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Jim Kelley Amplifiers is the trademark for the vacuum tube guitar amplifiers designed by Jim Kelley and manufactured by his company Active Guitar Electronics of Tustin, California between the years of 1978 and 1985. Approximately 600 of these amps were built during that time. The single channel version of the amplifier employed modest gain in the preamp stages, Baxandall type bass and treble controls, a split load phase inverter, and four 6V6GT output tubes. The amplifiers produce 60 watts RMS at full power, and include a half power (30/60) switch.
An improved version of the single channel amp was released in 1980 which included reverb, an additional stage of gain, and optional foot switchable gain boost. These guitar amps were the first to employ a matched quartet of Sylvania 6V6GT output tubes. The amps were offered with hardwood cabinets, or in a variety of vinyl covered birch plywood cabinets in a variety of colors. The amps were built as 1-12", or 1-10" combos, or as a head. JBL E-120 speakers were offered as an option.
Jim Kelley Amplifiers were also the first guitar amplifiers to be offered with an optional power attenuator. Jim developed these high power continuously variable L-pad attenuators as a means of controlling the overall volume of his amplifiers so that the output section could be overdriven at more modest sound pressure levels.
Further amplifier innovations were incorporated into the FACS (foot activated channel switching) model, which built upon the single channel design by including two similar switchable preamps and tone stacks, independent reverb level controls for each channel, and internal relay switching for the external power attenuator. These models were available with optional transformer-coupled effects loops, and were configured for either a master effects loop, or for a separate effects loop for each channel. Owing to its longer (22") chassis, the FACS model amplifiers was available additionally as a 2-10", or 4-10" combo. Another novel feature developed by Jim Kelley was the LED Bias Indicator as an aid in adjusting grid bias.
The final model to be developed and produced was the FACS Line Amp. It had all the features of a FACS amp, but the lead channel also employed a low power push-pull output section. The miniature output transformer was followed by the Main Gain control, which functioned as a Master Volume. The lead channel also had a post distortion passive LC tone control which could cut or boost mid-range.
A rack mounted, all FET stereo guitar amplifier with analog delay reverb was developed but never brought to market.
In 2012 Suhr Guitars (JS Technologies) began reissuing the single channel Reverb Model and Power Attenuator under a licensing agreement with Jim Kelley.