i have CA 740C and 740A with diy speakers , with the ca740c+740a alone the sound is similar to what you described . Luckly i have a tube preamp equalizer and a sub and it changes everything.
you can even control bass warmth by rising just a bit the sub volume (cutting at 90hz)
The problem with the 640C V1 V2 650c, Dacmagic and 740C is they all have really cheap capacitors. Changing all the caps on the digital rails to Oscon SEPC and analogue rails to something like a rubycon ZA/ZLG brings very good gains. Also the opamps are pretty poor. LM4562ma are decent in these players. Look at removing the poor smoothing caps to and fitting much larger and better quality caps instead.
Brent
Brent
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Thanks for the replies,
Brent when you refer to the main smoothing caps are you referring to the ones I have highlighted in my previous posts? The stock/factory value is 2200uF, 35v. What value would you suggest replacing them with?
I have also installed 8-pin sockets so I may trial various op-amps. s
Thanks for the advice,
Kind Regard
Dom
Brent when you refer to the main smoothing caps are you referring to the ones I have highlighted in my previous posts? The stock/factory value is 2200uF, 35v. What value would you suggest replacing them with?
I have also installed 8-pin sockets so I may trial various op-amps. s
Thanks for the advice,
Kind Regard
Dom
I did simulate the circuit just using a 1kOhm resistor as the load and I found that there was an amount of ripple present. I didn't measure the Vripple, but obviously the voltage regulators deal with this.
However I am wondering how well these particular voltage regulators cope with ripple.
It would also seem appropriate to look at enhancing the voltage regulations as these supply the op-amps.
Just thinking out loud
Dom
However I am wondering how well these particular voltage regulators cope with ripple.
It would also seem appropriate to look at enhancing the voltage regulations as these supply the op-amps.
Just thinking out loud
Dom
Yes I do mean those poor 2200uF caps. We fit our own branded Si caps but the Mundorf Si caps are the same. We use 25V 22000uF, they do not fit in the standard location so you need to mount them at the side of the pcb and hard wire down to the pcb.
Yes standard regs do address some ripple but they also emit their own noise. This is where low noise regs come in but I would sort out the capacitor and opamp problems first.
Opamps I recommend LM4562NA or even better the metal can LME79720HA. Both offer very linear sound that does not peak certain frequencies (obviously). They do however high lite problems in the rest of the circuitry due to there honesty.
Brent
Yes standard regs do address some ripple but they also emit their own noise. This is where low noise regs come in but I would sort out the capacitor and opamp problems first.
Opamps I recommend LM4562NA or even better the metal can LME79720HA. Both offer very linear sound that does not peak certain frequencies (obviously). They do however high lite problems in the rest of the circuitry due to there honesty.
Brent
Thanks for that Brent, I will give that a try. I am curuoius how that value of cap was obtained, is it calculated or just a case of trial and error?
I have some OPA n opamps on order, can't recall the exact series number at the moment, I have also read the LM4562 are very transparent as you mention.
There appears to be practically no filtering on the o/p of those voltage regs! Are there better direct reacements or is it a case of purchasing/designing a voltage reg with additional filtering?
Kind Regards
Dom
I have some OPA n opamps on order, can't recall the exact series number at the moment, I have also read the LM4562 are very transparent as you mention.
There appears to be practically no filtering on the o/p of those voltage regs! Are there better direct reacements or is it a case of purchasing/designing a voltage reg with additional filtering?
Kind Regards
Dom
I'm not a fan of OPA opamps as they tend to have a over bloated bass and messy treble. And when you upgrade properly it shows.
Generally the larger the uF in a psu (pre reg) the better, also larger uF have lower esr and better ripple rejection (thats pretty much all companies like Naim and Cyrus do with their off board psus). We use our SI caps in our own headphone amps, pre amps and power supplies as well as upgrades. The most expensive item to receive the caps was a DCS dac. They are quite popular on the CD63 thread with diy members too.
With a proper low noise reg you don't need filtering afterwards as the reg does it all for you. I prefer simple but good quality.
Brent
Generally the larger the uF in a psu (pre reg) the better, also larger uF have lower esr and better ripple rejection (thats pretty much all companies like Naim and Cyrus do with their off board psus). We use our SI caps in our own headphone amps, pre amps and power supplies as well as upgrades. The most expensive item to receive the caps was a DCS dac. They are quite popular on the CD63 thread with diy members too.
With a proper low noise reg you don't need filtering afterwards as the reg does it all for you. I prefer simple but good quality.
Brent
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Unfortunately there is no ic drop in reg. So yes a SPower or equiv is the best option. But like I said do the caps and opamps first, all the fundamentals
Don't forget clocking too. With the correct clock you can supply the dac section and the servo section seperatly and remove the buffer circuit used by CA
Brent
Don't forget clocking too. With the correct clock you can supply the dac section and the servo section seperatly and remove the buffer circuit used by CA
Brent
Hi Brent,
I have seen where I can purchase the Mundorf caps, but I am also trying to source the Oscon SEPC caps, have you any ideas?
Are the op-amps you mention direct drop in replacement, or they pin for pin with the original? Just wondering off the top your head/by experience if the IC's are pin for pin. I havnt had chance to cross reference the datasheets.
Kind Regards
Dom
I have seen where I can purchase the Mundorf caps, but I am also trying to source the Oscon SEPC caps, have you any ideas?
Are the op-amps you mention direct drop in replacement, or they pin for pin with the original? Just wondering off the top your head/by experience if the IC's are pin for pin. I havnt had chance to cross reference the datasheets.
Kind Regards
Dom
Most opamps are pin for pin replacements (dual for dual / single for single). The LM range are spot on. The HA range are TO99 package with rounded layout of the legs, this is not a problem as you simply bend them into 2 rows of four to match the std pins of the original opamp. Note - the tab is pin 8 NOT pin 1.
The SEPC are hard to get, I could sell you some from my stock if you would like. Send me a email to brent@fidelityaudio.co.uk and we can arrange it. I don't work weekends so don't think i'm ignoring you, i'll pick up the email monday
Brent
The SEPC are hard to get, I could sell you some from my stock if you would like. Send me a email to brent@fidelityaudio.co.uk and we can arrange it. I don't work weekends so don't think i'm ignoring you, i'll pick up the email monday
Brent
It seems "SRPP with 6H6P" is pointed as a preference. How to take signal out is pretty clearly shown. But how to build that tube stage? Or whatever that should be called.. Is there a simple step-by-step instruction somewhere to be found for a tube-newbie-dummy? Per what I find on that huge site, there's actually rather little what a newbie is able to follow in regard to building the tube-thingy. Advice in regard to the PSU + tube thingy build?
I have a 540C V2 and the manual for the similar 640C V2. Looking at the schematic, the cheap upgrade is to put R-C filters in front of the critical 5V regulators, especially the clock. 10-100R and 470uF should be about right. There will be enough ripple on the "21V" on the 4700uF bulks for significant ripple to break through the regulators.
Another cheap upgrade would be to lift C1 and C3 across the rectifiers and put 100R in series as snubbers. There was a post very early in this thread noting that this player was fussy about mains quality.
Another cheap upgrade would be to lift C1 and C3 across the rectifiers and put 100R in series as snubbers. There was a post very early in this thread noting that this player was fussy about mains quality.
I decided to pull out the 640c v2 and replace caps I had on hand.I didn't have any 4700uf psu caps.I replaced all of the other polar caps with combos of Panasonic fc,few Nichicon KZ,etc...
I had no 10uf caps for all 8 of the 47n caps but I had Kimber .22uf film caps to parallel to them.Added Solen 1uf to the 4700uf and replaced all 330uf polars with Panny fc 470uf and added small low cost poly caps to those as well.Have not touched the servo board yet but will in time.Just doing this yielded favorable results that are noticeable to my 48 year old ears. Music is tighter,little bit more bass,and definitely exposes some micro detail from recordings that were hindered before. It amazes me the choice of deplorable capacitors used in this $600.00 cd player.I wish I had the values in my cap stash to change out those on the servo board.
I had no 10uf caps for all 8 of the 47n caps but I had Kimber .22uf film caps to parallel to them.Added Solen 1uf to the 4700uf and replaced all 330uf polars with Panny fc 470uf and added small low cost poly caps to those as well.Have not touched the servo board yet but will in time.Just doing this yielded favorable results that are noticeable to my 48 year old ears. Music is tighter,little bit more bass,and definitely exposes some micro detail from recordings that were hindered before. It amazes me the choice of deplorable capacitors used in this $600.00 cd player.I wish I had the values in my cap stash to change out those on the servo board.
Yes, the biggest problem of this player is the ultra cheap components.
Regarding the servo board I replaced C46, C47, C50, C56, C83, C84, C85 to low ESR ones.
It yielded to some improvements in the sound, maybe in some added smoothness. The change is subtle, not as huge as when I replaced something on the DAC board.
And it is a good playing ground also. I just counted how many components I replaced in this player until now and get 95
Regarding the servo board I replaced C46, C47, C50, C56, C83, C84, C85 to low ESR ones.
It yielded to some improvements in the sound, maybe in some added smoothness. The change is subtle, not as huge as when I replaced something on the DAC board.
And it is a good playing ground also. I just counted how many components I replaced in this player until now and get 95
Ok,I pulled the main board back out again and replaced a lot of the Panasonic fc's with Rubycon zl,zlg,Nichicon Muse,and several Blackgates I still had.The servo board I replaced all caps with Rubycon,Nichicon muse, and Panasonic fm except the main 3300uf which I did not have.Needs some time for these caps to burn in and settle.
Gotta be careful with the Rubycons as they are very revealing capacitors...sometimes to much depending on ac mains correction.In my opinion,they are just as good as Blackgates std and nx.Been using them for years in lots of equipment when I basically overhaul the capacitors.Man,I've opened up so many pieces of stereo equipment,tv's,dvd-blu ray players etc....and they are loaded with sorry as hell Chinese garbage capacitors.
This time,I think I'm done for a bit and will just let the music flow and leave the circiut boards alone considering I've replaced more than 90% of the caps.I'll change out the main power caps down the road.
Gotta be careful with the Rubycons as they are very revealing capacitors...sometimes to much depending on ac mains correction.In my opinion,they are just as good as Blackgates std and nx.Been using them for years in lots of equipment when I basically overhaul the capacitors.Man,I've opened up so many pieces of stereo equipment,tv's,dvd-blu ray players etc....and they are loaded with sorry as hell Chinese garbage capacitors.
This time,I think I'm done for a bit and will just let the music flow and leave the circiut boards alone considering I've replaced more than 90% of the caps.I'll change out the main power caps down the road.
The player is really starting to open up. I can attest to using Rubycon zl series,Blackgate std, Elna Silmic II,Nichicon Muse,and Panasonic fm with the 47n caps bypassed with Kimber film caps really makes a difference !
I was a little worried using so many different brands would not be optimal soundwise,however,it's literally perfect for me. I'm happy and glad to be using the old stash of caps .Now,for the first time in several years I'm starting to really like this cd player finally.I cant say for certain the caps changed on the servo board made any difference in sound.At least I have piece of mind 99% of those deplorable Chinese junkers are gone and much better quality caps installed.
At least the circuit is more stable and improved the lifespan of the player also.
I was a little worried using so many different brands would not be optimal soundwise,however,it's literally perfect for me. I'm happy and glad to be using the old stash of caps .Now,for the first time in several years I'm starting to really like this cd player finally.I cant say for certain the caps changed on the servo board made any difference in sound.At least I have piece of mind 99% of those deplorable Chinese junkers are gone and much better quality caps installed.
At least the circuit is more stable and improved the lifespan of the player also.
Hi
The 640 V1/V2 is not very good as a transport thanks to the psu. But this can be improved on.
To remove power from the output section remove the +/- 15V regulators U2/U3
You now need to fit a new transformer as the winding out of the original tx is pretty crap. You can see the wires that go to the servo pcb (near the front). We fit a 12v 50va next to the original tx.
regards
Brent
The 640 V1/V2 is not very good as a transport thanks to the psu. But this can be improved on.
To remove power from the output section remove the +/- 15V regulators U2/U3
You now need to fit a new transformer as the winding out of the original tx is pretty crap. You can see the wires that go to the servo pcb (near the front). We fit a 12v 50va next to the original tx.
regards
Brent
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