Jitter question

[needto]

Hi!

I'm wondering, does the cpu load on the pc affect the amount of jitter when recording, and if i can fit my not-so-modern computer for tracking, or is it better to use some more powerful pimped-out rig?

If, when using ASIO, the jitter amount is dependant only on the audio interface clock, then almost any even not the most modern pc, or laptop can be used for tracking, and the results won't vary with the same interface, as long as there are no obvious clicks or skips in the audio.

On the other hand, if system processes are interfering, the best low-jitter way to record is a clean system install on a pc with a powerful cpu and only the absolutely needed processes running.

One recording engineer said to me, that there is a great difference between Protools TDM and something like Nuendo in cleanness and openness of sound, because Protools, with its hardware integration, doesn't let system processes interfere with the audio processes, hence less jitter. I'd be glad to hear someone's thoughts about such a comparison also.

Thanks!

 

[LydonB]

I may be completely off base but I think jitter really only comes from digital devices not being in sync and has very little to do with the speed of your CPU. I am using a Powerbook G4 (which is definitely not top of the line these days) with a 003 and have no issues with jitter that you speak of. If you are using your audio interface as the master device with only your computer, you shouldn't have any issues. But if you are using an interface and a pre via ADAT and you are not syncing, then you will have jitter problems.

I have never heard that comparison between Pro Tools and Nuendo (or other DAW's). I know that Pro Tools essentially takes over the computer, or at least however much you allow to to take over your system. You can allocate how much processor power it uses. I am not sure if other DAW's do that, but it is certainly a very useful feature.

 

[Melodeath]

As far as I know, jitter is referred to in regards to an audio interfaces clock. Jitter in the timing can cause the A/D to sample at late or early points, as opposed to perfectly evenly, causing distortions in the signal since time information is not stored in digital audio.

 

[LydonB]

As far as I know, jitter is referred to in regards to an audio interfaces clock. Jitter in the timing can cause the A/D to sample at late or early points, as opposed to perfectly evenly, causing distortions in the signal since time information is not stored in digital audio.

Exactly. Which is why I don't think his computer has anything to do with this stuff. It sounds more like buffer errors to me.

 

[AudioGeekZine]

Jitter is only an issue when connecting multiple digital devices.

For example I run a s/pdif cable out of my soundcard into my interface. The soundcard only runs at 48kHz and the interface is set to 44.1 usually. It's not playing at the wrong speed or anything, there's just occasional clicks. If I set the interface to clock to the s/pdif there's no clicks. But then I can only record @ 48kHz.

I'd rather have jitter than use up two inputs on my interface just to hear youtube videos.



Needto, you are a bit confused and misinformed.

 

[needto]

Thank you very much for the replies, guys.

I wanted to be sure i could use the older pc without loss in audio quality

As i understood, when the ADC fills it's buffer with samples, it does have enough time to get them to the recording program safely and intact, so if the clock comes from within the interface, the audio isn't affected by the system, if the cpu is not massively overloaded.

It's just this PT-loving guy got me worried about windows recording quality, i googled all around about the jitter-cpu dependency, but didn't find anything. Thanks for your help, i can be calm now