This is how I transformed my Jet City JCA100 into a high-performance tone machine with SLO100 mods and power supply upgrades. This video dives deep into the modifications, including increasing power supply capacitance and upgrading rectifier diodes, resulting in improved tone and performance.
Upgrade Summary:
1. Increased filter capacitors to match the Soldano SLO100 specs, improving ripple filtering, tightening bass response, and reducing noise.
2. Replaced stock rectifier diodes (1N4007) with UF5408 ultrafast diodes for quieter operation, reduced switching noise, and improved reliability.
3. Achieved modern tonal clarity with tweaks like 'Marshallizing' V1B, balancing feedback resistors, and optimizing transient handling.
What These Changes Achieve:
1. Improved Ripple Filtering: Larger capacitors clean up unwanted hum and noise, especially at idle or low volumes.
2. Enhanced Dynamic Response: With more energy stored, the amp delivers tighter bass and a punchier, controlled tone, perfect for aggressive playing styles.
3. Reduced Power Supply Sag: Increased stability under load creates a more immediate, responsive feel, ideal for modern high-gain tones.
4. Increased Headroom: A stable power supply ensures consistent performance at higher volumes with greater clarity and definition.
5. Quieter Operation: Upgraded diodes and capacitors reduce high-frequency noise and improve the overall noise floor of the amp.
These modifications align the JCA100's power section with the SLO100’s legendary design, resulting in a cleaner, tighter, and punchier amplifier. Whether you're a gear geek, a guitarist exploring amp repairs, or a modding enthusiast, this video offers insights to elevate your own Jet City to the next level.
Chapters / Time stamps:
00:00 - Intro
00:39 - What I did
00:57 - The standard SLO100 Mod
01:44 - Power Section mod
02:41 - Understand what you're doing
03:49 - SLO v JCA Power Supply Filter Caps
08:05 - Good outcome but it was missing top end bite
08:51 - Gut Shots
16:40 - 'Marshallising' V1B to get the bite
19:09 - What I learned, the outcome
23:16 - A very short tone demo - more to come later!
Videos you should check out when doing this mod. Subscribe to all of these if you haven't already:
📽️ Rubber Duck Tech: https://youtu.be/LC4DRfiM20o?si=7dI_O1ThbyYjdKy0
📽️ Ricky's videos: https://youtu.be/qVCIcfiD61k?si=bc1Glji4f9BOaDZa and https://youtu.be/OdgOIKDKV6I?si=0tFiefvc4oJsgDhf
📽️ Headfirst's different take on mods: https://youtu.be/zJl_t0LsLmw?si=Q9-l9l1NP533-KMw
Full Signal Path:
၊၊||၊ Guitar: PRS Tremonti
၊၊||၊ Drive Pedals (if any): Fractal FM9 (none were active in this video)
၊၊||၊ Noise Management: Morley Hum Eliminator
၊၊||၊ Amp Switching: Radial Headbone VT
၊၊||၊ Amplifier: Jet City JCA100H
၊၊||၊ Attenuation, Dry Guitar tone & Effects Loop Management: Boss Waza Tube Amp Expander
🎙 Mics - SM57 (left, Zilla), MD421HN (Boogie cab, Centre/Dry), e906 (right, Jet City Cab).
🕪 Speakers - All EVM12L from 1988 or 1992.
Signal Flow:
🔊 Amp Setup:
Boss TAE FX Loop Send → Fractal FM9 (wet effects and dry signal processed via out 1 (wet) and out 2 (dry))
🔊 Wet Effects Routing:
Fractal FM9 Output 1 (L/R, stereo) → Seymour Duncan Powerstage 700 → Zilla SFB & JCA 2x12 Cabinets (100% Wet)
🔊 Dry Signal Return:
Fractal FM9 Output 2 (Centre, dry) Boss TAE FX Return → Boss TAE Speaker Out → Mesa Boogie (100% Dry)