VAC 70/70 mk3 tube rolling question

@lowrider57  Thanks for the helpful information. Forgive me as I don't understand all the details of the williamson circuit and I can't upload photos here. 

So basically there are four 6sn7 tubes in the front row of 70/70. Assume they are V1, V2, V3, V4 from left to right. My understanding is that V1, V2 are for channel 1, and V3, V4 are for channel 2, is that right?

My question is which ones are for gain stage and which ones are for phase inverters? ( If my above assumption is right, is v1, v3 for gain stage; v2, v4 for phase inverters ?) Thanks!  

@lowrider57  I heard back from Kevin this morning. Actually it is V1 and V4 are drivers and V2 V3 are phase splitters. Here is Kevin's response:


"Yes, it is perfectly fine to mix brands of 6SN7. In your scenario, use one brand for the V1x positions, and the other for the V2x positions.

Technically, 6SN7 GTA or GTB types should be used, but we have not heard of any significant problems with earlier NOS version, although they do have lower maximum ratings.

With respect to matching, when operating the 70/70 with zero negative feedback, matching the gains of the tubes between the left and right channels helps to keep the center image centered. Section matching within each V2x tube is desirable but not highly critical."

Anyone needs the diagram he send me, I can also email to you if needed. 

@lowrider57  Yes I checked the user manual online here: http://www.vac-amps.com/manuals/Manual_Ren70-70.pdf

Unfortunately the Figures that shown the tube placement are missing. (figure 2).

@drrsutliff  Thanks for the info! Too bad the figures that are showing which socket is which are missing in the online manual. I sent Kevin an email asking about the placement. Hope he can get back to me soon. 

@rodman99999  Thanks a lot for these info! I purchased my two pairs of 6sn7 from Brent at audiotube.com. He helped me picking up those sets. Personally I don't have a lot of experiences with tube rolling. 

@lowrider57  Thanks! I came across this ad https://www.canuckaudiomart.com/details/649558669-vac-valve-amplification-company-renaissance-7070-mk-iii-mint/ and by checking at the pictures my best guess would be that V1, V4 are phase inverters and V2, V3 are gains.