[MikeW]

From my testing 7.95 volts is not nearly enough to avoid clipping at 180R. You'd definitely have to attenuate the spdif source. You'd need around 8.3-8.4 volts at 180r. As I need damn near 8.2 volts at 175R

 

[rhodes54]

I found some new drawings of the Chameleon PCB.
As far as I can see quite some changes have been made.

Two things that got my attention right away are:
1. The DAC board has been re-designed
2. It looks like changes are made to the reclocking board
3. A relay at the analogue outputs. Following the traces it looks like a stereo/mono switch.

 

[Pars]

Looks more like a muting relay.

 

[rhodes54]

Quote:

Originally Posted by Pars /img/forum/go_quote.gif Looks more like a muting relay.

Didn't think of that yet. Maybe it is meant as "soft start". That would also explain the 8 pin spot above it (between the purple line) which will probably be a delay timer then...

 

[Wood]

Chameleon PCB - Windows Live


Curious as why have a delay timer at all, its not an amp?

 

[rhodes54]

Quote:

Originally Posted by Wood /img/forum/go_quote.gif Chameleon PCB - Windows Live Curious as why have a delay timer at all, its not an amp?

I don't know. Maybe to get rid of all the noise/pops when switching on the Chameleon?
Anyway, It was not my idea. Would be the last thing to worry about.

 

[marcelnl]

muting relay or an absolute phase switch would be my first choice...will try to have closer look when I have more time available.

 

[Bill Allen]

Most likely its the analog filter bypass switch I suggested they add. Hard to believe but with some systems people prefer the sound with the analog filter engaged.

Now you will have a choice. Filter or no filter.

 

[Bill Allen]

Quote:

Originally Posted by MikeW /img/forum/go_quote.gif From my testing 7.95 volts is not nearly enough to avoid clipping at 180R. You'd definitely have to attenuate the spdif source. You'd need around 8.3-8.4 volts at 180r. As I need damn near 8.2 volts at 175R

Yes the Chameleon DAC can clip when pushed to the the limit, the irony is this also near where it tends to perform its best. In airplane lingo they call this Mach Tuck. Mach tuck - Wikipedia, the free encyclopedia With that said, the only time I have heard clipping is with my friend PC laptop. My transport, PC laptop and Mac Mini never clip the signal. I suspect some PC's are outputting a higher digital audio signal for some unknown reason.


Woody clearly demonstrated in previous posts what happens to the sound when you remove DAC chips and adjust the value of the I/V resistors, I concur. Above Mike measures clipping scenarios in his system, not quite the same results in my system, but here again I concur with the overall results. Crucial to understand are the correlations between Mike's clipping test and Woody listening results. There is a fine balance that must be achieved with such simple amplification circuits. Understand that you must optimize the voltage to any given I/V resistor value to provide the best overall sound... "in your system".


Once again the Chameleon DAC analog output is an amp. Sometimes what provides the best clipping results does not provide you the best listening results. This is true of all amplifiers. You must find your own balance!

My results have shown 180 ohm I/V with 7.95 VDC to be the tipping point with the Chameleon DAC. Your Mach Tuck limit may vary!!!

 

[Wood]

Nice to see you back Bill, we thought after you found that Ongaku, lying around your basement, you were understandably otherwise engaged.

I agree about the clipping, I found, by reducing the number of chips, so effectivly reducing the IV value you got a 'safer' sound. Bit like having a smaller sensible engine in your car. So lower IV value should come with a 'Baby on Board' sticker.

 

[Bill Allen]

Yes I have been busy busy busy continuing the simplification of my entire system circuit path. Also working on starting my own blog to discuss circuit simplicity at more length. Bill Allen Modifications, with the main modifications being the ones inside your mind. BAM!

Modifying One Audiophile at a Time. (Fill in your Moat)

If you can spring for a pair of Dueland VSF coupling caps I think you will be shocked how much more natural & musical the soundstage is. Probably get away just fine with 1uf caps. This is not your normal, it sounds different, but a completely different soundscape. Lunar Lander Perspective with an RV to roam. I am looking for more affirmations on the Duelands, so far it's just myself, Driguy & Rhodes.

Chris Young of Jupiter caps has sent me a pair of his latest development. "Flat" 3.3uf vintage style Jupiter's bee's wax caps. Maybe its only flat caps that have the LLP soundstaging, I will find out shortly and report back.

Nice move with the MKP-1837's, Steve Nugent has encouraged me to try different decoupling caps at this position. Glad to hear they made a bid difference, I will give them a try when I get a chance.

 

[qusp]

bill, totally agree re the VSF copper. (I assume you mean copper) great caps, fantasmagorical soundstage depth and very natural. I tried them (3.9uf)bypassed with mundorf SIO (0.68uf) and tho I liked the mundorfs in there, the SS became somewhat unnaturally wide and a touch etched, so I took them out. this was in my valab. the duelunds are now in my active monitors tho as I found I wasnt using the valab much, with my sabre dac getting all my listening time. my main system is using AES and BNC with solderless digital inputs on a cryo silver breakout cable. the duelunds are pretty amazing signal caps considering they are made for crossovers

 

[Wood]

Those dac stock smd's are ok, but proved to be a bit of a bottleneck to the other mods, replacing them (with good caps) let a lot more through. At some point will try .1 bg nx here as well as they have a different flavour to the 1837 (please dont't use Wimas here anybody). The TDA decoupling caps are as critcal as the ouput coupling caps, to a lesser extent the digital board, I've found.

Love the Jupiters I am using, but if you find the Duelands even better, well, thats it next on my list, along with AN TX, look forward to your findings on the new flat Jupiters as well (and your blog).

Hope that Teradak are putting in a filter bypass switch for the stock user, and hope its in time for the 6moons review, would be a lost opportunity if the reviewer hears the dac, only, with the filter in place.

Qusp, I saw you were selling some spare Dueland's on another forum, missed that sale, some lucky b*****d got a bargin there!

 

[skibum]

Quote:

Originally Posted by Bill Allen /img/forum/go_quote.gif Yes I have been busy busy busy continuing the simplification of my entire system circuit path. Also working on starting my own blog to discuss circuit simplicity at more length. Bill Allen Modifications, with the main modifications being the ones inside your mind. BAM! Modifying One Audiophile at a Time. (Fill in your Moat) If you can spring for a pair of Dueland VSF coupling caps I think you will be shocked how much more natural & musical the soundstage is. Probably get away just fine with 1uf caps. This is not your normal, it sounds different, but a completely different soundscape. Lunar Lander Perspective with an RV to roam. I am looking for more affirmations on the Duelands, so far it's just myself, Driguy & Rhodes. Chris Young of Jupiter caps has sent me a pair of his latest development. "Flat" 3.3uf vintage style Jupiter's bee's wax caps. Maybe its only flat caps that have the LLP soundstaging, I will find out shortly and report back. Nice move with the MKP-1837's, Steve Nugent has encouraged me to try different decoupling caps at this position. Glad to hear they made a bid difference, I will give them a try when I get a chance.

I don't have a Chameleon but I am just finishing up the mods on my VALAB. I bought a pair of Dueland VSF's due to your recommendations on the VALAB thread. I haven't tried any other caps but the sound coming out of my VALAB has a reality about it that is magical. Soundstage is HUGE and very three dimensional. Yes they cost me about the same price as the VALAB but I have no regrets! Thanks Bill!

 

[Bill Allen]

Thanks Gusp and Skibum for chiming in on the Dueland VSF caps, yes they are most definitely not just for speaker crossovers. In fact Tony (Driguy) has just put a pair of 400V VSF couplers inside his custom 26 Tube CCS preamp. He now has them in both his 26 Pre and Chameleon DAC, he also reports outstanding results.

Chris over at Jupiter told me that back in the 30's it was common for the wax caps to be flat. (In lots of ways audio reproduction has gone backwards since WWII. I will elaborate further on this subject in my new blog). Well with my constant needling Chris has finally released his "New Vintage" flat Jupiter caps, and yes they come factory Cryo'd. Aluminum foil, bee's wax, and paper, just like the original orange version but now in the new look "flat" format.

Well first off, I am happy to report that 3.3uf Jupiters fit just dandy inside the Chameleon.
Here are the pictures; Picasa Web Albums - Bill - Jupiter New V...

Unlike the new 600vdc HT Jupiter's which take forever to break in, these flat 100vdc Jupiter's started singing after only 4 hours. And yes just like the Dueland's they too have the big lunar landscape perspective, must be something do with flat caps. From my vantage point all round coupling caps are now obsolete ...

Ok, but how do they compare ... well ... first off they are made out of aluminum, not copper, like my Duelands. (Chris reports that flat copper foil caps should be ready by the end of summer). Compared to my Duelands the soundstage is more brightly lit, I think this would be of great benefit to those with copper hookup wire or whose system could use some more sunshine. Inner detail is there in spades and they maintain overall system balance even with my all silver wire system. Wide open yet relaxed soundstage, another words they're keepers.

Naming names, I really dislike the sound of Audio Note & Jensen copper foils caps. Rolled off, slow sounding, and to top it off they have the curse of round caps. Balled up excess center soundstage energy. This is just plain wrong, no wonder people that can afford them gravitate to custom output transformer solutions. However getting output transformers to work properly is yet another can of worms. On the other hand coupling caps are dirt easy to use ... but they suck in comparison.

Well that was until the "phat" flat Duelands and Jupiters arrived on the scene.
Get yourself a pair and relax.

(Tell Chris I sent you for a 20% introductory discount.)