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 .

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 .

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...

I should probably mention that the Sonic Frontiers SFD-2 is modular, so the DAC, power supply and output stage are on separate PCBs so (in theory) it should be very easy to remove the DAC portion...

Ok, so let me get this straight:

You paid $900 for a very old dac, and now you want to replace the dac part of it since it's bad. No chance you can just return it?

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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).

<more snip>

I'm with Grawk that the first thing I would be doing is getting my money back from the seller. You had problems with it immediately upon getting it home (which is when I would have contacted the seller). I'm also not sure it would be that easy for your repair person to isolate it to the D20400A? At any rate, these do come up occasionally:

http://www.diyaudio.com/forums/search.php?s=&action=showresults&searchid=1164282261&sortby=lastpost&sortorder=descending

Ok, so let me get this straight:

You paid $900 for a very old dac, and now you want to replace the dac part of it since it's bad. No chance you can just return it?

Well, I've tried but since the seller tested it for me, I couldn't tell him it was already broken when I received it. He pretty much said I was on my own.

I'm with Grawk that the first thing I would be doing is getting my money back from the seller. You had problems with it immediately upon getting it home (which is when I would have contacted the seller). I'm also not sure it would be that easy for your repair person to isolate it to the D20400A? At any rate, these do come up occasionally:

http://www.diyaudio.com/forums/search.php?s=&action=showresults&searchid=1164282261&sortby=lastpost&sortorder=descending

It seems like the going price is at least $200 for a D20400A. I could get a buffalo DAC for slightly more (of course subject to availability). You are right that since I don't have any DIY skills, I can't verify what the repair guy is saying.

One additional advantage of replacing the entire DAC portion is that it completely modernizes the entire DAC and removes any worries of using a vintage DAC.

One additional advantage of replacing the entire DAC portion is that it completely modernizes the entire DAC and removes any worries of using a vintage DAC.

Also defeats the entire purpose of buying it in the first place no?

That's what it seems like to me. I'd explore every avenue you have for getting your money back.

You may also want to contact PartsConnexion.

And no, it doesn't completely defeat the purpose*, just the primary reason.

*He is right in that if he can get a DAC that would be compatible with the output stage, it is a good one, and we all know how important that is.

Spending $900 on a used output stage doesn't make any sense to me any way you put it, sorry. The purpose was not to buy a project as far as I could tell.

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?

You may also want to contact PartsConnexion.

And no, it doesn't completely defeat the purpose*, just the primary reason.

*He is right in that if he can get a DAC that would be compatible with the output stage, it is a good one, and we all know how important that is.

I second this. Chris Johnson who was the man behind Parts Connection/Connexion and Sonic Frontiers would know best about the serviceability of this DAC. He very well may have ultra analog chips still lying around to service this and the other dacs that used this chip that Sonic Frontiers produced.

You may also want to contact PartsConnexion..

I contacted Chris Johnson at PartsConnexion but they didn't have any.

Also defeats the entire purpose of buying it in the first place no?

Obviously the situation is not ideal. I'm just trying to make the most of it I guess.

That's what it seems like to me. I'd explore every avenue you have for getting your money back.

Well since I paid him in cash, the only possibilities left that I can think of are calling the cops or threatening to break his legs

Spending $900 on a used output stage doesn't make any sense to me any way you put it, sorry. The purpose was not to buy a project as far as I could tell.

Well I've already spent it so there's really nothing I can do! Either it's a project or I'm left with a 13kg brick.

Start with the head -- it makes the victim all...fuzzy.

well the guy was pretty big so unless I pay someone it would just have to be threats unfortunately. Might as well pay to get it fixed...

Yeah I dunno it's going to be pretty hard I think Filburt mentioned that these chips are calibrated through trimming via resistors on the board so even if you can locate replacement chips they won't be a simple swap in replacement you'd have to do some fancy calibration which would require equipment along the lines of a Prism analyser, but more likely something like what Audio Precision or SRS makes and know how to use that equipment to do a good job of it.

Also there were 3 versions of the chip made. 1 with internal I/V. Then the A series which came with internal I/V or no internal I/V (Spectral and I believe the processor 3 use these).

Anyways.. I highly suggest you try and get your money back.

I contacted Chris Johnson at PartsConnexion but they didn't have any.

What about having them fix it somehow else, knowing what the problem is?

You can at least talk to the guy instead of crossing it out as an option before trying.

You might point him to the previous thread where you indicated it didn't work as soon as you got it home. I would be very doubtful that he wasn't aware of the issue however .

I cant figure right now if you're the ideal victim or you can reach some level of self control few of us can only dream about....

Good luck anyway.

Amicalement

I vote first option

You can at least talk to the guy instead of crossing it out as an option before trying.

I did try calling him but he brushed me off.

I cant figure right now if you're the ideal victim or you can reach some level of self control few of us can only dream about....

Good luck anyway.

Amicalement

It's probably more the former rather than the latter..

Anyways, the new turn of events is that someone from Sonic Frontiers emailed me to say they have the part (Chris Johnson gave me his email) and the price is far less than I thought it would be...($150). So should I replace the DAC with the original part or a Buffalo DAC?

The original.

Original part. That way if you have to turn around and sell it, you don't have to explain how it's a buffalo DAC in a Sonic Frontiers chassis, you can just sell a Sonic Frontiers DAC.

Somehow, I'm thinking that that's not that distant a probability.

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.