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PostPosted: Wed Mar 28, 2018 11:02 am 
Bottle Rocket

Joined: Mon Jul 20, 2015 3:26 pm
Posts: 14
I have the above amp and want to swap in some of the preamp tubes I have to get the best ( for me) sound out of it. I have some basic questions on functions of the tubes. I am operating under the assumption that since 12ax7s have two sides, the A and B denote the sides and if the schematic says A&B that means the amp uses both sides for that function.

Per the owners manual :
V1 A&B - Ch 1 input stage
V2 A&B - Input stage for Ch 2
- 2nd gain stage for Ch 2
V3 A&B - Tone control Driver for Ch1 & Ch2
V4 A&B - driver/ phase inverter
V5A - Loop return stage
V5B - Reverb mixer
V6A - reverb return gain stage
V6B - Reverb Send stage

Question 1 ) If I am on channel 2 does the signal go thru channel 1 tube V1 then to ch 2 v2 tube, or is V1 or V2 only in play when on that channel?

Question 2) The amp has a pull pt on Ch 2 gain to add extra gain. When that is NOT pulled I am only using the A side of the V2 tube?

Question 3) Do all the preamp tubes add gain? For example does the V3 tone control add gain? Does the V5/V6 loop and reverb tubes add to the gain?

Thanks for any assistance! I have a handful of 12ax7's of different mfg and some older RCA 12ax7s and an AT7 to swap in and I'll let my ears decide, but knowing what each V position does could help me as I swap them around.

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