…Time to rethink the daughter board power supply
1 Like
I don’t want to ask meaningless questions, but please forgive my curiosity.
If we are creating an independent supply for the opamps we will install, will 12 volts be the limit for us? 5 v is taken into account in the new power.
No, there are a lot of details. If you build your own output stage on a new board (or point to point wire it) you will have more freedom. But the current design wasn’t designed for modifications. For example, there are 8V caps and 10V caps around the current regulator and if any of the new opamp supply voltage flows upstream it will also push other regulators past their safe operating area. If you are DC coupled, the input rage is about from 3V to 4.2V and there’s no “gnd” reference. …
You’d need to pay attention to a lot of details that aren’t obvious to avoid hurting the rest of the board.
4 Likes
I’m trying to follow @yuriy’s footsteps. I started collecting the pieces.
1 Like
Yes that was one of the big questions about changing the DS Mk1 OA section to a bi-polar supply- what to do about the fact that the bit slinger (re-clocker) that feeds the OA inputs has about 3-3.5V DC offset on it… But now your OA with bi-polar PSU will be “wanting” a 0V reference input basically. Hmm… What I did may not be perfect but it does seem to work at least. Sounds really good, nothing blown up 
Spent the day with DW and his cousin A- we started at the Focal powered by Naim and heard a lot including the big daddy Dali Kore. Then we hit another shop to hear dCS DACs in very high end systems including Wilson Alexx V. Also high end Sonus Fabers. All with very good electronics.
We also got hear again how a Roon powered streamer generally underachieves sonically. You have to nag your demo person(s) to get that aspect out of the way. In this case the built in dCS ethernet port/streaming stomped all over the Roon setup… It’s truly amazing to me how many streaming setups are seriously under-achieving, and so widespread lately. Of course, people don’t generally know until they hear it gone…
We ended the day back here and heard some things including the DAC3 with JK trafos, sitting on top of and connected directly to the proto amp via some new short pure silver ribbon jumpers in teflon tubing. Trying to make the most direct connection between the 2 with no “interconnects”, per se. It sounds pretty fabulous.
But the DAC1 with bipolar OA PSU and no DC blocking caps or trafos continues to win the day. Connected to the amp via a simple, buffered Hattor dual mono pre with Staccato OA in it doing the buffering. Using Audience Front Row interconnects. BTW I’m a N America partner with Staccato now and sell them (also Audience). DW also brought some new In-Akustik IC to hear, which I definitely believe in the design principle. They seem to deliver on the clear and transparent front, which one would expect based on the design principle (air dielectric).
Speaking of buffered pre, had an interesting experience trying Muses audio OA in it this week, which is a great place to experiment with that. Went out on a limb to try them as I liked their effort to make a better OA- Pure Cu lead frame, separated dies, etc. I went with a pair of 01 (JFET) and a pair of 02 (BJT). Muses BTW makes the volume control IC’s used in Pass preamps for example. The OA aren’t cheap either but yes, they do sound pretty darn good. It has been my experience that JFET sound quiet and impressive overall but somehow lose necessary texture that engages; they kind of bore in that regard. It was also same experience with JFET in the proto amp front end as well a few years back (it has matched BJT again). Seems to be a characteristic of JFETs. The BJT OA was very impressive with great texture and richness, but seemed to get a little congested sounding in comparison. The Staccato strikes a happy medium between the 2 and I declare it the winner (and it’s playing now).
Anyway after all that listening today to super systems cousin A is going to commission a DS Mk1 modded build Both he and DW want bi-polar PSU versions too. Hmm… Once that level of clarity is heard, there’s just no going back.
TK
2 Likes
Happy cake day @tedsmith!
Happy birthday TS! And many more!!! T
1 Like
Cake day is your forum anniversary. If it’s Teds birthday then he got the wrong cake!
1 Like
Oh haha. sorry But still. many more 
1 Like
Now it’s your Cake Day in the proper time zone!
Happy Cake Day!
Happy Cake Day @tedsmith!
I couldn’t see the cakes when people first started wishing me a Happy Cake Day, and I was a little confused. But now they are there. Thanks all.
9 Likes
Happy cake day Ted. Thanks for all your help.
Happy 
Day Ted! 
Happy Cake Day 
@tedsmith!
It’s hard to believe I’ve been here since 2014. This is a nice respite from the craziness out there.
15 Likes
Happy cake day 
@tedsmith !
You’ve consumed a lot of cake! Thanks for your unfettered information and assistance on this crazy train.
2 Likes
I did the Vocm mod a few days prior to swapping out the Edcor transformers for yours, two weeks ago.
@toolbox149 said it far better than I could. Well worth it, even having already changed the transformers once.
Massive thanks to @tedsmith, @Turbotk and @jkrichards for pursuing the continual efforts for better sound from the MKl.
Cheers
4 Likes
Well an amazing revelation tonight, just wanted to share. I took the plunge and ordered some AN Niobium silver resistors for the series element in the Hattor dual mono pre shunt volume control. They are not cheap. And the dual mono is full differential so x4 rather than just x2. But I generally love tantalum R and these are supposed to surpass that, so had to try it.
Holy smokes… LOVE what I’m hearing(!) And this is vs Z foil that I had in there. Musically it makes them sound like cr*p in comparison really. Again, wow(!)
On the down side, the proto amp let some smoke out tonight sigh. Not sure why, but I’ve been running it with no DC blocking caps in it (for best clarity) and just being careful about DC in. Ok, maybe I wasn’t careful enough tonight after the preamp change sigh. Hopefully the rancid smell in the house will be gone soon That thing has been running for years. Sad to see it give up some smoke.
On the plus side, we get to roll some other amps meanwhile. I just ordered a Schiit Aegir; we’ll see if it can at least hold down the slab for awhile (I assume it can, but…). I don’t feel like lugging the big Apollo or EXM7 in tonight, so have a Zero Zone “NAP 180” wannabe running in there (I bought it to use the case for another proto basically, eventually). It has surprisingly good clarity and great tonality, driven by the souped up Niobium equipped Hattor, and dynamics are fine actually. Just the soundstage is a little shrunken vs where it should be. Interesting at least.
TK
That red PRP resistor (lower middle) is not supposed to have a black burn band around it 
4 Likes