1972 Twin Reverb

THIS PAGE has little (okay, nothing) to do with writing, but it has a bit to do with research. When I was a kid,  I had a Fender Twin Reverb amp, probably a ’74, which was much too much amp for me. It was the dominant piece of furniture in my early teen-aged bedroom. It also weighed a ton (well, 70 pounds, but it feels like a ton when you’re hauling one around). Because the room and the house were small, it was impossible to turn it up loud enough to where it began to sound good without shaking stuff off the walls. In fact, I don’t think it ever got above a 2 or perhaps a 3. Eventually, and with no musician friends to play in a garage band with, I become discouraged and traded the amp for a dirt bike. Yes, a dirt bike. Thirteen or fourteen years ago, however, I had a little money from some royalties and bought a used 1972 twin. The primary difference between this amplifier and the one I had as a kid was that it was on casters, which make it much easier to move around. It had been bought new by an older guy who wanted to learn pedal steel, but his family said he didn’t play it much.  So, it sat in storage (a barn, as I recall) for 27 years, and was sold after the aspiring pedal steel player died. As you may know, being stored is harder on a tube amplifier than gigging with it every day. The good part was that cosmetically, it looked pretty good, except for some scuffs on the faceplate. The bad news? The sound was weak and finally died. It was the filter caps, I guessed (correctly, as it turned out). The large electrolytic capacitors used to filter the AC ripple from the DC voltage need periodic charging, or else they go wonky and leak,  puke  their toxic guts out, or even explode. About a month ago, I decided to have a go at finally repairing the Twin. The inspiration was David Chase’s film Not Fade Away, which is about American grassroots rock-and-roll in the 1960s and 1970s and how we as a nation contributed two things to the world: this distinctive music and the atomic bomb. The question is, which will prevail? In one of the last scenes of the movie the young protagonist is standing in front of  a closed Los Angeles music store window at night, hands in coat pocket, staring at the instruments, and what appears to be an early 1970s  silverface Fender Twin Reverb.  This 100-watt tube the amp was workhorse for many performing American rock bands of the era (for recording, a smaller, practice amp, the Fender Champ, was a common choice–and we may get to that amp later in these pages). What follows are photos of my 1972 Fender Twin before work began.

THE TWIN, awaiting resurrection. The hardware on the sides are tilt legs that pivot back, allowing you to tilt the amp toward the ceiling for a better sound.  Note also the blue sparkle grille cloth and the tailed Fender logo. The amp is on casters, which is a good thing, because it weighs 69 pounds.

 

 

THE CHASSIS, in a composite photo. The chassis is long, nearly two feet, so it took three photos to get it all in and in roughly the same perspective. Some of the components visible in this photo have been replaced, especially the electrolytic capacitors. What you can’t see well in this photo are the two 470 ohm screen resistors in the back right, over the power tubes, that had failed in a spectacular fashion: they split down the middle and crumbled.

WHO WERE CBS Fender employees at the Fulleton plant B. Kehoe, M. Gowan, J. Mendibles, and R. Espinoza? I’d love to know. Their names are stamped on the side of the chassis, hidden unless the heavy chassis is removed from the cab. If these names mean anything to you, drop me a line.

SERIAL NUMBER on the speaker. They are originals, Utahs, not as collectible as some other versions, such as JBLs, that came in Fender Twins.

THE REVERB TRANSFORMER sits in the middle of the six preamp tubes. The last three digits–136–means the transformer was produced in the 36th week of 1971, which is typical for a 1972 Twin.

IT TAKES TEN TUBES to make the Twin roar, and there’s a paper chart glued to the inside of the cab that shows their placement. There’s a stamp, J 007, on chart. These stamps are used to date Fender amplifiers from 1953 to 1967, but are of lesser importance after. I don’t know what the “J 007″ means, other than it’s a cool combination. If you know, drop me a line.

BACK OF THE AMPLIFIER with upper panel removed to show tube complement. The speakers can be clearly identified as Utahs because of their labels. The four big vacuum tubes on the left, 6L6S, are the power tubes. The preamp tubes, mostly 12AX7s, are beneath the spring-loaded aluminum cans.

THE OFFENDING, leaky electrolytic capacitors. Not only are they dimpled, the stuff is soaking through the skins. The codes on these Mallory caps show they were made between the 39th and 42nd week of 1971.

THE SCUFFED silver faceplate. This Twin has a master volume, but it is not the dreaded push-pull know introduced in 1974.

THE SERIAL NUMBER is A 37555, as seen here stamped into the chassis. According to every reference I’ve consulted, this is consistent with a 1972 Twin.

 

RSS feed for comments on this post. TrackBack URI

Leave a Reply