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CDROM control KITs VFD version

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#281
fredlock said:
It also says on that site, that replacing the NE5532 to LM4562 will also sound better and can be comparable to a tube out put.
Click to expand...

That´s NOT true, we tried that.

The DAC leaves A LOT of room for modifications, but the board you mention is multiple layer and not so easy to modify. You can also read that on the page I mentioned. There Lukasz says that the small board is more suitable for modifications.

Greetings,
Mischa
 
#283
Hi Fred,

Yes, that´s the one.

The costs for the tube stage depend on how much parts you buy second hand. The transformer you can take from an old tube radio, just like the tube foot. For the rest: what would some 1 Watt resistors and a handfull of high voltage caps cost you?

I would say something like 30-40 dollars including tubes. 😀 When you have friends who are active in tubes you might even have some old parts for free. Just look on ebay and you will come across old stock parts. Don´t order high quality parts for the test, you can always upgrade when you like the tube-sound.

When you have contact with the seller, please say Hi from Mischa Gielen from the Netherlands to her. Just orderdered 31 DAC´s there :devilr: .

Best regards,
Mischa
 
#288
Adventures in I2S

My Mitsumi CDROM was not "perfect". Even though I was able to tap the I2S (strictly speaking it is not I2S, but generic PCM, since it is 16-bit right justified), the channels were reversed (left was right and right was left).

Then I found a Sony CDROM from an old IBM PC. Tapped the PCM and this one has the channels correctly. I really liked the Mitsumi. The Mitsumi had metal parts and one button started and stopped the drive. The Sony has plastic parts and requires separate buttons to start and stop the drive. Both sounds really good through my Opus DAC. The datasheet for the Sony controller chip was easy to find.

I also disassembled toshiba, ricoh drives. Couldn't find the data sheets for toshiba and ricoh chips.

So if you could find an old Sony CDROM, that's a winner. The model have is Sony CDU511, and the controller chip is the Sony CXD3000R.

One note: if you get rid of the tray, the you will have to play with the switches and figure out what combination will start and stop the drive.
 
#289
Here is a picture tapping the PCM

http://picasaweb.google.com/lh/photo/lGtwXI-yvrz4-F8VjPu3Rg?authkey=XPCnSxjQnD8&feat=directlink

I used one of those 4 pin connectors you find in motherboards (the white connector) and the 4-wire you also find inside computers connecting the CDROM to the motherboard (those cables are shielded)

Here is a closeup

http://picasaweb.google.com/lh/photo/Hwp8kF1wjkXBYPR0T72kSA?authkey=XPCnSxjQnD8&feat=directlink

showing the soldering of the wires to the vias. It is pretty easy just put a bit of solder to the wire and a bit to the via. Hold the wire on top of the via and heat up the wire
 
#290
qlt,

If you say tapping on I2S signal, your taking this signal output (SCLK, DATA, LRout and MCLK) from the CDROM and connect to the OPUS DAC? Can you explain this a little bit further now that I have the chance to ask you. Sorry I'm a newbie on this DAC thing and I'm trying to experiment what's best that will work on my system.

Thanks.
 
#291
Well, indeed you need four signals plus ground into OPUS (or any DAC), but I can only find 3 signals from the two CDROM I've hacked: BCLK, LRCLK and Data. No MCLK. But I also have the OPUS Metronome which is a asynch resampling and it does not take the MCLK because it generates its own clock.

If I try hard, I would probably find MCLK somewhere since there has to be a master clock in the CDROM otherwise it will not play music and the spdif output would not work

But I have not looked very hard for master clock since I don't need it.

In the two CDROMs I've hacked, the three signals I need are conveniently located in adjacent pins, so once I find one, the others are right there.

I also have a mini-oscilloscope (the one advertised in this forum for $50) and I can see these signals. The LRCLK is a steady 44.1 KHz square wave. The BCLK looks like a staircase sine wave (maybe because the scope has limited bandwidth since it is not steady) and Data is just data all over the place.
 
#294
glt said:
The LRCLK is a steady 44.1 KHz square wave. The BCLK looks like a staircase sine wave (maybe because the scope has limited bandwidth since it is not steady) and Data is just data all over the place.
Click to expand...

I've noticed the same wave (all but square wave!) in my cdrom, using a 20 Mhz CRT scope. It's a miracle that a DAC is able to use that.

:bigeyes:
 
#299
@ audio-kraut
for digital output, you have to open your cdrom, and try to find spdif or I2S signals. Sometimes it's really difficult... start from analog outputs and trace that signals behind, You'll find the dac IC or a "all in one" IC. Try to find datasheet :bawling: and then the digital signals pins...
 
#300
I just opened a slimline CDROM. The controller chip is a Mitsubishi general purpose 16 bit microcomputer. I was able to find the datasheet and (obviously) the I/O pins are just described as generic I/O. Besides, the pitch size of the pins and components are even smaller. In theory, you can check each I/O pin and determine the BCK, LRCK and data lines with a scope. The Microprocessor has a built in DAC.
 
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