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Vintage DAC replacement...Buffalo DAC?


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I/Vs generally aren't universal, are they? There's no telling whether the SFD output stage would work well with the Buffalo DAC.

If the guy is local, maybe a police report might work?

$150 isn't a bad price for a new Ultraanalog DAC though.

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I think it should work simply by connecting the +, - and ground from the buffalo DAC to the +, - and ground of the output stage of the sonic frontiers (for each channel).

I wouldn't bet on it. These are almost certainly current (I) out DACs. All of the I-out DACs that I have seen have different quiescent currents that you need to deal with to put the I/V input at virtual ground with a very low input impedance (I-out DACs really want to drive a dead short or 0 ohm impedance load). The Buffalo can operate in either current out or voltage out fashion (programmable? I haven't read the datasheet). The chances of the SF output stage being configured just right for the Buffalo are slim or none.

I don't know if the DAC I'm getting from SF is the MK2 or MK1 version (or maybe even the MK3!) so I may actually gain something here. :D

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I wouldn't bet on it. These are almost certainly current (I) out DACs. All of the I-out DACs that I have seen have different quiescent currents that you need to deal with to put the I/V input at virtual ground with a very low input impedance (I-out DACs really want to drive a dead short or 0 ohm impedance load). The Buffalo can operate in either current out or voltage out fashion (programmable? I haven't read the datasheet). The chances of the SF output stage being configured just right for the Buffalo are slim or none.

Thanks for the info! I guess what I'm thinking of won't work then. Am I right in saying that if the sonic frontiers was a voltage out DAC then one wouldn't have this problem?

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Thanks for the info! I guess what I'm thinking of won't work then. Am I right in saying that if the sonic frontiers was a voltage out DAC then one wouldn't have this problem?

If it was then the tubes aren't actually doing any I/V, but only buffering the output, which is a common practice in chinese "tubed" DACs.

The mk2 is using the same DAC, while the mk3 used PCM1704 (which definitely can't replace your D20400A) me thinks.

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The story starts here:

http://www.head-case.org/forums/home-source-components/5712-vintage-dac-sonic-frontiers-sfd-2-a.html

So to summarize the story: last week I bought a vintage Sonic Frontiers DAC and I come home and the right channel is completely distorted. Although it managed to work for a few hours (giving me a taste of its magic), afterwards the distortion came back and never left :palm:.

So I take it to a repair shop and the person confirms it is the right DAC is at fault. Yes, the one with the bizarre foil on it :palm:.

So I've been had.

The D20400A chip is probably quite hard to find these days and probably obsolete as well so a solution occurred to me which is to replace the entire DAC module with a Twisted Pear Audio Buffalo DAC and its power supply. That way, I can still take SOME advantage of the Sonic Frontier's tube output stage (which looks pretty good).

In my mind, this seems like a great idea....what do you peeps think? I can't see why it shouldn't work, and it must sound better than the standard IVY output stage. The other problem, of course, is my inability to solder but I guess I could get the repair person to do this for me...

Too bad about how it worked out, but it seemed like you refused good advice to not buy it and you lost. I hope you get it fixed.

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Too bad about how it worked out, but it seemed like you refused good advice to not buy it and you lost. I hope you get it fixed.

I think this is just one of those phenomena that could have happened with any piece of gear. I'm still in the market for vintage since there are only a few modern DACs that use the PCM1704, and the good ones that do are $5000+.

To the OP, my suggestion still stands...

I'm going to suggest the obvious, but did you try replacing the tubes? Or swapping tubes to see if the distortion moves to the other channel?
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Too bad about how it worked out, but it seemed like you refused good advice to not buy it and you lost. I hope you get it fixed.

I guess you are right about the advice part but if it worked I wouldn't have regretted it at all (based on what I heard while it was working). I'm just waiting for the replacement part from Sonic Frontiers and then I should be all set. (Hopefully).

To the OP, my suggestion still stands...

I wish it were that simple...This was my first instinct as well..I've tried swapping them as well as a different tubes but no change.

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But for the price paid, it wasn't a good deal even if it was working.

Well there are a few listings for at least $1000 on Audiogon so at least it's a better deal compared to those..if it was working..

If I get it working again, I don't think I'll have a problem selling it on for the same price...

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that people ask that much doesn't mean it' sworth that much or they sell for that much

I've monitored results from a sonic frontiers query pretty closely on audiogon for the past several months... sfd-2 mark 2s do seem to regularly move for 900-1300 dollars.

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So... going back on topic, @OP: Have you gotten a new Ultraanalog DAC?

Yes I have, but it turns out that instead of getting the entire module, I was just sent the DAC chip :palm:. I'm not sure it's such a good idea to use the brand new one along with the older one. Anyways, I'm resigned to making a significant loss with the whole thing now.

BTW, it turns out that the D20400A is voltage output:

K&K Audio / Lundahl Transformers - UltraAnalog D20400A? - danlaudionut, December 04, 2003 at 00:29:31

..so I guess the output is just a line-stage. I guess those Chinese tube DACs are doing something right :P.

If it was then the tubes aren't actually doing any I/V, but only buffering the output, which is a common practice in chinese "tubed" DACs.
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Yes I have, but it turns out that instead of getting the entire module, I was just sent the DAC chip :palm:. I'm not sure it's such a good idea to use the brand new one along with the older one. Anyways, I'm resigned to making a significant loss with the whole thing now.

BTW, it turns out that the D20400A is voltage output:

K&K Audio / Lundahl Transformers - UltraAnalog D20400A? - danlaudionut, December 04, 2003 at 00:29:31

..so I guess the output is just a line-stage. I guess those Chinese tube DACs are doing something right :P.

I don't know what made you think they were sending an entire PCB (module?). It was pretty clear to me that they were just sending a single UltraAnalog D20400A module (more like an HDAM than a DAC chip).

As far as trusting anything that is put up on AudioAsylum, do so at your own risk. Personally, I wouldn't. The technical level of many seems to stop at what kind of faceplate to use on their Oyaides... :palm:

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