Back in the early '70s the overwhelming demand for lighter, louder, lower-maintenance amplifiers for steel guitarists brought about a wave of new designs to replace the standard tube amp options offered by Fender, Standel, Sho-Bud, and others. Hartley Peavey clearly saw this demand and with the helpful guidance of Curly Chalker, Buddy Emmons, and other steel guitar masters developed the Session 400 amplifier in or around 1973 and released its first production models in 1974. These amplifiers used open back cabinets sized like a Fender Twin Reverb and offered the option of 2-12" speakers or a single 15" speaker. The main innovation with these amps was the 6-transistor based 200 watt power amplifier and the all discrete transistor preamp section with tremolo, reverb, and a passive, sweepable midrange control for critical voicing of the steel guitar tone. Today, after 30 years, these classic Peavey amps are still widely used professionally and have proven to be rugged, reliable, and most importantly, great sounding amplifiers. Soon after the release of the Session 400, Peavey released the smaller counterpart, the LTD 400. The LTD is based on the exact same preamp and power amp, but squeezed it and a 15" speaker into the smaller Peavey Pacer cabinet. The LTD sounds different only in that the smaller cabinet reduces the bass response quite a bit.

This unofficial page has been created partially as a tribute to these great amps, but also as a guide to keeping them running. The main factor in keeping a 20+ year old amplifier running properly is to replace the old electrolytic capacitors. These cap's simply age and need to be replaced as general maintenance. These old Peavey amps can be brought right back to life with a re-cap job. This page will also offer information for upgrading the quality of a few other capacitors in the amps that will help enhance and improve the tone. The upgrades are NOT modifications. The original design remains unchanged, only the parts quality is improved. All of the required capacitors can be found thru large electronics suppliers like Digi-Key or Mouser. [this page still incomplete]

See this link for the old Session 400 site:
Old Session 400 page