This line bothers me a bit. If you only removed these caps and didn't put anything back, that means the DAC doesn't have any local decoupling. That's not good. You should really insert some decent caps there!
I know in my mods list it says 'remove' at these caps, but then you're only doing half the job. You are supposed to add the new caps at CD05, 06, 12 and 13, with the original 100n decoupling added at the back of the board. The point is that these positions are closer to the DAC-chip, so they give better decoupling.
Ray
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Hey guys, I'm plucking up the courage to have another go at fitting regs to my DAC's digital supply. I've refined my implementation of Martin's 'simple but good' 5v reg, this time with solid tantalum caps. It didn't work out last time, so I want to double check with you guys first.
As far as I understand it, I can remove RD01 and RD04 and connect the 5v supply there. I'm OK with that part... but I'm still not 100% about the other pins. Can someone please advise me?
Where's the best place to wire the regs to ground if I'm leaving CD04/CD07 in place? Should they both go as close to the ground pin of the chip as possible?
Also, where's the best place to take the input from? (I was thinking C813).
Thanks in advance,
Ben
As far as I understand it, I can remove RD01 and RD04 and connect the 5v supply there. I'm OK with that part... but I'm still not 100% about the other pins. Can someone please advise me?
Where's the best place to wire the regs to ground if I'm leaving CD04/CD07 in place? Should they both go as close to the ground pin of the chip as possible?
Also, where's the best place to take the input from? (I was thinking C813).
Thanks in advance,
Ben
I'm not following you? so did the bass improve when using the CD directly into this amp? I'm surprised that AUX works for a TT, but thats not the issue here!
So what local decopling do you have on the DAC? I'm not sure it says anywhere to remove those 4 elco's and replace with nothing!
CD15&16 are local decoupling for the DAC analogue rails
CD07 is the local decoupling for the DAC digital rail
CD04 is the local decoupling for the DAC clock rail (also digital)
The analogue rails need to be something like Rubycon ZA or ZLG at 220uF or 470uF and the digital rails should be Oscon SEPC 470uF. (Caps are very much a personal thing but this is what I would use 2nd only to Black Gates on the Analogue rails)
PM Thomo on this thread he should be able to do a set for about £11 plus postage.
Whatever you do, you NEED these caps. They may or may not be the total cause of the problem but without them you are very likely to have seriously downgraded the audio quality by some margin!!!
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I removed those caps a long time ago, so is it possible I have caused permanent damage to the DAC? Does this explain the huge lack of bass or is this a different problem?
With the 100n caps, do you refer to the ones I removed or CD05/06/12/13? Also, I don't know where exactly these should go.
Thanks for the help and sorry for asking way too many questions...
Using the amp did not result in any improvements.
RD01 and RD04 are o.k., the other pins are 17, 21, 22 and 26. You can separate them from the supply by removing RD17 and RD18, which are wire-bridges and are not documented in the schematic.
The ground is indeed best connected close to the appropriate ground-pin of the DAC. This can be tricky because the wiring then has to go under the board, and long wire lengths are not good. So the next best solution is to solder the ground of the reg to the top ground-plane. But if CD05 and CD06 are moved to the back of the board, you could also use these empty holes to connect the grounds.
C813 is the right place for taking digital supply.
Ray
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LMAO!!! you beat me this time Ray!!! I was too slow typing my reply!!!
Sloooooooow woman!
The 100n are the little blob caps or ceramic (cant remember) these are CD5,6,12 & 13. The reason you remove these to to put the larger elco caps CD4,7,15 &15 in the holes left by the 100n. The is to get the new caps as close to the pin of the DAC chip as possible. You can then use X7R 100n caps directly on the pins of the dac if you want (google accoustica cd63 clock hack). Make sure you observe polarity with the elcos' It doesnt matter with the 100n caps.
You shouldn't have damaged the dac running without local decoupling but you will be making a horrid sound from it!! Anything will be better than nothing.
now now RaySloooooooow woman!
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I don't think there will be any damage. Everything is still working, right?
Just follow the mods list. For example, CD04 and CD05 are on the same supply-pin, look at the schematic! CD04 is removed, and CD05 is a small 47n ceramic cap originally. The new electrolytic is now place at CD05 instead of CD04 (closed to the IC), and the extra decoupling which used to be CD05 is now soldered at the back of the board, between the pins of the new cap at CD05.
Ray
Thanks so much for the help. I feel stupid needing a detailed explanation to do anything right...
So looks like I still have quite some things to get done. Can I get the necessary parts somewhere without a minimum amount to order? Does Thomo sell many kinds of caps?
Also, I'm ashamed to admit that I replaced C605/606 with regular ceramic caps. I honestly don't think my ears are good enough to notice the difference. The fact that I have no decoupling on the DAC and with some extra bass it sounds great to me should prove that...
So looks like I still have quite some things to get done. Can I get the necessary parts somewhere without a minimum amount to order? Does Thomo sell many kinds of caps?
Also, I'm ashamed to admit that I replaced C605/606 with regular ceramic caps. I honestly don't think my ears are good enough to notice the difference. The fact that I have no decoupling on the DAC and with some extra bass it sounds great to me should prove that...
Yes, that seems like a nice number. You can't separate 17 from 21 and 22 from 26 unless you start cutting some tracks, and I don't know about you but i'm not very fond of that. The two are on the same channel anyway.
Ray
Where are C605 and 606? Cant see them on the diagram for looking!!! Don't worry about asking questions, no one ever learned anything by doing nothing and keeping quiet!
Those are hard to find on the schematic, but they're the filter caps. 470pf for Bessel filter (I adjusted the resistors too of course).
And you're right. I'm interested in this stuff, otherwise I would have given up a long time ago. I haven't noticed huge improvements after my mods but I love and will keep doing it despite the many frustrations it brings
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They are not ideal but they are probably not the problem (assuming they are the right value). I would use polystyrene caps at at least here. Look at the part numbers in rays docs in post 1. You will see what they look like. I would use Silvered Mica in the audio path but for the type of mods you are doing here, styrene caps are fine. As these caps are in the signal path and are part of the filter circuit, an incorrect value component here will change the filter characteristics.
To be honest, to start you should stick to the PSU and decoupling cap mods.
If you are going to order a few caps this is what I would suggest.
C803 & C804 Panasonic FC 8200uF/25v these are the PSU smoothers for the opamp and hdam supply. Or even better, Panasonic TSUP 10,000uf 35v but they will need to be mounted on short leads off the board.
For C813 you definitely want to go off board with short leads. Use Panasonic TSUP again 22,000uF/16v. You may as well do C814 with the same while you are there. These are the smoothers for the servo drivers and all of the other analogue and digital rails.
There are better caps than TSUPs for all of these rails if you want to spend a bit more. Audio Upgrades SI (same as Mundorf/ F&T) are awesome here if the budget allows.
Next I would change the decoupling caps around the DAC as per my previous post. I would also change C611,612,613 & 614 (opamp decoupling caps) to Rubycon ZA's same as the ones on the DAC. The other must do is the opamps. Install sockets and change to LME49720 or 4562's (same chip) again Thomo can supply these. Do not bypass the HDAM's until you have done at least the above as you will end up with a thin sound!!!
To be honest, to start you should stick to the PSU and decoupling cap mods.
If you are going to order a few caps this is what I would suggest.
C803 & C804 Panasonic FC 8200uF/25v these are the PSU smoothers for the opamp and hdam supply. Or even better, Panasonic TSUP 10,000uf 35v but they will need to be mounted on short leads off the board.
For C813 you definitely want to go off board with short leads. Use Panasonic TSUP again 22,000uF/16v. You may as well do C814 with the same while you are there. These are the smoothers for the servo drivers and all of the other analogue and digital rails.
There are better caps than TSUPs for all of these rails if you want to spend a bit more. Audio Upgrades SI (same as Mundorf/ F&T) are awesome here if the budget allows.
Next I would change the decoupling caps around the DAC as per my previous post. I would also change C611,612,613 & 614 (opamp decoupling caps) to Rubycon ZA's same as the ones on the DAC. The other must do is the opamps. Install sockets and change to LME49720 or 4562's (same chip) again Thomo can supply these. Do not bypass the HDAM's until you have done at least the above as you will end up with a thin sound!!!
I've done the mods Ian mentioned above, using Silver Mica, Mundorf 22,000uF X3 and Black Gates elsewhere, and I'm happy to confirm that my player has just as much weight to the sound as it did with the HDAM, and bags more detail. I got away with leads about half an inch long for the 3 Mundorf caps.