5v noise coupled to output
Hi,
Thanks for the advice!
I'm actually using the Marantz cd63 as a transport to a tda1543 NOS dac. Works fine as a transport.
I guess you lot managed to cure that boomy bass that my Marantz cd63 exhibits!
Looked at the dac datasheet now.
The dac has cmos op amps at the output powered by the noisy 5V !
The noise from the 5V is coupled directly to the audio outputs.
I see why you are buying a tx.
Hi,
Thanks for the advice!
I'm actually using the Marantz cd63 as a transport to a tda1543 NOS dac. Works fine as a transport.
I guess you lot managed to cure that boomy bass that my Marantz cd63 exhibits!
Looked at the dac datasheet now.
The dac has cmos op amps at the output powered by the noisy 5V !
The noise from the 5V is coupled directly to the audio outputs.
I see why you are buying a tx.
Re: 5v noise coupled to output
Hi, yes, but it takes a good few mods to fix:
- op-amps
- hard cone feet
- damping
- add-on clock with psu
- removal of dc blocking caps
All of these help to fix the bass. I think some people like the original 'boom n tizz' style sound. Too 'hi-fi' and not enough 'real music' for me tho
Btw guys I just had my transport out and took the HF board off. I cleaned any grease off that I could see, and of course gave the lens its routine wipe with a cotton bud wet with antistatic spray. I also antistatic'd lots of plastic in there, and generally got rid of any crap. It now hasn't skipped once that I've heard in about 20mins
ash_dac said:
Hi, yes, but it takes a good few mods to fix:
- op-amps
- hard cone feet
- damping
- add-on clock with psu
- removal of dc blocking caps
All of these help to fix the bass. I think some people like the original 'boom n tizz' style sound. Too 'hi-fi' and not enough 'real music' for me tho
Btw guys I just had my transport out and took the HF board off. I cleaned any grease off that I could see, and of course gave the lens its routine wipe with a cotton bud wet with antistatic spray. I also antistatic'd lots of plastic in there, and generally got rid of any crap. It now hasn't skipped once that I've heard in about 20mins
Re: Re: Fixing the 5v supply!
How much noise are you measuring off the +5v rail
I put the scope on mine and Q811 with jamicon 4700Uf cap bypassed 0.1uF U208 earthed measured on leg of reg <.1mV noise
Q871, standard caps-c871 c813, no bypass cap earth point U267 10 to 17mV noise.
both measurement taken playing. and mV P-P
think i will try a bypass cap and measure again
allan
poynton said:
How much noise are you measuring off the +5v rail
I put the scope on mine and Q811 with jamicon 4700Uf cap bypassed 0.1uF U208 earthed measured on leg of reg <.1mV noise
Q871, standard caps-c871 c813, no bypass cap earth point U267 10 to 17mV noise.
both measurement taken playing. and mV P-P
think i will try a bypass cap and measure again
allan
The biggest problem is not the reg its self its the fact so many circuits use the same rail, each one putting noise and drain on the rail.
I have fitted cd63's with 3 extra 7805 to the DAC and Decoder on the relevent rails and the improvement in the sound is very good.
Do this mod with better regs and you are really laughing.
Ofcourse nice caps and bypassing will always improve things
The only way you can make this player noise free is to isolate all or most 5v rails. You may not measure all the noise on the reg either, there is probably noise say around the DAC - a localised noise where one circuit in the chip creates noise on the other.
I know when you look at what has to be done it looks a nightmare but really its not that hard.
I have fitted cd63's with 3 extra 7805 to the DAC and Decoder on the relevent rails and the improvement in the sound is very good.
Do this mod with better regs and you are really laughing.
Ofcourse nice caps and bypassing will always improve things
The only way you can make this player noise free is to isolate all or most 5v rails. You may not measure all the noise on the reg either, there is probably noise say around the DAC - a localised noise where one circuit in the chip creates noise on the other.
I know when you look at what has to be done it looks a nightmare but really its not that hard.
rowemeister said:The biggest problem is not the reg its self its the fact so many circuits use the same rail, each one putting noise and drain on the rail.
I have fitted cd63's with 3 extra 7805 to the DAC and Decoder on the relevent rails and the improvement in the sound is very good.
Do this mod with better regs and you are really laughing.
Ofcourse nice caps and bypassing will always improve things
The only way you can make this player noise free is to isolate all or most 5v rails. You may not measure all the noise on the reg either, there is probably noise say around the DAC - a localised noise where one circuit in the chip creates noise on the other.
I know when you look at what has to be done it looks a nightmare but really its not that hard.
not to mention internal chip niose.
the low noise line i have is the same value noise anywhere in the same line.
simple things like choke and beads instead of link wires for voltage lines.
the noise(emf) from the tansformer inself is a pain in the ***.
allan
poynton said:
Yes, the analog stage is the same, except for one 220u inductor.
Hi guys,
Been simulating some more, and for those who are interested: here are the results. First I simulated the original CD63 and 67 filter to see what that does. This is the first schematic. The notch frequency in the CD63 is at 339kHz, and as you can see in the first graph, the group-delay is not very constant in the last area of the audio-band.
Now I took Pedja's advice and changed both filters so the group-delay is more constant. I also re-tuned the notch filter to better match 8*Fs. The inductor value is the least flexible with available values, so I started by lowering the 1000p cap and matching an inductor with it, to tune the notch filter. Then I raised the two 10k resistors a little to make the group delay as flat as possible.
If you own a CD67 and you wish to leave the notch out, you can find those values too in the second schematic. The resistors are optimised for a more common 470p cap.
The second graph clearly shows a more relaxed group delay but the cost for that is about 1dB roll-off at 20kHz. The notch is not visible here, but it is at 353.9kHz theoretically.
Regards,
Ray.
Thanks guys.
Brent,
I have the 470p in my CD67, instead of the 1000p, but not the notch filter. My impression is that the highs are more "clean", less grainy. I still have to listen to it with the notch filter in, but I have to wait for some parts.
Allan,
Would you like me to scan the CD67 parts list? (need I ask?)
Regards,
Ray.
Brent,
I have the 470p in my CD67, instead of the 1000p, but not the notch filter. My impression is that the highs are more "clean", less grainy. I still have to listen to it with the notch filter in, but I have to wait for some parts.
Allan,
Would you like me to scan the CD67 parts list? (need I ask?)
Regards,
Ray.
6h5c said:
I had to move some pots and plants in the living room, 'cause I noticed a slight diffraction of the highs on the right hand side of the stereo image after this mod
Ray.
heheOn a silly note, has any one cupped their ears forward when listening to music, very open and bright
I get bored sometimes
6h5c said:I had to move some pots and plants in the living room, 'cause I noticed a slight diffraction of the highs on the right hand side of the stereo image after this mod
Ray.
Hi,
Funny you should say that because I had a bit of a listening session last night and felt that this player is starting to expose weaknesses elsewhere. I have some simple DIY diffusers (2x 'poly' and 1x spiky), but there's a bit more wall that needs dealing with....
I very much enjoyed listening to the Peter Malick gp featuring Norah Jones, Diana Krall, Katie Melua and Eleanor McEvoy. Funny how I had an urge to listen to female vocals
I do feel that I need to work on my psu now, as the sound is still not 100% there (and I thought it was at one point). The simpler passages are scintillating, but when it gets dense there's just a little confusion (partly room reverb tho). The bass is great, the mids are good, but the treble is not realistic. However, I've never heard realistic treble recorded really, and partly of course it takes a good tweeter (mine is good, not great - Seas NoFerro 900, PP film/foil cap).
People who doubt the importance of a great source need to hear my hi-fi, or indeed any of our modded CD63/7s.
I am going to add a transformer or two, schottky diodes and some LM317 regs and feed a few parts with dedicated regs. I'm yet to decide whether its huge overkill external macho psu, or delicate small psu in the cd63. The latter option is risky for a newby like me, as it means I'm more likely to break things. The former option of course allows oversized transformers, and as many as I like, and huge unnecessary smoothing caps, which I have (cheap using Ebay). I have yet to see the 'mine is bigger than yours' approach to the psu on this cd player!
Simon