Hi Jon; the pin #s in my mistake ... was wrongly thinking the tweed ran on 12AX7s and the crest 6EU7s forgetting that both models use 6EU7s ... whose pins 4 and 9 are cathodes.
In B'rer Rabbit, the tigers (amp owners) ran around the (Gibson schematics) tree until they turned in maple syrup ... let's not do that but instead ... let's review the bidding.
In the tweed schematic I have, the only " ... 2.7K resistor, but with a .02uF cap ... " is on V3A ... the other half ... V3B ... at least on the schematic, isn't shown. Go you Gibson engineers ... :evil: V3 in the tweed model is a voltage amp downstream of the vol/tone controls.
In the crest schematic I have (with the tube ID #s reading from R to L), V3 ... the 6C4 .. a single triode ... is just ahead of the reverb transformer and can ... the reverb driver. V2A ... just for distinction, is the reverb recovery section amplifying the verbed signal and returning it to the line.
V2B (with its 4.7K R / .1uf C) does what V3A did - act as a voltage amp downstream of the controls and it mixes the wet and dry signals ahead of the phase inverter. I'm not engineer enough to understand why one R/C combination is 'better' than the other. It may also be one of those itty bitty changes that somebody made because they thought it would sound better ... it being that the market was heading towards the cleaner, brighter sound of 7591s/EL84s ... who knows.
My now-gone tweed Gibson GA19RVT w/ Weber 12A125 speaker:
Congratulations on your back-dating the amp ... maybe a little darker with slightly earlier breakup ... a little more compression in the mids ... pretty much the signature of all the Gibson 6V6 amps ... a sweet, golden, crunchy-brown tone.
In B'rer Rabbit, the tigers (amp owners) ran around the (Gibson schematics) tree until they turned in maple syrup ... let's not do that but instead ... let's review the bidding.
In the tweed schematic I have, the only " ... 2.7K resistor, but with a .02uF cap ... " is on V3A ... the other half ... V3B ... at least on the schematic, isn't shown. Go you Gibson engineers ... :evil: V3 in the tweed model is a voltage amp downstream of the vol/tone controls.
In the crest schematic I have (with the tube ID #s reading from R to L), V3 ... the 6C4 .. a single triode ... is just ahead of the reverb transformer and can ... the reverb driver. V2A ... just for distinction, is the reverb recovery section amplifying the verbed signal and returning it to the line.
V2B (with its 4.7K R / .1uf C) does what V3A did - act as a voltage amp downstream of the controls and it mixes the wet and dry signals ahead of the phase inverter. I'm not engineer enough to understand why one R/C combination is 'better' than the other. It may also be one of those itty bitty changes that somebody made because they thought it would sound better ... it being that the market was heading towards the cleaner, brighter sound of 7591s/EL84s ... who knows.
My now-gone tweed Gibson GA19RVT w/ Weber 12A125 speaker:
Congratulations on your back-dating the amp ... maybe a little darker with slightly earlier breakup ... a little more compression in the mids ... pretty much the signature of all the Gibson 6V6 amps ... a sweet, golden, crunchy-brown tone.