Hi,
I'm going to build a transport with a CDM Pro2 mech and would appreciate a little help with deciding how to implement the PSU's.
I need +5V and +9V for the module, +5V for the display driver PCB.
I intend to keep these on seperate LM317 based supplies which gives me the freedom to optimise each one.
What kind of solution would be best for the 9V supply? I understand that the servo circuit can pull short heavy current peaks at all sorts of frequencies, is a LM317 up to this?
Thanks,
Simon
I'm going to build a transport with a CDM Pro2 mech and would appreciate a little help with deciding how to implement the PSU's.
I need +5V and +9V for the module, +5V for the display driver PCB.
I intend to keep these on seperate LM317 based supplies which gives me the freedom to optimise each one.
What kind of solution would be best for the 9V supply? I understand that the servo circuit can pull short heavy current peaks at all sorts of frequencies, is a LM317 up to this?
Thanks,
Simon
Hi,
I suggest you can buy miniPCB from below website.
http://home.kimo.com.tw/ucccap/
This website is built in Chinese, so you may not understand
its content. You can directly send your mail to the webmaster.
mail: apple-audio@yahoo.com.tw
Its pp Cap are also good and cheap.
I am just an user. You can reach him by youself.
I suggest you can buy miniPCB from below website.
http://home.kimo.com.tw/ucccap/
This website is built in Chinese, so you may not understand
its content. You can directly send your mail to the webmaster.
mail: apple-audio@yahoo.com.tw
Its pp Cap are also good and cheap.
I am just an user. You can reach him by youself.
simon dart said:
Simon,
Out of interest did you get a pcb for the microcontroller for the cdmpro 2?
I remember reading that the cdpro power supplies have to be switched on, and off in a particular order!
See one of the application notes here:-
http://www.daisy-laser.com/products/CD/modules/CDPro2/downloads.htm
Kind regards,
Ashley.
Hmm.... I was hoping you got one from a UK source. €400 is a bit much for the transport to be honest.
Yes, very good power supply regulation will help. To put things in context, I have some hair trimmers from when I lived in Canada. On a cheap UK step-up transformer where the output is unregulated, you can hear them speed up to excess or slow down too much due power supply variation. I used to have a turntable with a stroboscope where the same effect is visible although not always hearable.
The same thing happens with the drive spin speed of the transport although to a much lesser degree - however, the laser pickup may read the odd bit early or read the odd-bit late and this may transpire into timing errors with your DAC. Note when I say 'bit' I am referring to the microscopic pits in the CD.
Also, because tracking a disc itself is no small feat (Tag McLaren used to have some white papers on this on their website, since Audiolab are back, maybe you get get in touch and get hold of them) this is why clamping and various transport methodolgies have been used over the years. As a CD spins, it becomes a gyroscope and wobbles to a lesser or greater degree depending on how good the transport and clamping mechanism is. The CD-Pro2M is the best, but your goal is to allow the electronics to function as perfectly as possible to minimize read errors. All of this take place before you handle the raw output signal .
Most read errors are handled by some type of chip based error-correction methodolgy which makes the error imperceptable to the human ear except for that the overall sound is not quite accurate and not as transparent or crystalilne as it could be. In other words, really bad errors are smoothed over, but the original waveform is still lost for a fraction of a second.
In an ideal situation you need to keep the CD rotational speed as perfect as possible so that the raw data stream output can be as error free as possible. A DAC will collect a sequence of bits and essentially convert them to a value. DAC clock timing errors (jitter) mean that the wrong data sequence can be seelcted and create erroneous values. Fixing this with a good supply to your DAC will help, but it doesn't fix it entirely if the raw data stream itself contains errors as this will manifest itself as erroneous value generation in the DAC.
So:
1) A good DAC clock is essential for reducing jitter.
2) Point 1, may only solve half the jitter-problem if half the errors are read errors. For top quality sound, ensure you read the disc correctly.
This is partly why Meridian Audio shifted to CD-ROM or DVD ROM readers from PCs. These spin the disc many more times per second (max of current CD-ROMs is 52 times normal audio speed). This potentially allows 52 samples of each 16-bit block to be taken and the average of each of the bits used (ie, where there is usually a 1 in bit 'x' where x is position 1 to 16, the output will be a 1 else 0 at position 'x'). This helps drastically reduce read errors without spending too much money on a fancy supply, although it will still help in the cost-no-object commercial design. For a DIYer, depending on what you want to achieve, you should do all you can, but remember the supply to the transport is just as crucial. If it wan't, one reference transport would not sound much different to a cheap transport when both used with the same DAC. As a Chord DAC64 owner who has used it on the end of both cheap universal players and CD players from the likes of Meridian and others, I can tell you without equivocation that the better transports help produce better sound.
InfiniteGain
Yes, very good power supply regulation will help. To put things in context, I have some hair trimmers from when I lived in Canada. On a cheap UK step-up transformer where the output is unregulated, you can hear them speed up to excess or slow down too much due power supply variation. I used to have a turntable with a stroboscope where the same effect is visible although not always hearable.
The same thing happens with the drive spin speed of the transport although to a much lesser degree - however, the laser pickup may read the odd bit early or read the odd-bit late and this may transpire into timing errors with your DAC. Note when I say 'bit' I am referring to the microscopic pits in the CD.
Also, because tracking a disc itself is no small feat (Tag McLaren used to have some white papers on this on their website, since Audiolab are back, maybe you get get in touch and get hold of them) this is why clamping and various transport methodolgies have been used over the years. As a CD spins, it becomes a gyroscope and wobbles to a lesser or greater degree depending on how good the transport and clamping mechanism is. The CD-Pro2M is the best, but your goal is to allow the electronics to function as perfectly as possible to minimize read errors. All of this take place before you handle the raw output signal .
Most read errors are handled by some type of chip based error-correction methodolgy which makes the error imperceptable to the human ear except for that the overall sound is not quite accurate and not as transparent or crystalilne as it could be. In other words, really bad errors are smoothed over, but the original waveform is still lost for a fraction of a second.
In an ideal situation you need to keep the CD rotational speed as perfect as possible so that the raw data stream output can be as error free as possible. A DAC will collect a sequence of bits and essentially convert them to a value. DAC clock timing errors (jitter) mean that the wrong data sequence can be seelcted and create erroneous values. Fixing this with a good supply to your DAC will help, but it doesn't fix it entirely if the raw data stream itself contains errors as this will manifest itself as erroneous value generation in the DAC.
So:
1) A good DAC clock is essential for reducing jitter.
2) Point 1, may only solve half the jitter-problem if half the errors are read errors. For top quality sound, ensure you read the disc correctly.
This is partly why Meridian Audio shifted to CD-ROM or DVD ROM readers from PCs. These spin the disc many more times per second (max of current CD-ROMs is 52 times normal audio speed). This potentially allows 52 samples of each 16-bit block to be taken and the average of each of the bits used (ie, where there is usually a 1 in bit 'x' where x is position 1 to 16, the output will be a 1 else 0 at position 'x'). This helps drastically reduce read errors without spending too much money on a fancy supply, although it will still help in the cost-no-object commercial design. For a DIYer, depending on what you want to achieve, you should do all you can, but remember the supply to the transport is just as crucial. If it wan't, one reference transport would not sound much different to a cheap transport when both used with the same DAC. As a Chord DAC64 owner who has used it on the end of both cheap universal players and CD players from the likes of Meridian and others, I can tell you without equivocation that the better transports help produce better sound.
InfiniteGain
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