68 Super Reverb Project

[milosch]

Awhile back I bought a 68 Super Reverb from a friend. It worked, after warming up for a bit. Now, as I am poking through it, it needs a lot of work. Looks like a lot of resistors are off by quite a bit, and I can't really be sure about what looks like a replacement power transformer. There are a couple of mods in there from when it was replaced.

 

I guess I can completely rebuild it, cleaning up the mess, and this is probably my best option. At some point, a certain amount of mojo has been replaced by major wear and tear. I suppose I am just fishing for a nudge. Should be a sweet amp when it's done but I don't really want to gut it.

[Elias Graves]

Nudge.

My take is that if it's a working tool then it needs to be in good condition.

If it's a museum piece, put it under glass and display it.

 

EG

[lowbrow]

Ah, c'mon...Fender amps are so easy to work on...just buckle down and start, accomplish a little at a time, and before you know it..tonez!

[guitarcapo]

My philosophy is to play it if it sounds good. If it doesn't sound good address what you'd like to do from what you're hearing. Just because the transformer isn't original...that doesn't mean it needs to be replaced.

 

The first places I consider is the tubes, speakers and filter caps. An amp can sound a lot better if worn out or blown speakers are replaced. Save the originals for "returning it to stock" when selling it to collectors. Same holds for tubes. replacing the major filter caps is easy. Only after all THAT is done and you don't like the sound would I consider replacing components that have drifted too far off spec. Start with the larger electrolytic caps and maybe the screen resistors. Then maybe the cathode bypass caps and resistors...and then maybe the feedback loop resistor. Also check the caps and resistors in the tone stack. Compare the sound in the vibrato channel with that in the normal channel too. That can tell you a lot about where the problem is. Overhauling the whole amp from the bottom up is too much work and devalues the amp too much. You might as well buy a SR kit with all the money and time spent.

[milosch]

It's rough and well-used, so not a museum piece. I've semi-restored my 73, but that was babied most of its life (I've had it since 85 or so.) This one definitely has issues such as no sound until warm up, loose sockets, questionable workmanship on the replacement tranny including spliced wires, etc. Caps are in good shape for the most part with some replacements. I think I'll redo sockets and resistors, and I already have a output and rectifier set for it.

[milosch]

...and by resistors I mean mainly those in the power section to start. I want that to be stable for sure.

[milosch]

For some reason, instead of biasing from the 50VAC tap, they installed a series 82K 1W resistor to the bias circuit from one leg of the feed to the rectifier. Very strange. I am going to feel better with a new tranny and none of this spliced and incorrect wiring.

[milosch]

New tranny, 5AR4, and power section on the way.

[csm]

Super Reverbs from this era sound WONDERFUL (I have a '69 which is still in regular use) ... despite the silverface cosmetics, they're still essentially the same as the legendary (and way pricier) blackface models; Fender hadn't yet started 'improving' them.

 

Fix it, use it and be prepared to blush prettily but modestly when all those compliments on your tone start flooding in.

[milosch]

Yes, I love my 73. I removed a couple of caps at the output tubes and it sounds even sweeter.

[Furtive]

An amp definitely needs to be working correctly. If this requires replacement of components - then do the needful. I have more than a few very old Fenders; some are nearly completely original, some have been completely restored. My advice:

 

- get the circuit back to spec.

- if speakers are original and blown, have them reconed.

- if the tolex is original but trashed, have it recovered by a pro.

- if the grillcloth is original and not trashed, don't touch it.

 

Paying to have a great amp professionally restored is not cheap. If you can do the electronics yourself, you'll save a couple hundred. Cabinet restoration is better left to people that know what they're doing, because anything less than a pro recover looks like some kind of arts & crafts project by a 6 year old.

 

Pics would be helpful.

[milosch]

I did the retolexing on my 73. Where I used the right glue, it looks great. The wrong glue looked good for awhile and needs to be reattached. It helps to have the original tolex come off in one piece (per panel). Then you can use that as a guide to cut the new stuff.

 

Anyway, the speakers on this are original and appear to be ok. The tolex would need to be redone at some point but I'm not in a rush. The only reason I redid the 73 was that it had been in a flood and I had to replace the baffle.

[guitarcapo]

I'm one of those guys who doesn't like the sound of speakers that get old. They seem to get muddy sounding and lose definition. I never understood guys who went nuts over the "original speaker from 1952!"...I'm thinking that that rusty thing with the paper cone with the fuzzy fibers and dirt isn't going to sound great. At least they never seem to to me. They just wear out over half a century. Some things do get worse with age.....

[milosch]

You can clean the fuzziness away. As long as it's not rusted inside it should work. Even then you can probably rock that away

[guitarcapo]

I'm talking about when all the fibers that make up the paper cone basically lose all connection to each other and the paper cone looks like A HUGE HUNK OF LINT and some guy is convinced this is the ultimate tone speaker because it has decayed into perfection. I gave up trying to get these people.

[milosch]

Well, that is just silly. It's a recone candidate at best.

[milosch]

Got the parts in today including some nice-looking old-school resistors. Pics once I get started on the rework.

[milosch]

Before:

[lowbrow]

 

The burned resistor doesn't look stock.

[guller1]

Looks like it has a 3 prong cord installed, if that's what that green wire to the replacement transformer lug is. Yea those are some shady splices.

 

Does it have any of the blue molded tone caps left?

[milosch]

 

Looks like it has a 3 prong cord installed, if that's what that green wire to the replacement transformer lug is. Yea those are some shady splices. Does it have any of the blue molded tone caps left?

 

 

Looks like they're all there. It did actually work before so I expect it to work even better now. So, anyway, I wrote a little song to the tune of Stumblin' In:

 

The parts have arrived

and so it begins

Carefully taking the iron from the cradle

Solderin' 'em in.

 

Pics coming in a minute...

[milosch]

 

Old caps:

 

 

New caps:

 

[guitarcapo]

I read in some vintage guitar magazine that old transformers actually get MORE efficient after they rust because the rust is less conductive or something. They had meter readings proving it.

All I can say is that rusty iron looks scary knowing that wall outlet volts are being fed right into it.

[guitarcapo]

 

Jesus. Monster size orange drop caps there...

[milosch]

Well, the old tranny was the wrong tranny, unfortunately. It was also made to mount upright instead of sideways. About to fire this up, hopefully not with actual fire.