[Davi]

Hi All,

So this may be my next digital adventure……

It’s called the Altmann Attraction. To me very interesting. BUT I am a straight wire with gain sort of guy. If I can convince my wife I will roll the dice. I did find a short thread in our forum but no one who actually listened to it.

Properly configured with outboard JISCO function this dac will colt me $1300.00 but read the review by Disk Olsher. He says that this is the best digital that he has heard in his system. Disk Olsher (formally from Stereophile) has been in the business for many years and has listened to a lot of fine equipment. I am intrigued.

http://www.enjoythemusic.com/magazin...mpling_dac.htm

http://www.audioasylum.com/audio/dig...es/117961.html

http://www.mother-of-tone.com/attraction.htm

 

[rodentmacbeastie]

Great, I would love to hear your impressions if you do go this route. The only thing that has stopped me from buying one is that it is 4X the price I want to spend and a DAC and twice as much as the, "if it is that good..." budget. I would be using it for a SB3 and maybe my DVD player and the big money is to be spent on a dedicated Modwright player. However, if the Altman DAX is that good it could very well change my plans.

 

[choariwap]

here's a review on one of our local forums:
http://wiredstate.com/forum/viewtopic.php?t=12255

you'll have to register, but its agood review. puts it up against a Museatex Bidat DAC with great results.

 

[Garbz]

One of the local RF engineers nearly had a seziure on another forum when they discussed that. I agree with him it's a wonder it works at all.

But if it does work it's the final sound that matters not the implimentation

 

[Davi]

Quote:

Originally Posted by Garbz One of the local RF engineers nearly had a seziure on another forum when they discussed that. I agree with him it's a wonder it works at all. But if it does work it's the final sound that matters not the implimentation

Yes I read that too. But after speaking with Charles Altmann over the phone and going over his well documented web site, I have confidence that his approach is the right one. Regarding engineers, I oftet have audio arguments with them. You know, They take the side that if you can't measure it you can't hear it so it doesn't exsist ETC BUT I could be wrong......davi

 

[Davi]

Quote:

Originally Posted by Garbz /img/forum/go_quote.gif One of the local RF engineers nearly had a seziure on another forum when they discussed that. I agree with him it's a wonder it works at all.

[size=small]The following is a portion of a discussion from another forum re the technical aspacts of the Attrattion from Charles Altmann himself. It is mostly over my head but maybe somone here can review his
words and comment on it.[/size]


Hi everyone,

to answer your questions:

On the Attraction DAC I use the TDA1543 because it is R2R and because it can be used with a single-ended power supply.
As you already know, the Attraction DAC is designed to be powered by a Optima Red Top 12V car battery which eliminates the need of wall powered (noisy) supplies.

I use active I/V conversion 1 OPA134 per channel, and 4 OPA134 per channel as output buffer. The DAC can power a speaker directly

The output level is as high as it possibly gets with a 12V supply, so it is
about -3.5 Volts to +3.5 Volts full scale (which btw. seemed to be enough to
overdrive DUC's preamp).

The input (spdif) receiver is custom. I programmed it into a Xilinx device. It
has a switchable JISCO option and all DACs come with the UPCI (ultra-precision
PLL) which synchronously reclocks the data.

There is 2 custom made VCXOs for the frequency generation and tuning and one
custom XO for the JISCO function.

All features programmed into the Xilinx, which was really fun, but no walk in the park, btw

The Attraction DAC runs up to 192kHz on spdif input. It uses neither upsampling nor oversampling. Just straight conversion.

So above the more obvious stuff. But why is it so damn good ?

Okay, the pcb is flat on the bottom, which means that all through-hole
solderjoints have to be flat.

There is no housing and the high-quality RCA jacks are not connected via wire, but directly soldered to the pcb.

Then this pcb is screwed on a spruce board which is the reason the pcb-bottom has to be flat.

Mounting to the spruce board adds body to the sound (which otherwise is not
there).Then there are a couple of other tricks I apply with the DAC which I better not mention here, in order to prevent some avalanche-kind of response

However, now you have something to play with ...

Fun

Charles

ALTMANN MICRO MACHINES

Quote:

Charles, have you experimented powering the OPA134s with a separate battery? Would be easy to implement and probably would further improve performance.

I think it would mess up performance.

However, the OPAs get the pure battery current, then comes the DAC (regulated)
and then comes the digital section (regulated separately). Ground plane
separation plays an important role too among other things.

I think if anyone of you would spend 5..10 years of his life tweaking with DAC
issues - add a portion of luck - add an extra portion of ignorance - you would
all come to quite similar results ...

Charles,


Quote:

If I may ask how do you make a dual supply for the op-amp with a single 12vdc ?

Hi Will,

I feed the signal at 6V, just about in the middle.

That's the reason that the Attraction DAC has coupling caps at its output.

Charles

 

[Jon L]

Quote:

Originally Posted by Davi /img/forum/go_quote.gif [size=small]The following is a portion of a discussion from another forum re the technical aspacts of the Attrattion from Charles Altmann himself. It is mostly over my head but maybe somone here can review his words and comment on it.[/size] Hi everyone, to answer your questions: On the Attraction DAC I use the TDA1543 because it is R2R and because it can be used with a single-ended power supply. As you already know, the Attraction DAC is designed to be powered by a Optima Red Top 12V car battery which eliminates the need of wall powered (noisy) supplies. I use active I/V conversion 1 OPA134 per channel, and 4 OPA134 per channel as output buffer. The DAC can power a speaker directly The output level is as high as it possibly gets with a 12V supply, so it is about -3.5 Volts to +3.5 Volts full scale (which btw. seemed to be enough to overdrive DUC's preamp). The input (spdif) receiver is custom. I programmed it into a Xilinx device. It has a switchable JISCO option and all DACs come with the UPCI (ultra-precision PLL) which synchronously reclocks the data. There is 2 custom made VCXOs for the frequency generation and tuning and one custom XO for the JISCO function. All features programmed into the Xilinx, which was really fun, but no walk in the park, btw The Attraction DAC runs up to 192kHz on spdif input. It uses neither upsampling nor oversampling. Just straight conversion. So above the more obvious stuff. But why is it so damn good ? Okay, the pcb is flat on the bottom, which means that all through-hole solderjoints have to be flat. There is no housing and the high-quality RCA jacks are not connected via wire, but directly soldered to the pcb. Then this pcb is screwed on a spruce board which is the reason the pcb-bottom has to be flat. Mounting to the spruce board adds body to the sound (which otherwise is not there).Then there are a couple of other tricks I apply with the DAC which I better not mention here, in order to prevent some avalanche-kind of response However, now you have something to play with ... Fun Charles ALTMANN MICRO MACHINES I think it would mess up performance. However, the OPAs get the pure battery current, then comes the DAC (regulated) and then comes the digital section (regulated separately). Ground plane separation plays an important role too among other things. I think if anyone of you would spend 5..10 years of his life tweaking with DAC issues - add a portion of luck - add an extra portion of ignorance - you would all come to quite similar results ... Charles, Hi Will, I feed the signal at 6V, just about in the middle. That's the reason that the Attraction DAC has coupling caps at its output. Charles

According to that, Attraction DAC technically has nothing special going on. It's the age-old formula of TDA1543 with op-amp I/V conversion and op-amp output stage. A output coupling cap thrown in as well.

Not having auditioned it (how many really have?), IF it sounds as "good" as reported, it must be due to the miscellaneous factors, mainly tuning the sound by ear by the spruce wooden board, huge battery power, and several other tricks he mentions he won't reveal. These tricks likely will sound like black magic to engineers and could involve things like further damping tricks, resonance control, etc.

The "custom" input receiver sounds interesting at first, but technically, I don't see why it would be any better than something like the established CS8414/6 receiver. The jitter reduction is nothing more than synchronous reclocking.

So far, nothing to tell me it's worth the ridiculous price compared to other TDA1543 DAC's, UNLESS it sounds truly state-of-the-art. I kind of doubt it.

 

[Davi]

Quote:

The "custom" input receiver sounds interesting at first, but technically, I don't see why it would be any better than something like the established CS8414/6 receiver..

I think that I remember reading something from Charles to the effect that he needed to design a custom input receiver because none off the shelf could accept up to 192hz going in this configuration to a TDA1543.


Quote:

The jitter reduction is nothing more than synchronous reclocking

Perhaps on the circuit board but did you investigate the optional "Switchable JISCO function (Jitter Scrambling Decorrelator)"? This apparantly is a seperate device to be connected to the input.

Quote:

So far, nothing to tell me it's worth the ridiculous price compared to other TDA1543 DAC's, UNLESS it sounds truly state-of-the-art. I kind of doubt it.

Did you read this review by Dick Olsher?

http://www.enjoythemusic.com/magazin...mpling_dac.htm

 

[Jon L]

Quote:

Originally Posted by Davi /img/forum/go_quote.gif I think that I remember reading something from Charles to the effect that he needed to design a custom input receiver because none off the shelf could accept up to 192hz going in this configuration to a TDA1543.

TDA1543 is an ancient chip that ONLY operates at 16-bit resolution (at best) and 44.1 kHz. Accepting/passing 192kHz doesn't matter, really.

Quote:

Originally Posted by Davi /img/forum/go_quote.gif Perhaps on the circuit board but did you investigate the optional "Switchable JISCO function (Jitter Scrambling Decorrelator)"? This apparantly is a seperate device to be connected to the input.

This is a very questionable, unproven claim. They are claiming JISCO somehow "shifts" jitter under 10kHz to over Mhz range, which is better handled by the input chip jitter attenuator EVEN THOUGH the total jitter becomes higher.



Quote:

Originally Posted by Davi /img/forum/go_quote.gif Did you read this review by Dick Olsher? http://www.enjoythemusic.com/magazin...mpling_dac.htm

Yes, I read it months ago. You must understand something about Dick Olsher's sonic preferences. He definitely is in the tube/SET/analogue/single-driver camp, and while I also like my music warm, dense, full, and rich, it isn't exactly what I call neutral. What Dick needs to do is to directly A-B the Altman to some of the latest modern DAC de jour..

 

[maxchau]

I am an Attraction DAC user since 2006. I was just informed the current price of the dad is $6000. Obviously a lot of wealthy guys think it worths at least that much!