Fender Blues Junior Modifications
$ 99.95
Take your Blues Jr from good to boutique. These Fromel mods unlock clean, sparkling top end, a huge sweep of mids, and rich, tight bass — with smooth, articulate tube breakup and lusher, smoother reverb. Every tone-critical cap is upgraded with high-quality MOD Filter Caps and top shelf components chosen for tone, reliability, and an exact fit in your Blues Jr.
Most players with basic soldering skills can finish the mods in a couple of hours using our detailed, illustrated instructions.
Which version should I order?
- Supreme for USA — if your Blues Jr was made in the USA.
- Supreme for MIM — if your Blues Jr was made in Mexico.
- Recap — a filter & cathode cap refresh; the same kit fits either the USA or MIM version.
Not sure which you have? The build location is printed on the back panel of the amp — message us and we'll help you pick.
Note: the Standby switch kit and Mod reverb tank are sold separately and are not included in the Supreme kit.
“Just installed my mods. Easy to follow instructions. Good God! It brought my amp back to life. A 20-year-old amp has new life. Thanks Fromel Electronics.” — Lee, Blues Jr. USA
Everything the Supreme kit upgrades (full breakdown)
Tone Stack — Replaces the thin Bass and Mid caps with high-quality WIMA caps at corrected values to open up the tone and lose the boxy sound. Leads are pre-formed for a perfect fit. The Treble ceramic cap is swapped for a high-quality MLCC cap, shifting the mids up slightly so the amp sounds huge and warm instead of boxy and thin.
Twin Mod — Tightens the mids and cleans up a flabby bottom end. Lets you pull mids fully out for more flexibility. Done with a single short jumper wire for far better control of your tone.
Power Stiffening — Doubles the capacitance in the first filter stage to reduce hum and add reserve power for solid bass and strong picking — the extra torque to push through when you play hard. All filter caps are replaced with MOD Filter Caps and the bypass caps are audio grade.
Cooler Bias — Stock, the amp cooks its output tubes. This mod runs the amp cooler without sacrificing tone or drilling your PCB. A new bias resistor sets idle to about 8.5W, right where it should be, so your tubes live a long, happy life.
New Input Jack — The stock input jack is soldered straight to the circuit board, so tension on the plug can damage the board. This replaces the flimsy plastic jack with a high-quality jack on its own board.
Proper Lead Dress — Boutique amps twist and route their internal wires to minimize noise and oscillation; the Blues Jr just zip-ties them together. Clear instructions walk you through dressing the leads for lower noise and better stability.
Reverb & Tone Mod (older Blues Jr's) — Amps made before 2001 have a harsh reverb; this converts it to the newer, lush classic-Fender voicing. On the oldest units (pre-1996) the tone mod also brightens things up and adds clean headroom.
Reverse “Sparkle Mod” — Blues Jr. III amps ship with Fender's “sparkle mod,” which some find brittle and ice-picky. We include the part and instructions to reverse it, taking a III back to a series-II MIM voicing.
The other kits explained (Recap, Standby, Footswitch, Reverb Tank)
Recap Kit — Replaces all power-filter and cathode-bypass caps with high-quality MOD Filter Caps and top shelf components. USA-made Blues Jr's are all due for new filter caps, and many current MIM units have leaky ones. This kit resolves both.
Standby Switch Kit — Swaps your power switch for one with a middle standby position. Very easy, no soldering required. (International amps not supported.)
Reverb Footswitch Mod Kit — Converts the rear footswitch jack (which normally toggles the FAT circuit) into reverb on/off. Includes full-color instructions, the wire for the USA version, and a new Fender-brand footswitch.
Mod Reverb Tank — Replaces a weak reverb tank with a Mod tank for richer, fatter reverb. A great upgrade if you have a Belton tank or simply want more than the stock Accutronics.
Prefer we do it for you?
“Have us install” covers parts and labor. We bill return shipping on completion (comparable to what you paid to ship it in); you can estimate USPS Parcel Select rates here by the zones between you and us in the Pacific Northwest. Info on sending your amp in →
Install instructions
Made-in-Mexico guide · Made-in-USA guide
Hear it
“I really appreciate what your mods have done. It's a quieter amp and the bottom end is so much more useful… I'm absolutely in love with the tone of my Strat through this. So damn natural and earthy! I'm a very happy customer!” — Mike P, Supreme mod & Tube Board
Safety & warranty
Warning: These modifications WILL void your amplifier's warranty. Amps carry deadly voltages even when unplugged — follow the instructions carefully. If you're at all unsure of your ability to perform them, stop and have a professional do it, or send your amp to us.
No warranty: This kit and its instructions come with no warranty of any kind. Modifications are done at your own risk and you agree to hold the seller harmless against any and all claims. Tube amplifiers contain parts that operate at very high temperatures and deadly voltages; if you are not sure of your abilities, do not perform these mods.
All orders are processed within three business days. International shipments may be delayed up to six weeks depending on customs.
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