In 1960, the design was changed, and the amp, which had its power increased to 80 watts in 1958, received the new "blonde" cosmetics, with a rough textured blonde vinyl Tolex covering and oxblood (dark maroon) grille cloth. These Twins were so high powered for their time that the speakers of the era generally couldn't hold up when the amp was turned up loud on a regular basis. Various speakers were tried, including models from JBL, Jensen and Oxford. Within a few years, speaker performance and power handling capabilities increased enough to make this a non-issue, but finding an all-original amp with stock speakers from this era is fairly rare today.
By 1965, the Fender Twin had reverb and "vibrato" added to the amp. The "vibrato" was actually misnamed -- instead of producing pitch fluctuation like a true vibrato, the effect can be more accurately described as tremolo, which is cyclic volume fluctuation. The power level of the 1965 Twin Reverb Amp was also increased and it was rated at 85 watts. The cosmetics were well into the "blackface" era by this point, with a black control panel, black vinyl Tolex covering and a silver sparkle grille cloth. Later Twins used "silverface" front panels, and added master volume controls and increased output to 100W and beyond. Prized for their exceptional clean tones, Fender Twin amplifiers have been used for practically every musical genre. Their ability to get very loud and yet stay clean is legendary. They are also known as being very "pedal-friendly" amplifiers, and many players use distortion and overdrive stomp boxes with Twins for when they want to play dirty, and switch them off and let the Twin do what it does best for their clean tones.