Reference Transports: An overall perspective


Teajay did a great job by starting a threat called "Reference DACS: An overall perspective."
I thought it might be beneficial to start a similar thread on transports.
Unfortunately I really have nothing much to say; I just hoped to get the ball rolling.

I'll start by throwing out a few names and a question:

Zanden 2000
CEC TL-0X
Metronome Kalista; T2-i Signature; and T2-A
Esoteric P-01; and P-03(?)
EMM Labs CDSD
47Labs PiTracer
Weiss Jason
Accustic Arts Drive 1
Ensemble Dirondo
Wadia 270se

I know that there are very few companies that actually make the drives themselves. The few I know about are:
Philips
TEAC
Sanyo/CEC

Do the various Philips drives or the TEAC VRDS transport mechanism each have a particular sonic signature regardless of which maunufacturer uses them in their designs?
exlibris
So, you are saying that mis-reading a "0" for a "1" or vice-versa with some random frequency will cause the sound to become like a blender? It won't just misrepresent the amplitude value of the complex wave at those particular sampling points? Assuming a .1% error rate, that's still 40 some errors in amplitude resolution/sec.

Again, I don't offer this as conclusive proof, but why would a company such as Esoteric spend mucho $ on developing and manufacturing a massively overbuilt (by an order of magnitude in weight alone) transport when the machines they are placing them in also buffer the data to SRAM? I don't think it's reasonable to attribute this decision to marketing bs...way too expensive without meaninful return for that.

Jordan
Jordan/Germanboxers,

it appears that you have not spent much time in thinking about the CD transport stuff. When you write your posts, you seem to be writing ex-tempo & there does not seem to be much depth. you are also blowing the importance of the transport -w-a-y- out of proportion, if I may say so. Transports are very important but they are a means to an end. The end being to get the data read reliably & as quickly as possible. Spend some time & research the matter.

Lktanx has understood the subject matter exactly!

>> The question that neither of us can answer conclusively
>> is to what degree does a transport that exhibits less
>> random errors have on the final sound quality?
I can't remember exactly when this was (maybe it was in grad school) but I remember spinning a CD that had holes drilled in it. NOT THROUGH HOLES; rather, holes drilled deep enough where they encroached into the recording material. These holes were made in the N-S-E-W directions so it looked like an equal-legged cross. Also, the holes were NOT made in the TOC area just so that the CD player would actually play the CD. The objective of this was to demonstrate to us the robustness of the error correction. So, obviously the disk had to play! There was an exact 2nd copy of this disk that was pristine (like the one you'd get from a store). How did it sound? For all practical purposes it sounded just like the pristine copy.
So, what does this tell us? If there are certain # of errors while reading a disk, the error correction system can neutralize them & the sound of the reproduced music will be practically unchanged to the user listening. If the # of errors increases to the point that it overloads the error correction system, then, the sound will be degraded & will "It will sound someone turned on the juice blender for a brief period".
The CD error correction has an enormous appetite for errors & it takes a significant # of errors to break it. Randon errors are just that - random! They do NOT occur at a high enough rate to overload the disk error correction algorithms. Just as Lktanx wrote, if you have a unit that does create a high rate of random errors, you have a defective unit & the transport needs to be repaired/replaced.

>> Again, I don't offer this as conclusive proof, but why
>> would a company such as Esoteric spend mucho $ on
>> developing and manufacturing a massively overbuilt (by
>> an order of magnitude in weight alone) transport when
>> the machines they are placing them in also buffer the
>> data to SRAM?
there are many aspects in the design of a transport. what distinguishes a good one from an average one is: (1) the disk clamping system. A CD spins at 200-560RPM (most of the time, I've read 360RPM). The edges of CDs are not perfectly smooth or straight. Hence, at that speed, if the CD is clamped only in the middle, the CD will wobble. In effect it becomes akin to reading a newspaper placed on your lap in a subway train! In the transport there are surges in electrical current drawn from the digital supply by the laser optics electronics. This has the effect of dirtying the digital power supply & this crud pollutes everything it touches. Also, as the disk wobbles, the laser beam becomes unfocused. An unfocused beam can make errors reading data. So, TEAC's VRDS system was designed to clamp the ENTIRE disk. Does this come for free? NO! it adds weight to the whole transport but it is 1 possible solution to preventing the disk from wobbling. a 2nd solution is available too - a CD cutter w/ a fine edged knife. I believe that it cuts 200 CDs before the blade needs replacing. Solves the same issue by having the user spend less money than buying a TEAC VRDS system. (2) the laser system in an average CD transport has to tilt or rotate so that it can read the entire CD surface. This has the bad habit of spreading the laser beam. this is said to increase jitter & also possibly cause read errors. So, what TEAC does in its VRDS & VRDS NEO systems it that it has the laser pickup on a sled. This pickup operates just like a linear-tracking tonearm on a TT. However, this sled has to be stable. Does this come for free? NO! it adds additional mass to the transport. Plus, it needs a motor & a clean power supply, which add further weight to the system.
I believe that TEACs solution is one manuf solution to these problems & I believe that they have kept the overall transport system as simple as possible but NO SIMPLER. This, of course, does NOT mean that their solution is simple; rather, it is only as complex as it needs to be. If you look at one of their VRDS transports, it is one serious work of art & engineering - I have SE transport in my Wadia.
There is one other factor that is part of the Japanese culture (that an American consumer will probably not understand): the Japanese are favourably disposed to over-engineering. It is in their products since the 1970s. Look at old Sony Walkmans, Sony TVs, etc: they look beautiful inside just as they do outside.
What I'm saying is that there is some element of over-engineering in the TEAC VRDS transports. However, the Japs take it in their stride as they have their home market in mind 1st. The fact that Wadia, the only American company AFAIK, uses it as well is just some side business for them.

there is 3rd aspect that plays superbly into the American manuf's hands: the US audiophile LOVES heavy weight audio gear! If it's heavy, it must be good! To that effect, name 1 European CD player manuf using the TEAC VRDS transport?

Once again as Lktanx wrote, computer-based audio has come a very long way in catching up w/ CD transports. The CD/DVD drives in today's computers are superbly robust & when they get done reading the data from the CD, it is practically 100% correct. CD/DVD drives have always been built with on-board SRAM & they have always been accompanied by hi-speed buses (IDE or SCSI in former years & USB 2.0 today) to carry the data to the CPU. This plays superbly into the hands of a PC being used as a transport for audiophile grade sonic quality.
I have personally pitted my 861 against the my friend's higher-end PC which he uses as a transport into a Scott Nixon Tube DAC+. His floor-stander PC uses a gaming chassis so it has a fancy blue flashing light, it uses higher speed hard-drives & a Lynx sound card. It was self-assembled & probably costs $2000-$3000, which is less than half the cost of my Wadia! Sonically, the difference is even less than the cost disparity. I love my Wadia & I won't part w/ it but it would be utterly foolish of me to ignore the "threat" PC audio is giving TEAC VRDS transports. You can ignore it but at your own peril.

Germanboxers,

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So, you are saying that mis-reading a "0" for a "1" or vice-versa with some random frequency will cause the sound to become like a blender? It won't just misrepresent the amplitude value of the complex wave at those particular sampling points? Assuming a .1% error rate, that's still 40 some errors in amplitude resolution/sec.
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It is due to the way PCM is encoded. Once again do not think of this as an analog signal. For CDs you have data which is 16 bits long. If any of the LSBs (least Significant Bits) were transfered in error, then you would probably not notice this. But as you mentioned since this is random, any of the 16 bits could be transfered in error. If any of the bits which did not reside among the lesser significant bits were corrupted the amplitude error would be huge. Yes, it would actually sound worse than a blender. Just think of what happens if one iota of a note went from very soft to very loud almost instantaneously.

Fortunately, this never happens for a properly designed player. Because there should be ZERO errors after error correction. Like I said, if your transport is failing, you will know it. It is not subtle.
Bombaywalla, ALL CD/DVD/SACD players have a sled with linear tracking for the Laser, except for the famous Philips "swing arm" transport which is now obsolete. The big VRDS-NEO and some newer Philips transports are using a combination between radial and linear tracking where the focusing lens is "suspended" on magnetic field. Since this type of “suspension” is inertia-free, it is the fastest and most accurate reading technique available.

You CAN NOT prevent the disc from wobble, especially with higher than x1 rotation speeds when SDRAM buffering is used, without having a FULL disk support on the top (or bottom in the case of Pioneer "Stable Platter" system). With the Audio Desk Systeme Lathe you're talking about, you can balance the disc and prevent from vibrations caused by eccentricity, but NOT wobbling.

From what I know, the Esoteric VRDS you have in your Wadia spins at x1. The VRDS-NEO spins at about x10 using a large SDRAM buffer from which the data is clocked out. This allows the Laser to go back 10 times and re-read the data should there is error sensed by the DSP. Also, the VRDS-NEO is the ONLY transport currently available which is NOT suspended in any way. Still, even at this very high rotation speed, there is NO vibration you can sense. The READ error rate of the VRDS-NEO is almost 0 (if not 0) but Esoteric still uses the latest Digital Signal Processing with the most powerful error correction AND memory buffering in order to make sure that the error and jitter are indeed ZERO. There is no other disc spinning device (including CD/DVD-ROM) to offer these qualities.

Also, even though with computer based audio certain "error free" software can be used, this does not exactly mean that there are no transport device READ errors.

Any current $150 universal player uses powerful DSP and memory buffering which according to your and Lktanx theory is sufficient to do the job providing error and jitter free data output. Why don't you get one of these and hook it up to an external DAC together with your x1 reading and non-memory buffering VRDS Wadia and see which one will sound better? I can tell you right now; your Wadia will be a LOT better. Also, when you were talking about your friend’s computer based audio with external DAC did you try your Wadia as a digital transport through the same external DAC? If you have not, please do that and let us know if the computer based “error free” “transport” can provide the same bass extension and the same top octaves clarity, air, openness and resolution as your Wadia will.

In conclusion, it is a real fun for me to read all these "error free" discussions, but at the end of the day, there are many other VERY important things when it comes to digital audio other than "Zero" error.

Regards,
Alex
"Also, even though with computer based audio certain "error free" software can be used, this does not exactly mean that there are no transport device READ errors."

Alex, if one uses (and correctly sets up) Exact Audio Copy (EAC) along with a good CD-ROM drive that supports both C1 and C2 error correction (a Plextor Premium or similar) then you *will* get bit perfect copies, as long as there is nothing inherently wrong with the disk. If there is, EAC will give you an indication each and every time an error is detected. Any scenario which would cause a read error that was not detected by this set up (I'm not really sure that's possible) would neither be detected by a dedicated transport.

Having said all that, I agree with you completely that a bit perfect audio image is only part of the picture. But the tradeoffs between a server based bit perfect image and a fine transport are smaller than the D/A conversion of either of these signals, IMO. I've just recently moved to a server based world (a Squeezebox into my D/A converter), and guess what? That does not sound quite as good as my transport (a Proceed PDT3) into the same converter. Is it comparable to some of the other transports I've tried over the years? Yes. Is it scary close to what I have now? I'm afraid to say, yes, with the deficiency being (I believe) in the Squeezebox, and not in the server based delivery of a bit perfect signal.