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  #321  
Old 04-19-2002, 04:31 PM
RKrizman RKrizman is offline
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Default Re: HD 192 bass-lite? Impedance mismatch?

[QUOTE]Originally posted by Bushpig:

NOW REALLY, REALLY LISTEN TO WHAT YOU HEAR!!!! Focus on a bass drum or something low for a few flips back and forth. Listen very hard to vocal sounds and the "SS's". Are they smoother or nastier or more smeared or is the stereo image different??

Enough. Please get back to me when you've all tried this test.
/QUOTE]

Okay Steve, I tried it (I'm trying it right now in fact). I listened to some Keb'Mo and the new Eels and the first Gillian Welch, through JBL LSR28's. I listened blind, flipping back and forth until I thought I had some grounds for making a choice, then I looked. I guessed correctly 5 times and incorrectly 5 times.

That doesn't mean there isn't a difference, just that I don't hear it. I'd love to try the same thing at a mastering studio, but I'm guessing the results would be the same.

Anybody else?

Rick Krizman
KrizManic Music
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  #322  
Old 04-19-2002, 09:45 PM
Bushpig Bushpig is offline
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Default Re: HD 192 bass-lite? Impedance mismatch?

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
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2 x Systems: MacPro 5.1 (Nehalem) 2 x 2.26 Quad Core, OSX 10.9.5 (Mavericks), PT10.3.10HD, 32 Gig RAM, PCIe HD3, 192's, Sync I/O, Midi I/O.
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  #323  
Old 04-22-2002, 11:02 AM
RKrizman RKrizman is offline
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Default Re: HD 192 bass-lite? Impedance mismatch?

Quote:
Originally posted by Bushpig:
[
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[/QB]
<font size="2" face="Verdana, Arial">Steve,
Whether or not you have a valid issue here, it's certainly being lost in the noise of the tail end of this thread, and Dave C would probably be reluctant to address the issue here for fear of muddying the waters. Moreover, although I'd allow for the possibility that you may be onto something, I've concluded that it must be so subtle that it has little or no bearing on the issue at hand, namely the significant loss of low end that was perceived during a transfer from analog tape. I can't imagine how that could have been a jitter issue, nor can I imagine how it could significantly affect listening to test results using Protools. I for one will feel quite comfortable using Protools as the environment for listening to MM's test results.

Again, I'm not saying you're not onto something, but maybe you should serve it up in its own thread so it can be given the focused scrutiny it deserves.

Rick Krizman
KrizManic Music
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  #324  
Old 05-23-2006, 09:27 PM
LostVinny LostVinny is offline
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Default Re: Impedance questions 192 specs

I know this is a really old post but I am hoping others may be reading these and have some info??? Thanks

I have been custom designing an op amp circuit that has led to the design of a mic pre/line amp for a custom mix console to be utilized with an Hd system. Currently, I am working on the frequency response for the line in stage with the tests to be placed at various stages of the circuit and input transformer. In developing an H pad for the line levels at the input transformer I have found no luck in my search for absolute specification on the input and output impedance of the 192. I have found a previous post by Dave Clementson in regard to the output impedance of the 192. "The output impedance of the 192 I/O's discrete class-A DAC buffer is 50 ohms per leg. The DAC is DC servo balanced, and the LF -3dB point is about 0.1 Hz. The frequency response is flat within 0.05 dB to 20Hz, and because of the slow LF rolloff, should be within a fraction of a dB down to below 5 Hz". I am assuming that this would mean 100 ohm output impedance. I have not been able to find any information in regard to the input impedance for the other leg of my work. Both of these would help in designing the most true reference possible for my amplifier circuit. I know the standard hi impedance H pad values would suffice but since this is a custom affair...Why not.... Id love to see if it makes any difference.
If anyone out there has any information on the actual input and output impedance of the unit that would be great. Thank you...

By the way, Daves specs are spot on with my tests. (With good clean a/c power and a good clock). I did find With a .5 db spike at 120 on a non conditioned power test, it messes with the response considerably...As expected on any digital unit. It was consistant with other a/d's as well. These things are getting pretty true. The noise floor on all brands is amazing. Personally, I love the new level of digital recording. I still feel I have to bit my tounge becuase I was that analog guy who back in the day said, "I doubt we'll ever see a digital unit that can come close." Well, they surpassed it. (And I am not that old). I also remember many debates over the geo poles (north and south) effect on analog recording and how the electrons are layed out on tape.

From an engineers perspecitve I love putting my attention on things I could never hear before and Only see on a scope.. Like the change in sound that one polyfilm cap can make in a circuit. It used to take recapping a few to hear any change or the clarity in low frequency of an upright bass.

From a producers perspective. Digital is yet another tool in our amazing arsenal of gear and ideas. I honestly don't know if a polyethelyne hammer handle is better than a polypropelene or that old wooden one. I am sure to those who work with them everyday they will have a strong passion for which they prefer. At the end of the day, I know, I just don't want any blisters.....

Thanks for any impedance information you may have.....
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  #325  
Old 05-24-2006, 08:52 AM
Lee Blaske Lee Blaske is offline
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Default Re: Impedance questions 192 specs

Quote:
I know this is a really old post
Man, what a post to resurrect. Those were contentious times. Bringing this up for another go around would be about as much fun as refighting the Civil War.

Hopefully, this will die quickly and descend back into the depths of hell where it belongs.

Lee Blaske
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