Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: jukelemon on March 09, 2015, 02:13:01 pm

Title: Fender Excelsior-getting more depth in Tremolo
Post by: jukelemon on March 09, 2015, 02:13:01 pm

Hi all.

I am hoping you all can help.

I just picked up an Excelsior. Tone knob has been added already. New speaker. Tubes.

It is really a nice amp for the money.

My question is about the Trem.  It is a nice Trem but the depth is set and I would like to have more in the signal when it is turned on.

Schem attached.

I am thinking that R15 could be changed to a smaller value in order to increase the signal?

Am I off on that idea?

Thanks all.

Title: Re: Fender Excelsior-getting more depth in Tremolo
Post by: tubenit on March 09, 2015, 03:13:56 pm

There is quite a bit of information about tremolo mods in ARCHIVES.  Maybe something there would be useful to you?

http://el34world.com/Forum/index.php?topic=604.0 (http://el34world.com/Forum/index.php?topic=604.0)

With respect, Tubenit

Title: Re: Fender Excelsior-getting more depth in Tremolo
Post by: octal on March 09, 2015, 03:15:48 pm

Seems like reducing R15 should work.  The bias modulation of the trem signal is basically divided in half by the two 470K resistors going to the oscillator versus the 470K resistors going from the output tubes grids to ground.   Try it and see!

Title: Re: Fender Excelsior-getting more depth in Tremolo
Post by: jukelemon on March 09, 2015, 03:31:45 pm

Quote from: tubenit on March 09, 2015, 03:13:56 pm

There is quite a bit of information about tremolo mods in ARCHIVES.  Maybe something there would be useful to you?

http://el34world.com/Forum/index.php?topic=604.0 (http://el34world.com/Forum/index.php?topic=604.0)

With respect, Tubenit

Thanks.

I cannot find a similar Trem circuit to even compare. The archives seems to focus on trem circuits that are traditional.  This uses an IR in the circuit.

Title: Re: Fender Excelsior-getting more depth in Tremolo
Post by: octal on March 09, 2015, 04:26:41 pm

The mosfet at the output of the trem circuit is like a cathode follower tube stage. Just try reducing R15!

Title: Re: Fender Excelsior-getting more depth in Tremolo
Post by: jukelemon on March 09, 2015, 06:27:00 pm

Quote from: octal on March 09, 2015, 04:26:41 pm

The mosfet at the output of the trem circuit is like a cathode follower tube stage. Just try reducing R15!

Good deal.

Thank you sir

Title: Re: Fender Excelsior-getting more depth in Tremolo
Post by: jukelemon on March 12, 2015, 02:53:41 pm

I wired in a 1m pot in place of C15 and Bam!  I get a full range of just a smidge to deep deep swamp.

Thanks all.  Well worth the change.