JCA Circuits Inferno “Hi Power” Amplifier (Circa 2010)
Inferno utilizes concepts I originally uncovered while designing/building the Purpleheart amp throughout the 1990’s. Inferno was conceived to be the ultimate fixed bias, interchangeable output tube head. Inferno also includes concepts from the GR 1.6 preamp with the The Hi/Lo Tilt & Lean/Plush controls. These controls are proprietary and unique circuits I designed to work within the preamp/EQ section to give a large variety of tones and performance from the fewest parts in the signal path. They are unique, super effective, and function perfectly for any style of music, IMO.
Inferno Hi Power may be considered to be more of plug straight in and play type of amplifier. Due to the slightly higher gain/clipping character within the preamp, it can require more care and attention from the user when setting up reverbs and delays. This amp plays well with fuzz/distortion/overdrives, compressors, and modulation without much fuss.
The signal cleans up perfectly-like all of my creations-with the guitar volume. The drive, push, and sensitivity of this circuit is exemplary and is unlike anything else out there to my knowledge. Like all of my amplifiers, the noise floor on this amplifier is among the lowest of ANY amplifier I’ve ever experienced. Signal emerges from a literal inky black background in space and presents itself quite prominently to the listener. It truly is among the very best vacuum tube amplifiers in terms of performance-at any price point and design topology.
I love to use pedalboards and am a fan of trippy, atmospheric guitar tones like Gilmour, Edge, Fripp, Summers, Lifeson, Robin Guthrie, Buckland, Corgan, Anthony Gonzalez-M83, Michael Jurin-Stellastarr, John Squire-Stone Roses, Kimock, Hendrix, Trevor Rabin, Phil Manzanera, Etc.
The basic circuit architecture of Inferno is along the lines of highly tweaked Plexi Marshall/5F6A Bassman/AC30 Top Boost using a 2+1 cascade preamp with the cathode follower. The cathode follower is a personal favorite of mine-I use it a lot in guitar, bass, and stereo designs.
•6V6/5992, KT-66, or EL-34 Class AB1 Output Stage
•6V6 Duet Approximately 22 Watts RMS @ Clipping , EL-34 & KT66 Duet Approximately 35 Watts RMS @ Clipping
•Adjustable fixed bias output stage. Provides concentric 10 turn dial counter & test points for convenient approximate adjustment and swapping of output tubes.
•Like the Purpleheart & Golden Ratio Amps, the Inferno Preamp is also a proprietary take on the basic architecture of an 1959 SLP Plexi/5F6A bassman-a 2+1 cascade cathode follower driving the tone stack
•Hi/Lo Tilt is a resistor/capaticor network in the treble phase cancellation tone stack. It completely changes the operating parameters of the entire tone stack and generates several different and unique harmonic spreads
•Lean/Plush changes the slope of the tone stack network
•Treble, Middle, Bass, Cut, Presence, and Negative Feedback Controls
•Ohmite RCN Series 2 Watt/750 Volt Carbon Film Signal Resistors
•Mallory 150 Series Metallized Polyester Signal Capacitors
•Angela/Azuma Made In Japan Ceramic & Silver Tube Sockets
•PEC 2 Watt Carbon Composition & Clarostat/Honeywell 2 Watt Conductive Plastic Signal Pots
•Alpha Silver/Teflon Signal Wire
•Custom, Proprietary CNC Milled Chassis