DAC Project D1 Circuit available?

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#21
Lithium Tantalates

No problem , I'll just turn it over to Ms. T'Pol in purchasing.

Thanks

H.H.
 

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#22
VCO

Fujitsu made the VCO. This has unfortunately been discontinued by them (new types). The last batch came from a broker. For a single dedicated frequency a crystal VCO will work. The Lithium tantalates have better stability and pullability though.

This is also not the 96K 24 bit version we last made.

Wayne
 
#24
<a href="http://edevice.fujitsu.com/fmd/en/products/a_vco/">Fujitsu LiTa<sub>3</sub> VCO's.</a>

First Saw LiTa<sub>3</sub> VCO used in the Stax Dac talent, it used a V-12M288.
Dac Talent BD page <a href="http://www.hoops.ne.jp/~asd123asd/dac-tb.htm">here</a> with a link to the schematic at the bottom.

Regards
James
 
#25
Nelson,

In the owners manual you say that you've tested it extensively against the most highly regarded D/A products available, and didn't stop until the circuit sounded better than anything elso on the market.

So what did you compare it with and could you describe the differences ?

Xcel
 
#27
Just curiousity, Mozfet....Because some people are more easily satisfied then others. By the way, in a competitive marketplace one can expect questions like these. And Nelson isn't afraid of a little competition otherwise he wouldn't have made such a claim regarding this point in the manual.

Xcel
 
#28
Nelson/Wayne,

Thanks for sharing the schematic. A few questions:

1. There is no gate resistors on Q2 and Q5. You usually put them on all mosfets. No oscillation here?

2. You guys seem to be big fans of current sourcing. None of the mosfets are current sourced, just 1.5K and 3.3K resistors. Sound worse with current sources?

3. How about cascoding Q3 and Q6? Overkill?

Thanks, if you answer or not.

Ric Schultz
 
#29
output stage

I built the output stage and appended
it to my small dac (a Crystal cs4390).
Had to use 2k2 resistors to make current out of
the dac's voltage output.
It sounds very promising, but 4 x 50 euros for the BB DACs
(you could probably use BB's 1704, they should be even better?)
are too much just for experimentation...

- How do I connect unsymmetrical output?
The manual says 150 ohms impedance for unsymmetrical. So I would just connect positive
output and ground, and the negative half of the
circuit would be completely unnecessary?

martin
 
#30
D1 Q2 Q5

There is enough real impedance to not cause oscillations.
I never tried current sources on the DAC so I can't say.
The output on the RCA only uses the + half. 96K 24bit units have a summer not shown on the 20 bit unit.

Wayne
 
#32
Nelson:
Thanks for answering Excel's question. Interesting.....

Do you guys at Passlabs really have as much fun (we know you work hard, too) as it seems in your postings and manuals? What's a typical day like for you or Wayne?

mlloyd1
(who obviously dreams about doing fun stuff again while dodging axes in telecomm)
 
#35
Hi,

does anybody know, where to buy (and get information)
an AT/T optical receiver?

I plan to do a diy project similar to the D1.
The DAC will be a PCM1704.
The digital filter a DF1704.
The receiver a CS8415.
I found a source where to buy fujitsu VCOs.
(Unfortunately You need two of them to work with
44.1 an 48 / 96 kHz).

Any comments / recommendations?


Zelter
 
#38
Get in touch with Agilent, they may sample you one. That's where I got mine that is going into my Assemblage Dac 2.6 (whenever I get around to building THAT. I've got two unstuffed boards, most of the digital chips. Just not looking forward to all of that SMD soldering).

RonS
 
#40
Pass D1 I/V stage

Anyone

A couple of questions:

1. For unbalanced, presume you just use one half the circuit with the attenuator be simply to ground (and R values half that shown)?

2. Are the MOSFETS IRF610s? (They are labled 610)

Nix
 
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