12AX7 tubes for Music Reference RM-10


I looking to replace the 12AX7 tubes in RM-10 amp. Looking at the manual it says something about "V1" being grade AB and "V2" being BA. Below is a quote from them:
" Note that V1 is a RAM grade AB (section 1 selected for low noise) and V2 is grade BA (section 2 low noise). It is essential to have a grade A section as the first amplifier to achieve the very low noise of which the RM-10 is capable."
The question is: do I need some type of special 12AX7 tube? Do they have to be matched? Balanced? etc...
Any feedback will be greatly appreciated, thanks in adavance to everyone.
jmcp60

Showing 1 response by clio09

Yes they have to be matched. The plates should be matched between the tubes in the method specified by RAM, AB for V1 and BA for B2, meaning the outer plates of each tube and the inner plates of each tube.

Best to get the tubes from Roger. I use the stock tubes as supplied by RAM and they are very quiet. The sound is also more than acceptable. I believe Roger can supply some nice Sylvania NOS 12AX7 tubes in addition to the stock Yugo tubes.