Fender Twin Reverb. 135W 1977-1982

Blackfaced/

Twin Reverb/ Silver Face 

1977-1982/ 135W/ Ultra Linear Output Transformer and Master Volume, Hum Balance (see silver face history below)

I rescued a 135w  twin reverb silverface chassis  from a flea market just out side St Louis when I had a short break between tour dates. I needed a project to work on. The  goal was to learn about tube amp technology and learn what makes great amp tone. I had two great teachers from Santa Cruz Tube works to help and guide me. First, my best friend, Alan Bartz, I grew up with and started our first garage band together. Alan is a protege' of Howard Dumble,  a guitar player,  a tube amp guru and was the amp/guitar tech for Bob Dylan and Doobie Brothers tours. And his partner at the tube works, Jack Smith, long time cohort and friend of Howard's and former Production Manager at Fender. I spent the summer hanging out with these guys at the shop and learning about what makes an amp tick.  When the amp was done, I had a friend in Austin build a Fender style 4x10 cabinet to fit the chassis and installed the 4 10" Jensens I had at home in the studio. It is awesome! It's loud, It is good for knocking down walls. It is also weighty somewhere around 80 pounds with that giant ultra linear output transformer.  It gives a new meaning to heavy metal. It is also very unique with all the mods Alan and Jack did. 

Twin Reverb History

The Fender Twin is a guitar amplifier made by Fender Musical Instruments Corporatio. It was introduced in 1952, two years before Fender began selling Stratocaster electric guitars. The amps are known for their characteristically clean tone.
The Twin has seen a number of revisions since its introduction, both internal and external, with its designs sometimes varying greatly from one year to the next. Several variations on the amp's original design have been produced through the years, including the Twin Reverb, the Super Twin, the Twin Reverb II, and the Twin Reverb '65 Reissue. The Cyber Twin, which combined a tube amp with a digital processor, was introduced in January 2001.

Silverface Twin Reverb

In 1968 the Fender amplifier line switched from the original black faceplate to a new brushed aluminum faceplate with light blue labels (except the Bronco, which has red) and changed the color of the grillcloth from silver grey to silver with sparkling blue threads embedded within it, ushering in the Silverface era. Other blackface cosmetic features were retained. The first silverface Twins used the blackface AB763 circuit until May 1968, when Fender switched to the AC568. Since the tube complement was the same, Fender just used up their stock of printed tube charts saying AB763 until they ran out.[13]

The earliest silverface Twin Reverbs, along with all other silverface models, had an aluminum frame (trim) surrounding the sparkling blue grillcloth from late 1967 to 1969. Early silverface amplifiers made between 1967 and 1968 had black lines on the brushed aluminum faceplate, still retaining the '60s "tailed" design on the amp logo, installed on the upper left side of the grillcloth. This feature was offered on models produced prior to the "tailless" period in 1973. Some later models came with an unusual silver grillcloth with sparkling orange threads ("orange sparkle"); a black grillcloth was even fitted on some production runs. During the silverface period, the Twin Reverb's chassis and AA769 circuit was shared by the Dual Showman Reverb, effectively producing the Twin Reverb in a head form, although the matching speaker cabinet for the Dual Showman Reverb sported a pair of 15-inch JBL speakers rather than 12-inch.

In 1972 a master volume was added, then in late '73 it was fitted with a push pull "boost" or acentric potentiometer in the master volume position. The rating of the amplifier's output power was upgraded to 100 watts and between 1977–1982 an ultra linear output transformer was used, increasing the power to 135 watts. A Hum Balance was added at this time.