kach22i,
check this:
This is the mechanism we want.
SONY CDP-557ESD
Or, if gear is involved, sturdy as hell. "Weak motors are good for the sound" - please apply yourself @ a marketing department of any home electronics company!
When I was a child, playing around with a brushed motor (maybe around 6V) caused interferences on my parent´s analog TV. This is why someone added condensers later...
check this:
This is the mechanism we want.
SONY CDP-557ESD
Or, if gear is involved, sturdy as hell. "Weak motors are good for the sound" - please apply yourself @ a marketing department of any home electronics company!
When I was a child, playing around with a brushed motor (maybe around 6V) caused interferences on my parent´s analog TV. This is why someone added condensers later...
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Hi Salar,
Basically, its a KSS-151A transport. I think this is where we were early on in the thread. But watch out for the "lampizator.eu/" ding dong. He is at best - misguided. I'm being polite here.
So, look at the comparison he made. His reference transport was a CEC TL1X. This is the stupid design that ran the disc table from a belt designed and sold by the company responsible for the super cheap (and delicate) Nikko terrible CD players. I am impressed by one .. no, two things this company achieved. One, it successfully avoided its shoddy reputation in the past. Two, it very successfully marketed a design that only appeals to people who don't understand the differences between turntables and CD players.
It would be very interesting to see how he reviewed the KSS-151A designs (also Technics had their own version that they stuck with).
Lastly, he had not heard of the PCM-64P DAC. Nor could he figure out how to pull out a signal from them. This should be bloody frightening to anyone considering his technical input. Lampizator should approach this from a technical angle, but it appears he is getting his opinions and information from the audio press.
Anyway, we would be very well served by any transport like the BU-1E or KSS-151A style heads. That includes transports made by Technics as they are just as good.
-Chris
Basically, its a KSS-151A transport. I think this is where we were early on in the thread. But watch out for the "lampizator.eu/" ding dong. He is at best - misguided. I'm being polite here.
So, look at the comparison he made. His reference transport was a CEC TL1X. This is the stupid design that ran the disc table from a belt designed and sold by the company responsible for the super cheap (and delicate) Nikko terrible CD players. I am impressed by one .. no, two things this company achieved. One, it successfully avoided its shoddy reputation in the past. Two, it very successfully marketed a design that only appeals to people who don't understand the differences between turntables and CD players.
It would be very interesting to see how he reviewed the KSS-151A designs (also Technics had their own version that they stuck with).
Lastly, he had not heard of the PCM-64P DAC. Nor could he figure out how to pull out a signal from them. This should be bloody frightening to anyone considering his technical input. Lampizator should approach this from a technical angle, but it appears he is getting his opinions and information from the audio press.
Anyway, we would be very well served by any transport like the BU-1E or KSS-151A style heads. That includes transports made by Technics as they are just as good.
-Chris
Interesting - Technics linear drive:
http://www.thevintageknob.org/technics-SL-Z1000.html
http://www.thevintageknob.org/technics-SL-Z1000.html
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Hi Jay,
One thing is for certain. A poorly performing servo will not show a clean eye pattern, and the EFM output will be not send the digital section the clean information it needs.
So, I am agreeing with you on this. I just wanted you to know that "transport" in my mind includes the servo section and diode I-V stage as well. The term "mechanism" may have been used arbitrarily here, but in general would refer to the actual CD mechanism without any electronics (except the head assy).
Once a head and mechanism has been decided, you will see the servo section would then be discussed in particular, but right now it is too early to focus on the support electronics.
-Chris
The way I assess "transports" includes the servo chip set. Most manufacturers use a chip set that is used in the applications section for a CD head. All the work has been done for them. A few designed their own servos, and others (more) simply adapted a different chip set to the new head. That is actually a sound practice as well.
One thing is for certain. A poorly performing servo will not show a clean eye pattern, and the EFM output will be not send the digital section the clean information it needs.
So, I am agreeing with you on this. I just wanted you to know that "transport" in my mind includes the servo section and diode I-V stage as well. The term "mechanism" may have been used arbitrarily here, but in general would refer to the actual CD mechanism without any electronics (except the head assy).
Once a head and mechanism has been decided, you will see the servo section would then be discussed in particular, but right now it is too early to focus on the support electronics.
I would disagree only on one point. The servo section ends with the EFM signal, which is where the DSP section begins. You can switch between the following chips without ill effect as long as the servo section gets its regenerated clock and reference clock signals. along with servo mute signals which generally comes from the MPU control section (MPU runs the keys, displays and signaling the various modes [like pause, skip, read TOC] from user input). That means that electronically speaking, we have the main sections Servo, DSP, D/A conversion, MPU control (incl user interface) and Power Supply. All these require consideration in turn. The ability to use various options for D/A conversion and possibly user interface and features would also require discussion.
-Chris
Talking about datasheets: Salar regards post 293 as equally important for the moment
http://www.diyaudio.com/forums/digi...et-us-build-one-ourselves-30.html#post4531690
Nothing. And the diode you posted is not on the Rohm website -
hece it is not produced any more. They only produce combos.
Again, for the fourth time: Could anyone please help me in modifying an APC
for a Rohm diode?
A direct comparison of the datasheet of the widely used LT022 with an actual Rohm diode can be found in
Post #293
also an example of an APC of a Sony CDP-502. Sony SLD104 might be another candidate for later mods.
When I am looking to replace a part or make a new design, I contact the suppliers to find out if what I am planning will work and if there is any help they can give me. Mostly they are very willing to help. The link gives you a new contact for help and a single laser option.
You would think after asking 4 times you would understand that you will need to do this yourself or explain better why you think it needs a redesign.
Why do you think the APC needs to be redesigned? Is it not a matter of adjusting the pot for the new laser?
You would think after asking 4 times you would understand that you will need to do this yourself or explain better why you think it needs a redesign.
Why do you think the APC needs to be redesigned? Is it not a matter of adjusting the pot for the new laser?
I'm a bit reluctant to accept the argument that's a bad thing to add weight to the parts that's spinning.
Well, if you are defending the use of standard Mabucci motors then low rorating mass is an absolute requirement.
I'm into slotracing so I know you have to buy 100 motors and test each of them to find a good one to race with.
If you use a better motor then the problem with higher rotating mass is gone.
Well, if you are defending the use of standard Mabucci motors then low rorating mass is an absolute requirement.
I'm into slotracing so I know you have to buy 100 motors and test each of them to find a good one to race with.
If you use a better motor then the problem with higher rotating mass is gone.
Hi jasse,
Which week of high school physics did you miss? I can help. You missed the section on inertia. Why the hell do you want to create a bigger problem to solve with a bigger motor?? I have confused me to no end. Repeat after me.
A CD player is not a turntable ...
A CD player is not a turntable ...
A CD player is not a turntable ...
A CD player is not a turntable ...
and so on.
-Chris
I'm tired of explaining this ... Baby steps I guess.
Which week of high school physics did you miss? I can help. You missed the section on inertia. Why the hell do you want to create a bigger problem to solve with a bigger motor?? I have confused me to no end. Repeat after me.
A CD player is not a turntable ...
A CD player is not a turntable ...
A CD player is not a turntable ...
A CD player is not a turntable ...
and so on.
No! It isn't. All you did was make it less of a problem by throwing more energy at it. Never put yourself at a disadvantage where physics is concerned.
-Chris
Hi Salar,
It isn't that hard to compensate for a different LD. Think of it as an LED. Look at the intended output light power and compare that to the circuit you want to adapt it to. In reality, you may not have any need to modify anything. The included monitor diode is the key to controlling the laser output power.
If you can find the laser current (printed on the head or flex cable), which varies widely between heads of the same type, you just monitor the current across a resistor and set the current to be what is printed on the head.
In a more round about way, look at the expected RF level in the circuit you want to use and adjust the power to give you that amplitude. More efficient pickup diodes will require less current. It should be within the adjustment range of the circuit you are borrowing the design from anyway.
I will very happily test things once you are at the prototype stage. I have some CD players I could try this with if the LD fits. I just use one with a toasted laser.
At the moment, I am demolishing my office, so I may be out of touch. Once the new bench is in, I can be in contact more. Today and tomorrow are moving days (as was the last of last week).
-Chris
It isn't that hard to compensate for a different LD. Think of it as an LED. Look at the intended output light power and compare that to the circuit you want to adapt it to. In reality, you may not have any need to modify anything. The included monitor diode is the key to controlling the laser output power.
If you can find the laser current (printed on the head or flex cable), which varies widely between heads of the same type, you just monitor the current across a resistor and set the current to be what is printed on the head.
In a more round about way, look at the expected RF level in the circuit you want to use and adjust the power to give you that amplitude. More efficient pickup diodes will require less current. It should be within the adjustment range of the circuit you are borrowing the design from anyway.
I will very happily test things once you are at the prototype stage. I have some CD players I could try this with if the LD fits. I just use one with a toasted laser.
At the moment, I am demolishing my office, so I may be out of touch. Once the new bench is in, I can be in contact more. Today and tomorrow are moving days (as was the last of last week).
-Chris
I am with you on this, but only if one starts at the first track and plays the whole CD through to the end.
The minute you want to skip a track, or go back and rehear a track, you will send the momentum mass of the mechanism into a frenzy, fighting a battle with physics which it will never win.
For my listening habits, a high mass system with clamping system would work very well.
My McIntosh MCD-7009 which uses the same magnetic clamping Teac drive as the Esoteric CD players is an example of such a system.
My CD player seems to struggle a bit when doing system changes and tweaks which involve lots of song backtracking and cuing to hear the same parts of the same passages over and over again.
I think the people which want to skip and change tracks frequently need to be up front about their habits, needs, wants and goals.
It would go a long way in explaining their motivations for a low mass CD drive with little to no disc clamping.
And then they would not need to explain over and over again why mass is their personal enemy.
It is the ability of the system to control the scanning velocity and not the RPM that is important. And, even that has some flexibility because the corrected (audio) data is buffered before released to the DAC. If the disc would rotate below what was required then the buffer would run low, this would then cause an increase of the scanning velocity.
It is like driving your car at a constant MPG instead of MPH.
It is like driving your car at a constant MPG instead of MPH.
To use another analogy:
The scanning velocity is the "horse" and the RPM is the "cart"?
I would have thought it was the other way around.
Horse pulls the cart, therefore horse is in front of the cart.
This changes my mindset, not sure how much, but the mush I call brains is starting to pulse...........just not in zeros and ones yet.
EDIT:
I'm sure that this has been covered, but aren't there laser assemblies which twirl around the disc, thereby controlling their own rate of scanning velocity?
Maybe there aren't, that much mass spinning doesn't sound practical either. And it would need it's own servo/controller.
Maybe use mirrors somehow?
Yea, I don't know what I'm talking about, just unplug me before I go spinning off.
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Hi kach22i,
At least you accept that changing the RPM does go easier with lighter mass. But even if you do listen all the way through with no track jumping, a slightly off-center CD will tend to accelerate the wear of the disc motor. So will spinning the CD up to read the TOC. Why fight physics? Work with it and you will have better performance whenever things shift from the perfect situation to one that is sub-par. Even if you use a more robust motor, you are still making its lifetime shorter with a high mass rotating system.
Maybe the timers can be extended to allow a slow wind-up to read that TOC without rejecting the disc. The same for getting to that first track, and also the final braking when you wish to eject the disc. That will make for a sluggish drive, but it would allow for a higher mass system to operate. So the only issue you will have is with off-center discs that may be rejected due to the response time. You would probably loss lock on those discs even if they aren't rejected.
I guess the fundamental question really goes to the heart of why you feel a high mass rotating system is a benefit to begin with. Keep in mind that it is relatively easy to absorb any vibrations coming through the bottom feet, and air-borne vibrations are also easy to attenuate to levels lower than the high mass model provides. All this while using a low mass, magnetically clamped system. There is no vibration with a rotating disc unless they begin in the motor bearings (need a new motor), or through the top clamp (clearance adjusted incorrectly). The old pressure clamp systems were problematic as they coupled the rotating disc to the sub-chassis while also being affected more by vibration from acoustic sources. Once that system was discarded in favor of magnetically clamped systems, these problems evaporated. The only problem machines were those cheap ones with light, stiff chassis and mechanisms. The machines using heavy chassis's and good isolation for the CD mechanism never looked back and performed to levels far beyond what the later "Stable Platter" folks could attain.
Do you want to see an amazing transport that focused on mechanism isolation from the environment? Look inside the Denon DCC-8920 car CD player (and any others that used that same mechanism). Look for machines that have a separate tuner from the head unit. The inside of the case is occupied by a very robust CD mechanism with amazing isolation from impacts the car endures without skipping (no increased memory either).
After servicing CD players since the introduction of the format, I have yet to see a properly operating mechanism that created any vibration that impacted the CD. They cannot be allowed to vibrate simply because the laser would not be able to maintain a lock on the CD surface. Vibration would destroy an eye pattern. I've serviced a scary number of CD players so far. Being warranty for many brands really ups the number of units I would see compared to anyone without warranty contracts. I have yet to see (or hear) any CD player that had problems with vibration while spinning a CD. They are running smoothly, silently unless they have defects. The clicking you might hear comes from the lens moving abruptly, not the CD. It continues it's noiseless spin without any vibration at all.
I do know of one situation where the CD does suffer vibration issues. That occurs when the clamp isn't firm enough, or the gripping surface of the disc table and clamp are slippery. The minuet speed changes create a situation where the CD always overshoots the target RPM. The situation may become worse until the point is reached when the CD unchucks and attempts to escape. This generally marks the CD rather badly and may even jam the tray so it cannot be opened. But this is a fault situation, not a problem with the overall design of the transport.
Save making a direct reference to a turntable, I can't see even one benefit from a higher mass "stable platter" type mechanism. The super heavy designs from Teac - Tascam were problematic at the time. Adjustments were finicky and really shouldn't have been necessary. The bearings in that mechanism for the "stable platter" also contributed problems of their own. So you end up with top and bottom contact points having bearings. Compare that with the normal motor only contact point. Very few adjustment problems for the disc table and magnetic clamp, only one set of bearings that are replaced when the motor is replaced. I am convinced through direct observation of these machines that the "stable platter" is a solution looking for a problem.
-Chris
At least you accept that changing the RPM does go easier with lighter mass. But even if you do listen all the way through with no track jumping, a slightly off-center CD will tend to accelerate the wear of the disc motor. So will spinning the CD up to read the TOC. Why fight physics? Work with it and you will have better performance whenever things shift from the perfect situation to one that is sub-par. Even if you use a more robust motor, you are still making its lifetime shorter with a high mass rotating system.
Maybe the timers can be extended to allow a slow wind-up to read that TOC without rejecting the disc. The same for getting to that first track, and also the final braking when you wish to eject the disc. That will make for a sluggish drive, but it would allow for a higher mass system to operate. So the only issue you will have is with off-center discs that may be rejected due to the response time. You would probably loss lock on those discs even if they aren't rejected.
I guess the fundamental question really goes to the heart of why you feel a high mass rotating system is a benefit to begin with. Keep in mind that it is relatively easy to absorb any vibrations coming through the bottom feet, and air-borne vibrations are also easy to attenuate to levels lower than the high mass model provides. All this while using a low mass, magnetically clamped system. There is no vibration with a rotating disc unless they begin in the motor bearings (need a new motor), or through the top clamp (clearance adjusted incorrectly). The old pressure clamp systems were problematic as they coupled the rotating disc to the sub-chassis while also being affected more by vibration from acoustic sources. Once that system was discarded in favor of magnetically clamped systems, these problems evaporated. The only problem machines were those cheap ones with light, stiff chassis and mechanisms. The machines using heavy chassis's and good isolation for the CD mechanism never looked back and performed to levels far beyond what the later "Stable Platter" folks could attain.
Do you want to see an amazing transport that focused on mechanism isolation from the environment? Look inside the Denon DCC-8920 car CD player (and any others that used that same mechanism). Look for machines that have a separate tuner from the head unit. The inside of the case is occupied by a very robust CD mechanism with amazing isolation from impacts the car endures without skipping (no increased memory either).
After servicing CD players since the introduction of the format, I have yet to see a properly operating mechanism that created any vibration that impacted the CD. They cannot be allowed to vibrate simply because the laser would not be able to maintain a lock on the CD surface. Vibration would destroy an eye pattern. I've serviced a scary number of CD players so far. Being warranty for many brands really ups the number of units I would see compared to anyone without warranty contracts. I have yet to see (or hear) any CD player that had problems with vibration while spinning a CD. They are running smoothly, silently unless they have defects. The clicking you might hear comes from the lens moving abruptly, not the CD. It continues it's noiseless spin without any vibration at all.
I do know of one situation where the CD does suffer vibration issues. That occurs when the clamp isn't firm enough, or the gripping surface of the disc table and clamp are slippery. The minuet speed changes create a situation where the CD always overshoots the target RPM. The situation may become worse until the point is reached when the CD unchucks and attempts to escape. This generally marks the CD rather badly and may even jam the tray so it cannot be opened. But this is a fault situation, not a problem with the overall design of the transport.
Save making a direct reference to a turntable, I can't see even one benefit from a higher mass "stable platter" type mechanism. The super heavy designs from Teac - Tascam were problematic at the time. Adjustments were finicky and really shouldn't have been necessary. The bearings in that mechanism for the "stable platter" also contributed problems of their own. So you end up with top and bottom contact points having bearings. Compare that with the normal motor only contact point. Very few adjustment problems for the disc table and magnetic clamp, only one set of bearings that are replaced when the motor is replaced. I am convinced through direct observation of these machines that the "stable platter" is a solution looking for a problem.
-Chris