[ODG]

Reading that review was so funny. He talks about masturbation and having orgasms. I guess seeing a naked DAC board on a piece of wood made him horny

For 1250 euros at least get a nice case for it. Sheesh

 

[thomaspf]

Quote:

Originally Posted by Carl Quote: Originally Posted by thomaspf It is hard to tell from the jitter.de web site what any of these devices really do. There are also no measurements that would show they do anything but they might of course be great My understanding is that they are a deemphisis filter that makes the effect of jitter less audible.

I believe you are referring to the JISCO and not the UPCI option. There is very little real information on both..

 

[00940]

There are big incoherences in this review. For example a long promotion of the R2R DACs ending on how good the TDA1543 is. But the TDA1543 is not a R2R DAC.

As far as the JISCO is concerned, the explanation are rather vague. Altman claims that by introducing massive jitter in the signal, he shifts the original jitter higher in frequency, where the receiving chip can better deal with it. I'd love to see measurements or at least detailled explanations on how jitter is moved but there are none. Not very surprising on a website selling lacquer to improve the sound. At times, I'm wondering if the whole Altman website is not a joke, seeing stuff like that : http://www.altmann.haan.de/tonearm/

I really wish the reviewer had reviewed a Bel Canto DAC2 (as an exemple of good oversampling DAC) at the same time...

 

[325xi]

LOL!!!

Too bad he didn't build it from kamagong wood, it would look much more impressive.

http://www.arthagallery.com/EbonyDragon.html

 

[Carl]

Quote:

Originally Posted by 00940 But the TDA1543 is not a R2R DAC.

???

If it's not a sign-magnitude DAC, then what is it?

 

[00940]

A strange hybrid. There is simply no way to produce real R2R DAC suitable for audio for the price they were made. Just look at the prices of the AD1862, PCM63, PCM1704.

Quoting Thorsten Loesch : Yes, they are "multibit" Chips, however their operation internally drastically differs from R2R Architectures, by using a mixture of active switched current sources for the lower bits and multiemitter transistor current dividers for the upper bits. The operation methodes between R2R and the Philips devices could not be more different.

Have a look to the datasheet of the TDA1543.

 

[Carl]

Quote:

Originally Posted by 00940 A strange hybrid. There is simply no way to produce real R2R DAC suitable for audio for the price they were made. Just look at the prices of the AD1862, PCM63, PCM1704. Quoting Thorsten Loesch : Yes, they are "multibit" Chips, however their operation internally drastically differs from R2R Architectures, by using a mixture of active switched current sources for the lower bits and multiemitter transistor current dividers for the upper bits. The operation methodes between R2R and the Philips devices could not be more different. Have a look to the datasheet of the TDA1543.

Multi emiter current dividers? Wow, I have no idea what that is. Still, while it may not be based around a resister ladder, and is a unipolar design, it still seems to be a sign-magnitude DAC, just a really down 'n dirty way of doing so.

 

[Ruppin]

Quote:

Originally Posted by Carl Multi emiter current dividers? Wow, I have no idea what that is. Still, while it may not be based around a resister ladder, and is a unipolar design, it still seems to be a sign-magnitude DAC, just a really down 'n dirty way of doing so.

English please?

 

[Carl]

Quote:

Originally Posted by Ruppin English please?

Come to think of it, that would have made no sense whatsoever to those who aren't familiar with the terminology. Oh well.

 

[Chucky]

Quote:

Originally Posted by thomaspf Hmm, if i am not completelty confused then the author has the numbers on jitter pretty much wrong. This is the main reason many DACs are designed with a secondary jitter reduction stage. This can either be an asynchronus sample rate converter driven by a stable local clock (DAC1) or a synchronous dejittering circuit controlled by a VCXO (Lavry). With these trick you get the jitter down to 100-150ps. Cheers Thomas

Hi Thomas,

the Attraction DAC has a VCXO jitter reduction (UPCI) as well as an optional and switchable jitter scrambler (JISCO) -> also see http://www.jitter.de

The jitter processing functions are supported by a proprietary receiver chip, a feature you normally find only in units that start at 10x the price (Levinson, DCS, Accuphase, etc...)

Charles

 

[Chucky]

Quote:

Originally Posted by thomaspf Sorry that does not explain how the dejitter circuit with the the VCXO works either. To get a general idea on how to use an VCXO to implement a synchronous reclocking circuit there is very informative paper on the Lavry site. It is hard to tell from the jitter.de web site what any of these devices really do. There are also no measurements that would show they do anything but they might of course be great Cheers Thomas

As for measurements: The Hifi-News wrote two articles about the UPCI and JISCO. There are also a couple of measurements.

They are here:
http://www.jitter.de/pdf/UPCI_JISCO.pdf

Charles

 

[thomaspf]

Quote:

Originally Posted by Chucky the Attraction DAC has a VCXO jitter reduction (UPCI) as well as an optional and switchable jitter scrambler (JISCO) -> also see http://www.jitter.de

The link to the hifi news article only has a reference to the dejitter unit and does not have any hard numbers either. Do you have a copy of the September issue which looks at that.


By looking at the data sheet of the UPCI they only specify 0.25ppm residual output jitter. This a somewhat unusual way of specifying jitter since it only says that the clock will be very close to the nominal frequency.

If we are to interpret this to mean that the clock can vary around the nominal frequency up to 0.25ppm relative to the nominal frequency then one could compute the peak jitter from this. However, I am not sure what the 0.25ppm are actually referring to. Is that word clock 44.1Khz, data rate 2.8224Mbit/s, or biphase-mark-code clock of 5.6448Mhz. Overall this seems very dubious.

Quote:

Originally Posted by Chucky The jitter processing functions are supported by a proprietary receiver chip, a feature you normally find only in units that start at 10x the price (Levinson, DCS, Accuphase, etc...)

Are you claiming that Levinson, Accphase, or even DCS uses any of this technology? I am rather doubtful of that.

Cheers

Thomas

 

[stefan]

Quote:

Originally Posted by 00940 At times, I'm wondering if the whole Altman website is not a joke, seeing stuff like that : http://www.altmann.haan.de/tonearm/

That tonearm is fantastic, by the way. Not sure about the C37 lacquer though...

 

[creyc]

I'm not buying anything akin to "mental masturbation"!!

lol

The guy that makes those PCB's must be rofling in his pile of money. "I got your suckers to pay $2500 for a single PCB worth $20!!"

This is getting unreal. It fits into my pile of: What Next?

 

[Lad27]

Quote:

Originally Posted by stefan That tonearm is fantastic, by the way. Not sure about the C37 lacquer though...

Wait till I treat my RS1 woodies with this magic C37 stuff.

No match in known universe. But again it may cost $1000 per bottle...