D08 "Kenshiro" bass guitar amplifier is my latest amplifier. It's built on top of the reliable TDA2050 audio amplifier chip.
This project started, like many of mine, from a forgotten piece of consumer audio gear, this time, an old Trust PC subwoofer. A basic, cubic box made of MDF, plastic front panel, and a surprisingly decent speaker inside.
Once I pulled it apart and confirmed the speaker still worked, I gutted the electronics and got to work turning it into something special. The case was dull, so I gave it a complete makeover: decoupage artwork featuring Kenshiro himself. It felt only fitting to name the amp after him.
This amp runs on a single +30V power rail for the power stage and a separate +9V line for the preamp.
At the heart of the power stage is the tried-and-true TDA2050, delivering solid output for small gigs or home practice. It’s simple, tough, and very effective when paired with the speaker I'm using. The final stage it's based upon the Fender Rumble 15 schematic with some modifications.
The preamp section is based on the classic J. Tillman Discrete FET Guitar Preamp(http://www.till.com/articles/GuitarPreamp/), using a J201 JFET for that sweet, tube-like response. There's another J201 stage after the tone stack to recover some lost gain and push the signal forward with character.
Tone shaping is simple. I've included a Low and High control.
Then I've added a distortion switch that activates a pair of 1N914 diodes for symmetrical clipping. Combined with a gain-boosting cap, this adds a touch of grit and aggression to the sound. Not too much, just enough to growl without getting muddy.
The control panel is mounted on the back, I kept things simple: just a wooden panel with cutouts for the power input and a handle.
The sound is tight and responsive. The distortion is very usable, great for vintage vibes or even light fuzz. Volume is not very high, but this is a practice or studio amplifier, not a live one. It won’t fill a stadium, but for home practice or small rehearsals, Kenshiro delivers more than enough fury.
Notes
- read risk disclaimer
- excuse my bad english