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Inside Fender's Excelsior

Figaro

Silver Supporting Member
Messages
12,492
BillM, Do you have your tone control mod for the Excelsior available for sale yet?
 

Billm

Member
Messages
574
I have a new version of it installed in my amp, but it's too woofy. I need to use a smaller cap. Working on it when I can fit it between all the Blues Juniors.
 

Billm

Member
Messages
574
OK, I whipped up a different version of the control. Less woofy when you turn it all the way down, but it feels kind of midrangey. If I get a chance tomorrow, I'll record both and put 'em out there for comment. It has a pull-up bypass, so you get the raw tone of the amp. Gotta say, the raw tone is pretty midrangey, too.

These experiments certainly show the limitations of a single-knob control and only two gain stages. There's no opportunity to re-amplify the losses your get from a two- or three-knob tone stack. Then again, the Excelsior was designed to be a funky amp, and it remains a funky amp pretty much no matter what you do to it.
 

Figaro

Silver Supporting Member
Messages
12,492
I prefer the 2nd version. It's more effective both ways. I assume the 2nd version can get all the tones of the 1st version and more?
 

guitarrhinoceros

Senior Member
Messages
2,557
I modded my Excelsior for faster tremolo. There were some songs that just didn't "play right" when you incorporate the tremolo beat into the tempo. It's an easy mod if you do it quick and dirty, and not much more difficult if you do it "right."

The speed pot is bounded by two 100K resistors, R21 and R37. If you make these resistors smaller, it will increase the maximum tremolo speed without affecting the minimum speed. You can do an easy top-of-board mod by soldering another 100K resistor across the leads of R21 and R37. Two 100K resistors in parallel gives you 50K, and lets the circuit oscillate faster.

The maximum speed, according to my meter, goes from 5.3Hz to 6.4Hz. That doesn’t sound like a lot, but it’s a 20 percent increase. Using 82K resistors (effectively 45K) only gets you to 6.5Hz. I have 82K resistors soldered into mine, and I’ll probably leave it that way.

Note that if you go too low or try to run without resistors, the tremolo circuit may not oscillate. It’s fussy.

Wow.
 

Stonebandit

Member
Messages
1,773
Nice work there Billm.
I may well have to repurchase the Fender Excelsior. I think with the mods and a tube change, it would be close to a prefect vintage sound.
 

IM4Tone

Member
Messages
3,773
I too prefer the 2nd version. However, depending on the complexity of installation and cost, I don't see enough difference vs. the original 'pot replacing switch mod.' to necessarily want to do it. If I were starting with a new stock amp, probably would want version 2.
 

Billm

Member
Messages
574
This morning I tried changing the coupling caps that drive the 6V6s from the phase inverter. The stock caps are .01uF, and I've never seen a value that small driving 6V6s. I kludged in some .1uF Orange Drops and recorded it both ways. Unfortunately, the camcorder mic totally misses the change in tone. It's not earthshaking, just a little deeper, a little more articulate. When you get to distortion level, the larger caps drive the 6V6s a little harder and the breakup sounds nicer to my ear.
 

THiwaTT

Member
Messages
1,887
Not to derail the thread too much - Billm any plans for a Fender Greta Mod?
I have one that I adore and would love to see what you can do with one
 

Billm

Member
Messages
574
I've never seen and never played a Greta. It doesn't seem to have grabbed people the way the Excelsior has.
 

Billm

Member
Messages
574
I finally came up with a tone control that sounds good and is easy to install. Nothing to clip, just two joints to solder. Pulling up on the control bypasses it completely and gives you the amp's raw tone.

The brown vintage-style Fender knob works for me; the difference in color isn't as great as it seems here:



As you can see, you can turn the upper chassis around and mount it, so the amp is easy to work on when modding. That Orange Drop peeking out is an experimental larger coupling cap from the phase inverter. It didn't make much difference.
 

i8guitar

yelling at clouds from outer space
Gold Supporting Member
Messages
627
Thanks for posting that Billm. I've been thinking about that tone control mod, but have been ok with setting the setting the switch halfway between bright and dark, using the stock speaker. We'll see if installing the Weber Vintage Chicago 15" will change my mind.
 

blake480

Silver Supporting Member
Messages
255
I finally came up with a tone control that sounds good and is easy to install. Nothing to clip, just two joints to solder. Pulling up on the control bypasses it completely and gives you the amp's raw tone.

The brown vintage-style Fender knob works for me; the difference in color isn't as great as it seems here:



As you can see, you can turn the upper chassis around and mount it, so the amp is easy to work on when modding. That Orange Drop peeking out is an experimental larger coupling cap from the phase inverter. It didn't make much difference.
Just installed this mod yesterday on my amp. IT IS A MUST HAVE. Totally take the Excelsior to the next level. Especially with the pull up and raw tone. Seriously love it. Worth every penny.
 

imguitardan

Member
Messages
3,916
Looks like Billm isn't making the part now as he's on the mend. Any ide the specs? I'd like to throw one together (unless Bill's ready to build them again).
 

hacinador

Member
Messages
768
It is sad that chinese cheap amp has much better built quality compared to american made 1000 USD Fender amp...
 

Gary Ladd

Member
Messages
1,525
Bought the tone v2 kit today, it appears Bill's son has continued his legacy :aok

I'll be back with a review, once I get the kit and install it...

:wave
 




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