Help adding bass to Harvard 5F10

[mort]

Ah! I'm thinking of the Bronco.

Harvard/Bronco ... Just got a couple of oddballs confused.

It's actually Harvard/Tweed Vibrolux. Exact same circuit but the vibrolux adds a triode to run the vibe. Otherwise it's verbatim.

[Chuck H]

My mistake was which oddball was the Vibro Champ. The Bronco was a Vibro Champ.

[mort]

I just remember that one because I built a Harvard and then later was looking at the Vibrolux and thought hey I've seen this exact circuit before lol

[E biddy]

On my 5f10 build, I added a 1M resistor to ground on input 1, so it is more like the standard Fender input circuit. When I did this, it tamed some of the harshness from before I did this.

[CraigB]

Interesting question because so many factors affect tone.
Is this the amp you have? https://el34world.com/charts/Schemat...5f10_schem.pdf
With mods of pot replacing fixed 56k bias resistor
.047 cap replacing .02 coupling cap on V1
switch on 56k negative feedback resistor
Eminence Patriot ? speaker
anything else?
I have built some tweeds but never that one. Are you sure it is properly built? No reversed caps or wrong resistors?
The original circuit has some places that you could mod. The lack of a 1 meg resistor to ground on the input is the first thing I noticed. The Harvard also has limited preamp gain because there is no 22uf cathode bypass cap on the second stage. But before changing a classic circuit, I would do more speaker research. I have used three Eminence Patriot 10 speakers. The Ragin Cagun had good bass but very bright top end. The Copperhead had good bass and a bright top end. The Cannabis Rex had good bass and a smooth top end. None had the raunchy speaker distortion that I love in a tweed amp with a Weber alnico speaker.
Have fun.
--Craig