2. amps-preamps
  3. 1299262706

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
magnumpi205
504 posts
 
Roger from Music Reference is Roger from Ramlabs. Seems like the right person to call.
clio09
2,978 posts
 
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.
gmuffley
132 posts
 
Jim McShane can offer matched, low-noise tubes at a very attractive cost.
mt10425
1,138 posts
 
I'm very happy with the 12ax7 tubes I just got from Jim McShane.
pubul57
3,712 posts
 
The tubes are not special, the way they are measured and matched by Roger is, and they happen to be very good tubes, the Eis that is. That being said, I suspect you would do fine with a set of tubes matched by Jim McShane, or Andy at Vintage Tube Services for NOS. I stick with Roger's tubes because nobody matches better, and he voiced the amp around his tube - keeps tube neurosis from setting in:)
More to discover