Blues Junior Modification and Comparison

Blues JuniorI’ve been using Fender Blues Junior amps (I have two of them) since about 2007. I’ve never had any problems with them but decided that after seven years of use on the original tubes it might be a good idea to have them looked at. I’d also heard a lot of great things about the Eminence 12″ Cannabis Rex as a replacement speaker for the Blues Junior, so decided to pick one up and have it installed in one amp while the amp was in the shop.

I asked Athens area guitar and amp tech Jon Fluharty* to do the work for me. He tested the tubes and found out that all of the preamp tubes were pretty well shot and the power tubes were severely mismatched. I’m not at all knowledgeable when it comes to tubes so I went with Jon’s recommendations that he said would give me a bit more more headroom and better clarity. The tubes installed are as follows: V1 JJ 5751, V2 Sovtek 12AX7WC, V3 Sovtek 12AX7WC Balanced, and V4/V5 Sovtek EL84M. Jon also biased the amp and then took care of breaking in the new speaker by hooking it up to an old Jeff Beck recording and just letting it play for a good 40 hours. Who else would you rather break in your speakers?

There are a ton of mods out there for the Blues Juniors, and although I didn’t ask for this, Jon went ahead and made a couple of tone stack modifications. In the stock amp, it is impossible to completely attenuate the mid frequencies. Jon corrected this so that the mids can be turned down completely if desired. He also beefed up the response on the bass knob. Where once the bass was anemic and made little difference below a setting of about 8, it now has a huge bass response and with lot more even control.

Since I now have both a stock amp and the newly modified one sitting next to each other, I attempted to create a video to demo the differences. Please note that the camera’s internal microphone did not do a very good job of picking up just how much difference there is in the the low-end response and the noticeable volume boost the modded amp has. I don’t know if the changes would be everyone’s cup of tea and some might even suggest that I should have bought a different amp in the first place, but I’m extremely pleased with the result of the updates and mods and look forward to upgrading the other amp sometime soon.

*Jon Fluharty does not currently have a website but if you are interested in contacting him please leave a note in the comments or email me via the Contact John page and I’ll put you in touch!

5 thoughts to “Blues Junior Modification and Comparison”

  1. Very nice I wonder what he could do for my super reverb amp? You can really hear the difference. Great demo!!!!

  2. Hi John, i saw your video of the modified fender blues junior and i am very interested. The problem is i live in Italy, do you think that Jon Fluharty could sell a kit with the modified parts?
    Please let me know.
    Thanks a lot.
    Gianluigi Rossi

  3. Hello, Is there a way to purchase the parts to do the two tone stack mods yourself? If so, what parts? Sounds sweet! Thanks for the information and video.

  4. Unfortunately, the tech that did the mods for me no longer works in the music industry. (He has a real job now.) You might check at for similar items but it sounds like the guy who ran that site is dealing with very serious health issues and may not be available either. If there are techs in your area who work on fender tube amps they should be able to help you. Good luck and sorry I can’t be of more help.

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