Hi,
I've been following this thread since the beginning and it's been great. However, one thing I kinda don't understand is about the supposed lack of lasers and such for reading discs. Players are still being made, so what are the players using?
Also, in that same vein, Marantz currently makes and sells rbcd only players as well as sacd/rbcd players with self developed transports. While Marantz wouldn't be making the lasers for their own transports, they would be getting them from someone. So who?
I've been following this thread since the beginning and it's been great. However, one thing I kinda don't understand is about the supposed lack of lasers and such for reading discs. Players are still being made, so what are the players using?
Also, in that same vein, Marantz currently makes and sells rbcd only players as well as sacd/rbcd players with self developed transports. While Marantz wouldn't be making the lasers for their own transports, they would be getting them from someone. So who?
Hi stvnharr,
The laser heads are probably made entirely by an outside company. Rohm comes to mind, and Salar probably knows of some others. If I recall correctly, Cyrus in England also made their own transport. I'm not certain how true that is, it may have been a specific project with a normal supplier. This was to get away from the grief Philips caused with their lack of support and cheap transports. Creek handled this a different way by going to CDROM drives. It would RIP the material off the disc at a higher rate than the X1 standard, and it did make multiple passes to try and recover information.
I'm sure there are other players and solutions to these problems, but the most common is very likely the use of a DVD drive. It wouldn't be the first time some of the features of a sub assy were not exploited, making a CD only machine.
-Chris
The laser heads are probably made entirely by an outside company. Rohm comes to mind, and Salar probably knows of some others. If I recall correctly, Cyrus in England also made their own transport. I'm not certain how true that is, it may have been a specific project with a normal supplier. This was to get away from the grief Philips caused with their lack of support and cheap transports. Creek handled this a different way by going to CDROM drives. It would RIP the material off the disc at a higher rate than the X1 standard, and it did make multiple passes to try and recover information.
I'm sure there are other players and solutions to these problems, but the most common is very likely the use of a DVD drive. It wouldn't be the first time some of the features of a sub assy were not exploited, making a CD only machine.
-Chris
Well if everyone is going to jump on that comment now - I'll pipe up properly.
Let's just acknowledge that just because someone doesn't present a full white paper on their own technical experiences does not mean that it is anecdotal rubbish!
Some of the most insightful words into the workings of a system are found in idle chat in exactly that anecdotal chat about those expert's thoughts and ponderings. That goes for fundamental realisations in physics and other sciences as it does in engineering.
What you really are saying is that anything which you don't agree with must be "rubbish", must be considered so unless there are measurements to convince you (it's not only about you..) and that people should not even read things you consider as rubbish - in other words you'd like to see cencorship perhaps purely to make your life easier?
I don't understand your position on that - it is completely anti-enquiry, anti-education not to mention a little arrogant.
I quoted from two people I and others would consider experts; one who has done considerable work in building successful, sonically superior CD players in the 80s and 90s, and another who successfully designs superior sounding DACs who also underwent the very same CD technology training, holds the same expertise as any CD engineer on here, in this thread.
And lets not forget that 95% of DIYAudio is about anecdotal experience of DIYers.
I'd thought Cyrus did use Philips swing arms and then VAM - can't recall seeing anything different but then there are quite a few models..
The first I remember seeing using CD-rom drives was Meridian with the 808 using a DVD/CD-rom drive in 1999. The claimed reasons were about data buffers and 10x more effective error correction ( I guess due to higher speed?) - although not seen an explenation as to how the error correction is improved or what 10 times better actually means.
I think the Creek CD50 MkII I guess you're talking about was 5 years later. Also there was a period around the late 90s where some CD mechs were daftly unreliable (the CDM12?) so people looked for alternatives because of that.
Hi NATBERG, Calling it anecdotal rubbish was a bit harsh, but what are they saying? That they designed and build equipment without confirming/testing that the error correction works?
Hi NATDBERG,
-Chris
Yes, the VAM was the final straw. I think the new transport came out in 2005 or 2006. Redesigned from the ground up. I haven't seen any either.
That's good, because a larger memory doesn't do anything for error correction. They can use it to flag bad data and do a re-read of those sectors. The actual error correction works as effectively as it always did, no changes. If those sectors were unreadable, the larger memory is merely a waiting line for the information with all the errors that the disc has. No impact on data correction at all. Copying data to memory is precisely the same thing as ripping it to a hard drive. The only difference is that there is no hard drive to send the data to, but you have a copy (in memory). From there it could be sent anywhere. Pretty neat eh?
-Chris
No. One is saying that when they addressed vibration issues in the CD mech, the read errors of all types went down (i.e. they weren't to do with the CD itself) and this in turn sounded better compared to when the standard, unmodified mech was used. When they then addressed the same issues further on a cost-no-object design some years later, they found yet more room for sonic improvement and yet fewer read errors.
The other is saying that even though the error correction and mechanisms for covering un-correctable errors allowed the CD to play seemlessly, none the less these read errors had a descernable and repeatable negative effect on the sound. This being a disparity between the theory taught to him by Philips on the nature of error correction (and it having no sonic effect) and its practical application in the real world.
If one is going to design a mech, then surely it is good to "stand on the shoulders of giants" so to speak, or at least consider some other designer's good work (maybe a bit too much to say "giants"). Rather than the attitude of "theory says it shouldn't matter despite Mr X's work giving evidence to the contrary, so ... well, I'm not going to go against the theory!".
This depends on the nature of the project though entirely - is it to produce a sonically superior mech or just one which is of good mechanical quality in order to last and be serviceable? I was assuming the former but then I've just walked in and started talking my mouth off.. 😀
I think it's the case of the re-reading being their explanation. Errors not in the disc but in how it has been read imperfectly. That leaves only disc errors to be corrected. One could extrapolate that this shows a 10:1 relationship between read errors caused by the read method compared to errors on the disc itself.
The memory bit for their own data delivery methods for jitter reduction etc.
Yes goes to show in a way that CD mechs are kind of obsolete! But then again audio DIY is not only about being cutting edge or perfection, simply the enjoyment of making something can be enough motivation, a good CD mech would be a satisfying build.
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Hi NATDBERG,
Well, I have worked on "read once" CD mechanisms and know as a certainty that reduced read errors will improve the sound quality. If you improve data in, you get better sound out.
Above a certain amount of memory, the addition of more does not do any good whatsoever. This is assuming a single read transport (X1 speed). Increase it some more to gain multiple read attempts, but over that limit, more memory buys you nothing.
I do see a time when mechanical reading of media will be a memory. (<==get it?) Everything will be placed on high capacity memory "sticks". We are really almost there, but I think the RIAA guys are holding things up to create some method of copy protection. It will cost more. They did it with cassette, CDR blanks and likely DVD blanks. Too bad if you create your own content - still got to pay.
I will still want to play my records and CDs though.
-Chris
Well, I have worked on "read once" CD mechanisms and know as a certainty that reduced read errors will improve the sound quality. If you improve data in, you get better sound out.
Above a certain amount of memory, the addition of more does not do any good whatsoever. This is assuming a single read transport (X1 speed). Increase it some more to gain multiple read attempts, but over that limit, more memory buys you nothing.
I do see a time when mechanical reading of media will be a memory. (<==get it?) Everything will be placed on high capacity memory "sticks". We are really almost there, but I think the RIAA guys are holding things up to create some method of copy protection. It will cost more. They did it with cassette, CDR blanks and likely DVD blanks. Too bad if you create your own content - still got to pay.
I will still want to play my records and CDs though.
-Chris
I agree, the uncorrectable errors are a problem, that is why I have been promoting E22 and E32 detection, so that you can see when the error correction fails and concealment takes place. No argument here, concealment is not correct playback.
On the other-hand, when somebody describes something that makes no sense. Like placing a slab of concrete in their car and claiming better mpg. Or that red resistors sound better than black. Or that a green edged CD sounds better. Or.............
Over the years, I have seen Disc technology evolve and it is not only theory when you have been manufacturing Discs for almost 30 years.
On the other-hand, when somebody describes something that makes no sense. Like placing a slab of concrete in their car and claiming better mpg. Or that red resistors sound better than black. Or that a green edged CD sounds better. Or.............
Over the years, I have seen Disc technology evolve and it is not only theory when you have been manufacturing Discs for almost 30 years.
Hi Mark,
The problem with looking at error rates these days is to access those signals. Even if I wanted to, the flags are generally not accessible to mere mortals.
-Chris 🙂 couldn't resist the resistors
The problem with looking at error rates these days is to access those signals. Even if I wanted to, the flags are generally not accessible to mere mortals.
That's easy. Car now flat and flies through the air!
Okay, now that is true. Just line them up and tap with a hard object. The red ones ring nicely.
Everyone knows that the green makes the bass stronger. You did know that, didn't you?
-Chris 🙂 couldn't resist the resistors
Gents,
I've been lurking for some time now and do enjoy the wealth of info that has accumulated in this topic, however I'd like to make a suggestion:
How about we compile a tentative spec sheet of this CD mechanism and then start to work out the mechanical and electrical requirements? At least then we'll make some real progress.
Debating the shortcomings of existing CD mechanisms for another xx pages is not going to get us closer to an actual working CD mechanism.
I've been lurking for some time now and do enjoy the wealth of info that has accumulated in this topic, however I'd like to make a suggestion:
How about we compile a tentative spec sheet of this CD mechanism and then start to work out the mechanical and electrical requirements? At least then we'll make some real progress.
Debating the shortcomings of existing CD mechanisms for another xx pages is not going to get us closer to an actual working CD mechanism.
Give me a few hours and I will be able to find anecdotal prove of all of these statements. This is what is happening here, we apply analogue characteristics to digital and then find conformation on the internet.
To see how well my newest, cheapest laptop computer drive works with audio, I have installed NERO DiscSpeed. The program produces a graph of the speed (X), C1 and C2 for this drive.
C1 is fairly inconclusive when trying to detect between a good and a very good disc. BLER would give a lot more info and this was why I had little faith in the Cambridge error counter results. C2 clearly shows where a disc has uncorrectables and how high. Remember that C1 and C2 do not give you the level of correction that was applied, but that correction was not achieved for each of the error correction processes.
Hi SSassen,
I'm glad you piped up. We sort of had that figured out early in this thread. So I think it's only appropriate that Salar places a short list of his understanding and any serious optional paths. That way we can focus things as you've suggested.
-Chris
I'm glad you piped up. We sort of had that figured out early in this thread. So I think it's only appropriate that Salar places a short list of his understanding and any serious optional paths. That way we can focus things as you've suggested.
-Chris
Hi ridikas,
2. It isn't repairable
3. Manufacturing issues
Manufacturers who used this transports from Philips had trouble with them. They were far less reliable than the preceding ones while continuing the high, high cost of warranty service. What hobbyists and enthusiasts hear/see isn't the true picture. What manufacturer would ever say that the transports they picked to use are junk? Can you imagine the lawsuits and warranty costs as folks brought their machines in for skipping before warranty ran out just to get a shot at having a new transport??
During the warranty period, they ran out of those damned mechanisms. They started a refurbishing program which delivered defective mechanisms that ran, but not well. I had 1:1 experience with this from more than one manufacturer. It didn't help that one manufacturer with deep pockets bought a whole bunch as well. Many defective machines were simply replaced due to problems with sourcing the parts.
Even the first couple cast transports had problems. The replacement parts from Philips were always and only entire transports, it wasn't until Philips changed to linear tracking systems that we could get heads. Those VAM transports were complete garbage. That was the final straw for many manufacturers. Philips? Didn't care and never tried very hard to support their junk. They let their customers (the manufacturers) twist in the wind. Personally, I don't think that Philips has a right to exist.
Repair issues. The alignment procedure for the swing arm was extremely difficult, next to impossible to do properly. So both servicing and new manufacture is going to be expensive. The quality of the alignment will suffer as well unless an extremely accurate jig can be produced that will allow everything to be aligned exactly with one go. Read - extremely expensive.
The dollars to reproduce and support new swing arm mechanisms kill this as a reasonable choice. That, and the belief that these transports were problem free. CDM-9 was a disaster I would not care to repeat. You as a consumer should have a reliable transport that can be repaired in the field.
-Chris
1. Because it is not the best transport
2. It isn't repairable
3. Manufacturing issues
Manufacturers who used this transports from Philips had trouble with them. They were far less reliable than the preceding ones while continuing the high, high cost of warranty service. What hobbyists and enthusiasts hear/see isn't the true picture. What manufacturer would ever say that the transports they picked to use are junk? Can you imagine the lawsuits and warranty costs as folks brought their machines in for skipping before warranty ran out just to get a shot at having a new transport??
During the warranty period, they ran out of those damned mechanisms. They started a refurbishing program which delivered defective mechanisms that ran, but not well. I had 1:1 experience with this from more than one manufacturer. It didn't help that one manufacturer with deep pockets bought a whole bunch as well. Many defective machines were simply replaced due to problems with sourcing the parts.
Even the first couple cast transports had problems. The replacement parts from Philips were always and only entire transports, it wasn't until Philips changed to linear tracking systems that we could get heads. Those VAM transports were complete garbage. That was the final straw for many manufacturers. Philips? Didn't care and never tried very hard to support their junk. They let their customers (the manufacturers) twist in the wind. Personally, I don't think that Philips has a right to exist.
Repair issues. The alignment procedure for the swing arm was extremely difficult, next to impossible to do properly. So both servicing and new manufacture is going to be expensive. The quality of the alignment will suffer as well unless an extremely accurate jig can be produced that will allow everything to be aligned exactly with one go. Read - extremely expensive.
The dollars to reproduce and support new swing arm mechanisms kill this as a reasonable choice. That, and the belief that these transports were problem free. CDM-9 was a disaster I would not care to repeat. You as a consumer should have a reliable transport that can be repaired in the field.
-Chris
No doubt I disagree that CDM transports are junk 🙂 Okay, how about just cloning Sony KHM313? Isn't that the last remaining transport?
Lets see what Salar has to say.
Have you read the beginning of this thread? There were some goals laid out back there. Reading would give you a better feel for what is trying to be achieved here.
-Chris
Have you read the beginning of this thread? There were some goals laid out back there. Reading would give you a better feel for what is trying to be achieved here.
Well, if it doesn't work and can't be fixed ... it's junk.
-Chris
It was put into some quality machines from what I could tell. I did a Ctrl "F" for (KHM-313) and scrolled down this list.
CD-Player-DAC-Transport List
Then Google the name of the CD player to find out more. Do that a half dozen times and burn through an hour of your life.😎
As I'm not expert on these things, I take comments by others pretty seriously knowing all the while opinions are sometimes just opinions.
Here is an opinion by a "someone" on a different drive system as an example.
CEC TL51X CD transport (belt drive)
cectl51x
cectl51x
If small weak motors are indeed better sounding, then that JVC boombox based project in the forum, the "Shigaclone" might be on the right track - despite any observational criticisms discussed in this thread.
I'd have to hear the different systems myself and get educated on the topic before really having an opinion of my own.
By all means, somebody should post a first shot at a CD drive proposal.
My idea would to beef up the plastic frame housing on one of the current production CD/ROM-DVD mechanisms via 3D printing or CNC milling, but like I said I'm not expert, just a guy with a pair of ears.
Maybe there is a way to take the play out of the gears?
Print your own?
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(I noticed that focus of the discussion has been on the transport but not the electronics, or precisely the servo chipset)
The transport or laser assembly is just one issue. It is easier to know a good one, but when it is broken, it is a nightmare to replace.
When transports are good enough, their audibility are hard to differentiate between one another. But the stage after the laser is more critical, and it is more audible.
The servo mechanism is the critical engine to control the transport. Of course the transport must be mechanically precise and responsive but the servo itself is made of electronics, starting from reading the photo-diodes, doing some corrections and converting into 16 bit signals, just prior to the DAC stage.
I have experienced using the same transport (I mean the laser assembly) and use different electronics for the EFM and correction stage, and the sound difference is very audible.
In DVD, I think Mediatek is a good one. It is the one used by Pioneer that was "rebadged" (with better transport assembly) by Goldmund. This chip is known to be reliable in controlling the transport.
In the servo, tracking control is the hardest job. Often the accuracy of the tracking can be seen from the movement of the parts trying to align the laser for less tracking error. My two tricks here are using the RESET and REPEAT.
When the power is turned off and on, the RESET is usually engaged.
When the REPEAT is used for the first track, it seems the tracking assembly will find its comfortable positioning with less tracking error. Then after this stable position is achieved the REPEAT button can be released and the system will find less error than without doing the stabilizing trick.
But of course this doesn't apply with the best transport this thread is trying to look for, which supposed to have minimal tracking error. But the issue is already clear imo. It might be irreplaceable/irrepairable.
I expect people to come up with favorite chips 😀