This is another newbie post, and bear with me since I have virtually no knowledge of the subject I wish to discuss. Has anyone built there own CD player out of only-highest quality components so that they don't have to buy a high-end player and then mod it later. I'd like to build a tube player from scratch or a kit. I also have a general question about audio sound quality concerning tubes vs solid state and digital. Is the tube sound remarkable for any particular reason? I'd love to be schooled in this, as I'm sure there are many on this site who could do so.
Thanks a mill
Thanks a mill
There sure are people who build their own CD-player, some of the results are posted at this site.
I understand you are a newbie, if true, I wouldn't recomend you to build a whole CD-player. You could start with a DAC, which can be build from scratch or from a kit. Give a look at www.dddac.de, search for the TDA1543 DAC. This is simple...from here on things start to get complicated...
Here is a link to a tubed IV stage, for the TDA1541A
http://www.diyaudio.com/forums/showthread.php?s=&threadid=54817&highlight=
Give a look around, you sure will find (to much) information on this forum.
Erik
I understand you are a newbie, if true, I wouldn't recomend you to build a whole CD-player. You could start with a DAC, which can be build from scratch or from a kit. Give a look at www.dddac.de, search for the TDA1543 DAC. This is simple...from here on things start to get complicated...
Here is a link to a tubed IV stage, for the TDA1541A
http://www.diyaudio.com/forums/showthread.php?s=&threadid=54817&highlight=
Give a look around, you sure will find (to much) information on this forum.
Erik
the easyest way to go is to buy a GOOD cd player: no high end blabla unit, but a heavy, old marantz or philips player.
It takes about a hand full of compnents to modify the IV (this is the part that translates the minute CURRENT (i) from the DAC into output VOLTAGE (v) into a tube output.
This has been wonderfull and cheap for me. Spent about $20 on an old player and another $40 on components...
It takes about a hand full of compnents to modify the IV (this is the part that translates the minute CURRENT (i) from the DAC into output VOLTAGE (v) into a tube output.
This has been wonderfull and cheap for me. Spent about $20 on an old player and another $40 on components...
I couldn't agree more with Beamnet - to make or modify some electronics is far more easier than all the mechanics involved with a CD transport.
And... i personally believe in science, i do not believe in god, allah or audiophiles 😉
Before the DAC, a cd player is a cd player (basic quality provided)
Digital is digital.
Just a means to get little dents in a reflective layer into 0' an 1's. any failure there is eliminated by the checksum and big failures only occur in really bad players.
focus yourself on a good dac chip and a descent IV. Personally, the gain in quality by modifying the ss output was a lot bigger vthan the gain from midified ss to tubes. First get those crap capacitors and cheap opamps out of the way....
bas
Before the DAC, a cd player is a cd player (basic quality provided)
Digital is digital.
Just a means to get little dents in a reflective layer into 0' an 1's. any failure there is eliminated by the checksum and big failures only occur in really bad players.
focus yourself on a good dac chip and a descent IV. Personally, the gain in quality by modifying the ss output was a lot bigger vthan the gain from midified ss to tubes. First get those crap capacitors and cheap opamps out of the way....
bas
beamnet said:
Unfortunately not nearly that simple...a couple quotes from an interview with Julian Vereker...
dave
if cd players would make regular mictakes reading. Then how do cdroms work? If i'd type a simple asci text and copy it on a cd, the words don't change if i read it again..
Bas
Bas
beamnet said:
A CD-ROM can try as many times as it needs to get all the info... a CD-player had to play in real-time. When i ripped my CD collection to my hard drive with error correction, on average it took well over the playing time to get everything off the disk... a CD player can only guess when it has trouble.
This is one of the reasons that computer as transport has such large potential... now if we'd see some good USB DAC projects....
dave
well, let's say a cd player misreads one byte out of every 1000
that means 44.1 erros per second
that means, if it would read twenty seconds anew, it would have to read about a thousand errors. That means he still misses one.
one byte error in one million is fatal for a pc
the entire inside of a pc looks horrible when viewed on a scope, yet it works perfectly (in most cases)
If you had some figures on how often a cd player misses a bit, then you could calculate wther that would be beyond the noise floor of your setup
Bas
that means 44.1 erros per second
that means, if it would read twenty seconds anew, it would have to read about a thousand errors. That means he still misses one.
one byte error in one million is fatal for a pc
the entire inside of a pc looks horrible when viewed on a scope, yet it works perfectly (in most cases)
If you had some figures on how often a cd player misses a bit, then you could calculate wther that would be beyond the noise floor of your setup
Bas
beamnet said:
From my ripping CDs experience (relying on memory & an incomplete sample set -- i didn't watch the RIP on all of them) it was typically at least looking at half the bits twice, and as much as having to read each bit 4 x. On a multi-speed CD-ROM this isn't a huge hardship, but on a 1x CD-Player it means it is potentially making lots of mistakes. Unlike a computer a CD-player doesn't have the time to be perfect.
dave
CD players use CIRC Reed-Solomon code (cross-interleaved redundancy code) to make the digital data less corruptable by errors.
Both CD roms and CD players make errors most of which are corrected on the fly using reed solomon coding and similar. CD/DVD roms have the added advantage of being able to reread misread data packets as needed and generally have somewhat less robust error correction than an audio cd player for that reason.
See here: http://www.4i2i.com/reed_solomon_codes.htm for an explanation of how reed solomon codes work, note they are used in cds, dvds and digital transmission channels.
In the case of cds and dvd's the algorithm is also tuned so that the net dc content of the encoded bitstream is 0 so that AC coupling may be used in the HF amplifier following the optical assembly diodes. (Saves circuit complexity and hence cost.)
CIRC is a technique originally designed for use in audio cd players that interleaves RS code packets, an occasional dropped packet can be tolerated as other samples in the stream in conjunction with a checksum can be used to recreate the missing sample. All CD players have small buffers that hold samples while they are being re-assembled into a time coherent stream. (de-interleaved)
Hope the explanation is clear. Please read up further on the subject if you are curious. I'm not an expert and have little additional to add to this discussion.
In short, all drives make errors, try running a BER test on them, most aren't all that stellar - you don't notice it because of the robustness of error correction whether it be a cdrom drive, cd player or dvd player.
Kevin
Both CD roms and CD players make errors most of which are corrected on the fly using reed solomon coding and similar. CD/DVD roms have the added advantage of being able to reread misread data packets as needed and generally have somewhat less robust error correction than an audio cd player for that reason.
See here: http://www.4i2i.com/reed_solomon_codes.htm for an explanation of how reed solomon codes work, note they are used in cds, dvds and digital transmission channels.
In the case of cds and dvd's the algorithm is also tuned so that the net dc content of the encoded bitstream is 0 so that AC coupling may be used in the HF amplifier following the optical assembly diodes. (Saves circuit complexity and hence cost.)
CIRC is a technique originally designed for use in audio cd players that interleaves RS code packets, an occasional dropped packet can be tolerated as other samples in the stream in conjunction with a checksum can be used to recreate the missing sample. All CD players have small buffers that hold samples while they are being re-assembled into a time coherent stream. (de-interleaved)
Hope the explanation is clear. Please read up further on the subject if you are curious. I'm not an expert and have little additional to add to this discussion.
In short, all drives make errors, try running a BER test on them, most aren't all that stellar - you don't notice it because of the robustness of error correction whether it be a cdrom drive, cd player or dvd player.
Kevin
beamnet said:
I've done this as well, and it can yield great results. You need to pick a player that uses DAC chips that output a current for the analog audio signal, then use a resistor to do Ohm's law to make a voltage that is in turn amplified by your favorite tube line stage amplifier. See my web page http://pw2.netcom.com/~wa2ise/radios/tubedac.htm that describes several diffferent players I've modified. With schematics so you can see what I actually did.
you could buy an average quality cd player and fit a tube output stage straight after the dac- but you have to know what kind of dac it is and have access to the datasheet for it in order to know what pins to intercept- someone experienced in this could find this out with a scope, but being a newbie you want to stick to what has already been done, then change it as you get more experience if you see room for improvement.- if done right this can be a very satyisfying project for a beginner- an quite cheap too- you could change your power transformer to a toriod and get a small step down transformer to connect to the secondary supply of your cd players transformer to give you isolated plate voltage for your tubes.... but to get the right voltages you need to work that out for what player you have.....
hope this helps somewhat
hope this helps somewhat
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