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Chameleon DAC listening and modifications - Page 24

post #346 of 1144
My 3 yr old only wants to turn the volume down .
post #347 of 1144

The Rhodes54 Challenge

Quote:
Originally Posted by rhodes54 View Post
I succesfully fulfilled the 74HC04 mod tonight. The Chameleon works great but I can't test if the USB input works. Michael confirmed the USB input worked fine there.

You can perform this mod at your OWN RISK!
Make sure you don't set the temperature of your soldering iron too high. I set it to 275 degrees celcius.

How difficult is this mod? Well, this one is easy compared to the DIR9001 mod of the Valab. I could even do this mod without using a magnifying glass. If you've fulfilled the DIR9001 mod succesfully, this one is certainly doable as long as you work precise. :-)

So here's the deal:

STEP 1: Read this post first

STEP 2: Remove the 74HC04. Just cut every leg of the chip carefully with a sharp knive, one at a time. Once you've cutted them all the chip will come loose. After that, heat every solderpad shortly (watch your pcb traces!) to remove all cutted legs from the 74HC04.

STEP 3: Either remove the 3 SMD resistors (right from the 74HC04 in the picture down here) or bypass them with a piece of small solid wire



STEP 4: Look at this picture first:



1/2/3: I decided to remove the resistors so I needed to reconnect the solderpads again.
4/5: Connect pin 3&4 and 10&11 together.

That's it!

EDIT: How does it sound?
The Chameleon has now been on for 45 minutes and I noticed the bass got tighter and the highs less grainy which results in more transparency and better seperation of individual instruments. The effect of this mod is less noticable when the ASRC board is inserted but I can still hear the difference.

EDIT 2: It's 4 hours after the mod and have been listening carefully. This mod is a 'keeper' for sure. It is all just more accurate: Less speaker, more music! As X-Files fan I say: The Truth is (now) in here in stead of out there. :-)

Who dares to follow me?
p.s. Although there's no way back once cutted, the 74HC04 is really cheap so if you wanna go back, no problem as long as you keep your pcb traces alive.
Well I took the Challenge and won!

Very nice mod, less is king. Music seems more involving now. A keeper for sure, which is fortunate really as there is no going back.

Thanks Rhodes54
post #348 of 1144
Thread Starter 

kids

Quote:
Originally Posted by Wood View Post
My 3 yr old only wants to turn the volume down .
Kids have far more taste buds than we do and have more sensitive hearing.
So turning the volume down is no negative indication.
Probably wants to hear it better ... and knows.
post #349 of 1144

Mmm!

Quote:
Originally Posted by PatOMalley View Post
Kids have far more taste buds than we do and have more sensitive hearing.
So turning the volume down is no negative indication.
Probably wants to hear it better ... and knows.
Your right, now I think about it, she never turns down anything produced before 1990.
post #350 of 1144
I did notice a big improvement to the SPDIF input when I replaced the Russian K40y with a Multicap .1 uf. I would not be surprised if the majority of the improvement from the direct input mod is mostly related to bypassing that capacitor. The Multicap was a little to big, and I had to get creative with it's mounting. I'll upload some pics in a bit. You can also see where I rewired everything with Jupiter Silver wire, and replaced the stock metal impedance matching resisters with prp. New rca jacks for analog output too. have not replaced the digital input, as I may go with BNC there eventually.

So no one ever answered my question, can I float only the ground to the pulse transformer? Leaving the primary hooked up in it's stock location.
LL
LL
post #351 of 1144

Don't like Oscon sp/smd caps

Ripped out those Oscon sp from the digital board, and while I was at it the .1uf SMD as well. Kept blaming the over bloated bass and soft attack on the BG decoupling caps as they continue their difficult childhood, but not there fault.

Replaced the oscons with BG NX Hiq, and bypassed them with Wima 0.1uf, then replaced the rest of the SMD as well.

Its like this lizard just had a laxative and cleared out all the bloat.

50 wimas for the price of a beer, sprinkled liberaly in this dac works wonders.
LL
post #352 of 1144
Quote:
Originally Posted by Wood View Post
Ripped out those Oscon sp from the digital board, and while I was at it the .1uf SMD as well. Kept blaming the over boated bass and soft attack on the BG decoupling caps as they continue their difficult childhood.

Replaced them with BG NX Hiq, and bypassed them with Wima 0.1uf, then replaced the rest of the SMD as well.

Its like this lizard just had a laxative and cleared out all the bloat.

50 wimas for the price of a beer, sprinkled liberaly in this dac works wonders.
It is strange that you experienced this with the Oscon SP's. These are one of the best caps to use in a digital circuit. I did the same on my board and it works flawlessly! I got more transparency, less smearing and less agressive highs, tighter bass, etc.
Are you sure you used SP's and not SA's? When I look at your picture you caps are at least double the size of mine. Maybe you took SP's with a higher voltage rating? This is not needed and not preferred in a digital circuit.
post #353 of 1144
Yes you will get better results then me because these sp's are 270uf 16v, all I had handy, and your using 100uf I believe, but I still find the sp IMHO hifi sounding. The bg replacements are 22uf 6.3v (which gives me a comfortable 20% margin on the 5v board) despite the spec being 100uf , but everything is there. But I find great results getting rid of those smd caps, opens things up nicely.

I knew something was up when the sq did not match my diary, of the the changes in sq of Bg caps during burn in. I should of been getting a constrained/thin/rough sound, at this stage but have been getting a soft bloated sound. Now I can hear the Bg decoupling caps as they should sound at this stage. So I reckon that digital board is pretty transparent now. I kept that diary for exactly this reason.

Update, bin a few hours now, the wimas are loosening up and the music is really begining to flow. Its more musical then the Valab now, I'm listening to whole albums, just leaving them playing, rather then picking favs. Dont even care that the BGs are not there yet. I think Rhodes54 mod, and fast charging caps on the digital, has opened the door.
post #354 of 1144
Thread Starter 

palpability, impact, that kind of thing



The thing which drew me to the NOS DAC in the first place was the midrange texture/timbre. The transformer goes a long way in giving that sound as well. Now I have the CineMags wired to the Obbligato's and removed the Teflons. I would like to remove the Obbligato's as well.

When Kathy(wife) said the 8x was more throaty and velvety I knew going down the 'more dynamics, openness, detail' road was the wrong one for me. This does it but I know that I can't get much closer without removing the caps. I can use more expensive caps but really, they gotta go. They are in the way.

A good earlier test, and I know things are not always equal, was to hookup these transformers between my iPod and line pre. Incredible amount of room echo, bass extension, midrange texture, the whole deal.

Any one know how to safely hookup the transformer for output sans the output caps?


post #355 of 1144
Quote:
Originally Posted by PatOMalley View Post



Any one know how to safely hookup the transformer for output sans the output caps?[/COLOR][/B]


Bill, thinking about this out loud, wouldn't the topology be similar to the input pulse xfrmr section? That is 180R (iv) across the primary of the Ciniemag and 47KR across the secondary of the Cinemag? And all inductors, capacitors are gone from the circuit....
post #356 of 1144
Thread Starter 

2 volts

Quote:
Originally Posted by hifi2001 View Post
Bill, thinking about this out loud, wouldn't the topology be similar to the input pulse xfrmr section? That is 180R (iv) across the primary of the Ciniemag and 47KR across the secondary of the Cinemag? And all inductors, capacitors are gone from the circuit....
We have a possible 2v coming of the DACs. Will the 180R bring that to ground effectively? And if so, can we forgo the 47k on the secondary?

The primary may be able to deal with .5v but the worry is that 2 volts.

I am starting to think I am stuck with output caps.
post #357 of 1144
These guys did it, (but used op amps which we dont like, their way around the dc?) but I cant seem to find a schematic for you Pat. Be great if you can crack it though, for all of us (and those cinemags looks so cool). Will continue looking around. Is the dc that high, could try testing with some cheapy transformers, say run it for a week on the the valab? Think those 47k are for dumping downstream dc kickback.

Promitheusaudio Solid State DAC

Maybe this

http://www.sowter.co.uk/specs/8347.htm

or this

http://www.audiodesignguide.com/cdplayer/dac1.jpg
post #358 of 1144
the 2 V DC should not harm your trannies, as the power the DAC is capable of is probably nowhere near enough to saturate the iron core of those relatively large clunks of iron.

I'd dare to try it without, if you hear distortion your trannie cores may be saturating, but I'm betting that won't happen.

2mA output current per DAC, times 8 is ~16mA at 2 V DC , which does not amount to much and imho not nearly enough power to saturate those cores.

the 47 is not there to bring any DC to ground nor s the 180 R enough, your trannie will isolate the DC from the rest of the chain and will not be able to do any harm IMHO.
Your trannie is equivalent to ~600 Ohm AC input resistance if I read the right specs, which should be OK without any further resistors as the DAC has a lower output resitance, you are dealing with analog here and the risk of reflections is not as prominent as in the digital domain of the Lundahls.

(hey if you are bold enough to cut out a whole IC this should be peanuts)
post #359 of 1144
Looks like a new PSU design, the Black Chameleon

http://public.bay.livefilestore.com/...Q/IMG_0109.JPG
post #360 of 1144
Looks like a new PSU design, the Black Chameleon. Spot the changes elsewhere on the dac!!

http://public.bay.livefilestore.com/...Q/IMG_0109.JPG
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