68 Super Reverb in for overhaul

[punkykatt]

Hey guys, just got a 1968 Super Reverb (Silverface) in for a overhaul and blackfacing. The amp is a beater and been in a damp cellar for many years. It was found on the curbside out with the garbage by my wife`s Brother`s Brother-in- law. He is going to fix up the cabinet  himself and wants me to make this a players amp and wants to keep it.  It has the redish brown coupling caps. Are those the Dog turds everybody hates? Should I yank them  while Im in there or see how its sounds first?  Thanks Punky.

[SILVERGUN]

It was found on the curbside out with the garbage by my wife`s Brother`s Brother-in- law.

I look forward to watching it come together.......good luck and don't forget to get plenty of pics

[HotBluePlates]

...  It has the redish brown coupling caps. Are those the Dog turds everybody hates? Should I yank them ...

Always listen first.

Those are the "dog turds" but most people listening to them are listening to amps that deviated from the blackface formula in some way and may be condemning them unfairly.

The Super Reverb and Princeton Reverb had little-to-no change from blackface to silverface, so I'd suggest listening before swapping them.

[eleventeen]

What a find! I got a free Peavey Bandit the other night, allegedly crackly--just some noisy pots. Sigh, another amp. Though I am not and have never been much of a fan of Supers (don't like 10" spkrs, don't like the size & weight, especially in my old age) they are unquestionably great amps.

One thing I like to do, since fuses are not cheap any more, is to strip a short piece of stranded wire and solder a single strand of very fine wire across the terminals of the fuse post. No, not #18, not #20, not #22...just a single, thin strand pulled out of some stranded wire. On a Super, we're talking about a 2 amp fuse as normally supplied and in use. Remove the regular fuse.

I'd remove the rectifier tube and plug the amp in, perhaps with a light-bulb limiter as Doug suggests, and see if it blows the "fuse" or something else. If the amp lights up and does not blow anything, I would check the bias voltage and make it too cold, such that output tubes will be essentially shut off and not drawing any or much current. The rectifier tube is still out. Let the thing run for an hour. If it blows the fuse, you may be looking at a PT replacement. Unlikely, IMO. Now you replace the rectifier tube, which will bring up the HV. One thing I like to do in a 5AR4/GZ34 amp is to throw in a 5Y3 temporarily. The bigger voltage drop across a 5Y3 (60 vs about 20 on a GZ34) will be easier on the electrolytics and thus the rest of the circuitry. The amp will still work, and if you are going to blow up a tube, a 5Y3 is generally a lot cheaper than a GZ34. That's your moment of truth. If your fuse blows at that point, you're probably looking at a filter cap change, which you could expect even if it was in pristine condition.

Then, you move on to making the thing make sound, take note of any weird noises, shake the reverb can and see if it works. But you can't do that if the thing is catastrophically blowing up fuses and tubes and filter caps. Get it so those things are working (output tubes are still biased nearly off) and then you can move on to the finer points.

Congratulations to whomever found such a neat thing in the trash!

[punkykatt]

Thanks Guys for the great info as usual.  Pulled the dog house cover, filter caps shot and the 1k dropping resistor is fried crisp.  All those caps and resistors will be replaced pronto.  Did a turns ratio test on the OPT, get 4k ohm primary Z and 2 ohm seconary Z.  so the OPT is good so far. Did a voltage test on the PT without any loads on the secondaries.  With 120v on primarys each HT secondary reading 360v to ground, bias supply 51v to ground, voltage across heaters is 6.3v, voltage across rectifier heaters 4.9v.  Looks like the PT is good too.   
This amp has the nasty silverface caps on the power tube grids to ground, the 2- 150 ohm cathode bias resistors to ground and a cap across both cathodes of the power tubes. All of that is coming out. Screen grid resisrtors will be replaced also. Control grid 1.5k`s still read within spec, so they will stay for now.  Next will be the bias board supply upgrade and change from balance bias to fixed adjustable bias and next will be blackfacing the PI.   I love doing this stuff.  This is what you call cream of the crop work for the tube amp techs YEAH!!!

[eleventeen]

Looks pretty good....reasonably clean interior. And of course, fundamentally, you're starting with a great patient!

I would heartily suggest replacing all the 100K ohm plate resistors, the ones arranged in pairs in a "V" configuration, with the metal film 3 watt ones Doug sells, especially if you are going to be placing any kind of parts order. Forget what they measure, the plate R's are ALWAYS noisy by the time they are that old. And I'd probably replace all the 25/25 u cathode caps just for jollies...I mean, as long as you're inside the thing, we're talking $3 extra in parts, less than the freight if you need to place a subsequent order. Not even worth thinking about. If you really want to convince yourself how much noise replacing those plate R's will get you, go ahead and fix all the other stuff, without which the amp won't even work...and THEN do the plate R's. I'll guarantee it'll surprise you how much noise they make.

And if you're gonna rework the thing to use "normal" bias, most of us would like to install tip jacks and 1 ohm or 10 ohm 1% holdoff resistors under the output tube cathodes so you can measure output tube current...sort of optional.

What you found under the doghouse...is GREAT. It's talking to you and telling you what's wrong. Fenders are like that.

[eleventeen]

By the way, I'd reco tearing ALL components off the filter cap board and cleaning it off with some rubbing alcohol---try to get the 91% grade instead of 70%. You never know, maybe whatever arcing occurred might have created a mild path which might have accum'ed some dirt over time and is now carbonized and semi-conductive. Be sure to look at that board once it is cleaned up and stripped pretty carefully.

[TIMBO]

Hi guys, Great find,the only thing I find in curbside trash is trash  Anyway, I often wonder when finding these discarded treasures and giving them a new life by putting in modern components, are we able to make them BETTER than when first built.

I ask this, as I had thoughts of buying a local built amp (built in the 70s)for a $1000 but the thought of replacing some/all of the components would leave me with just the basic components (PT OT chassis cab etc......) for a $1000, when you think about it you can build a nice amp for that kind of money 

With new components in an old amp are you going to achieve better/worse tone/sound  Thanks

[Geezer]

Hi guys, Great find,the only thing I find in curbside trash is trash  Anyway, I often wonder when finding these discarded treasures and giving them a new life by putting in modern components, are we able to make them BETTER than when first built.

I ask this, as I had thoughts of buying a local built amp (built in the 70s)for a $1000 but the thought of replacing some/all of the components would leave me with just the basic components (PT OT chassis cab etc......) for a $1000, when you think about it you can build a nice amp for that kind of money 

With new components in an old amp are you going to achieve better/worse tone/sound  Thanks

Like HBP said above....LISTEN first

If the tone is good, the amp is good. No need to go replacing when it's not needed.

I had a similar vintage SR that was the best ROCK amp I've ever played, and it was totally stock.....crappy caps/snubbers and all.
All I had to do was turn everything up to "10" (with the exception of the verb and trem) and I could go from clean to mean with my LP volume and tone knobs.
That amp was TOUGH, too. I played it for two years straight on the road without a single failure....cranked wide open every night (this was 1979/80, so the amp was only ~10 years old at the time)
I bought it from a band mates mum. The band practiced in her basement, and a previous guitarist had left it there. It had a broken 6L6. I asked her how much....$50. That was a great deal, even at that time
At that time you could still buy tubes at the local drugstore or electrical supply house....oh, those were golden days......I bought a new 6l6 (yes, just one....we didn't need no stinkin' tube matching) and it was good for the two years I had it.
One of those amps I wish I still had.

G

[smackoj]

I owned a bf SR for many yrs. Bought is from a guy for 300 in about '72. Never changed a thing on it until somewhere in the late nineties and it just seemed to never want to disappoint. I thought at the time I sold it that I was going to be ahead because it needed all new speakers. dang, that was not smart for me to sell old 'blacky'! I wish I still had it now.

I really like the ten inch speakers as I spend more time trying to get the tone I like most. I think they define the music better than most 12s.

I don't think, it's subjective mind you, that you can hear that much difference after putting new parts into an old amp. Does it reduce noise and sound louder after new parts? Yes, but that doesn't mean it sounds 'better' to the player. But, if you're going to play an old amp that's been on this earth longer than you, you're going to have to replace some parts. But, for me, I wouldn't pay a thousand for an oldie because, you're right, you can build a real fine amp with that kind of money. Now, that doesn't mean if I found an original Tweed Twin that I wouldn't want it!

Best of luck rebuilding that Silver Soopy. I'm sure it will sound fantastic, but the condition of the four 10s will be critical.

 

[Ed_Chambley]

Is it a Drip Edge?  Reason I asked is it does not look like a 68.  The bias section has a strange resistor network.  The brown caps are fine if they are in good condition.  Filters are gone for sure.  My favorite amp and I have 4 of them.  2 are originais l and one is a 68 and it is/was an AB763.  Did Fender change it sometime in 68?

The best sounding one I have is a 73 which was "blackfaced".  I used yellow Vishay caps and sprague filter caps (did not like orange drops in it) as I prefer the way the fit the doghouse with the padding.  Used a switchable intensity pot which will increase volume and decrease sag a little.  Single wire reverb mod and setup the normal channel similar to a tweed.  Weber ALNICO 20 watts for the 2 top speakers and 30 watt weber ceramics on the bottom.  Gibbs tank for the reverb. All tubes are RCA except v2 where I prefer a smooth plate telefunken.

They are very durable amps as I have had the 73 since 75. Let me know if you plan to keep the speakers original.  I have 2 CTS speakers from that era that have very little use.  Almost new and I will let them go cheap to you if you find you need one or 2.

IMO, a Super Reverb is the best players amp there is.  Great cleans, lots of punch and will get absolutely nasty with no NFB and running on '7".  They love pedals too.  Great find.

[punkykatt]

Ed, I dont have the cabinet with me, the owner is fixing that up himself, BUT when I was there to pickup the chassis I did see AB763 on the sticker inside the cabinet.  All the transformers, choke, Mallory filter caps and pots have a date code of 68. 
The resistors in the bias is a bias balance circuit that is coming out.

[punkykatt]

Another question.  The diode thats in the can on the bias board reads good. Should I change that out to a 1N4007 while Im up grading?

[drew]

IMO, a Super Reverb is the best players amp there is.  Great cleans, lots of punch and will get absolutely nasty with no NFB and running on '7".  They love pedals too.  Great find.

Ronnie Earl knows Super Reverbs - Ronnie Earl and The Broadcasters - Hope Radio 2007

[eleventeen]

"Should I change that out to a 1N4007 while Im up grading?"

Kind of a toss up. The bias diode sees very little voltage (well under 100) and in service sees almost no current, maybe a mil or two. But 1N4007 = a 3 cent part.

[DummyLoad]

One of those amps I wish I still had.

G

ditto. mine was a 71 i blackfaced. sat in the corner so i sold it to a friend who was part owner of a local studio. 

the eminence legend 1028 are a good replacement speaker.

hope you client did't remove or paint over the tube chart...

once you get it all back together and play it, you'll be coming up with excuses to keep it a little while longer. ;-)

--pete

[punkykatt]

Installed 3 conductor grounding cord, disconnected the polarity switch and death cap, rewired fuse holder so hot is at tip, and hot goes to switch after fuse, replaced all filter caps and ps resistors, upgraded bias ps board and changed bias balance to fixed adjustable bias, blackfaced the PI, removed the 2- 150 ohm cathode resistors and control grid caps from the power tube sockets and grounded both cathodes, replaced both screen grid resistors, Cleaned all jacks, switches and pots.  All remaining resistors in the amp are still within spec. Fired it up  with the light bulb limiter(all is well) Install the rectifier tube( all is well) install power tubes(all is well) put the rest of the tubes in (all is well). Plugged straight in to wall receptacle and fired it up, adjust the bias, and check all voltages (fine).  Plugged in my Hondo plywood body LP copy test guitar and "HOT DANG"  this amp sounds GREAT!!!! Dog Turds in all.

[smackoj]

I'll bet all tuned up like that, she's got some real punch!     

[Ed_Chambley]

Love it.  I am sure it is going to be a very nice Super.  Let us know what the final cab configurations end up being.  I am always afraid to stray too far from a stock amp, but I am interested in different speakers.  I tried some Weber Blue Pups, 15 watts, no dope.  Really nice, but was missing some bottom.  It would be great in a band tho.  I also have a SR built in an old twin with 2, 12 Celestion blues with a center board in the cab like old bassman cabs.  It is vertical.  Tall amp, but sounds great.  I did have to tweak a little as the treble would rack your nerves.