In 1959, Fender began to use a cloth-backed vinyl product called Tolex to cover its amplifiers. This covering was far more rugged and durable than the tweed suitcase fabric introduced in 1948. Fender chose to debut this new material on its two newest amplifiers, the Vibrasonic and the Concert. The Concert was the offspring of the legendary 4x10 Bassman of the mid to late 1950s. Since the Bassman was being used primarily by guitarists, Leo Fender redesigned the circuit to optimize it for guitar and added a tremolo feature. Unfortunately, the circuit changes "sanitized" the sound since Leo was (wrongly) convinced that guitarists wanted clean tone rather than the slighty overdriven sound of the Bassman. As a result, the Concert was never as popular as the Bassman. Its lower gain and clean, but rich, tone is better suited to jazz than to rock and roll.
 

 Power Amp: Tube; 2 x 5881, 40 watts RMS @ 2 ohms

 Preamp: Tube; 3 x 12AX7, 3 x 7025

 Rectifier: Solid state; silicon diodes

 Speakers: 4 x 10" Oxford 10K5-1

 Channels: 2 (Normal, Vibrato); 2 inputs per channel

 Effects: Tremolo

 Controls: Normal - volume, bass, treble; Vibrato - volume, bass, treble, tremolo intensity, tremolo depth, presence; foot switch for tremolo

 Dimensions: 25 H x 24 W x 9 D inches

 Weight: 55 lb