FDP Home Page / FDP Forum / FAQ's

The FDP is made possible by the following companies and individual members like you.
Please use the links below to show them we value their sponsorship.

Apex Tube Matching

Antique Electronics Supply

Jensen Loudspeakers


Yellowjackets Tube Converters

Amplified Parts

WD Music


* God bless America and our men and women in uniform *

* Illegitimi non carborundum! *

If you benefit and learn from the FDP and enjoy our site, please help support us and become a Contributing Member or make a Donation today! The FDP counts on YOU to help keep the site going with an annual contribution. It's quick and easy with PayPal. Please do it TODAY!

Chris Greene, Host & Founder



Find musicians
in your area!
  Search the Forums  

FDP Forum / Amp Mods, Repairs, and Projects / Blues Junior Mods...



Sep 26th, 2017 05:09 PM   Edit   Profile  

Hi folks, new to the forums and to fender amps.

But I'd like to share a few Blues Junior Mods that are not widely publicized...we all know of the BillM mods...Hopefully some of you tweakers find these useful.

1st: the Fat switch. This engages a .22uf cathode bypass capacitor. Want more low end? Solder a .47uf cap in parallel on top of it..or replace it with a .68uf. Heck you could even make it switchable if so inclined.

2nd: Negative feedback. Want more low-end yet? Increase the negative feedback resistance. What I did was snip that purple wire from the output transformer and put a 100k pot in series with it. I can go from stock to lots more low-end..I mounted it on the steel plate that kinda protects the tubes so it's hidden and out of the way.

3rd: A second speaker jack. I don't a foot-switch for my "fat" switch...its just always on. So I disconnected the wires to it (red, white, & green). The red and white must be connected together for the face plate button to work and the green left disconnected. Then I jumpered from the existing speaker out jack to the former foot-switch jack. One could have just as easily drilled a second hole and installed a jack...but I didn't.

My other mods included a bias pot.
I snipped out the 33k (R37) and installed a 10k resistor to a 50k pot in it's place (the resistor prevents a ZERO ohm situation).

And since I started with the base model, I went with a Warehouse Guitar Speaker, the 55hZ Reaper.
I like it much better than the Eminence Lightning bolt. The Celestion 70/80 wasn't bad (its one I had on hand to try). The Reaper gives a nice warm tone and remains clear.

I did replace the EL84 Sovtek (Groove Tubes) with Tung Sols and put a JJECC802 (12AU7) in V1 to lower the gain (this allows me more adjustment in volume in both the pre and post amp areas) and replaced the V2 & V3 with Sovtek LPS 12AX7s.
The JJ5751 didn't lower it quite enough. I need to acquire a 12AT7 or 12AY7 for V1...I think that might be just right.
Clearly this make getting distortion more difficult, so unless you are a pedal user for drive/distortion, you may not want to decrease the V1 gain.

Contributing Member

Boston Area

Sep 30th, 2017 09:58 PM   Edit   Profile  

I miss BillM...

Contributing Member

Whitehorse Canada

I don't get out much
Oct 1st, 2017 05:51 AM   Edit   Profile  

Me too.

FDP Forum / Amp Mods, Repairs, and Projects / Blues Junior Mods...

Reply to this Topic
Display my email address             Lost your password?
Your Message:
Link Address (URL):
Link Title:

Moderators: Chris Greene  Iron Man  reverendrob  

FDP, LLC Privacy Policy: Your real name, username, and email
are held in confidence and not disclosed to any third parties, sold, or
used for anything other than FDP Forum registration unless you specifically authorize disclosure.

Internet Application Development

Copyright © 1999-2019 Fender Discussion Page, LLC   All Rights Reserved