VAC 70/70 mk3 tube rolling question

It goes without saying to anyone familiar how many people almarg has helped with their home audio issues here. Not only that, but he goes out of his way and spends time to do the proper research on products before speaking. His attention to detail is impeccable.  Best source of charitable yet reliable and unbiased audio advice that I know of. His absence leaves a real hole here I would say and hope he is back very soon.

He has helped me many times on and off this forum, and I have the utmost respect for him as a person.

@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. 

Interesting and valuable info.

The RCA red base is a 5692 which requires less voltage. But it's good to hear VAC is ok with running all versions of the 6SN7.