rowemeister said:
I only did the 16.9MHz MCLK that runs from the DAC to the decoder for starters. It's a job that requires a good light, and a sharp scalpel knife
. I bought the cable at Farnell, it's from Nexans. Overall diameter is 1.22mm! The inner conductor is a 0.1mm copper plated steel wire. Very cool stuff! Felt like a surgeon this afternoon .I used 75 ohm because that has less capacity/m.
The characteristic impedance doesn't matter much, because it's such a short run, compared to the signal's wavelength. I learned that here. Very good site, with lots of info. So I went for less capacity.
Standard there's a 470R resistor in series with the MCLK line. I noticed the clock signal became quite weak at the decoder after I inserted the coax, probably because of the larger capacity. I tried lowering the resistor to 75R. But the input of the decoder appears to be at ~2.5V DC, and there is actually a DC current running between the two chips
. That's probably why they chose the resistor so high. So I also inserted a 560pF SMD cap (had that laying around...) in series with the DAC's output, after the 75R resistor, and got rid of that. The signal is a lot stronger now and the decoder seems to work fine.My first impression of the sound is that it has become more like my tubestage
.This is definately a mod I can recommend. Thank you Brent!
Regards,
Ray.
6h5c said:
I only did the 16.9MHz MCLK that runs from the DAC to the decoder for starters. It's a job that requires a good light, and a sharp scalpel knife
I used 75 ohm because that has less capacity/m.
The characteristic impedance doesn't matter much, because it's such a short run, compared to the signal's wavelength. I learned that here. Very good site, with lots of info. So I went for less capacity.
Standard there's a 470R resistor in series with the MCLK line. I noticed the clock signal became quite weak at the decoder after I inserted the coax, probably because of the larger capacity. I tried lowering the resistor to 75R. But the input of the decoder appears to be at ~2.5V DC, and there is actually a DC current running between the two chips
My first impression of the sound is that it has become more like my tubestage
This is definately a mod I can recommend. Thank you Brent!
Regards,
Ray.
Just wait till you do the other coax mate, very worth while
Also my 63 has a cap and resistor between Dac and Decoder. The resistor is a 390ohm and the cap (I can't remember value) which I changed for a silver mica
Strange thing is the service manual shows no cap and a 100 ohm res!!!
Brent
How NOT to do a Mod !!
Hi.
I thought you might be interested in my latest project.
I have been asked to look at a CD6000 OSE. The guy had attempted to upgrade it by changing the rectifiers to Schkktsky ( you know what I mean - better ones ). When he switched on, it didn't work. He found he hed soldered 1 diode the wrong way round ( in the 10 / 5v supply ). So he corrected the fault and it still didn't work.
This model does not use glass fuses as per CD63 but PCB mount Wickmann fuses - both were blown, naturally!
But look at the soldering - I think he used a piece of steel rod and a lump of old lead pipe to solder the joints - every one is dry.
The sad thing is that this attempt to mod his CD-P disheartened him so much that he purchased a ready-modded one off Ebay. It was dead on arrival!!
Andy
Hi.
I thought you might be interested in my latest project.
I have been asked to look at a CD6000 OSE. The guy had attempted to upgrade it by changing the rectifiers to Schkktsky ( you know what I mean - better ones ). When he switched on, it didn't work. He found he hed soldered 1 diode the wrong way round ( in the 10 / 5v supply ). So he corrected the fault and it still didn't work.
This model does not use glass fuses as per CD63 but PCB mount Wickmann fuses - both were blown, naturally!
But look at the soldering - I think he used a piece of steel rod and a lump of old lead pipe to solder the joints - every one is dry.
The sad thing is that this attempt to mod his CD-P disheartened him so much that he purchased a ready-modded one off Ebay. It was dead on arrival!!
Andy
Attachments
Hi Ray,
isnt MCLK from decoder to DAC? So you added a 560pF cap in series with the dacs input? Sorry not trying to be padantic, but I want to try this one and want to understand what to do.
Also in the schematic there is a 10pF cap to ground before the 470ohm resistor. Did you leave this in place?
Can inagine that if there is 2.5V DC getting to DAC input as well as signal, then this must be harmful to sound quality.
Nice work!
Seeya arthur
Re: How NOT to do a Mod !!
Oh dear!!!
Looks like its been soldered by a flock of seagulls
I too have a 63 KI here that has soldering like that (bought off ebay) and the TX is O/C has it was fitted the wrong way round shorting a v rail to gnd.!!!
Thats why I want one of these custom TX
poynton said:
Oh dear!!!
Looks like its been soldered by a flock of seagulls
I too have a 63 KI here that has soldering like that (bought off ebay) and the TX is O/C has it was fitted the wrong way round shorting a v rail to gnd.!!!
Thats why I want one of these custom TX
DJNUBZ said:
Hi DJNUBZ,
No, I haven't tried it yet. A friend of mine has, and he reported a positive change. But as soon as my tubestage is done I want to do a comparison between the players I have, and in one of them I want to bias the opamps in class-A. But if you want to try it yourself, it's a 5 minute mod. Just solder a resistor between each output and the negative voltage rail. Somewhere between 3k3 and 3k9 for +/-12V supply. That should give you a pretty good idea of the change in sound. If you like it you can change the resistor into a more sophisticated FET current sink.
Probably posted this already: http://tangentsoft.net/audio/opamp-bias.html
Regards,
Ray.
Re: How NOT to do a Mod !!
Then you must have a MKII too, the cap is 10pF here. Why so small I wonder? The manual is an earlier version, probably standard CD63.
Sad story.....
So now he has two broken players?
Regards,
Ray.
rowemeister said:Also my 63 has a cap and resistor between Dac and Decoder. The resistor is a 390ohm and the cap (I can't remember value) which I changed for a silver mica
Strange thing is the service manual shows no cap and a 100 ohm res!!!
Brent
Then you must have a MKII too, the cap is 10pF here. Why so small I wonder? The manual is an earlier version, probably standard CD63.
poynton said:
Sad story.....
So now he has two broken players?
Regards,
Ray.
Luke said:
Hi Arthur,
Thanks! I'm very pleased with the result, and I want to do the other signals too.
In this case the master clock signal is generated by the DAC (or an external clock if you installed one) and then buffered by an internal gate. From there (pin4/CKO/clock out) it runs to the decoder through RD14. The decoder, in return, delivers SCLK (BCKI), WCLK (LRCI) and DATA (DI) signals to the DAC.
The 10pF cap (CD01) was not present in my player, so I didn't have to remove it
I didn't like the idea of DC either, so I inserted the 560pF cap. My guts say it should be a bit bigger, but I didn't have any in SMD.
Regards,
Ray.