Tuesday, August 12, 2014

Saffire Pro 26, Firewire, Windows DPC latency

For the last 6 or so months, I've had a big problem with crackles and pops when playing or recording music, due to DPC latency issues.

When I ran DPC Latency checker v1.3, it would show sudden red spikes every time there was heavy network traffic. Sometimes, just refreshing Chrome would do it.

This was not only happening within Reaper, while recording but also when playing back MP3 files via AIMP.

Extensive searches through the web failed to find anything that would work for me. The best I could do, was reboot the PC and the start recording.
Once the PC had been up for a while (especially if it had been put in 'Sleep' mode and then woken up), the crackles would come back.

At the time, I was running Win7-64 and used USB3 for all external devices.

So, in order to overcome this I decided to move the sound generation to external hardware and I bought a Focusrite Saffire Pro 26 for recording my music.

This provides me with A/D conversion from my guitar --> PC, as well as D/A when playing back music from the PC.

In addition to that, I get to use some of the best pre-amps around.

Alas, it would seem that USB3 does not provide sustained  high throughput, so most audio equipment manufacturers (including Focusrite) use Firewire.

Given that I was going to move to Win8 at some point, I wanted to make sure the card I bought worked well with Win8.
(It appears that MicroSchmuck saw it fit to stop supporting Firewire in Win8 and only a few chipsets actually work with it).

I ended up taking a chance and buying a generic Firewire card from CPL in Notting Hill, Victoria.

Against all odds, it worked perfectly well in Win7-64.
A few days later, I moved to Win8.1 and that card still works fine!

Additionally, the DPC latency seems to now hover around 1-3 ms, no matter what I do with the network!
I was copying 220GB over the network without any problem.

I hope this helps others struggling with DPC issues while recording/playing back music.

[UPDATE 16aug2014]
Hmmm, it would seem that VirtualBox can sometimes mess with DPC latency...
It is quite amazing running an i7 CPU and yet still struggle with performance at this level.
Something tells me Billy-Boy's creation is at fault.
If only Reaper and the VSTs I use were available under Linux!

[UPDATE 13oct2014]
So, even though I now run an i7-4790 CPU @3.6GHz, I still (sometimes) get atrocious clicks and buzzes when generating music from the PC itself.

See my article on how I moved my music playing off the PC and onto a Raspberry Pi.

ps: Comments and/or links to this article are most welcome!

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