Pars

Are you referring to the sigma BOM spreadsheet? You will need either plain IEC power entry (with fusing, some sort of power switch whether it is part of the IEC or not is your choice) or a filtered IEC inlet. Also, it might be good if Team Spain were to include some spare current diodes of both flavors, as these are getting hard to find reliably, at least here in the US.

Pics or it didn't happen! Seriously, hope you're OK...

Pedja Rogic (Audial) knows his shit. I'm building an earlier version of his TDA1541a NOS DAC (even though I don't believe in NOS ). This DAC was what Strohmie used in his DIY CD player also.

I guess I must be missing something here... why would you want to? Are these higher performance than a TL071, etc. as a servo? Increased pull in range (or whatever you call it in a servo) due to the higher rails? Free (kinda)?

That is actually black nylon techflex... must be the flash picking up the white teflon tape underneath it. I'm no photographer, that's for sure But thanks!

A 1 meter pair of RCA interconnects built with 28ga Neotech UP-OCC copper on cotton rope, similar to the ChrisVH silver recipe. Yarbo RCAs.

The one board layout from jacob that I saw had +/-15V regs for a more typical servo opamp in it...

I assume you mean have both sets of boards installed in a chassis at the same time? The inputs wouldn't be so bad I wouldn't think because they've already gone thru the pot at that point, so it would be like a selector switch (stereo or balanced). The outputs you might be able to wire in parallel if only one set of boards was powered. Otherwise, 2-4 more poles (or relays). Then there is power, which is the easiest as you would only need a DPDT switch for that (switching V+/V- DC power). Doing this all without pops, etc. is another matter.

I've never seen pics of the one(s) that KG built, and I don't recall him saying what he used for a PSU in them. He's the only one I know of who has built a DynaFET. On another note, have board pics been posted yet?

I'm not sure I can remember an order where I didn't forget something? Oh, maybe the ones that I went over for several days before placing

That is very good advice. Make sure the amp etc. is turned off before moving/connecting/disconnecting ICs and other pieces of gear.

Happy Birthday!

In the board pics on amb's site, it looked like the bottom ground plane extended under the sinks. I couldn't tell for sure whether the holes were actually tied to the ground plane or not, and being at work, can't measure one.

I'm not vvs, but I'll take a guess. The heatsinks are probably tied to board ground (looks like it on the sigma22). Normally you would use a ground loop breaker, which is a low value resistor and x-rated cap (AC line) in parallel, from the board ground to the case (i.e., wall ground). The heatsink touching could potentially short this ground loop breaker out, rendering it useless.

It seemed to me that ep3 showed us she might not be as erased as they think? I liked the 3rd ep personally; probably even better than the 2nd ep.

If you slap a Burson in it, it will be like putting a "bend over" sticker on, cuz at their price, you just did Colin gave a very good answer, BTW.

Happy Birthday Nate! Now, go shovel that driveway! Just kidding...

I figured you meant 2U, just wanted to make sure no one started ordering 1U cases

A 3" case is 2U, not 1U (U = 1.75"). The 1U cases from modushop are 40mm; 2U are 80mm. The 2.5" heatsinks would make for a tight fit. And I concur on the pins... not knowing exactly what they were, I tried to desolder some in an MD10 I was fixing. I didn't try real hard, but I could not get them to budge. Threaded as the stock ones are is far preferable.

Maybe I missed it, but looking at his initial build pics on headwize, he used onboard heatsinks on the sigma22s?

I would think it would be difficult (or at least not particularly clean) trying to use off-board heatsinks on a sigma22, as the output devices are on both ends of the board. Maybe I'm thinking inside the box too much?

In the original schematic, it is a 1K feedback resistor with a 100 ohm to ground, so should be a gain of 11 ((Ra / Rb) + 1). Per amb's advice on headwize, in order to change gain it is probably preferable to increase Rb (the 100 ohm) instead of lowering 1K to prevent loading the output. Something like 221 or 330 ohms in series with the 100 ohm and shorted by a DPDT switch (4.1 or 3.3 respectively) might work. Not sure how to adjust the compensation cap in parallel with the 1K. Intuitively I would think its value would need to decrease?

The original schematic shows a 1K feedback resistor with a 10pf compensation cap. I'm not sure how to calculate gain in this, so I don't even know what the stock gain is. If it is like the dynalo/dynahi, it is probably around 11?

I was asked by Icarium to mention the possibility of incorporating selectable gain into the design. I don't need it, but wanted to bring it up as a possibility. My thought was perhaps two positions? I know there was discussion regarding this in the Dynahi build thread on HF a couple of years ago, and it is certainly doable. Would probably require a different compensation cap, etc. Any interest in this?

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.