Mods for normal channel fender to use with archtop jazz?

[sidehatch]

I have decided to go a different route with the normal channel of my pro reverb.

Instead of more gain I'd like to turn it into an archtop jzz guitar killer.

I'd like less bass,cleaner more hifi -think pat metheny.

Anyone have any ideas on what to ask my tech to do?

Thanks

[Andy Le Blanc]

try a simple tube swap first..... use 12ay7 ..... its less gain a bit more like a
6sn7 in character.....

then to restrict bass...... theres typically a .047 cap after the second stage of
the normal ch. ....replace it with a smaller value cap say from .01 to .001
youll have to experiment a bit but its one value of one cap....

then I might look into recaping the signal chain with a better cap
like jensens oil and foil the aluminiums are affordable but theres a
wide selection of caps for hi fi out there check out /www.partsconnexion.com/
better caps means better detail.....

[El_Martin]

Hi sidehatch!

I'd reduce the cathode caps. Try 10 uF or 5 uF. Up the cathode resistors a bit. Try 1k8. Use slightly different values for first and second gain stage.
Sometimes a cut control in the power amplifier section is nice.
Reducing values of coupling caps after stages is also an option.
Insert attenuating serial resistances. Bridge w. small/medium caps.

Only change one component at a time. Take notes. Don't hesitate to switch back to original values...

Or just switch to another cab. Why not 2x10" for Jazz?

Ciao
Martin

[ic-racer]

Did you see this thread?

https://tubeamparchive.com/viewtopic.ph ... highlight=

[skeezbo]

Dumble preamps with the skyliner stack have great clean sounds. Try swapping out your .047 mid cap and replace it with a .01. This will give you an idea; if you hate it, swap back. If you like it (I did, but I was trying to get a jazz box sound out of my tele neck pickup) copy the rest one piece at a time until you get what you want.
Weber has a layout and schematic on his site for a kit amp I think he calls Halle that has a similar preamp; that is the one I used. The Dumble files here at ampgarage have the skyliner schematic too.

You'll probably need to at least swap in the smaller bypass caps and change your slope resistor to 150k to reduce bass and low mid, since that seems to be the sound you are looking for. The skyliner has a very interesting 250k mid pot, but you don't have a mid control to play with. If you need more mids you could increase the 6.8k on your bass pot to 10 or 15k or increase the size of your treble cap to 330 or 390p. Above 500p the mids flatten out too much, maybe.

I left my plate and cathode resistors alone, but you might experiment with those too; there has been a lot of discussion lately about what those changes add that might suggest an advantage if all you want is clean. I want to try it if I get a chance soon. If you do it, please report back!
I hope this helps,
Skeez