Cool!
I had 220uF OsCons and swapped them for 220uF ZA's!
TBH I didn't really notice any difference. I think its prob the value here thats making the best part of the difference????
Ian
I had 220uF OsCons and swapped them for 220uF ZA's!
TBH I didn't really notice any difference. I think its prob the value here thats making the best part of the difference????
Ian
Could be, 47uF / 16V ZA has MUCH higher impedance than the 220 / 20 Os-con. It's certainly a bit clearer sounding now, and the space and image width is nice. I have a spare 1000uF / 25V BG, which I might try and put on the -15V rail, if there's space. I think it will work better than the 220uF ZA currently there. I'll report. Proper changes soon though, I promise! 😉
The leakage current on that big cap might not be a good thing. In the TDA1541 the -15v rail is connected to the chip substrate, so keeping this rail quiet matters; leakage current = LF noise source. Suck and see!
[IIRC mine runs a 47uF oscon +47nF stacked-film cap here, it's good enough IMO 🙂 ]
[IIRC mine runs a 47uF oscon +47nF stacked-film cap here, it's good enough IMO 🙂 ]
Hey everyone!
I just had another little session on the cdp, and fitted 1uF Mundorf MKP on the MSB pins of the dac. I've mounted em underneath the board so they're out of the way.
It was a nice mod. Bass improved. Detail and top end spaciality seem to have improved also. Not the biggest difference in the world, but worth a couple of quid IMHO. Oh, I replaced 220n PPS caps btw.
Cheers, Lee.
I just had another little session on the cdp, and fitted 1uF Mundorf MKP on the MSB pins of the dac. I've mounted em underneath the board so they're out of the way.
It was a nice mod. Bass improved. Detail and top end spaciality seem to have improved also. Not the biggest difference in the world, but worth a couple of quid IMHO. Oh, I replaced 220n PPS caps btw.
Cheers, Lee.
Are your others all PPS now?
BG on -15V seems to be doing the usual BG tricks - smooth, silky and dynamic.
Simon
BG on -15V seems to be doing the usual BG tricks - smooth, silky and dynamic.
Simon
SimontY said:
Yep, they were all 220n PPS - I just changed the two MSB ones to 1uF MKP. I'd use box types in your player though, if space is an issue I just used these axial's as I've pulled them out of my preamp.
Cheers, Lee.
Oddly enough, I've got BG's on the +5 and -5 but not the -15 (ZA)!
sounds like the -15v is prob most important! I'll have a move round and see if it makes a difference.
I did look into the MSB decoupling caps, there is a bit on the NOS thread relating to decreasing values from 1uF on the MSB. I've also seen somewhere elco's used!?!? From what I understand, in theory, elco's would be rubbish here.
I'll prob follow lee and just go for 1uf Mundorf MKP on the msb and either pps or mks4's at 0.22uf on the others.
Also, got the other B chip in over the weekend, what a nightmare!
Swapped it over the no sound. Put the A back got sound. So thats 2 B chips that gave me no sound! I started to look into why. It seems that the B chip is a little more fussy about being held high on the mute (23) and -12db attn (22) pins. I measured voltage on the mute pin and got distorted sound! Next thing was to link pins 24 (+5v),23 &22. It all worked but with no muting between tracks there was horrible scratchy everytime I forwarded. I removed the link and started to investigate the muting circuits. I ended up inserting a 5k pot onto one of the assosiated transitors in order to raise the voltage to pin 23 during normal playback. I was still running the chip at -12db (pin 22 low) so I linked this out to the 5v again. As soon as I had just the attn pin 22 linked high, the muting circuit started to work properly. I removed the pot and replaced it with the original fixed R and all was well. 😕
Its def raised the bar again a good all round improvement. I can't believe that this player keeps on improving when I think there is nowhere left to go with it!
On the side, I've also been working on some braided 16 strand cat5 interconnects. The weave is pretty easy if a pain in the ****!! 1st impressions are pretty good, certainly not loosing out to my Van Den Hull's. I'll be fitting attenuators today (RC55Y 😉 ) so I can properly test back to back......
Ian
PS forgot to add, there are now a few service manuals on my website, follow the link below and then select manuals 😉 If anyone has one's I haven't got, PM me and I'll host them!
sounds like the -15v is prob most important! I'll have a move round and see if it makes a difference.
I did look into the MSB decoupling caps, there is a bit on the NOS thread relating to decreasing values from 1uF on the MSB. I've also seen somewhere elco's used!?!? From what I understand, in theory, elco's would be rubbish here.
I'll prob follow lee and just go for 1uf Mundorf MKP on the msb and either pps or mks4's at 0.22uf on the others.
Also, got the other B chip in over the weekend, what a nightmare!
Swapped it over the no sound. Put the A back got sound. So thats 2 B chips that gave me no sound! I started to look into why. It seems that the B chip is a little more fussy about being held high on the mute (23) and -12db attn (22) pins. I measured voltage on the mute pin and got distorted sound! Next thing was to link pins 24 (+5v),23 &22. It all worked but with no muting between tracks there was horrible scratchy everytime I forwarded. I removed the link and started to investigate the muting circuits. I ended up inserting a 5k pot onto one of the assosiated transitors in order to raise the voltage to pin 23 during normal playback. I was still running the chip at -12db (pin 22 low) so I linked this out to the 5v again. As soon as I had just the attn pin 22 linked high, the muting circuit started to work properly. I removed the pot and replaced it with the original fixed R and all was well. 😕
Its def raised the bar again a good all round improvement. I can't believe that this player keeps on improving when I think there is nowhere left to go with it!
On the side, I've also been working on some braided 16 strand cat5 interconnects. The weave is pretty easy if a pain in the ****!! 1st impressions are pretty good, certainly not loosing out to my Van Den Hull's. I'll be fitting attenuators today (RC55Y 😉 ) so I can properly test back to back......
Ian
PS forgot to add, there are now a few service manuals on my website, follow the link below and then select manuals 😉 If anyone has one's I haven't got, PM me and I'll host them!
It will get a nice regulator one day, but my priorities are clocking and output stage next.
I like the look of Ian's valve stage, but he's using the Burson module for I/V too.
Ian - did you try without the Burson, just passive I/V?
Simon
I like the look of Ian's valve stage, but he's using the Burson module for I/V too.
Ian - did you try without the Burson, just passive I/V?
Simon
SimontY said:
I did indeed! It wasn't very sucessful! I have a 1k78 RC55Y feedback r and a 2n2 in parallel to stop oscillation.
With the output connected to the Burson via 4.7uF DC blocking (allbeit I don't think its required as the latest burson has 0v on the output so i'm told!) the sound was thin and gutless. I don't know enough to start messing with impedance matching poss allowing better suited connection to the amp input. TBH I just connected it to see, didn't like it so put the DOS back on (no valves stage at the time). I believe people do have success just with I/V but i've not researched it enough!
It may also be possible to hook the DAC directly to the valve stage, I should really try!
Ian
From what you say I can't work out if you tried passive I/V with the valve stage connected after it as a buffer. I guess not but I know Lee thinks passive I/V is a waste of time. I shan't bother.
Sorry, Just read it and its not clear!
I tried the Burson with feedback and nothing else connected, i.e. straight to output phono's via the 4.7uF Supremes. It was not good! Lee was working on his I/V stage about the same time and he had a bad time with it aswell. I parked the idea and started playing with the tube buffer as an alternative to the DOS.
Hope thats a little clearer!
I tried the Burson with feedback and nothing else connected, i.e. straight to output phono's via the 4.7uF Supremes. It was not good! Lee was working on his I/V stage about the same time and he had a bad time with it aswell. I parked the idea and started playing with the tube buffer as an alternative to the DOS.
Hope thats a little clearer!
I dipped my toe into further re-clocking just now. I used some good coax to connect my Sercal C1 clock directly to pins 2 & 4 of the DAC. This just produced massive distortion so I hooked pin 2 back up as it was originally and connected the clock only to pin 4. I used a sharp knife to cut the track that links pins 2 & 4 under the PCB.
Success, music is now playing... sound quality report after some more tracks!
Simon
Success, music is now playing... sound quality report after some more tracks!
Simon
This mod seems to have brought out more detail and instrumental texture. Dynamics seem better, in particular I'm noticing some added energy in bass notes. It seems a tad smoother and more fluid too.
Krall sounds superb! The treble is getting quite decent and space and dynamics are very good.
Really the player just sounds that bit more accomplished, and as I was already using the C1 to feed the SAA7220 the mod was free! Nice one guys!
This evening's test-music:
* Andrew Lloyd Webber - Variations
* Diana Krall - The Girl in the Other Room
* Linn Selektions
Krall sounds superb! The treble is getting quite decent and space and dynamics are very good.
Really the player just sounds that bit more accomplished, and as I was already using the C1 to feed the SAA7220 the mod was free! Nice one guys!
This evening's test-music:
* Andrew Lloyd Webber - Variations
* Diana Krall - The Girl in the Other Room
* Linn Selektions
Hi Ian,
Lee told me it'd work at 11.2Mhz but be better at /2. Bear in mind in the CD650 pins 2 & 4 are directly connected on the pcb. So if pin 2 was already at /2 then so was pin 4.
It is sounding rather good at least. Next is to connect the clock signal directly to the decoder - I presume I simply lift pin 19 and connect here, right?
Cheers
Simon
Lee told me it'd work at 11.2Mhz but be better at /2. Bear in mind in the CD650 pins 2 & 4 are directly connected on the pcb. So if pin 2 was already at /2 then so was pin 4.
It is sounding rather good at least. Next is to connect the clock signal directly to the decoder - I presume I simply lift pin 19 and connect here, right?
Cheers
Simon
SimontY said:
Hi Simon, i'm pretty sure pins 2&4 are bck (/2) of sys clock as std. The /2 is generated from the 7220. I didn't have any joy with 11Mhz to both but it worked with /2. I have a /2 board supplying pin 2 and a separate feed from the master clock to pin4. as with the 650, pins 2&4 were joined on the board. hope that made sense!
with respect to clocking on the 7210 i'm pretty sure it's pin 19 that wants sys clock 11Mhz but check back in the thread (currently no access to service manual)
Ian