Monday, April 28, 2008

Harp Amp Project: Fender Silver Face Twin

Yesterday my girlfriend's brother-in-law said to me, "It's yours if you want it. Go ahead, see if you can get some use out of it." I looked down at a Fender silver face Twin Reverb amp.

So I took it home and plugged it in. The tubes glowed, and it made all the right smells. It sounded fantastic. I took a deep breath. Can I really accept such a huge gift? He has owned the amp since 1990; got it from his "guitar teacher" but hardly ever plays it anymore. I feel a little guilty, like I robbed the guy.

By the serial number it is a 1972 SFTR. It does not have the pull boost on the Master Volume, which dates it to late 1972. The tube chart is gone, it has an ugly black grill cloth, and it has Altec 417-8C speakers, code 391320. The power tubes are four beautiful 6L6 Mesas. It includes the footswitch; The reverb is lush but the trem does not seem to work. All the electronics look original to me.

This is a clean-sounding, loud guitar amp, and I play blues harp, not guitar. Twin Reverbs are not usually played by harp guys, with the notable exception of Magic Dick from J. Geils Band who sometimes played two SFTRs stacked. That was his rig on Whammer Jammer.

I plugged a bullet mic into the reverb channel, rolled off the treble, dimed the bass and had the mids on 5. I switched off the bright switch and turned the reverb up to about 3. I gotta tell ya, the tone was hypnotic; deep and full and powerful.

I think I just found my next project.

I'll restore this amp a bit. It needs cleaning up, and it is missing the handle strap, tilt-back legs, and casters. I have Gerald Weber's video about how to overhaul a vintage Fender amp, so I am very tempted to do this myself; replacing all the capacitors and resistors. The only change I think I'll make to it to adapt it for harp will be to try some lower-gain preamp tubes.

This early Fender Silver Face Twin Reverb is a 100-watt monster; a high-gain screamer on the order of Marshall or Mesa. It is a beast. I'm curious to see how it works as a harp amp. If it worked for Magic Dick on Whammer Jammer, it is way good enough for me. Stay tuned...

Back of the amp, with upper panel removed.

Altec Lansing speakers, with a note about new tubes back in 1980.

The left side of the circuit board.

The right side of the circuit board.

The caps with the pan removed.

The transformers.

* * * * * * *

UPDATE: Internally, this amp is in pristine shape. The brass grounding buss behind the pots and jacks doesn't have a bit of corrosion. Everything is original and perfect. I'm thinking of leaving it unmolested.

I've cleaned it up and changed some tubes. I'll try a 12AX7 in the phase inverter socket to induce earlier breakup and try a lower-gain preamp tube in the second channel.

The Altec 417 C8 speakers are much loved by vintage amp guys, comparable to the JBL D120 speakers. Altec 417s were Santana's favorite speakers in his early 70's era, when he got his best tone. I've seen good examples sell for $600 a pair on the used market, and the pair in this amp is excellent.

UPDATE II: I've decided to have the amp serviced by a good tech (I don't have the time or the skill) so I dropped the chassis off with Glen Whatley at MARS Amp Service in Englewood, CO for new caps and filters and a general overhaul. It should be finished in a week or so...

UPDATE III: Here is a pic of the SFTR in its current state. I've replaced the handle and casters with new Fender gear. The tolex has been cleaned and treated. This gives you a good look at the business end of the Altec 417-8C speakers. The chassis is still at the tech. I'm waiting for delivery of the Silverface grill cloth...


Joe said...

Nice score. Lots of guys have blown harp through Twin Reverbs. You could also search through some of the guitar forums. Some of the guys pull two of the 6L6's, but you've gotta pull the correct pair.

Ray Beltran said...

Throw a Kinder AFB+ in front of it, betcha you'll have a monster.