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Proposition: If the CD isn't absolutely level while playing AND because the CD is usually out of round physically, the CD will tend to wobble or flutter, which overloads the laser servo feedback system. Thus the wobbling degrades the sound. When the spinning CD is absolutely level the sound quality is much better.
The level of the CD player is normally NOT the same absolute level as the spinning CD. Actually, if you use a small bubble level you can see the top of the player isn't the same level at all points on the surface. Furthermore some CD trays insert the disc at an angle. So how can absolute level of the spinning CD be obtained? A prize to the first to come up with a correct answer. If there are more than two different correct answers they all win.
Follow Ups:
> So how can absolute level of the spinning CD be obtained? A prize to the first to come up with a correct answer.
> If there are more than two different correct answers they all win.
The best way is to rip the CD to an external USB hard drive and then use a FiiO R9 digital player to play the digital music files. You can plug the USB hard drive directly into the FiiO R9. I think you'll find the sound quality to be far better than your CD player, even when perfectly level. Of course, I could be wrong. You never know.
Happy listening!
John Elison
You might be right, but then you're not playing CDs. The best sound is actually from CD these days, if you follow my advice on fixes for CD playback problems. High on my list are stability of the CD, reduction of laser scattered light, and attention to things in the room that produce noise and distortion.
Edits: 08/21/24 08/21/24
What if the CDP is a vertical disc player?
Whether the disc is spinning horizontally or vertically, the dynamic stability of the disc should be obtained and verified. There can sometimes be mechanisms in a CD player for maintaining dynamic stability of the disc but many players obviously don't control dynamic stability, since the maybe designers are unaware of the issue, who knows, allowing the disc to flutter and wobble during play.Wobbling and fluttering are what produces laser read errors due to nano scale dimensions of the data spiral and laser beam width. Obviously for some players such as Sony SACD player, designed so the disc can't move during play, obtaining absolute level is not necessary. It would be an interesting experiment to see how important absolute verticality is for vertical players.
"Little things sometimes have big consequences."
One wonders if anyone ever compared vertical vs horizontal players for sound quality. What advantage do vertical player designers claim?
Pop quiz - for vertical player, how would you ensure the disc is absolutely vertical while spinning?
Edits: 09/13/23 09/13/23 09/13/23
The bits are correct but if the disc is not level they all move down the slope and run into each other!
As my wife would say, we've discussed this already so nothing more for me to add except I would still love to see the numbers of how deficient CD replay is and how much it can be tweaked into line.
Nt
nt
Boy, first one would have to have something with the "absolute precision" needed, then exposing the disc while it's in operation and measuring it at a number of points with perhaps a laser interferometer or other non-contacting method.
One could "infer" the issues you mentioned by looking at the variations in the servo feedback signal controlling the read optics and or look at the rate of the timing changes on the raw data before the buffer.
I think most cd players (at least used to) have a fifo buffer and what comes out is re-clocked internally. This means there is a tiny delay (latency) between the reading of data X and the clocking of data X out at the other end of the buffer where the D to A happens..
Buffers would not solve the problem of data corruption since the data corruption occurs while the laser is reading the pits and lands on the CD. The buffers would therefore contain the corrupted data. The reason why portable players use buffers is to prevent skipping due to the shock produced by walking. E.g., Sony Walkman.What CD players/transports do have to address the issue of data corruption are laser servo feedback system and Reed Solomon error detection and correction codes. But neither of those implementations are perfect, so data isn't perfect going forward from the laser reading process. And that's why the various CD and CD player tweaks are audible. Vibration isolation, scattered laser light absorption, CD stabilization and CD level.
Edits: 09/11/23
If it really was true that the data is perfect then how come all these tweaks like level CD playing work? Scattered laser light, stabilizing the disc, isolating the CD player, the Green Pen, CD fluids. Do you think people make this stuff up? I mean seriously.No matter how much you have at the end of the day you would have had even more if you had started with more.
But you can go back in time and educate yourself. Only Superman can go back in time.
Edits: 09/10/23 09/10/23
Hi
Who said anything about "perfect", what i am talking about are the things that allowed a portable CD player to be made and the mechanical basis of CD and DVD players.
Besides, what perfect is, is in the eye of the beholder, if any format can reproduce a complex musical passage that can be recorded and replayed to make a generation loss test, then clearly, the more generations it can go before being "bad" the closer it is to perfect. Perfect has no generation limit.
" how come all these tweaks like level CD playing work? Scattered laser light, stabilizing the disc, isolating the CD player, the Green Pen, CD fluids. Do you think people make this stuff up?"
IF they all work, regardless of which domain they act on, someone actually did have to make all those things up. Someone really had to think, what can i do to make this work better?
Modern devices are not as easy to "fiddle with the workings" as in the old days.
Open to experiment?
Play a CD through one speaker that you have moved to a distant room.
Have a friend play a good test cd of your choice and when it's at a good listening level, text your helper and tell them to start tapping on the CD player's case in increasing intensity...until you hear anything different.
Then ask how hard were you tapping on it then.
CD players are normally not microphonic like record players are, they do not pick up room sound unless it's bass that's so strong they mistrack.
Ah, I see now. You're a "perfect sound forever" kind of guy. I realized something was very wrong with CD technology a long long time ago.You can't fool Mother Nature.
Good is the enemy of great. - Audiophile axiom
Edits: 09/10/23
Again, who said anything about perfect or forever?
" I realized something was very wrong with CD technology a long long time ago."
Most regular folks aren't able to separate the limits of the medium from all of the steps and stages involved making and mastering a recording to CD, nor were most present at the time of the recording and have anything like knowledge to go on.
That makes a judgement of the medium itself vs content that "something was very wrong" based on an imagined faithfulness of a recording a pretty big leap.
Oh, dear, my disparaging remarks regarding CD transports have fallen on deaf ears. CDs themselves are fine.
Edits: 09/10/23 09/10/23 09/10/23 09/10/23
IF you have ever heard a single recording on CD that was good, that establishes the CD digital medium is capable of it.
The question is, how much if what you hear positive and negative is the art of recording, the technical limitations of the various elements in the chain. Unless it's a 2 mic live recording, it is an in studio contrived stereo image and unless you were there, a person is limited to a judgement about how "real" it sounds with no knowledge of what it actually sounded like. This is where doing your own recording can be enlightening.
Most of your comments reflect a "black and white" binary like view when in my experience engineering is mostly shades of grey and the concept of "perfect" is only a goal.
Perfect here could be what goes in is exactly the same as what comes out.
Euphonic coloration is not perfection even though pleasing with music (which is harmonic)
You're making it unnecessarily complicated. My proposition is very simple - all things being equal the absolute level of the CD affects the sound. Obviously many other things affect the sound too. Hold all other variables constant while changing one variable at a time.
Edits: 09/11/23 09/11/23 09/11/23
Good thought, so with your CD player, how much can you lift one side without hearing a change. A sheet of paper, a business card, a thin magazine??
Now, have a friend change the spacing while you face away and at what thickness can you hear it now?
When you said " I realized something was very wrong with CD technology a long long time ago. " is this the show stopper flaw you were speaking of?
Somewhere i have an old Sony disc-man that let you play a disc while you were jogging or whatever (i was more whatever).
It was able to do that because it had an especially agile head which could adjust focus very quickly AND it had a good size buffer (a guess would be maybe 2K samples) and variable speed drive so that the rate coming in could have short interruptions or bursts while a separate clock'd output reads to the next stage to the output.
Modern home units don't have to have that level of immunity but if they don't it isn't because they couldn't. Many home CD players are also DVD and or Blue ray players, the precision required to read those tiny pits is much greater than CD and the electronics much faster. Would the same flaw be present there or is it the disc itself?
Again, you're making it way too complicated. Look, all you have to do is make sure the disc is absolutely level while spinning. It's actually the same idea as putting lead weights around the rim of a car wheel to make it rotate more smoothly, I.e., dynamic stability, since most CDs are out of round, which makes then dynamically unstable, especially when not level. Of course, in a perfect work you want to use the disc trimmer to put the CD in round AND my black 3M tape method for stabilizing the disc against small perturbations. But since we don't have the (very expensive) disc trimmer we do the best we can, with Green Pens, Purple Pens, whatever we can, no? Otherwise one lives with the sound you've got.I have pointed out many flaws in the CD playback system. Have you been napping? You also asked me if I'm open to experimentation? You still haven't figured out where I'm coming from. You act like this is your first rodeo sometimes.
NOTE No one has yet offered the solution how to ensure the disc is absolutely level during play. If it was easy everyone could do it.
Geoff Kait
Machina Dynamica
Not too chicken to change
Edits: 09/14/23 09/14/23 09/14/23 09/14/23 09/14/23
Inquiring minds want to know
Since the top of the player/transport is not uniformly level and the tray may not be level with the top of the chassis, you must find a reliable way to ensure the disc is level during play. One way is to place a bubble level on top of the CD that's sitting in the tray with the tray ejected. Then hope the CD is the same level when it's inserted into the player. The balance/stabilizing of the CD is another issue, I recommend the 3M Super 88 tape to stabilize the CD. If it's a top loader just place the bubble level on the CD sitting in the tray.
Edits: 10/07/23
Nt
When placing bubble level on top of the CD sitting on the tray make sure the weight of the bubble level doesn't force the disc over to one side a little bit. Maybe measure the level of the tray only.
I don't think it can ever be perfectly level while playing.
I think the transport is suspended. I think a spinning motor applies torque that will tilt the suspended transport one way or the other. The torque will increase and decrease depending on the RPM of the motor and that is always changing. So the tilt will always be changing.
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
In my tests damping the micro-vibration of the CD laser-reader with a couple of Marigo Audio's 3mm green dots did more to improve CD ripping sound quality than all attempts at fine-tuning CD player unit/ tray balance.
one is vertical, the other horizontal.
Let us see if he edits one more time
Balance and level are two different things.
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