6G6-B Bassman Help

[Hardrock]

MLP brethren, I need some help. I have a blonde '63 Bassman I picked up on the bay a few years ago. Reportedly, the Bass channel tone-stack had been "re-voiced" professionally to better suit guitar. I do have the original blue molded caps that were swapped. Tranny's and choke appear original, as with all other signal caps/resistors. It does have newer Sprague Atom filter caps. No idea how old they are, but it has 2 Sylvania 5881's, and 4 JJ ecc83s's. I'm running this into a Mojo, 4x10 tweed cab (5F6-A cab minus the amp) with newer Jensen P10R's. Now that you know what I'm working with, here's my perplexion. The Bass channel is absolutely gnarly (think Black Crows). AND LOUD. Under 3 on the volume, and it's the most beautiful clean tone I've ever heard. Period. At 3 and above, well, playing in doors may deafen me eventually. However, the Normal channel is approximately half the (perceived anyway) volume. ~5-6 on the Normal channel is roughly the equivalent volume of 3 on the Bass channel. Is this normal? I know I have an extra pre-amp tube in the Bass channel, but do the later black tolex Bassman's respond the same way? Between the pages of Dave Hunter, Aspen Pittman, and you guys, I've learned a ton in the last few months since I discovered MLP, but I just can't wrap my mind around there being this a big of a difference in the volumes of the two channels. I don't suspect anything is wrong, I'm just hoping someone can explain this to me. And by the way, putting a 12AU7 in either V1, or the PI, seems to give little effect on headroom of the Bass channel, but it does on the Normal (was trying to drive the power tubes instead of the preamp tubes- curious if I could get a JTM-45 kind of tone out of it). Sorry for the novel, but I appreciate any and all comments.

[rocknhorse1]

Not sure about the other questions, but regarding the 12AU7 in the PI or V1 to "drive the power tubes harder" A 12AX7 will be the tube to drive the power tubes the hardest. It has a gain factor of 100, compared to the gain factor of 19 of a 12AU7, and a gain of 60 of a 12AT7. Here is a link. Guitar amp tweak - change the gain factor of your pre-amp

The 12AT7 is a great tube for a driver, but not for tone. Therefor, using it as a PI tube is a good choice. It will however lower the gain of the amp. It DOES have a higher current output, as well as a higher transductance than a 12AX7, but this would really only effect the touch sensitivity of the amp, as well as giving a tighter gain with less "swirl". If you want to drive your power tubes as hard as you can 12AX7 is the tube to use. I know it said out on the web that a 12AT7 will allow you to drive the output section harder, but this is a myth. Here is another link https://www.kcanostubes.com/content/faqs
scroll to the bottom and read the last question and answer.

[Hardrock]

Thanks rocknhorse. So I obviously had a mis-preconceived notion about what I was actually doing. I really thought that by using the U7 to lower the gain of the signal going to the power tubes, then that would allow me to get more drive from the power tubes, obviously with increasing volume. Guess my theory was wrong in this experiment.

I've never spent any time with other 2 channel BF amps (DR, SR, VR, etc.), so I'm still curious if there's this big of a difference in volume/response on these other amps. Though if I remember right, none of the other amps have an extra dedicated gain stage like this Bassman does. I'm thinking the extra tube or tubes are used to drive the trem/vib or reverb.

Appreciate the comments and links! Thanks