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Chameleon DAC listening and modifications - Page 50

post #736 of 1144
Quote:
Originally Posted by PatOMalley View Post
Newk, You need four resistors. Two for each transformer.
The schematic shows one transformer's wiring
Yes, my friend. Two of which are the Texas Components 330r I already have in the Valab (for the pos leg on the Cinemags). The carbon resistors are for the neg leg. I'm connecting the tranny circuits right off the DACs output, right?

Quarter watt spec okay for this? Mouser sells a set of KOA carbon film resistors with 2% tolerance, 330 .25 watt. They're something like 7 cents each when purchased as singles.
post #737 of 1144
sure if you have a problem with output impedance then it helps, I dont, if you have ground loop or noise problems it helps..I dont, but I still prefer that they are now totally floating; for me it was simplifying the output path and supplying both BAL and SE connections without any extra circuit (I was using a relay). my DAC is DC coupled as well, not a cap in sight. transformers have their own problems, like parasitic capacitance, but its the lesser of the evils IMO and the most important thing is they sound wonderful
post #738 of 1144

Very Impressive

Quote:
Originally Posted by rhodes54 View Post
I've been curious for quite a while if the Chameleon would benefit from a better clock.
The Chameleon has 2 XO's on board: 1) a 12 Mhz XO for the S/PDIF and USB input and 2) a 24.576 Mhz XO for the upsampling board.
I decided to go for the upsampling board first and I've replaced the XO by the Tentlabs XO 2.2 tonight.

Connecting the clock is easy:
1) Remove the 47uH choke
2) Remove the 100R resistor located in the middle at the top of the upsampling board.
3) solder the XO output of the tentlabs to the upsampling board as shown in picture 3 and you're done :-)

It has been on for 30 minutes only so I can't give a detailed description on the sound yet. One thing that was obvious right away: No more grainy highs coming from the upsampling board! ahhhh!

As usual some pics for you:
Very nice work, a lot happening around this thread, brilliant!!!
post #739 of 1144
Thread Starter 
Quote:
Originally Posted by Newk Yuler View Post
I'm connecting the tranny circuits right off the DACs output, right?

Quarter watt spec okay for this? Mouser sells a set of KOA carbon film resistors with 2% tolerance, 330 .25 watt. They're something like 7 cents each when purchased as singles.
Right off the DACs is best for connection.
1/4W is OK.

Can't wait to hear what you have to say.
post #740 of 1144
Quote:
Originally Posted by PatOMalley View Post
Right off the DACs is best for connection.
1/4W is OK.

Can't wait to hear what you have to say.
Just ordered the resistors so they should be here next week. Hopefully the work will be done during the week of Apr 11th. I'll post back in the Valab thread and mention it here. Unless I have issues, which is very possible, then I'll cry out here because this is where you guys reside now. Cheers!
post #741 of 1144

Chameleon XO vs Tentlabs XO

The new XO has been running a few days now and the changes in sound are as obvious as the differences I saw on the scope...
To keep it short: It's like a fuzz has been removed around all instruments. Like putting on glasses when you have -3 on both eyes. :-)
It sounds much more transparent, less grain, more details are revealed, tighter bass.

A few scope pics of the onboard clock and the new Tentlabs XO:



The clock of the onboard 1ppm 25.576 Mhz TXCO of the upsampling board. As you can see it doens't really look like a sinus, does it? :-S


A picture of the new clock from the Tentlabs XO 2.2
post #742 of 1144
Quote:
Originally Posted by rhodes54 View Post
The new XO has been running a few days now and the changes in sound are as obvious as the differences I saw on the scope...
To keep it short: It's like a fuzz has been removed around all instruments. Like putting on glasses when you have -3 on both eyes. :-)
It sounds much more transparent, less grain, more details are revealed, tighter bass.
I would jump on the Chameleon bandwagon if bypassing the clocks was an option. That's the single big issue that made me dismiss the Chameleon in the first place. Unfortunately, apparently there's an imagined need to improve the input signal whether it's needed or not. I would LOVE to see Michael introduce a plug-in board with just the pulse transformer and a very well implemented SPDIF circuit.
post #743 of 1144
Remove the re-clock board, and use SPDIF input, there is no clock at this point. Only the built in WM8805. As the 12mhz clock on the input board is for usb only. Bypassing the clocks is an option.
post #744 of 1144
Quote:
Originally Posted by MikeW View Post
Remove the re-clock board, and use SPDIF input, there is no clock at this point. Only the built in WM8805. As the 12mhz clock on the input board is for usb only. Bypassing the clocks is an option.
Is that right?! I thought everything coming in was routed through the clock on the first plug in board. Will the rest of you good gentlemen please agree with Mike so I can officially start waiting for the newest rev 4.5 to become available? I'll order as soon as it's announced here!
post #745 of 1144
Quote:
Originally Posted by MikeW View Post
Remove the re-clock board, and use SPDIF input, there is no clock at this point. Only the built in WM8805. As the 12mhz clock on the input board is for usb only. Bypassing the clocks is an option.
That's not correct. The Chameleon differs from the design of the Valab. The 12 Mhz clock is used for both the USB receiver as well as the WM8805. Look at my 74HC04 mod pics.

The advantage of the resampling board is not only that it resamples to 96 (or 192K, not sure about which samplerate is chosen) but also the FIFO buffer which the AD1895 has on board. This buffer will lower the jitter A LOT.
The only thing which is very important is that the incoming clock needs to be very good in order to do this asynchronous resampling job correctly.

Quote:
Originally Posted by Newk Yuler View Post
Is that right?! I thought everything coming in was routed through the clock on the first plug in board. Will the rest of you good gentlemen please agree with Mike so I can officially start waiting for the newest rev 4.5 to become available? I'll order as soon as it's announced here!
There's NO build in clock in the WM8805. It has two options:
1) Use an external XO (like in the current design of the Chameleon) or
2) It can use the recovered SP/DIF clock, but that's not what you want because then the quality of the Chameleon will totally depend on the incoming SP/DIF signal (one of the weakest points of the Valab) and a SP/DIF clock is ranging from "pretty bad" to "a total disaster" 99 out of the 100 times. I hope Teradak didn't decide to go this way because only people with a very clean, low jitter SP/DIF source can possibly(!) benefit... I can assure you that most (future) Chameleon owners won't have such a clean source. They would be much better off with that TXCO, or better a quality clock like I added.
post #746 of 1144

Lowering Jitter is the Game

Steve Nugent has successfully added an I2S jack and terminated it directly to the DAC chips of my Black Chameleon. I will now drive the DAC I2S direct from my Pace Car via a Northstar I2S cable. This is as clean as a digital interface gets my friends. I have working towards this point since the day the first Valab DAC showed up. My Black Chameleon is stock so it will take time to mod it & break in, but I will eventually report back with the results.

Since the Valab days I have been drilling home the message that lowering Jitter is the name of the game with these stacked NOS DAC's. Short of my solution I think Rhodes has the simplest low cost solution for lowering the jitter on the Chameleon. Add a Tentlabs or Audiocom Super Clock on the upsampler board. Nice job! You could even power the new clock board with a battery. I run the Pace Car on a Lithium-ion laptop external battery pack, I simply unplug the charger for critical listening. Something like this. Amazon.com: TOSHIBA Satellite 2105CDS External Battery: Electronics

For those that are ready to consider computer audio may I suggest you look into an M2Tech Hi-Face with direct I2S connection to the DAC chips. This will be a bit of an adventure but should provide superior results at very low cost. Right now they don't make an I2S output version but that may change soon. M2Tech
post #747 of 1144
No clock in the signal path is exactly what I want for Chameleon. Looking back at the March 09 Valab as an example, I'm feeding it by SPDIF from an Empirical Audio Off Ramp 3 with an Audiocom Superclock. This is an undoubtedly true low jitter source that would likely be degraded by clocks in Teradak's designs. Admittedly, I'm using the DIR9001 mod (and its clock) and a pulse transformer added in the Valab, but whatever affect it has on the integrity of the source, the Off Ramp is undoubtedly providing a far superior low jitter signal to allow the Valab to bloom and produce a very well focused sound stage. In fact, I take the performance as a big thumbs up to the quality of the DIR9001 as a SPDIF receiver, the mod you guys came up with for it, and the benefit from the pulse transformer.

Steve Nugent (Empirical Audio) has talked about the quality of SPDIF and proper implementation and how he's upgraded SPDIF circuits as mods to people's audiophile hardware. I have no doubt the SPDIF in the Off Ramp is first rate. He's said the Valab is an excellent NOS DAC with a proper output cap mod and when fed by SPDIF by an honest low jitter source.

My old question about Chameleon remains. How can I feed it by SPDIF and get around the clock on the input board?

Just saw Bill's post. I'd love to be able to feed my Valab (or Chameleon) directly by the I2S output on the Off Ramp, but a mod example will have to made. Perhaps a Hiface with an I2S output is exactly what we need as a starting point for a great step for Chameleon.
post #748 of 1144
Quote:
Originally Posted by Bill Allen View Post
Steve Nugent has successfully added an I2S jack and terminated it directly to the DAC chips of my Black Chameleon.
I'll bet some of us here would be very interested to see pictures and a good explanation of how it was done as a consideration for our own mods..........
post #749 of 1144
I see no reason why Teradak could in the future provide a board without a clock for those of us with a high quality spidf input, be it cdp, or exteral reclocker etc, the choice would be the provided at purchase. Or for that matter 12s input, though that would require a new chasis design.
post #750 of 1144
Quote:
Originally Posted by Newk Yuler View Post
My old question about Chameleon remains. How can I feed it by SPDIF and get around the clock on the input board?
I think you should check the WM8805 datasheet. I can't give you that answer yet.
What I can tell you is that the WM8805 can be used in two modes: Hardware and software mode. In hardware mode the WM8805 is quite dumb. Most settings are fixed and can't be changed. It is running in hardware mode on the Chameleon.
When ran in software mode it suddenly transforms into a chip with lots of options. For example: onboard input selection (which is now done by that 'jitter-switch') and the XO frequency can be changed (while fixed to 12 Mhz in hardware mode).
It is possible that it needs to be running in software mode in order to be able to switch to 'recovered clock'-mode.
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