[fran]

from the DDDac website:

Quote:

built for my self a version with 60 DAC chips in total (so 5 modules). This results in an stochastic improvement of 2,8 bits resolution. I believe it won't make much sense to go beyond this, as the amount of chips (AND Power consumption !!!) would grow ridiculously.....

and

Quote:

f you run (ANY !!) process many times, after each other or in parallel does not matter, the uncertainty or errors in the output of the process will improve with the function of SQRT(n) where "n" stands for the number of events. This trick can be used for example to get very precise resistors or capacitors by paralleling them. Thanks to the current source output we can easily do the same for the TDA1543.......

and:

Quote:

Is there an optimum? I am sure there is, but I was not so crazy to try all possible variations of "n".... I tried in a prototype 3 DAC's in parallel and this was a major improvement. The low level detail, known from high bit systems was really improved. Listening to the 8 DAC version, it comes very close to SACD.... not bad I think (again an understatement... So how many is realistic? well for each doubling of improvement, which equals 1 bit extra of linearity we need to multiply "n" with 4 !! so with 8 I get one and a half bit extra, which actually is already very good. If I want now 4 bits better performance I need to put 4x4x4x4=256 DAC's in parallel. This will consume 12A supply current and dissipates 100Watt. Feel free to do so, but it seems a bit unpractical to me, not even mentioned the circuitry needed to drive the 256 TTL inputs !!! Why did I mention 4 bits? Well, according to the datasheet, the 1543 is aprox 12-13 bits effective. A PCM63 by the way is also not much better then approximately 15 bits effectively. All the rest is marketing So the choice for 8 is purely based on a combination of maximizing "n" and keeping things within reason technically......... There is also an additional EXTRA bonus by doing this: by paralleling the DAC's we have to decrease the R(I/V) resistor as the current increases. So the Output Impedance is also reduced by "n". This helps a great deal driving the interlink to the pre amplifier of directly to the end stages if you do so...

What do you experts think? Is this all mumbo jumbo? The DDDac itself does have a good rep so it mustn't be complete BS...


Fran

 

[LingLing1337]

Yep, it sounds pretty BS to me. However, even with total nutters, it's all about how the final product sounds.

 

[Dougie085]

Well the DDDac started as a DIY project on DIYaudio.com so he has some sort of reputation, many people praise the DAC as well although I generally prefer an OS DAC.

 

[guzzler]

It's pretty much nonsense - the reasons the DDDac is popular are that it's easily available, doesn't cost too much, and is easy to build. The only thing that paralleling chips does is allow you to use a smaller I/V resistor as I is much greater now (V=I/R, so higher I allows smaller R for a given V). As DACs are current sources, they prefer to see a short to ground (ideally) and so a smaller R better approximates this.

 

[fran]

mmm. Yeah, the site kinda leans that way alright. I have another NOS dac here to compare against (audiosector) that I know performs very highly - it sounds great. So it will be very interesting to try out the DDDac. I have a buffalo DAC here too, an OPUS, that audiosector one as well so I have decent gear to compare it to.

Fran

 

[fran]

The DDDac arrived and is playing but I don't have it all optimised yet. But it plays and sounds very smooth. More work to be done on it yet though!

Fran

 

[Bill Allen]

Here is newest offering from TeraDak its called the Chameleon and features 16 parelled 1843 DAC chips and an outboard low noise power supply. The input receiver module accepts Toslink, Coax and USB. There is also an optional ASRC module for jitter reduction.

http://www.head-fi.org/forums/f7/ter...ml#post6275177

It was designed from the ground up for modding hence the name... Chameleon.

List price is $399 which is an incredible value. There will be an upcoming group buy with an even lower price.

 

[diditmyself]

If you need more current, add a buffer.

If you want the lowest possible noise, make sure you use a low noise high quaility opamp and low feedback and input resistor values.

 

[mcconnel]

What about when the DAC stack is the DAC in an iPhone whose output goes in to a FIIO 17 which has its own (superior) DAC? What does this do to the signal quality?