[Bushpig]

Hi Guys,

Blairl.

Thanks mate. That's an excellent read. Highly recommended. I guess my natural response (and this is just observational reporting, not a retort), is that during my "Radar II phase" and the subsequent detailed testing (written details of which sadly went west a while ago and I can't face the whole process again just yet), I still could not get a colourless sound from ProTools. Everyone in the room could pick it every time. A brief recap: Radar II, all AES/EBU interfacing to Protools, all 24 bit hardware, digital transfer of band takes out of Radar into Tools in sync, then ProTools set to playback, same sync and clock master etc,run the Radar and Tools in sync, hit the "all input" button to effectively switch between original and copy playing out of PT but monitoring through the Radar, Instant change in sound and loss of lower octave, a bit smeary like all the drum channels might have shifted phase ever so slightly(sounds like it could be jitter effects I suppose). We did however try every combination of independent house sync source and clock distribution we could think of (oh, and we tried to record an album at the same time).

Figure that one out!! One less potential Jitter source on that test, but using NVision 5500 house sync to all devices didn't affect anything.

Also, I forgot to mention on this thread that my CDR machine in the same "insert" configuration as the PT in the test, sounds identical to the source. I'm definitely not saying that what Dr Jitter says isn't true, but it sounds like I need to continue investigation with his info in mind to see if I can establish that a copy sounds better on playback and watch carefully for signs of potential jitter deterioration.

Thanks Rick too. I played the blind guessing game also for a bit and got 5 out of 5 right. But then maybe my odds were just "front loaded" and I was about to have 5 failures!! I'll try again later. Did you read the linked thread from Blairl?? If this Jitter issue can affect the results in most situations, then you and I are both probably right. Have you got the same type of Apogee unit as mine by the way?? I ended up plumping for some poncy "special edition" PSX-100 claiming something like super high tolerant components, so I use that to try clocking my Tools to sometimes, but it doesn't seem to make any difference to the sound.

This partly raises the question. If the under appreciated problems of this jitter phenomenon is common knowledge amongst digital engineers, doesn't it rather shoot down Dave Clementson's claim that numbers in, numbers out equals identical sound reproduction?? Although he may never have used those exact words, he has certainly implied it to me in my report on the other thread. If the article is really right (and even the author admits it needs much more investigation) and the effects of excess jitter won't show up on a strict "reading" of the numbers coming out but only by how those numbers "sound", doesn't Dave Clementson have to concede that his customers, who do nothing but use their ears for a living day in day out, MAY have a point about sound degradation?? Not that it's not our own responsibilty to do our best to alleviate the problem of jitter affecting our audio as best we can, but it certainly leaves a big "subjective" hole in Dave C's predominantly "objective" Numbers In = Numbers Out argument. It's just a thought I had!!

I don't want to bag on Dave C too much, but I do want him to answer people like me and Mixerman and stand up for his product and explain something like this jitter anomaly if he believes his equipment is either above these error possibilities or victim to them like everyone else. Just tell us what you know Mr C!!

Cheers for the info peeps.

Steve Bush