FENDER BLUES JUNIOR III MODS MOD GURU AND
FENDER BLUES JUNIOR III MODS HOW TO CHANGE THE

Fender Blues Junior Iii Mods Mod Guru And

Some of you may already be aware that Bill, one of the editors & columnists for PC Magazine, is also a major guitar & amps mod guru and pretty much the 'world's foremost authority' on Fender Blues Junior amp mods. These are all covered on Bill Machrone's website. I've been planning on doing some mods to my Blues Junior for several months, and finally got around to knocking 'em off last night. It's an all Valve Amp with the exception of the Reverb which is 'Op-Amp' (Chip) Driven, using an Accutronics (V2) -or- Belton (V3) 'Short. Great Build Quality with a wide choice of Speakers and Cabinet Finish/Colours. Now 'Made in Mexico', this is a VERY Popular 15w Fender Combo Amp and I have Modified Hundreds of them.

Fender Blues Junior Iii Mods How To Change The

Some find the 'sparkle mod' to be brittle and ice picky. III you'll have Fender's 'sparkle mod'. First, the tools you need:Reverse 'Sparkle Mod' - If you have a Blues Jr. Once you have decided on the speaker you want as a replacement, this is how to change the speaker out. How to change the speaker in Fender Blue Junior III. If an amp or guitar or whatever you messing around with does what you want and sounds like you prefer.Compatibility: I make sure each of the speaker I recommend can fit into the cabinet of the Blues Junior well without too much modding needed.

The mod involves nothing more than soldering a small jumper across two of the contacts of the pot. Twin Stack mod - This is just absurdly simple, and extends the range of the amp's Middle control pot to mimic the way it works in a b/f Twin Reverb. Here's a nutshell description of each:

I ran into some of that, though not enough to cause a problem. This gets rid of much of that perceived boxy character and gives a fuller, more open sounding amp.The one complication here is that the solder pads on the Blues Jr board are quite flimsy, and you have to be very careful that they don't crinkle/lift while desoldering the original caps. The effect is to bring up the bass and lower mids in better balance with the upper mids and highs, which the stock amp accentuates. Tone Stack mod - Just slightly more difficult than the prior mod, this one involves replacing two caps in the tone stack with ones of different ratings.

However, since most of us buy matched pairs of output tubes anyway, the ability to independently adjust the two tubes' bias seemed like overkill to me. This involves two trimpots and requires that several new holes be drilled in the amp's circuit board. 'Easy' Adjustable Bias mod - Bill lists a more involved adjustable bias mod on his site, which allows you to independently set the bias of the two EL84 power tubes.

Tonight, I'll crank it up and see how it sounds at volume-maybe even record a clip!Here's a photo showing the three installed mods:I also ordered a HUGE cap for power supply stiffening mod, but I didn't have the guts (or time) to drill 2 holes in my PCB. With the Twin tone stack mod, I can completely silence the amp now by turning down the three tone pots all the way, just like the Twin Reverb works. Piece of cake! You just need to be verycareful, since you're measuring voltage points in excess of 330V DC with a DMM inside the chassis.I finished up the mods and got the amp back together too late to test except at very low volume, but everything appears to be working perfectly.

Very easy installation.Last edited by duhvoodooman October 1st, 2010 at 09:53 AM. I slid some green heat-shrink tubing onto the new cap leads for insulation, and fastened the cap body to the PCB with a big ol' glob of hot glue, so it wouldn't rattle. The two caps sit side by side, and I just bent the leads of the new cap over, hooked them around the leads of the original 47 uf cap, and soldered them there. The way I installed it, no board drilling was required.