This Old Tube Amp... with Bob Vila (tons of pics!)
Posted: Tue Jul 09, 2013 4:37 pm
Geeez you're old if you remember that old PBS show! Bob's not here either, it was a trick... he stopped answering my emails 20 years ago.
*cue PBS music*
For awhile now I've wanted a big loud clean Fender amp, something old, something all tube, something with reverb, a big loud clean old Fender amp to call my own. I found it a couple months ago, a silverface Fender Super Reverb.
It's hard to exactly date old Fender amps but the features it has and doesn't have make it seem like a 1977. It's the kind of silverface that the blackface purists don't like as it's set up for maximum clean headroom, but that's perfect for me. It's 70W, got the ultra-linear transformer, master volume with pull boost, silicon rectifier, all tube signal path, tube reverb and tremolo, 4x10" speakers.
It's all original and it has a couple old amp problems... it's got a low level crackling static sound that runs through it every now and then, the reverb is very dark and distant, the power cord is frayed and the end is hanging on by a thread, one power tube socket is super loose, plus it has all original electrolytic caps inside. The stock speakers sound really good, really warm and clear, but they're in rough shape and have been used hard for many years playing country music in small town Alberta. I wish to break in new speakers hard with heavy metal.
So let's tune this ol' girl up! We're gonna open it up, replace all the electrolytic caps, replace the loose tube socket, replace a couple old worn out resistors in the power section, clean all the tube and pot contacts, replace all the tubes, replace the power cord, replace the reverb tank and cables, replace the speakers and cables, and put in a white jewel cover.
All this work is done with the amp cold and it's really easy to completely drain the charge from the power caps, you just have the amp on and conducting sound, then turn it off (not put in standby, turn off), and it drains completely. This is the only dangerous part of this process and if you don't know how to discharge the amp and where to measure with a volt-meter to make sure it's safe, you shouldn't open it up like this. On to the insides!
Here's the old power supply electros, these are the high voltage storing caps in tube amps, the things you have to discharge and make sure they're discharged or they can kill you, stock Mallory's, good stuff, 40 years old is too old though and these are one of the 3 things that I think could be causing the crackling static sounds.
I'm going to use as close to stock values as I can find for all the replacement parts and here's the new ones, Sprague and F&T caps.
There's a bunch of electros on the turret board too, here's the new ones, good ol' 'murican Spragues again. I'm not gonna touch the big blue tone caps, those can last a long time and I think it would change the sound of the amp too much which I'm not really looking to do.
to be continued!
*cue PBS music*
For awhile now I've wanted a big loud clean Fender amp, something old, something all tube, something with reverb, a big loud clean old Fender amp to call my own. I found it a couple months ago, a silverface Fender Super Reverb.
It's hard to exactly date old Fender amps but the features it has and doesn't have make it seem like a 1977. It's the kind of silverface that the blackface purists don't like as it's set up for maximum clean headroom, but that's perfect for me. It's 70W, got the ultra-linear transformer, master volume with pull boost, silicon rectifier, all tube signal path, tube reverb and tremolo, 4x10" speakers.
It's all original and it has a couple old amp problems... it's got a low level crackling static sound that runs through it every now and then, the reverb is very dark and distant, the power cord is frayed and the end is hanging on by a thread, one power tube socket is super loose, plus it has all original electrolytic caps inside. The stock speakers sound really good, really warm and clear, but they're in rough shape and have been used hard for many years playing country music in small town Alberta. I wish to break in new speakers hard with heavy metal.
So let's tune this ol' girl up! We're gonna open it up, replace all the electrolytic caps, replace the loose tube socket, replace a couple old worn out resistors in the power section, clean all the tube and pot contacts, replace all the tubes, replace the power cord, replace the reverb tank and cables, replace the speakers and cables, and put in a white jewel cover.
All this work is done with the amp cold and it's really easy to completely drain the charge from the power caps, you just have the amp on and conducting sound, then turn it off (not put in standby, turn off), and it drains completely. This is the only dangerous part of this process and if you don't know how to discharge the amp and where to measure with a volt-meter to make sure it's safe, you shouldn't open it up like this. On to the insides!
Here's the old power supply electros, these are the high voltage storing caps in tube amps, the things you have to discharge and make sure they're discharged or they can kill you, stock Mallory's, good stuff, 40 years old is too old though and these are one of the 3 things that I think could be causing the crackling static sounds.
I'm going to use as close to stock values as I can find for all the replacement parts and here's the new ones, Sprague and F&T caps.
There's a bunch of electros on the turret board too, here's the new ones, good ol' 'murican Spragues again. I'm not gonna touch the big blue tone caps, those can last a long time and I think it would change the sound of the amp too much which I'm not really looking to do.
to be continued!
