm it or not. The soundcard I'm using is an E-MU 1820m and I'm suspecting it might be part of the problem. A theory would be that the signal routing back and forth through the card can't keep up because of the resources stolen by the E-MU mixer. But I'm really not sure.

I'm planning to try running it on an Audiophile or even an AC97 with ASIO4ALL just to see if it behaves differently.

/Majken

funkynuts · Post by **funkynuts** » Mon Jul 04, 2005 9:20 am

do you have a pci graphics card?

Majken · Post by **Majken** » Mon Jul 04, 2005 9:23 am

Oh no, it's an AGP card - an MSI Geforce FX5700 to be exact.

But that's another theory of mine, that the PCI bus just can't keep up. Which does seem unlikely, still I dunno. I'm gonna try stripping my system down removing USB hardware, the network card and such and also try overclocking the PCI bus to see if it makes any difference.

/Majken

Lawnmower Of The Damned · Mon Jul 04, 2005 4:05 pm

Some specific motherboards have some issues with bandwidth hungry PCI cards. I'd ask on a UAD-1 forum to get the list of bothersome motherboards.

ammoniad · Post by **ammoniad** » Mon Jul 04, 2005 4:25 pm

I noticed some crackel and pops the other day with my set up. (SX and Uad-1). I was running a high load (BFD,Wavestation, Albino, Minmoog V, Battery,Soniksynth 2). I found freezing tracks made the pops go away.
I am running an AMD 2.6 gig and EMagic A26 audio card.
Not a bleeding edge system by any standard, but Its get the work done.

DevonB · Post by **DevonB** » Mon Jul 04, 2005 4:30 pm

2ms is EXTREMELY hard on your system. Why are you even eating up the extra CPU anyway? Why not drop down to at least 128 samples instead of 64 (or you at 96 samples?) I can tell the different between 256 and 512 samples for live playing, but below 256, I can't tell the difference anyway. But it does sound like the CPU can't keep with with the load, yes.

Devon

Majken · Post by **Majken** » Mon Jul 04, 2005 4:57 pm

Oh yes, 2ms at 44.1kHz sure is extreme. I wouldn't be bothered had it not been for the fact that I can run standard VST instruments without getting clicks and pops. The UAD-1 is supposed to not be cpu dependant however it's what causes the clicks and pops. Which just seems very strange to me.

Gonna do some more testing to see if I can work things out. Could be interesting to wake up my eternally slumbering onboard audio chip just to try running ASIO4ALL to see if there's a difference.

/Majken

DevonB wrote:2ms is EXTREMELY hard on your system. Why are you even eating up the extra CPU anyway? Why not drop down to at least 128 samples instead of 64 (or you at 96 samples?) I can tell the different between 256 and 512 samples for live playing, but below 256, I can't tell the difference anyway. But it does sound like the CPU can't keep with with the load, yes.

Devon

neverwhere2012 · Post by **neverwhere2012** » Mon Jul 04, 2005 5:18 pm

the UAD-1 card isn't designed for low latency use, it's designed for mixdown. increase your buffer size and it should work fine. hell, in logic, it requires a buffer setting of 1024 to get the best performance out of it. also, the UAD-1 does use some CPU power, but your problem is more due to the low latency you're trying to force it to run at.

AndrewSimon · Post by **AndrewSimon** » Mon Jul 04, 2005 6:10 pm

It's most likely a PCI bottle neck.
Running at 64 samples puts everything to the max.
There are many factors here but from what I am hearing changing your sound card might be the quickest solution.
The Audiphile 2496 is the best for running low latencies due to it's simplicity.
Also tweaking your PC can help a lot.

1 Run windows in "optimized for background services"
2 Disable all unused inputs/outputs in your daw (you will be surprised)
3 Disable all programs running in the background (antivirus, IM and so on)
4 Disable anything not is use, like serial,parallel and USB ports. (do it from the bios)
5 Make sure the video card is NOT sharing the same IRQ as the audio cards.
6 This probably not going to help but the host is a big factor in this, changing hosts can sometime do wonders for latency.
7 learn to use "msconfig" and again disable anything running in the background that is not needed for music making.
And the list goes on, you might also want to try DoubleDawg to restrict PCI hogging Video cards. (for AGP too)

Don't want to go for all these hassles? .... just raise the latency on the audio card.

I am running at 1.4ms with a UAD-1 card with no problems, it took me 6 months of tweaking to get there, for me it's important, I play live and run several UAD plugs on the instrument.
Each UAD plug doubles your audio card latency so it adds up fast.

I have repeatedly ask UA to come up with an "effect bank" where you decided the order of the UAD effect
and then have one hybrid plug in your track.
This way the sounds needs to run only once to the UAD card regardless of how many plugs you use.
The answer I got is "it's in planning but don't expect it anytime soon."

GypsyJazz · Post by **GypsyJazz** » Mon Jul 04, 2005 11:32 pm

Majken wrote:So if I run 2ms latency with 44.1kHz sample rate and have a 50% load on the UAD-1 it works just fine. However if I add more plugins and get up to 60-70% the audio starts crackling. If I raise the latency to 5-7ms I never get any crackle at all.

You could try running a little app called PCI Latency Tool.

It will allow you to put a cap on how much PCI bus
bandwidth the Graphics card and other PCI cards will use.

The idea is to give your sound card (and possibly the UAD card)
a greater chunk of PCI bus bandwidth.

It's usually the Graphics card (AGP included)which steals
bandwidth from the PCI bus.

You can find PCI LATENCY TOOL 2.3 at GURU3D:
http://downloads.guru3d.com/download.php?det=951

Another tweak I've found useful is to enable UDMA66.
There is a registry setting that is often not enabled
even if you think you do have it enabled in Device Manager.
I use a little prog called X-Teq to do these tweaks but you
can do it manually using Regedit as well.
Of course...all the usual caveats apply if you're fooling around
with the registry.

On this PC (Using XP Home) the key is:
HKEY LOCAL MACHINE\System\CurrentControlSet\class\{4D36E96A-E325-11CE-BFC1-08002BE10318}\0000\EnableUDMA66

Not sure if it's exactly the same for all PCs and versions of XP....
but if you don't have that key in your registry, just do a search
for EnableUDMA66 (in Regedit)
Give it a value of 1 and reboot.
This tweak solved an issue I was having with H. G. Fortunes STS17 & Swamp
synths where I would get tiny little clicks as the Oscillators moved through their
wavetables.........
Since applying the tweak, no clicks at all with these synths.

UAD-1 - Snap, Crackle & Pop