Sonic Frontiers SFD-1mk2 Vintage DAC for $750 That Stomps Most Modern DACs

Here you go...

 

Thanks Edwyun! That helps a lot.

I don't have a lot of knowledge about the SE+ upgrade. Hopefully, someone like Luckbad (lots of knowledge and experience in SFD-1) will post about all of the elements. I remember some discussion about silver wire, but I'm not sure.

The output caps seem to be a big part of the upgrade and the ones in my SFD-1 are linked below. They replace the caps that are labeled on the pcb as C14, C16, LC14, LC16. I wish I had more information.

https://www.partsconnexion.com/MUNDORF-76432.html

Jac

 

@lehmanhill, yes I am familiar with replacing the output caps, but there have been several versions that I have seen.

Some PCX SE+ use the 2.7uF mundorfs, others use the 3.3uF mundorfs, and still others use the 3.9uF mundorfs. While these caps are +/- 3%, depending on which are used for the SE+ mod, there are other changes/removals of caps or resistors in some cases. I am trying to find that out. Hopefully, some other SFD1 owners will post some pics of the innards. I've just ordered the parts are will post a DIY thread eventually.

So far, this is what I have compiled:

 

Here you go. Page 2 just shows the total cost so it is omitted.

Let me know if you want to see any particular pics of the inside. You should do a guide and post it here.

 

@magnium

Wow, thanks, that really helps. Your parts list is from 12/2019, so probably the most recent. I was trying to get a a few pics of the areas circled in orange regarding the caps/resistors on the left/output side and the diodes on the right/power supply side. That would help a lot. Definitely will post up a guide as - so far - it does not seem like a big issue to remove the PCB.

 

@magnium

Thanks so much. That's great information.

Edwyun,

While you have the pcb out of the case, I would recommend also replacing C501 and C502. They are timing capacitors that don't have any affect on the sound, but it is an old dac and when those parts failed, no music comes out. Those caps control the delay for warming up the tubes. Actually, all of the electrolytics are old and probably should be replaced.

Jac

 

My attempt at the photos you requested. I'm am not totally sure that mine has the full SE+ package. For example, I don't have the FTech RCA, the damping material, or the Cree diodes (although I have used those in another project and they are great). Mine may be an older SE+ update or a partial update.

Starting in the upper left, the Mundorf Evo's squeeze the little caps, so it's hard to see. They appear to have a brand marking something like mu-i-pi.






The power resistors next to the tubes is next.




I have white caps where you have blue. Here is a photo of mine.




The diodes in the upper right of your photo. Note that the D300 series diodes are larger than the D200 series below it. I can't make out enough of the markings to identify them, but they are not the Cree's which are TO-220 types.




The lower right diodes.




I would love to see someone with a known SE+ upgrade post pictures.

Jac

PS Yeah!! Stupid me finally figured out how to post photos that actually show in the thread.

 

Thanks. Yes, I believe C501 and C502 are replaced by NICHICON-76206 (100uF, 16v) from the invoice @magnium posted.

 

@edwyun 1/2

Here are some closeups for you.

Near the Output


Near the Tubes


Near the Top Transformer

 

@edwyun 2/2

Here is near the bottom transformer

 

Thanks. I believe those caps are MIT. Those are the ones missing in the photo in post #236 by @magnium on his SE+.

The resistors are what I saw, one of each pair were removed. The white caps look original to me.

 

@magnium

Thanks again for your help. It now makes it a lot easier to see what was/wasn't changed. I will have to order a few more parts for the SE+ mods but it is much clearer now. Will update once I start on the mods. Can't wait.

 

@edwyun

Your welcome! Hope your upgrade goes well. Reading this site inspires me to look into DIY though I need to learn how to solder and how circuits work.

 

You probably already know this, but I discovred that the MIT caps are Reliable MIT Multicaps. Obviously, these were not changed in SE+.

It is interesting to see that mine has parallel 39k, 2W resistors in R15 - 18, LR15 - 18, probably Amtrans AMRA. I suspect that those were part of an earlier SE+ update, but I'm not sure. That gives the circuit 19.5 kOhms. magnium's list shows a single Mills 18k, 5W wirewound resistor. I personally prefer wirewound power resistors over metal oxide like the AMRA's.

It is also interesting to see the value of the caps (for example C22) has changed from 0.22 uF for the white caps to 0.82 uF for the blue ERO caps. When I get the pcb out of the box at some point in the future, I will have to do some circuit tracing to see what those white/blue caps are doing. Of course, I'm not in any hurry because the SFD-1 sounds so good.

I will reiterate that tubes make a big difference in the sound of this dac. The cheap and cheerful Matsushita/National tubes I started with sound good, but I have tried several from the Siemens/Telefunken sound family and the bass is much better, plus the mid-range gets even nicer. The Tesla tubes mentioned in magnium's list are in that family of sound.

 

Agreed. I've tried a couple variants over the years. Settled on late 60s Amperex JAN 7308 for now.

 

As an update, I am essentially done with removing the parts, cleaning the PCBs and through holes, and getting ready for the parts to come in. Wasn't too difficult to remove the board...

 

@edwyun

I find the PM notification is a little uneven sometimes, so this is just to let you know that I just sent a PM to your Inbox.

Speaking of removing the board, that is an interesting case design, isn't it. I'm referring to the heavy stainless steel face and the hidden fasteners. It had me scratching my head a little until I figured out what they were doing.

Jac

 

Sent a reply via PM.


If there are any SFD1 MkII owners with the red WIMA capacitors throughout (instead of the blue ERO capacitors), please speak up as I have a question. On the output stage (left side of the unit near the vacuum tubes), it looks like the DAC with original blue caps used ERO MKP1841, 0.56uF, 250V, 1W, 5% tolerance, while the DAC with the original red caps used WIMA MKP4, 1uF, 160V, 10% tolerance. A few detailed pics of those red caps and the output stage in general would really help. Thanks.

 

Detailed pics at https://imgur.com/a/UtLAKS7

 

Thanks so much.