Hi Jonssen,
Interesting read, thank you.
The first Marantz CD player over here was the CD-73. It was a gold coloured unit with green LEDs.
The change in motor driver is fairly common and would not constitute a "tuned" transport. Whenever servos are involved in the design, they are tuned as part of the design - every one of them.
Too bad the story wasn't true ...
-Chris
Interesting read, thank you.
The first Marantz CD player over here was the CD-73. It was a gold coloured unit with green LEDs.
The change in motor driver is fairly common and would not constitute a "tuned" transport. Whenever servos are involved in the design, they are tuned as part of the design - every one of them.
Too bad the story wasn't true ...
-Chris
Which part of the story? Let's get back a few steps.
NATDBERG had mentioned about the use of heavy "pluck" on CD. The "weight" of the pluck might not be the purpose as it will increase the torque required from spindle motor, and it will wear the bearing as you have explained.
I'm not discussing the purpose of the pluck, but it has been mentioned that the heavy plug and the weak motor might in combination form suitable mechanism to control speed, acceleration, stability of the motor, or whatever that seems to contribute to sound quality.
For me, the effect of transport to sound is a mystery, and I don't care much actually. Jitter is one popular variable often mentioned (I will relate to jitter later).
But related to tracking, I have observed that DVD transport have sled mechanism that is more frictionless than CD mechanism. Also I often observed how a slight movement of the motor doesn't move the sled at all... And I have intuition that this contribute a lot to transport performance and that it relates to sound quality...
So, I was expecting the debate about the "pluck" would end in conclusion that we need strong motor (not that Mabuchi) or a frictionless mechanism and a responsive servo electronics. Salar already chosen a good mechanism (sled) and motors but we haven't discussed about the servo chipset...
The CDM-1 were used widely with TDA1301T servo IC (or motor driver) for tracking etc (but not spindle control). This is a very CHEAP IC. The "tuned version" of CDM-1 mechanism do not have this chip, instead, discrete driver using discrete components and basic ICs.
So what is the claim regarding this "tuned CDM-1"? If we assume that a servo is a servo, it doesn't contribute to the sound, then no further discussion needed....
But I prefer to assume that there could be audible difference, or at least improvement in certain aspects, e.g.:
1) The programming logic in an IC might affect operation, such as quick track jump, etc.
2) Control of the motor would be easier if the servo electronics is capable of sourcing the current required by the motor. A cheap low-power IC might not be what we want (Who knows).
3) Third party IC is designed to be able to work with various vendor mechanisms. It means that the clocking/PLL technology should be flexible, e.g. by introducing frequency divider circuit. This, and the cheap nature of the product, will naturally introduce high jitter circuitry.
I believe that even Chris will have difficulty in judging the required thresholds for every variables in a transport design. Therefore, why not assume the worst-case scenario, especially when it CAN be done. (Don't listen to Chris' wife: "just because you CAN doesn't mean that you should").
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Hi Jay,
The only affect that the transport will have on sound quality will be in the amount of errors in the data stream. Defects affect all frequencies and levels, so there isn't a sound type associated with a transport.
Assuming that a low error rate data stream is sent to the RF and DSP sections, there would not be any difference between transports. However, once the CD departs from the accepted standards, you will have impairment. What that sounds like is up to the DSP section. A "less good" transport will pass more errors upstream, and so might sound worse than a good transport.
So, to assess the CD transport you need to look for both the lower error rates. I usually look at BLER rates, or just by looking at the C1 - C2 flags to get a feel for things. You also want a transport that can maintain these low error rates over a long period of time. How transports deal with disc defects is another important factor. All these things tend to converge with the better transports.
1. - Yes as far as the user interface is concerned.
2. - There are times when the available current should be limited.
3. - Most chip sets will work with other transports as long as the laser head matches the RF amp type (single vs three beam types). As long as we use a better chip set, there shouldn't be many problems. The digital data bus needs to agree with the micro-controllers too.
-Chris
The only affect that the transport will have on sound quality will be in the amount of errors in the data stream. Defects affect all frequencies and levels, so there isn't a sound type associated with a transport.
Assuming that a low error rate data stream is sent to the RF and DSP sections, there would not be any difference between transports. However, once the CD departs from the accepted standards, you will have impairment. What that sounds like is up to the DSP section. A "less good" transport will pass more errors upstream, and so might sound worse than a good transport.
So, to assess the CD transport you need to look for both the lower error rates. I usually look at BLER rates, or just by looking at the C1 - C2 flags to get a feel for things. You also want a transport that can maintain these low error rates over a long period of time. How transports deal with disc defects is another important factor. All these things tend to converge with the better transports.
1. - Yes as far as the user interface is concerned.
2. - There are times when the available current should be limited.
3. - Most chip sets will work with other transports as long as the laser head matches the RF amp type (single vs three beam types). As long as we use a better chip set, there shouldn't be many problems. The digital data bus needs to agree with the micro-controllers too.
-Chris
Hi Jay,
Where is this 'TDA1301T chip' normally physically located and where are the alternative 'descrete components and ICs' to be found please? (Just so I can quickly look for them.) Any chance of any pics for guidance?
My simplistic understanding of the CDM-1 is that it's an electromechanical 'lump' with a small PCB attached. That carries sockets into which other stuff plugs. So when I read 'CDM-1 tuned version' I expect some difference in that lump either which I can physically see, or in the quality or tolerance of the components, or some additional quality control adustments (tuning) that took place at the factory. Similarly I would expect and service and spares information to reflect the differences. Other than production progressions over time, I don't recall seeing any obvious differences between CDM-1 'lumps'. I'm wondering if I'm not being sufficiently observant? Thanks.
Jon.
P.S. As an aside, there are reports of a 'Japanese version' of the CDM-1. Here's said example in a Marantz CD-84: Inside Classic Audio
I've had and still have various CD-74s and CD-84s but with 'normal' looking CDM-1s.
This is getting ridiculous now.. it now looks like you're trying to get me chucked off a thread by making accusations .. which are not being made. I assure you it is you who is not taking time to actually understand the point I am making.
Again: The CD701 for example does work and it works well. It might not be ideal in your world but there is no denying that it does work. Therefore a mech with a mass as high as TEAC's CMK 3 has no problems working.
Therefore, anyone on this thread suggesting the use of a disc clamping scheme should absolutely NOT be shut down or argued against on the basis of it adding mass. It can be argued against on the basis of efficacy of a clamping system but not one of mass.
Can you see my point yet (after all this time)? I'm not even advocating, necessarily, a disc clamping system! I'm putting it out there so that OTHERS may be able to discuss their experiences of the benefits.
Just because you and Mark have decided it's not good, should absolutely NOT mean that all discussion of such things should now be stopped because you feel it has already been discussed enough now and that you have already spoken as to why not... hopefully you can see how that comes across (and hopefully you will keep your word about not replying).
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I have specifically stated that I do not. Again and again and again
CD flattening in some form: well, it should be discussed for aiding real CDs found in real CD collections if warped CDs are a real problem and do cause extra errors and worse sound. But it should not be dismissed out of hand on the basis of the extra mass it might cause because that can be overcome as shown in real-life CD players which actually exist and still work 30 years later.
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I would guess that the only real reason for a heavy puck is to raise the clamping force without adding strong magnets which could affect laser movement. With heavier pucks which are designed as part of the system, you'd have thought the whole mech set up would have that angular mass taken into account with a suitable motor with enough torque.
A non-technical reason that is still important is that a heavy puck feels much much nicer and does increase the pleasure of using such a top-loader. Pleasure, happiness... what is the point in hifi if an increase in pleasure is not the goal?
A tapped centre spindle could be a good optional extra - means lighter-weight pucks/clamps can be used and provide greater clamping force.
I have specifically stated that I do not. Again and again and again
CD flattening in some form: well, it should be discussed for aiding real CDs found in real CD collections if warped CDs are a real problem and do cause extra errors and worse sound. But it should not be dismissed out of hand on the basis of the extra mass it might cause because that can be overcome as shown in real-life CD players which actually exist and still work 30 years later.
Do warped discs playback at higher error rates? And, probably more importantly, do they playback at higher error rates on the newer and faster players?
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Hi Mark,
If the warp was severe enough, you would expect to lose focus lock. If the servo had extra power capability, you might see a melted head cover and / or focus coil. These are things I have seen over the years on consumer machines running at 1X the audio CD speed.
-Chris
If the warp was severe enough, you would expect to lose focus lock. If the servo had extra power capability, you might see a melted head cover and / or focus coil. These are things I have seen over the years on consumer machines running at 1X the audio CD speed.
-Chris
Non of my discs have melted anything (or lose focus). The point is that we don't need to fix something that is not broken.
Hi Mark,
My point as well. We agree 100% on this.
I just included observations on higher powered servos when the gain is adjusted too high. Damage can and will occur if you aren't careful using high energy servo outputs.
-Chris
My point as well. We agree 100% on this.
I just included observations on higher powered servos when the gain is adjusted too high. Damage can and will occur if you aren't careful using high energy servo outputs.
-Chris
Hi Jon, I have never heard about this "tuned CDM-1" before. I thought it was in your linked page:
The difference between the CDM-1 and the "tuned" was the "tuned" was minus the TDA motor driver as Marantz made their own driver. But apparently, it's not as simple as bypassing the TDA chip 😕
It appears that there is no TDA motor driver in CDM-1 machine? Except may be in Revox B226 where there are TDA5708/5709 chips for amplifying photo-diodes and control the lens. Most other machines use the "discrete" components plus basic ICs such as opamps (NE5514, LM324) to process lens error signals.
You are right that the servo shouldn't be considered as part of CDM-1 lump. There are many variations of the servo.
Now how about the motor? Is it part of the lump? If so you must have been aware that there are more than one motor versions as mentioned by TVK of your link:
Although there were quite a few versions of the associated servo / control PCBs and of the motor itself (single-phase vs. triphase), the lens, articulation and diecast chassis remained exactly the same.
I have read about CDM-1 using brushed motor, but what I have seen (the internal) is a brushless version. I think the "tuned" ones or the higher end machines all use brushless motor.
If you're curious about this "tuning" modification, then what about tuning the laser and the focus lens (the 3 pots on the small pcb)? Oh, of course, like Chris said, all are "tuned". But what about changes made to the stock mechanism such that they need different tuning? For example, the motor bearing can be adjusted so the lens distance is optimal. Or between laser and monitor diode.
Still curious? Because you already have the None-"tuned" version and be familiar with the components, why not check (and compare) visually with the following web where CD95 components are pictured in detail:
My Marantz CD95 CD Player -- fotop.net photo sharing network
So that's the reason for choosing low current servo. It's fine with brushless motor, how about brushed motors from cheap players? They are hard to move, and the transmission (gears) makes it worse.
What makes cheap DVD motors are more efficient? Aren't they brushed as well?
Hi Jay,
We've seen brushed motors die early deaths due to a lot of HF hash on the motor coming from poorly filtered servos. I have also had to insert resistors in series with the focus and tracking coils in some machines (factory "fixes"). There have been replacement laser heads with the coils changed so they wouldn't burn. All of these things are due to poor servo design and unlimited power from the output stages.
Geared transmissions allow the motor to move more easily. When they get stuck (feed motor usually), it normally is where the brushes are between commutators in the motor. One manufacturer went as far as to gate pulsating DC from the power supply to literally kick the motor across these zones. It worked, but made alignment difficult (mod back to original, set up and redo the mod). Ugly. Keep in mind that the feed motor drive is a filtered version of the tracking coil that responds to averages (another useful test point). These are geared down so that the motor isn't held in a stalled condition that required little movement. Much better with lots of motion while advancing the sled a little. Obviously the motor really spins on track skips.
With DVDs, are you referring to the disc motor, or the feed motor? It's the same situation as the CD version. DVDs are made pretty lightly, so I'm sure that mechanical losses have been reduced. I think they are allowed to be noisier while operating as well. Movies have next to continuous sound whereas a CD has a lot of low level and silent areas. The extra noise is not masked then.
-Chris
We've seen brushed motors die early deaths due to a lot of HF hash on the motor coming from poorly filtered servos. I have also had to insert resistors in series with the focus and tracking coils in some machines (factory "fixes"). There have been replacement laser heads with the coils changed so they wouldn't burn. All of these things are due to poor servo design and unlimited power from the output stages.
Geared transmissions allow the motor to move more easily. When they get stuck (feed motor usually), it normally is where the brushes are between commutators in the motor. One manufacturer went as far as to gate pulsating DC from the power supply to literally kick the motor across these zones. It worked, but made alignment difficult (mod back to original, set up and redo the mod). Ugly. Keep in mind that the feed motor drive is a filtered version of the tracking coil that responds to averages (another useful test point). These are geared down so that the motor isn't held in a stalled condition that required little movement. Much better with lots of motion while advancing the sled a little. Obviously the motor really spins on track skips.
With DVDs, are you referring to the disc motor, or the feed motor? It's the same situation as the CD version. DVDs are made pretty lightly, so I'm sure that mechanical losses have been reduced. I think they are allowed to be noisier while operating as well. Movies have next to continuous sound whereas a CD has a lot of low level and silent areas. The extra noise is not masked then.
-Chris
Great questions to ask.
Also, how badly does a poorly filtered servo effect other PLLs or other parts of the mech via "HF hash" as mentioned by Chris above, or even power supplies or ground planes in the rest of the machine when that focus or tracking servo is working at near it's limits? The harder the servo works, the more HF hash you get.. and vice versa.
I couldn't find that in the thread.
Did you discuss the general construction of the mech? That to me stands out as the most interesting part of it - how the motor section is contructed and then linked to the laser part. Such separation could make manufacture cheaper and allow different parts to be made at different locations as well as such modularity easing the repair or modification/upgrade.
That could be one of the reasons why the newer drives use a brushless motor for the spindle and a stepper motor and lead screw for the sled. Both should also be fairly quiet and be more reliable than the older brushed motors. Stepper motors are also good at positioning and holding.
https://www.youtube.com/watch?v=2iGyP5hpfAg
It would be academically interesting to know by how much the various turntable/platter devices and loose pucks increase the rotating mass when compared to the average magnetic clamper as seen in the vast majority of players. If it wasn't the general mounting / locating inconvenience of top-loaders and the inconvenience of a loose puck one might think that such a system would be advantageous to transport/player manufacturers as it avoids the need (and cost) of a loading tray mechanism. But the fact is such are generally used in 'higher end' product (with the possible exception of Pioneer's stable platter) and marketed as such. One might well conclude that it's more about the marketing than any true technical advantage. The VRDS makes little sense to me with a plastic 'above the disc' turntable. The Pioneer stable platter is quite pleasing to use and seems quite a light (and true) alloy turntable. I'm guessing it doesn't add much mass. Maybe the black rubber turntable mat has some advantages on discs where the silvering is thin (translucent). The Pioneer stable platter players do seem to read ok and given some of the more conventional ones (PD-73, PD-91 for example) seem to have some reading problems it's perhaps understandable why people think the stable platter is 'good'. On Sony players (CDP-XA series) with the separate puck - brass and quite heavy - the centering locator cone on the shaft is sprung loaded, so some of the weight there is used to overcome the spring pressure. I think Sony may have used pucks on their early broadcast decks which I think were top-loaders. I don't think a puck adds to user experience personally, it's just a loose item that you have to put somewhere and try to avoid dropping.
As Chris has pointed out, speed of reaction has to be better with less mass. Overcoming this with a more powerful motor doesn't make sense - firstly it would increase the mass (and hence inertia) even further and secondly the current draw would increase needing a bigger power supply and likely increasing noise. Equally there has to be some mass to retain stability. Given that there is a change in disc speed (500-200rpm) when reading from inside to outside, could it be that an increasing mass would act to stabilise reaction to servo input in any advantageous way? That is to say is the electrical stability of the servo just a fixed value across the whole read or does it vary with the speed of the disc?
When it comes to CD-R drives and alike, I've read of concerns expressed that recording a CD at 1x speed does not necessarily result in the best 'burn' and that better results have been achieved at 4x or higher. I'm wondering if this might be in some way related to the low rotating mass in modern high speed drives?
I've not seen any discs that I would call warped (in normal use) nor have a seen any which are significantly dished. I can't see how a big turntable platter (e.g. VRDS) would help. Maybe a platter would help a little with an off-centre punched disc (by way of stabilisation), but players generally seem to cope with those anyway. If the disc is 'out of limits' it shouldn't be sold and if one 'got away' it's not reasonable to expect it to function properly.
I'm no service engineer but having seen and tried loads of used players (good, bad and indifferent). They behaviour is just as Chris says and it makes perfect sense that the primary concern is to get the best 'read' possible from the media before it gets anywhere DSP / error correction / data substitution.
Mark's 'testing lab' example earlier really just showed itself as not being so much a test of the discs itself but the ability of the drives to read them (particularly as they degraded). I don't see there is a sensible comparison between the 1x drive and the high speed (40x?) drives. Knowing than any media must have errors embedded and, given 40 passes as opposed to 1, you would expect a better 'averaged' result from a high speed drive before it even hit the error correction. The point with a conventional CD player drive is that you only get one pass, so you need to get the best read possible in what is effectively real time. The fact that a high speed drive like Plextor (not sure if they even make their own drives anymore) had better DSP / error correction (or even data substitution, which must be a CD-DA function only as you couldn't use it for CD-ROM data) is a useful secondary attribute.
Getting back to the point of the O/P, what users would want is a new drive (transport) to replace the on in their favourite player when the original packs up. Clearly that isn't going to happen. The next best has to be just a decent transport with S/PDIF output (and perhaps ST) which they can feed to their favourite DAC. I see this as the best way to go as there are oodles of DACs out there, new and used, at prices to suit every pocket. The old players can be kept as display pieces or fixed as donor machines/parts become available. I'm of the view that the performance of separate DACs now exceeds anything available as a player. Some might argue with that, but what's the point of paying thousands for a high end player which can only have a lousy 'soon likely to fail' mechanism in it.
I wonder if Philips / Sony were to produce a CDM-1 / BU1-KSS190 transport now, at what price it could be made for and how many they could sell.
Jon.
As Chris has pointed out, speed of reaction has to be better with less mass. Overcoming this with a more powerful motor doesn't make sense - firstly it would increase the mass (and hence inertia) even further and secondly the current draw would increase needing a bigger power supply and likely increasing noise. Equally there has to be some mass to retain stability. Given that there is a change in disc speed (500-200rpm) when reading from inside to outside, could it be that an increasing mass would act to stabilise reaction to servo input in any advantageous way? That is to say is the electrical stability of the servo just a fixed value across the whole read or does it vary with the speed of the disc?
When it comes to CD-R drives and alike, I've read of concerns expressed that recording a CD at 1x speed does not necessarily result in the best 'burn' and that better results have been achieved at 4x or higher. I'm wondering if this might be in some way related to the low rotating mass in modern high speed drives?
I've not seen any discs that I would call warped (in normal use) nor have a seen any which are significantly dished. I can't see how a big turntable platter (e.g. VRDS) would help. Maybe a platter would help a little with an off-centre punched disc (by way of stabilisation), but players generally seem to cope with those anyway. If the disc is 'out of limits' it shouldn't be sold and if one 'got away' it's not reasonable to expect it to function properly.
I'm no service engineer but having seen and tried loads of used players (good, bad and indifferent). They behaviour is just as Chris says and it makes perfect sense that the primary concern is to get the best 'read' possible from the media before it gets anywhere DSP / error correction / data substitution.
Mark's 'testing lab' example earlier really just showed itself as not being so much a test of the discs itself but the ability of the drives to read them (particularly as they degraded). I don't see there is a sensible comparison between the 1x drive and the high speed (40x?) drives. Knowing than any media must have errors embedded and, given 40 passes as opposed to 1, you would expect a better 'averaged' result from a high speed drive before it even hit the error correction. The point with a conventional CD player drive is that you only get one pass, so you need to get the best read possible in what is effectively real time. The fact that a high speed drive like Plextor (not sure if they even make their own drives anymore) had better DSP / error correction (or even data substitution, which must be a CD-DA function only as you couldn't use it for CD-ROM data) is a useful secondary attribute.
Getting back to the point of the O/P, what users would want is a new drive (transport) to replace the on in their favourite player when the original packs up. Clearly that isn't going to happen. The next best has to be just a decent transport with S/PDIF output (and perhaps ST) which they can feed to their favourite DAC. I see this as the best way to go as there are oodles of DACs out there, new and used, at prices to suit every pocket. The old players can be kept as display pieces or fixed as donor machines/parts become available. I'm of the view that the performance of separate DACs now exceeds anything available as a player. Some might argue with that, but what's the point of paying thousands for a high end player which can only have a lousy 'soon likely to fail' mechanism in it.
I wonder if Philips / Sony were to produce a CDM-1 / BU1-KSS190 transport now, at what price it could be made for and how many they could sell.
Jon.
Hi Jay,
I was just interested to try to find out if a 'tuned version' of the CDM-1 ever existed, or if it was just a figment of someone's imagination which has been repeated and transcribed to the point where 'history is writing itself'.
Whilst the info. on TVK is generally believable and believed, it's still only the writings of one guy. And in this case it seems to be copied from the Dutch Audio Classics site (again one guy) who, in turn, credits it to a Japanese magazine article.
As for the motors, no idea , they look the same to me - didn't look at the wires, connections or wiring, nor have I had one apart.
The reason why I'm interested in this was simply to understand that if a CDM-1 fitted in a CD-12, CD-95/95 etc. failed it could be replaced with a CDM-1 taken out of a low-end player without being detrimental to performance. Clearly, if this 'tuned version' is just a mith, then the answer is likely to be 'yes'.
I've several players both low and high end with CDM-1 and from recollection of quick isolated observations the mechs. all looked the same. I just haven't had all the players with the lids and covers off juxtaposed for a full scrutiny.
Jon.
I was just interested to try to find out if a 'tuned version' of the CDM-1 ever existed, or if it was just a figment of someone's imagination which has been repeated and transcribed to the point where 'history is writing itself'.
Whilst the info. on TVK is generally believable and believed, it's still only the writings of one guy. And in this case it seems to be copied from the Dutch Audio Classics site (again one guy) who, in turn, credits it to a Japanese magazine article.
As for the motors, no idea , they look the same to me - didn't look at the wires, connections or wiring, nor have I had one apart.
The reason why I'm interested in this was simply to understand that if a CDM-1 fitted in a CD-12, CD-95/95 etc. failed it could be replaced with a CDM-1 taken out of a low-end player without being detrimental to performance. Clearly, if this 'tuned version' is just a mith, then the answer is likely to be 'yes'.
I've several players both low and high end with CDM-1 and from recollection of quick isolated observations the mechs. all looked the same. I just haven't had all the players with the lids and covers off juxtaposed for a full scrutiny.
Jon.
Jonsson, as you say, all discs contain errors. Data must be processed by the C1 and C2 to become an audible output (or correct data for rom). DSP is active when C2 (E32) has failed to correct the last errors. The 40X drives still only preforms one read. It just does it at a higher speed.
If a company were to build the old transports. Would it be like building any other product from the eighties? Intel 80286 or an 1985 Opel Kadett. Would many want to purchase these?
If a company were to build the old transports. Would it be like building any other product from the eighties? Intel 80286 or an 1985 Opel Kadett. Would many want to purchase these?