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Chameleon DAC listening and modifications - Page 29

post #421 of 1144

1543 Voltage

Quote:
Originally Posted by MikeW View Post
Wow wood, you are runing at 7v eh? You did not notice any negative effects of this? Like a thinner sound? That is interesting. I thought they where supposed to run at 7.5 volts min. I'd say run them as low a voltage as they sound good at, it can only help heat/stress. chips run cooler, psu runs cooler etc.



off topic: Does anyone have experience with different OPAMPS? Im thinking of trying a pair of AD797BRZ on a browndog adapter.
The DAC chip specs are: 3 volts min., 5 volts normal, 8 volts max. As one of my engineering profs was fond of saying, "Don't guess!"

OPAMPS, They will sound different but IMO never that great. Lots of feedback. See Operational Amplifiers or Op-amps Tutorial
Feedback plus transistors, well it is just not my cup of tea. See page one where it states that the ideal opamp has infinite gain. Gotta have feedback.
post #422 of 1144
second that Driguy!

digital transformers are not that exact a science, as with their analog brothers.
Most digital outs on CDPs have one and that will most likely be a 75 Ohm version to ensure compatability with 75 Ohm RCA interlinks. Now designing much of your system (DIY) different choices can be made.

If in your setup impendance matches closely and your interlinks behave well you may not even need the transformer pull down resistors and I would think that less is more would be true.


Impendance mismatches however are likely to make themselves heard...
post #423 of 1144
Thanks marcelnl,

In what way do impedance mismatches like to be heard?

What I am hearing now, its a good idea to find away around these drop down resistors for sure.
post #424 of 1144
Thread Starter 

subtle

Quote:
Originally Posted by Wood View Post
Ok its off.

There is a difference, will have to listen longer but I think its better. Perhaps more transparent but a touch less body, like less pressure!?!?.

Update, yes it different, more relaxed, less in your face. Well there's a thing!

Yep the changes in pace of musical perfomance is more apparent. Less strident. Gives more connection, otherwise there is no detriment I can hear, or no improvement in SQ. Subtle stuff.
Yeah, but the subtle stuff is what wins you over.
Work CPU powered down, iron heating up, right behind you.

That Pulse is 75:75 ohm because I used the exact same one on my VALAB.
post #425 of 1144
hard to say Wood, as it differs per combination..but it can be rolled off highs or lows etc in the analog domain but in the digital domain I'd expect reflections and time smear would be the main result probably ending up in musicality, pace etc so the type of qualities you mention.
post #426 of 1144
Thread Starter 

it's off

not dramatic.
But taps on cymbals seems cleaner and the metal sounds more like it 'should'.

When I put the Lundahl in the sound gained weight. I know we are on the digital side but that is what I heard.
I expect the same from the AN and they are easy to place. Maybe some Blue Tac on the board to hold em in place.

I think tapping direct from the RCA onto the board using just the leads form the TX is the way to go.
post #427 of 1144
I am not overly impressed with the build quality of the AN as shown, shrink foil is probably not enough to keep the windings from moving around...could be my audio-paranoia flaring up again, but I;d expect these pieces to be encased in resin/wax or other gunk ....BluTac would be my cure all after removing the shrink foil.

Just out of curiosity, do you guys use a 75 Ohm interlink? ( my digital cable is non coax)
post #428 of 1144

DAC chip caps

Quote:
Originally Posted by PatOMalley View Post
I guess I'm not done, tony.

Those DACs need the caps on each. I can still bypass the BG with a small Vishay cap, and bring the power rail right from the connector straight to the DAC board getting off the trace.
Hey Pat, if you don't mind being the "test case" you may want to try these:http://www.wima.com/EN/WIMA_MKS_2-XL.pdf
Personally, after hearing how good the WIMA caps were I would not hesitate to use them in lieu of the BlackGates at all. The polyester caps are much smaller than the polypropylene caps and should work well in this case. They are available from 10-22uF and do not vary much in size for the larger capacitance values. If I had not done it with the BG caps already I would do it myself. They are pretty pricey at 20uF ($9.75) vs. $4.22 @ 10uF. All prices are from Mouser. Personally, I do not think that the value is quite as important as the type but that is just me. They also make a 15uF @ $7.68 but they are on order. Just think, better sound w/out the 400 hour break-in.
The other advantage is that you would not have to use a bypass with them.
Just a thought.
Tony
post #429 of 1144

DAC chip voltage

Mike, it may be the psu running out of steam at higher voltage, the reason Bill did the yellow wire mod. After I reversed the yellow wire mod I notice the bass was softer, so I reduced the voltage to 7v to the chips, this seemed to tighten the bass a little.[/QUOTE]

I was running mine at 7.6 volts and the sound was pretty damn good but as I did all the mods the clarity increased so much that it started to sound like hi-fi more than music. Very interesting to listen to as I could hear so deeply into the recording. Problem being that it could wear thin with very revealing recordings. It started to sound a little "in my face". Pretty much like an oversampling DAC, kind of cool at first but after a couple of hours, not so much.
I reduced the voltage to 7.0 and it feels much more relaxed. The detail is there but it doesn't make such a big deal out of it. The guys using headphones may be able to hear it a little more. Pat posted a while back that he compared his Chameleon with his Valab and found that the Valab was better in certain areas. I think this simple little adjustment brings the Chameleon towards the Valab without losing the increased resolution. I would be interested to see if anyone else hears this. Of course, your system will be the final arbiter in this case. Of course, one could go even lower to try to reach the lower limit of what may work in their system. Of course, YMMV.
Tony
post #430 of 1144
I was asking about opamps suggestions for my headphone amp. Not the dac. I know of their limitations.
post #431 of 1144
Thread Starter 

OS vs US

Quote:
Originally Posted by driguy View Post
It started to sound a little "in my face". Pretty much like an oversampling DAC, kind of cool at first but after a couple of hours, not so much.
I already ordered 16 Nichicon finegold caps for the DACs.
I may still go fetch the Wima for the power rail coming in but I did order a Vishay Roderstein to bypass that BG on the power rail.

But the argument you have convinces. I hear an easy sound on simple music but on more complex faster stuff there is a blending together. I wont say mush but more ease would be appreciated.

Are you still running the upsampling board?
Take it out and have a listen.


marcelnl,

I use the Belden cable from bluejean. I was going to go for the silver one from VALAB but bluejeans has a fair argument for their cable saying that theirs is a tested 75ohm etc etc.

I like it better than vdH's brown cable that I was using.
post #432 of 1144
Thread Starter 

ease

btw, the pulse tx breathes a little better with that 75R off there, if you know what I mean.
post #433 of 1144
TAW Electronics is another good US source for Wimas. They stock a more extensive range than Mouser does, and will get you anything you want. Their online catalog/shop is kind of difficult to find what you are looking for. Contact Laura Salciccioli (Laura@tawelectronics.com) and she'll help you out.
post #434 of 1144

Yep

Quote:
Originally Posted by PatOMalley View Post
btw, the pulse tx breathes a little better with that 75R off there, if you know what I mean.
Thats what it is, nice one Pat
post #435 of 1144
Quote:
Originally Posted by MikeW View Post
I was asking about opamps suggestions for my headphone amp. Not the dac. I know of their limitations.
I for one was not aiming at Opamps in a DAC but in general, IMHO the only place they are tolerable is in budget portable gear and I'd still suggest replacing them with discrete components ....

Bear in mind that all this sort of stuff, as with transistors, was designed to shrink gear sizewise NOT to improve SQ. They got their priorities wrong back in the fifties, the choice should not have been to go to the moon but to design better audio tubes!
(dunno what I would have done without the allmighty computer, having a tube monstrosity with the calsulating power of the first electronic calculators would be an interesting challenge today )

For the WIMAs ; I'd advocate using 2*10uF for speed, not just because I'm cheap

Pat: try make your own cable, especially the digital kind is very rewarding and it provides a ton of insight ! Buy some hich Q RCAs (or even better replace all cinch with solid silver BNC connectors) some thin 5N annealed silver or platinum wire, paper and silk or cotton and you're in business!

Good show on the 75 Ohm, less is more (as usual in a well designed circuit)
As they say in Germany ; Limitation shows the master
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