Vac Sig MKII tube circuit upgrade

I`ve heard this linestage many times and it sounds wonderful, but is`nt it hard wired point to point rather than a circuit board?

Best described as a "hard wired" circuit board. The board is there for location, routing, and support. The wires are individual and not "printed" on the board.

I'd be interested in hearing from anyone who has done the update as well.

Interesting. I recently purchased a Renaissance 2 preamp on Agon and sent it in to VAC for just this upgrade. The Ren2 is a very similar circuit as the Sig2 (both transformer coupled), but the Ren2 does use the circuit board. VAC also added the ability to add resistors into the MC circuit to change the loading (accessible by resistor receptacles on the board)and upgraded some of the wiring and grounding to be consistent with the newer Sig2. I was really impressed with their customer service. The updated Ren2 originally blew me away ("I didn't know my system could do all of that!"), but I'm now feeling it's a bit forward/aggressive in the mids. Brent at VAC told me that the Ren2 is more forward in the mids than the Sig2. I only have about 30 hours on it since the upgrade, so there may need to be more breakin. And I haven't tried anything but the stock tubes yet (I've been too busy).

Interested in hearing the experience of others. Particularly how much tube rolling can vary the sound on the Ren2 or Sig2.

Thanks, Peter

I'm not aware of an upgrade to the Sig. 2A, his website does not say there is an upgrade as well.

I believe just the MKII as the IIA has that tube swap option installed already.

I believe Drummermitchell is right about this.

04-11-12: Drummermitchell
I believe just the MKII as the IIA has that tube swap option installed already.
Drummermitchell (Threads | Answers | This Thread)

Not true. Only the later Sig MKIIa has the tube swap option. I ordered my Sig MKIIa in mid 2011 and it has the option.

I spoke with Kevin and there's no circuit change, just a switch out of the signal path to deliver 6.3 or 12.6 volts depending on the tube type.

I hear the IIA is going to get a stellar review in next months issue of the Absolute Sound.

Must have understood Vac's website.
The earlier II and IIa can be upgraded so a user can swap out
different tube types.

Knghifi,don't suppose you have been experimenting with different tube types by chance,any thoughts on the extra possibilities.

My Phi Beta preamp has the switchable option of using 6922 or 8416. I briefly listened to one of my favorite 6922 tubes, Hamburg Valvo Red Labels from the early '60s. I like this tube's combination of body, clarity, and extension. Frankly, it sounded virtually identical to the 8416, so I stuck with the 8416. I guess it's not all that surprising since they're both essentially of the Amperex PQ family.

Drummermitchell, finally settled with 60's Siemens Cca and Telefunken 12au7 ribbed plates. From my experience, the 12au7 position is as sensitive to tube rolling as 6922/e88cc/7308. I found the stock Philips 6189w too warm and congested for my taste.

I also HGHLY recommend the Audio Magic fuses. It replaced all my HiFi Tuning Supreme and Gold fuses. It's unbelievable how a fuse can improve the sound ... bloom, tone ... This is probably one of the BEST ROI I found in this crazy hobby.

I see Vac's website now has a picture of the switch and the different tube types the sig will take.
Mine will leave tomorrow for the upgrade.