Any suggestions to reduce bass in Hot Rod Deville?

[Steve A.]

My friend picked up one of these amps (don't ask me why! LOL) and has tried about 8 different speakers in it. His main complaint is that the amp has way too much bass, even when he turns the bass control down to 0.

My thought on this was to reduce the value of the 0.022uF cap going into the phase inverter (to 0.01uF or even lower). And also maybe reduce the value of the Ck cap on the first stage to something like 2.2uF.

Any thoughts on this? I don't like to work on these fancy-schmancy modern PCB amps with channel switching, et al, and just want to take it apart once, do the mods and be done with it. I figure if we cut the bass too much he can always boost the bass control...

Thanks!

Steve Ahola

EDIT This is a Deluxe with one 12" speaker

[MWJB]

5751 in V1 and/or 12AT7 in V3.

If the 4x10" version - Rewire speakers at 2ohms in parallel and replace spkr & ext jack with a single 1/4" socket using the white 2ohm tap. Stock Emi's are a bit thick sounding.

Check plate current, these can be biased very hot & overly thick. Sovtek 5881, or EH6L6will skinny up the sound if you have thicker sounding tubes in?

Tone stack is plate fed rather than CF, a ton more gain, will always be a bit prone to woofiness.

If after this, still need to shed some bass then try the cathode bypass caps.