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Chameleon DAC listening and modifications - Page 38

post #556 of 1144
Nice clean up job

How are you liking the T1 Teflon bypass caps Pat ? The only drawback to them is the burn in time....they take a long loooooong time but stick with them

Anyone tackle the PSU yet or is Bill hard at work on that still ?

Peete.
post #557 of 1144
Glad you started on that power in recabling Pat, I've got some 18awg transformer copper staring at me that I've been to lazy to do anything with yet. I was going to wire the 7.5v directly to the where it inputs did you do that or wire to the PCB?

Pete, I think you can see we playing around on the peripherals of that power supply. I'm to dumb to do any serious stuff, but am planning on changing caps and things. What I would like to do is put larger capcity transformer in to make sure those dac chips get everything they need, but dont know what would fit in the case and do the job. But you know this stuff, what would you do Pete?
post #558 of 1144
Thread Starter 

power - heat - teflon

Careful with larger wire because the three ping connector does not like too much heat. Best to attached the power calbe as a heatsink when using larger guage so you protect against a meltdown.

Been using the Teflon caps in a few other places and I like them coupled with the Obbligato's a lot. The give a nice dynamics open top and help to add the illusion of detail lower even though they are only .015.

But they will not alst for long as some Mundorf 1uF are arriving and they will go in un bypassed.
post #559 of 1144

Sink

Quote:
Originally Posted by PatOMalley View Post
Careful with larger wire because the three ping connector does not like too much heat. Best to attached the power calbe as a heatsink when using larger guage so you protect against a meltdown.

.
Thanks, nice tip, may well of saved me from some unpleasantries down the line there. Be interesting to see what you find with those silver in oil Mundorf.
post #560 of 1144

Conductive grease

Hey guys, I got that Conductive grease in the mail today. There's alot of silver in this stuff..

I applied it and it worked pretty well the first application, almost completely removing the whine noise. I took it back apart and applied it again, this time the whine was back in full force.. but it was clearly a connection issue.

So I tinned all the leads to the board again making them slightly thicker for a tighter fit, and again applied the grease. Careful to not short anything, this stuff go's everywhere, but it's supposed to it's grease.

Alas the whine is gone, it appears briefly on power on for a couple of seconds and then go's away. Im not 100% satsified with this but it is good enough as long as it continues this way. Maybe when the grease warms up and settles a bit it will improve. It may be my imagination, but the sound seems a bit cleaner overall as well. The noise seems to be improved a bit as well. Without the reclock board the noise is very good, not audible at all at very loud listening levels. The reclock board has always introduced a signifigant amount of noise for me, I may try applying the the grease to it as well and see if that improves it. I've actually been listening without the reclock board for awhile, and I think I may prefer the sound without it anyways. Which is somewhat surprising really, as I very much preferred the reclocking in the beginning before any mods where done, but maybe with the accumulation of all the mods It's not preferred anymore..
post #561 of 1144
Thread Starter 

burn baby burn

It's best to never turn the DAC off.
Except if your modding it - especially the power rail. But other than that, leave it on.
post #562 of 1144
Thread Starter 

don't know what fixed it

A while back I bought the conductive grease to fix the random pop issue I had. It did quiet the machine down but did no alleviate the issue completed.

Now after running the solid core and cleanup up the star ground the issue has appeared to have compelted disappeared. [not kidding this time.]

This issue was with the machine pre star ground and after so I do not think it was connected to that. The only identifiable change that can be connected to it [pun] is the solid core for the 7.*v.

Now watch that pop resurface again right after I post ... just like it did before.
post #563 of 1144
I have long suspected a poor ground connection between the input board and main board, but I've tried to wire the ground connections on the input board directly to ground and it made no difference for me. I also wonder what would happen if you connected all those GND pins on the reclock board and grounded them directly. The reclock board has a ton of GND connections.
post #564 of 1144

Teachable Moments

Quote:
Originally Posted by Wood View Post
Yes indeed this is a great dac with no inherent problems, and nobody means to imply that there are any. But this is a modding thread, and my DC30 has been modded. Indeed near the begining of the tread Teradak advised against the yellow wire mod. That is why we are drilling holes, putting it upside down and even, CrazyTown style, adding fans, as in my case, and in your case Tony, putting the whole dac and psu into its own shiny new box. I don't want to see anybody here discouraged from experimenting because it may damage the products reputation, it won't. We Mod, not because there is something 'wrong' with the original, we just want to fine tune. In fact Bills discovery has improved the dac and it seems Teradak has taken that mod on board now, which is good news for anybody who buys one now, as they won't need to do this specific mod.

As far as I know, nobodys 'moded' DC30 has broken down yet, and thats how I would it to stay.

Mod on!
It seems as though the whole reason for my post has been completely lost here. In my past career as an engineer (6 as Chief Engineer) there are always instances of "teachable moments". Whether they are from instances of good work or from mistakes they are all usable to teach something to the group at large. This profits everyone as the errors are reduced and the fixes are passed on as well.
I simply asked people to correctly assess their definition of "hot". The products reputation is just an adjunct to the main thrust of the post. I certainly did not want to imply that I am against modding. It is perfectly obvious that I am not. The intent is to apply knowledge and REASON to the mods. This allows knowledge to spread, not voodoo explanations when none are required. The theory works fine in at least 90% of instances when it comes to (even) audiophile electronics. That is why I asked people to reference the PDF. It also prevents folks from making erroneous conclusions and perhaps messing things up. That is why I explained the Reservoir Mod, so that people would know what the hell it was doing and why it works (or doesn't when not done correctly). That way they can have the knowledge to apply in another instance down the line. Instead of thinking " I remember a power supply mod with caps" they might remember the reason it worked and they will have a better idea as to it's possible applications in the future. It is not just about modding, it is about learning. To me, if one passes on that opportunity, they are passing on one of the really satisfying things in life. Slinging solder without knowing why may get you better sound if you are lucky but relying on knowledge plus experience (yours and others) will net a much better success ratio and more satisfaction. Not only that but you will be much more able to pass on the mods in a rational form if you understand the reason they work.
BTW, putting my unit in a box would if anything REDUCE air flow versus any free standing unit. Also, it is neither shiny or new. It is an old box (3+ years old) and made from wenge wood. Not shiny! As stated in the post where I mentioned it, I put the unit there to accommodate the output caps I use.
Wood, putting a fan on the unit has the following potential downside(s). They put out audible noise. Maybe not a problem if using headphones but even 20db (about average ratings for those muffin fans) can be heard in a quiet room. Also, as I have seen with my own mods, someone may not take the care to use a separate power supply thinking that "hey, I have 5 volts right here!". Now they have electrical noise as well.
I could not see any other holes in your unit other than the one for the fan. Without them there can be only very minimal air flow. If the fan is blowing down then the case becomes pressurized and there is almost no flow. If it is blowing outward, the case pulls a vacuum and the only flow is from leakage around the case edges. The "flow" you may feel is just the air churning. Think of the fan as an air pump (cuz that's is what it is). If you close off the suction of a water pump you won't pump water for long. If you close the discharge, same thing. That's why you need holes somewhere else in the case. Top, bottom, front, or back will do fine. So long as the intake air can freely replace the air inside the case that has picked up heat. Of course, putting the same fan completely outside the unit blowing across the case (heatsink) would accomplish the task even better. The total area of the holes should at least equal the area of the fan to avoid adding more noise.
As far as folks not having things "break down" I disagree.
From the Valab thread:
I got my replacement TDA1543 and put that back in. Still had HUGE amounts of distortion as before though....

After some VERY close looking about I found that the center leg of my LM334 current source was broken. Was very hard to see.

Ordered another one up so hopefully that will sort me out!

It is amazing. I am generally a very careful (OK anal) guy. I have so far managed to rip the legs off one of my TDA1543 DAC's, broke a leg of off my LM334 AND blew the fuse (piece of wire laying on the table).

AND I was REALLY TRYING to be careful!

Appreciate the help from everyone.

Modding is inherently risky even when someone knows what they are doing! My point is; if you are going to take these risks, make sure that you know what the risks are and why you are taking them. Just "doing" something is not a plan! Also, just as important, can you fix any mistakes you make?
post #565 of 1144
Thread Starter 

alright

Free test CD = http://binkster.net/extras.shtml
post #566 of 1144

Maths ugh!

Mike, Based on the assumption that the optimum IV value for the Chameleon is 175 r then:

Where r=resistance n=number of TDA1543

r = f/n, where f=2800

r = resistance, n = number of chips.

n=16 would be 175r



But, because you found the stock 160r are better for reducing clipping, and if therefore we assume the actual optimum IV value is 160r then;




r = f/n, where f=2560

So if you removed 2 TDA1543 so that n=14 then;

r=2560/14 = 183r which is only 9r higher the the Texas resistors value we are using so should be ok.

Other benifit would be more power available to the remaining TDA1543, which will go some way to compensate for loss of dynamics sans 2 TDA.




In fact this design for 10 TDA1543,

http://pavouk.org/hw/spdifdac/en_index.html

uses 210r for IV, in which case f=2100, at 8v supply to the chips

that would mean the optimum no of TDA1543 for 175r texas would be exactly 12 TDA1543 which would, by almost uncanny coincidence be Michaels original suggestion for experimenting with. So we could pull 4 TDA1543 in this case, and run it at 8v.
post #567 of 1144
Well nothing like putting money where you mouth is, I am now running on 12 TDA1543, and I think it is better. Actually sounds more dynamic. And no need to change the 175r Texas.

But will give it a some time to decide.

Update Bit more listening now. Positives, sound is more fluid, leaner, less weight/gravitas, Sopranos are clean as a bell, (got a touch of break up in the highs before I put down to recording quality, not so) sound stage seems deeper. Negatives, soundstage is slightly less wide, less bass (but not sure if this is bad) less contact sound on percussion (I think) less output volume, to be expected.

Update2, 2 hrs now. Sq is wetter/liquid, it was dryer before. Presentation is more Chamber as opposed to Symphonic as before, more intimate, engaging. Nice midrange clarity, but def some low bass rollof.
post #568 of 1144
That's very interesting wood, I may experiment with 12 tda's as well. Does it matter what order you remove them in?
post #569 of 1144
Hi Mike, I took the first row of facing the front of the dac. Will also try 14 TDA when I've got a handle on the SQ of 12. Please try it Mike be great to get your opinion on this!
post #570 of 1144
Ok now trying with 14 dacs. I already like it more then 12. More bite, bass has more presence wider soundstage. But the liquidity is preserved, and larger midrange presence. 12 dacs was closer to the Valab sound and 14 closer to Chameleon which one would expect. Sounds very nice.
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