Mark 2B Preamp Tube Positions (Non Reverb)

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MK IIB
Mark III
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Joined: Tue Sep 20, 2011 11:15 am

Mark 2B Preamp Tube Positions (Non Reverb)

Post by MK IIB » Thu Feb 13, 2020 9:41 am

Hi Folks,
I'm looking for some definitive information on what preamp tubes perform what function in a non reverb amp.

I know that on the reverb model 2 tubes are being used for the lead channel.Half of V3 and half of V4 are for lead drive with the other 2 halfs of each tube being used for the reverb.

I can't seem to find definitive info on the tube layout for the standard (4 x 12ax7) non reverb amp.

I'm thinking that perhaps the V3 tube on the non reverb model is soley being used for the lead channel with V4 being the phase inverter?

I'm really looking to find what tube has most effect on the lead channel(I know V1 affects the whole amp Rythym/lead but for tube rolling purposes more drive etc)

On the reverb equipped amp it goes like this
V1a=Input amp
v1b=Tone control amp
V2a=Effects send
v2b=Output amp
v3a=Reverb return amp
v3b=1/2 lead drive amp
v4a=1/2 lead drive amp
v4b=Reverb Driver
v5=Phase inverter

Any help/info would be much appreciated.

Thanks.

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