Jaguar brand boutique top boost thing

[maxkracht]

I am planning to make some changes to this weird topboost preamp with a jtm45 power amp, "boutique" thing. The grounding scheme is awful, so redoing that, and its owner has had reliability problems that I hope to remedy. It currently has a couple 22k resistors branching off of the screen node and going to 16uf caps for the pre and PI tubes like in an old vox. Any benefit to doing this instead of the normal totem pole thing? Just slightly higher voltage at the pre? Would it change the feel too drastically to put the filters in series like just about every other amp and lower the dropping resistors a bit, or maybe even add another filter stage for the pre?

Lots of room for improvement in this thing regardless. The layout is weird and a lot of extra wire was just shoved under the board to make it look "neat". It will be quieter when I am finished...

[maxkracht]

Won't have it back on the bench for a couple days, so I don't remember exact numbers, but I do remember there was 460v on the plates. (Currently using 450v caps!) So, plenty of voltage to play with, unlike an original vox. I'm guessing adequate preamp voltage is the original purpose for the weird ac15/30 power supply? I'm sure the amp would be fine with the current setup, just seems like it could easily be better.

[maxkracht]

Started to dig in. I think there is over an inch of unneeded wire on every tube socket connection. Realised the mains were wired wrong and so many burned wires in here as well...

[maxkracht]

Lots of work, but the noisefloor is much lower and the amp should be safer/more reliable. Didn't notice before, but power tube grid stoppers were 47k. Not sure if that was intentional or not.. I lowered it a little bit, but the owner was happy with how the amp sounded so I didn't want to change too much. I also found it weird to have 1 ohm resistor between pins 1 and 8 on EL34s, guess it doesn't matter, but moved it anyway. Elevated heater, took out a lot of extra wire, shielded a few things, rotary brilliance control, cut control, some other little things. Kept the standby right after the rectifier, but added a bleed resistor/cap. Opted for 10k 10k series totem pole after the screen node instead of branching 22ks, preamp voltage is about the same and I didn't really notice a change to the feel. Turrents weren't the completely non-stick kind, but they were weirdly hard to solder, even with some degreasing. Not sure what that's about. Anyway, It's sounding better and I am happy with it. Looks busier, but easier to see what is going on...