Fender Pro Junior Modifications
$ 99.95
A good little amp becomes a great one. The Fender Pro Jr is a terrific value and already sounds good — the Fromel Supreme kit makes it more reliable, quieter, and far better sounding. For a total tonal transformation it replaces every cap and resistor in the signal path: WIMA caps for larger values, MLCC caps for smaller ones, and 1% ½-watt metal-film resistors for low noise and precision.
Which option should I order?
- Supreme — the full tonal transformation (tone stack, power stiffening, cooler bias, input-jack module, lead dress). Start here.
- Recap — refreshes all the electrolytic caps with high-quality MOD Filter Caps and top shelf components to keep a tired amp running clean.
- Standby switch — adds a standby position for gentler startup and tube life.
- Have us install — send us your amp and we'll do the whole job (parts + labor).
Most players with basic soldering skills can finish the mods in a couple of hours using our detailed instructions.
Everything the Supreme kit upgrades (full breakdown)
Tone Stack — Replaces the thin Bass and Mid caps with high-quality caps at corrected values to open up the tone and lose the boxy sound. The Treble ceramic cap is swapped for an MLCC, nudging the mids up slightly so the amp sounds huge and warm instead of boxy and thin.
Power Stiffening — Doubles the capacitance in the first filter stage to cut hum and add reserve power for solid bass and strong picking — the extra torque to push through when you dig in.
Cooler Bias — Stock, the amp cooks its output tubes. This runs it cooler without sacrificing tone or drilling your PCB. A new bias resistor sets idle to about 8.5W, right where it should be, for longer tube life.
Input Jack Module — The stock input jack is soldered straight to the circuit board, where plug tension can damage it. This replaces it with a high-quality enclosed jack on its own board, not soldered to the main PCB.
Proper Lead Dress — Clear instructions for twisting and routing the internal wiring the way boutique amps do, for lower noise and less oscillation.
Electrolytic Cap Upgrade — Replaces all the filter/cathode caps with new, upgraded MOD Filter Caps and top shelf components. USA-made Pro Jr's are due for new filter caps, and many current Mexico-made units have leaky ones — this resolves both.
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); estimate USPS Parcel Select rates here by the zones between you and our Pacific Northwest shop. Info on sending your amp in →
Hear it
Safety, warranty & shipping
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, 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.
Available for international shipping; shipments (especially to the EU) can take up to four weeks due to customs.
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