Luke said:
Hi Luke,
I didn't expect this high value. The DAC datasheet says 102dB S/N, so I guess better should be possible. I think the analog section is the problem, maybe not symmetrical enough. If there are more people that would be so kind to measure their output, to confirm this, that would be great.
Franz G said:
Nice speakers
. Just a thought Franz: is your muting circuit still active? My CD67 with relais is also dead silent. That's why I never noticed the noise before.Pins 17, 19, 21, 22, 24, 26 are all called "analog" supply pins, but the output signal is far from analog: it's a PWM signal. So I wouldn't connect it to the analog PSU. I used a separate regulator for these pins, and draw power from C813.
Regards,
Ray.
6h5c said:
Hi Andy,
I changed the 150R divider resistors (R124/125) to 1k, to give better filtering with the caps. In the CD67 they are standard 1k. I didn't think of a TL431 yet, it is an easy drop-in replacement.
Regards,
Ray.
Hi Ray,
The Vref does not need to be exactly 2.5v ( I think ) dut it does need to be 'clean'. These are in effect audio amps....... what effect does the psu line noise have on performance??? Cleaning it up cannot do any harm!
Pins 17, 21, 22, 26 supply the output amplifiers so could be considered analog. I think the optimum solution is to power the DAC from 3 independant 5v supplies, clock, digital & analog. Well, thats my plan!
The supply to the servo chip is 5v analog to pin12.
VRef is taken from the feed to pin28, digital supply!
Andy
I can honestly say seperating the 5V rails to DAC and Decoder helps the cdp no end. Everything just feels more complete.
Also I have fitted the HF upgrade components and my initial response here at work is wow! it isnt a massive improvement but its good and cheap. Everything is more controlled, better resonance on piano and the vocals are very smooth.
Diana Krall The girl in the other room sounds soooo good.
Roll on the RF mod.....tomorrow hehe
Also I have fitted the HF upgrade components and my initial response here at work is wow! it isnt a massive improvement but its good and cheap. Everything is more controlled, better resonance on piano and the vocals are very smooth.
Diana Krall The girl in the other room sounds soooo good.
Roll on the RF mod.....tomorrow hehe
An externally hosted image should be here but it was not working when we last tested it.
poynton said:
I agree, the actual value of the 2.5V is not that critical, as long as it's stable and clean. It will give the drivers a nice solid reference.
Sounds like a healthy idea to me, separate regulators for every part. At least you'll be sure the noise is as low as possible.
Hmm, looks like there's room for improvement. I investigated the tracks, and it looks like the schematic doesn't match the PCB. In my player Vref is connected directly to +5V, and not through R122. Also the +5V for the drivers that is supposed to run through R122, via pin 28, is connected directly. But I think this is a good thing, the digital supply has it's own separate RC filter now.
Regards,
Ray.
Is there any good evidence of fitting blue/green led's inside the player (level with disc) as a way of improving things.
I have read about lots of gimicks but wondered if there is any truth in it. I understand a blue green light will have some affect on the red light of the laser but how much?
I have read about lots of gimicks but wondered if there is any truth in it. I understand a blue green light will have some affect on the red light of the laser but how much?
Ray:
No, I dont use some muting devices at the output, but I should
What I mean: there is some nasty noise, switching the player on and off. And some minor noise, while positioning the head.
I plan to insert relays, like you did.
Yes, I modified the ground, following the recommendations from Gerald Gessner.
Thats why I cannot publish them. But here are many people involved and I am shure: you they will find good modifications for the grounding layout. Just let things happen...
Another hint (the last one): sometimes simple zener diode solutions can be the best and simplest (pin 21/22 of the DAC).
Happy ears!
Franz
P.S.
Ray: yes, nice speakers! I got them cheap some weeks ago. But I had to refoam the woofers (did it the first time). It was a ACR kit from 1988, a four way system (me as fullrange freak...)
No, I dont use some muting devices at the output, but I should
What I mean: there is some nasty noise, switching the player on and off. And some minor noise, while positioning the head.
I plan to insert relays, like you did.
Yes, I modified the ground, following the recommendations from Gerald Gessner.
Thats why I cannot publish them. But here are many people involved and I am shure: you they will find good modifications for the grounding layout. Just let things happen...
Another hint (the last one): sometimes simple zener diode solutions can be the best and simplest (pin 21/22 of the DAC).
Happy ears!
Franz
P.S.
Ray: yes, nice speakers! I got them cheap some weeks ago. But I had to refoam the woofers (did it the first time). It was a ACR kit from 1988, a four way system (me as fullrange freak...)
Have been doing a few things. I have the one 63 as ref. and the other as mod. platform. And a 63SE as second ref.
I did the clock hack first. http://www.acoustica.org.uk/t/63/63hacks.html. Didn't impress me. The sound became "nicer" but less "live". I would say less music and more HiFi. More like the SE, but still less PRaT. Didn't like it, undid it again.
Then I bypassed the HDAM's (still with the 2140D sitting in) together with the DC blocking caps and removed the muting transistors. NOW it became more "live" - more PRaT. I still like what I'm hearing now.
Now I wonder, when I did the clock hack I simply re-arranged the 2 caps CD02 and CD03 and did the ground bounce hack. _AND_ I did this:
"Knock yourself out. Whilst you have the player apart, find link U200 on top of the board - this feeds +5v (at c.2mA) to the SM5872 onboard analogue output stage. Tin the link, cut it then connect the RHS next to CD15 (as you look on the player from the front panel) to your new +5V supply as added above. Now the DAC has separate analogue and digital feeds, lowering noise feedthrough."
Can anyone confirm feeding of the "analog" part of the DAC together with the clock power is a good idea?
/avr300
I did the clock hack first. http://www.acoustica.org.uk/t/63/63hacks.html. Didn't impress me. The sound became "nicer" but less "live". I would say less music and more HiFi. More like the SE, but still less PRaT. Didn't like it, undid it again.
Then I bypassed the HDAM's (still with the 2140D sitting in) together with the DC blocking caps and removed the muting transistors. NOW it became more "live" - more PRaT. I still like what I'm hearing now.
Now I wonder, when I did the clock hack I simply re-arranged the 2 caps CD02 and CD03 and did the ground bounce hack. _AND_ I did this:
"Knock yourself out. Whilst you have the player apart, find link U200 on top of the board - this feeds +5v (at c.2mA) to the SM5872 onboard analogue output stage. Tin the link, cut it then connect the RHS next to CD15 (as you look on the player from the front panel) to your new +5V supply as added above. Now the DAC has separate analogue and digital feeds, lowering noise feedthrough."
Can anyone confirm feeding of the "analog" part of the DAC together with the clock power is a good idea?
/avr300
Franz G said:Ray:
No, I dont use some muting devices at the output, but I should
What I mean: there is some nasty noise, switching the player on and off. And some minor noise, while positioning the head.
Franz
Hi Franz,
Thanks for the tips. I will try the passive filter with the first opamps still in place, and the secret zener mod. See how that sounds. I think I have an idea of what you mean.
The noise at the output I was talking about is present when the player is in stop mode. If you have no muting circuit installed you should be able to measure it. Could you see if it is present with your player? If not, your analog stage must be the solution
!!Regards,
Ray.