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In Reply to: RE: How so? posted by cbrady on August 01, 2007 at 15:32:04
...how my Rockport Sirius III works in this area?
reading about your approach on this issue makes me wonder how it compares. i remember spending time in your room at RMAF and how much i enjoyed the Certus.
my understanding is that the Rockport uses an 'eddy current' motor with direct drive with an air bearing, 55 pound platter, and a servo which samples the speed 10,000,000 times a second which is 'said' to eliminate groove modulation.
it is at speed within three revolutions and stops completely within 1/2 revolution.
my ears tell me that is that it has a solidity and tonal correctness not otherwise heard.
mikel
Follow Ups:
Well, all turntables have measurable wow & flutter. What are the specs on yours? Furthermore, all analog tape recorders have measurable wow & flutter and so do cutting lathes.
With regard to the digital recordings that I made from your turntable, they sound just fine. However, they don't necessarily sound any better than similar recordings made from my belt-drive turntable.
Therefore, I think speed stability is a bit overrated. The reason is because if speed stability is so overwhelmingly important, then digital should sound absolutely spectacular to all speed stability enthusiasts. However, I don't think this is the case.
Another reason I think that speed stability is overrated is because multiple re-recordings on analog tape machines for mastering purposes in conjunction with cutting lathe wow & flutter sometimes produces excessive wow & flutter in the final stamped vinyl products. This doesn't include the effect of off-center spindle holes, yet none of these problems can be corrected by the most perfectly speed-stable turntable in the world.
In my opinion, speed stability is important, but analog in general, and vinyl specifically, produce speed stability issues that no turntable can correct. If you want audibly perfect speed stability, you need to go digital from beginning to end.
Best regards,
John Elison
"With regard to the digital recordings that I made from your turntable"
What turntable might you be referring to? Have you had access to a non-belt drive Teres?
"If you want audibly perfect speed stability, you need to go digital from beginning to end."
What about digital jitter? Jitter is a well documented problem that degrades the sound of digital recordings. It is a distortion in the time domain and remarkably small amounts of jitter are easily heard.
Analog is no different. Small errors in the time domain are easily heard. Wow & flutter measurements are coarse errors that are low in frequency and generally do not correlate well sound quality. It's like harmonic distortion. Easy to measure but not useful. Very small time distortions similar to digital jitter exist in analog and have the same sort of effect on sound. Many do not recognize it as such.
All sound recording techniques share the challenge of accurate reconstruction in the time domain. It's naive to say that digital is somehow immune.
> What turntable might you be referring to?
I made some digital recordings from Mike Lavigne's Rockport Sirius III.
> Have you had access to a non-belt drive Teres?
No!
> What about digital jitter?
Jitter has nothing to do with turntable speed stability. Furthermore, the audible effects of jitter in CD players has basically been eliminated years ago. The jitter specification on my 12-year old CD Transport via its I 2 S buss output is 5-picoseconds.
> Very small time distortions similar to digital jitter exist in analog and
> have the same sort of effect on sound. Many do not recognize it as such.
I don't believe "very small time distortions similar to digital jitter" exist in turntables with 27-lb platters. Sorry! I don't buy it!
> All sound recording techniques share the challenge of accurate reconstruction
> in the time domain. It's naive to say that digital is somehow immune.
Digital does not have measurable wow & flutter and jitter is a non-player in this discussion. Sorry!
The point I'm making is that there is so much wow & flutter already recorded into LPs that the effect of a turntable with perfect speed stability is insignificant compared to a turntable with reasonable speed stability.
Best regards,
John Elison
The audible improvements I've heard through three generations of clocks in my CDP down to the latest Superclock 4, argues that there is still progress to be made in eliminating digital jitter. With each successive clock the unit sounds more like an analog front end. I therefore suspect that digital jitter in a CDP is a bigger problem for the ear than speed stability in a high-quality TT.
Actually, I don't think either one is a problem. If you want a CD to sound like an LP you simply take a CD recorder and copy an LP. I do it all the time.
BTW, what is the jitter measurement on your best clock?
Best regards,
John Elison
Unfortunately Audiocom doesn't publish jitter data. In any event, jitter in a transport or player is a product of other circuitry in the digital section as well. However, the SCD-1 had pretty low jitter figures even in stock form, so the improvement one hears with aftermarket clocks is happening at low thresholds of jitter. If you don't believe there has been meaningful recent progress in clocks (such as the external clock option available in Esoteric's premier 3-box solution), then I'm certainly not about to convince you.
Are you implying that your CD recordings are indistinguishable from LPs played on top-quality TTs? If so, then perhaps I should trade in my $10K battery-powered SCD-1 with Silver Rock transformer analog stage for your 12 year old transport.
> Are you implying that your CD recordings are indistinguishable from LPs played on top-quality TTs?
Well, they sound pretty close. Check out the following:
The Challenge!
per Challenge terms---$250 to the audioasylum done
So how many times out of five did Lavigne fail to detect the difference?
The shootout results are indeed surprising if you're burning CDRs that are being played back with standard RBCD sampling. Your results would be less surprising if you recorded and played back hi-rez. In recent TAS, Bob Ludwig reports that his 96kHz/24-bit masters contain over an octave more HF when pressed to vinyl as compared to transfer to RBCD. As to degredation contributed by clock jitter, Robert Harley reports hearing an improvement moving through three successive clock sources for an Esoteric X-03 with accuracies of 3 parts per million, 1 part per million, down to .05 parts per billion. It's particularly interesting that vanishingly low jitter in a digital playback system improves the listening experience even for CDs that were recorded with more compromised jitter control. Perhaps there are analogies to be drawn regarding the quest for the grail of speed stability in analog front ends...
Admittedly there is more to a player than its clock, but all other things being equal, it's remarkable that the ear can detect such small errors in timing. Whether your ear is trained to hear the difference or whether you care about the difference is a separate matter.
Mike failed to detect one out of six trials. It was number 3, I believe.
The test was stacked in his favor because he picked all the pieces and he was intimately familiar with all the pieces as well as being intimately familiar with his mega-buck audio system.
The test was conducted using a Redbook CD-R played back on my 1995 Audio Alchemy CD player connected with Monster Cable interconnects. I also used Monster Cable interconnects to connect my Alesis Masterlink CD recorder.
There seemed to be a slight sonic difference between my CD-R and the real thing from his Rockport Sirius III, but it was pretty close. In fact, two others attempted the blind test after Mike and they failed every trial. Of course, this proves there was an audible difference, but I found it interesting that the others thought my CD-R sounded more like vinyl than vinyl itself.
Best regards,
John Elison
That's certainly food for thought. I've kept AA DDSII and PS Audio Lambda II transports for comparison to the SCD-1 I've been modifying over the years. The SCD-1 transport section is more resolving & dynamic, but the AA is notable for smoothness and continuousness similar to vinyl. Perhaps the human ear in series with the loudspeaker adds the most jitter or worse kinds of instability.
I remember in the 90s putting up to two AA dejitter boxes in series between the Lambda II and a Theta Pro Gen Va. For whatever reason the AA boxes added hash to the sound. Perhaps if I'd used the then new I2S interface things would have improved.
Regards,
Dave
"the audible effects of jitter in CD players has basically been eliminated years ago"
Eliminated??? I would not call 5ps eliminated. Yes great progress has been made to reduce jitter but it is still there and it still affects sound. Sounds like the perfect sound forever mantra all over again...
"I don't believe very small time distortions similar to digital jitter exist in turntables with 27-lb platters"
Fair enough, but I do. I have done plenty of experimentation that clearly indicates that jitter like distortions do exist and when properly dealt with the sound is correspondingly better. I will admit that I could be wrong about the particulars about my "belief" but I have no doubt that there is something going on with vinyl that behaves like jitter. So do you have any experience or even measurements to back up your belief?
"The point I'm making is that there is so much wow & flutter already recorded into LPs that the effect of a turntable with perfect speed stability is insignificant compared to a turntable with reasonable speed stability."
Your point is logical and even sounds reasonable. But the truth is that improving speed stability does make for better sound. Maybe if we were closer to perfect speed stability then it would not make a difference.
I've heard a Rockport Sirius III and in my opinion it sounds no better than my Sota Millennia Vacuum.
'Nuff Said.
John Elison
"The point I'm making is that there is so much wow & flutter already recorded into LPs that the effect of a turntable with perfect speed stability is insignificant compared to a turntable with reasonable speed stability."
'Nuff Said.
The speed stability of the Rockport is entirely down to the accuracy of the servo loop. I struggle to understand how any servo loop can possibly achieve the stated levels of performance but that probably just says that they know more about it than I do.
Mark Kelly
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