NAD: 1968 Super Reverb

itsGiusto

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I've been on the lookout for a good deal on a super reverb for 2 years now, and one finally came up locally for $500. It was selling for so cheap ostensibly simply because the original tolex, back panels, grill cloth, reverb tank bag, and speakers are gone. But the amp is fully functional.

I've looked over the amp, and to my knowledge, I think it was a really good buy for this price - I see super reverbs from 1968 that have their tolex and grill cloth but without original speakers that sell for $1300 these days. And if they have the original speakers, I see them selling for $1900. However, I would love the opinions of some of the community folks who know their way around vintage amps, to see if there's something I'm overlooking about the functional condition of the amp.

I should note that for me, I don't ever buy vintage amps for the purpose of owning a vintage amp, or for resale value. I purchase amps like these when they're cheaper to buy and restore than it would be for me to build from scratch. I'm mostly interested in playing the amp, but not really interested in it as a collector's item. So it doesn't bother me in the least that the tolex and grill cloth are gone.

Here are some shots of what's inside the chassis.

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My first impression is that the lead dress on this seems pretty damn good compared to my two other silverface amps (a 1972 princeton reverb and a 1972 twin reverb). The the heaters are elevated significantly above the signal wires, wires mostly seem to try to cross each other perpendicularly, etc.

I do have some concern about some solder joints, and I'm thinking maybe I should solder-suck them, and reflow solder.
This picture shows some where maybe there isn't enough solder, and the connection looks tenuous:
20230111_004256.jpg


And this picture shows some where there seems like there's way too much globby solder, and the solder also looks really dull, like maybe it's a cold joint:
20230111_004311.jpg

I'm interested in your advice, should I leave these joints be, or preemptively try to fix them?


Interestingly, the amp has a Trainwreck Type-2 master volume installed. It's not something I'd choose to put on there myself, but I guess I might as well keep it, at least for now. It sounds fine.


The previous owner thought this might be an AA270, AA1069, or AB568, however, I do think that the circuit seems like it may have already been blackfaced to AB768 specs, or at least close. I'm glad about this, since that's something I would have done myself anyway.
In a cursory glance, I'm not seeing some of the telltale signs of the later silverface circuits. For example:
1. If there were power tube caps from grid to ground, they've already been removed. None exist now.
2. The input cap to the PI seems to be 0.001uf, not 0.01uf
3. I think it has a bias circuit, not a balance circuit like on later amps
However, the amp does seem to have a 5U4, not a GZ34, so it's not full AB768, at any rate.


The owner indicated that the amp had been recapped within the past decade, and this seems to hold up. I see sprague electrolytics, not original white fender ones. However, the original blue molded caps still seem to be there for coupling caps, which may be good, I know people tend to think highly of those.

The doghouse seems to also have what I think are spragues, based on them saying "ATOM". Can anyone confirm? I'm pretty sure these aren't original at any rate, so it's unlikely I'd need to swap them out.
20230111_010048.jpg



One slightly concerning thing is that there seems to be something melted on the power transformer:
20230111_004553.jpg


However, I didn't see any sign of this in the chassis. Maybe it got too hot at some point? Advice would be useful!


The cabinet is one that has screws to keep the baffle on, which I like! It's not one of the glued-in kinds.
20230109_005616.jpg



I guess for my next steps I plan to go through it and check some more values to see if it's really blackface specs, and take some voltages. I want to look at the PI plate resistor values, at least.
I'll install 1 ohm cathode resistors on the power tubes, and make sure the amp is biased right.
I also want to make back panels for it out of some plywood, and get a reverb pouch and make a cardboard bottom for the tank.
I will also remove the death cap, or at least disconnect it from the high-voltage end.



I also am going to swap the current ceramic Carvin VL10 speakers for something closer to CTS alnicos. I have 2 eminence made fender 10" blue alnico speakers from the 90s (which I hear are pretty similar to CTS), and 2 Jensen 10" alnicos. I'll put those in for now, but I may want to swap the jensens out later for something more CTS-like, if anyone has any suggestions.


I'd love to hear your thoughts! Do you think this was a good purchase, or is there something big I'm overlooking? Please let me know if you see anything that I should address in the amp, I'd like to try to spruce it up, get it in great functional shape!
 
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Jon Snell

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Not enough solder? ... the components are soldered together, the eyelet is for support. In my professional opinion, there is plenty of solder on the joints in question but reflow them if you have time to spare, it won't make it dmore reliable but it will satisfy your needs.
I would change those 65°C capacitors as they won't last long in a valve amplifier. Fit at least 85°C or better still, as I do, 105°C.
I never see them again with 105°C capacitors except for a re valve every 5 - 7 years.
I would though, replace those old "Molded" capacitors. They have seen better days. If you are careful when removing them, you will get a good price for them on fleabay. Some one will think they see a bargain and snap them up.
 

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Jowes_84

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but I guess I might as well keep it, at least for now. It sounds fine.
This.
Is the AC wired correctly, death cap gone? Is the trem working, is the noise floor acceptable?
Does it sound good?
If yes, I‘d say play it for a while first and see how you like it, if you determine to keep it long-term, only then change those e + tone caps and do some minor cosmetic changes or change speakers.
I would like to find out which speakers these are first and how they sound compared to speakers of your liking.
Nice amp!
Congrats.
 

itsGiusto

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This.
Is the AC wired correctly, death cap gone? Is the trem working, is the noise floor acceptable?
Does it sound good?
If yes, I‘d say play it for a while first and see how you like it, if you determine to keep it long-term, only then change those e + tone caps and do some minor cosmetic changes or change speakers.
I would like to find out which speakers these are first and how they sound compared to speakers of your liking.
Nice amp!
Congrats.
Three prong power cord is installed, and seems correct. Death cap is still there, I gotta take it off. The trem is working, and noise floor I think sounds typical for a vintage fender amp.

I think it sounds good, and I think it sounds the way it's supposed to. I think. But I also don't really feel like I'm too qualified to say what it's supposed to sound like. Part of the reason I was interested in getting a super reverb was so that I could learn what everyone talks about. A lot of people seem to indicate that super reverb is somewhat of a magical amazing sound, and so I wanted to experience that for myself, learn what is the sound that people like so much. So it's somewhat important for me that it is in configuration close to the iconic super reverb sound that has gained so much popularity over the years. To that end, that's why I'm interested in having the blackface circuit, and something similar to CTS alnico speakers.
 
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Jasonpatrick

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Not enough solder? ... the components are soldered together, the eyelet is for support. In my professional opinion, there is plenty of solder on the joints in question but reflow them if you have time to spare, it won't make it dmore reliable but it will satisfy your needs.
I would change those 65°C capacitors as they won't last long in a valve amplifier. Fit at least 85°C or better still, as I do, 105°C.
I never see them again with 105°C capacitors except for a re valve every 5 - 7 years.
I would though, replace those old "Molded" capacitors. They have seen better days. If you are careful when removing them, you will get a good price for them on fleabay. Some one will think they see a bargain and snap them up.
That’s 159 degrees F!? I think they are fine over in the preamp corner! Also, Don’t replace the tone circuit blue molded caps. That’s horrible advice. Leave them be. With that logic, might as well replace the OT, it’s probably at the end of its life 😂
 
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Jasonpatrick

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Three prong power cord is installed, and seems correct. Death cap is still there, I gotta take it off. The trem is working, and noise floor I think sounds typical for a vintage fender amp.

I think it sounds good, and I think it sounds the way it's supposed to. I think. But I also don't really feel like I'm too qualified to say what it's supposed to sound like. Part of the reason I was interested in getting a super reverb was so that I could learn what everyone talks about. A lot of people seem to indicate that super reverb is somewhat of a magical amazing sound, and so I wanted to experience that for myself, learn what is the sound that people like so much. So it's somewhat important for me that it is in configuration close to the iconic super reverb sound that has gained so much popularity over the years. To that end, that's why I'm interested in having the blackface circuit, and something similar to CTS alnico speakers.
Transformer is fine
 

mrface2112

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If it's truly a '68, then it should've either been AB763 or AB568. I'd have to go through it in a bit more detail than I looked at your pics in order to truly tell which one it is (there are a few differences here and there, largely in the PI), but overall it looks largely unmolested to me outside of the places one would expect to see the normal maintenance work (filter caps, electrolytics, etc). Based on what I can see of the resistors in the PI, they look like 47K, which would indicate an AB568.

The transformer is fine. I've seen plenty that look like that.

I'd take it to your usual tech for a once-over and circuit verification, but otherwise leave it as it is! Great score for $500, IMO.
 

Jasonpatrick

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If it's truly a '68, then it should've either been AB763 or AB568. I'd have to go through it in a bit more detail than I looked at your pics in order to truly tell which one it is (there are a few differences here and there, largely in the PI), but overall it looks largely unmolested to me outside of the places one would expect to see the normal maintenance work (filter caps, electrolytics, etc). Based on what I can see of the resistors in the PI, they look like 47K, which would indicate an AB568.

The transformer is fine. I've seen plenty that look like that.

I'd take it to your usual tech for a once-over and circuit verification, but otherwise leave it as it is! Great score for $500, IMO.
Wouldn’t the 568 have the added 2000 pf caps off the power tubes? I think it’s prob a end production 763 with factory mods before the new circuit was implemented with the changes
 

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charlie chitlin

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Looks like a proper service to me.
The Spragues in the doghouse were part of it, as was the bias circuit which, for some reason, seems to get ignored.
Crabby old man comment of the day:
Everybody wants nice breakup at lower volume, but nobody wants the ceramic speakers that give it up.
The best-sounding SR I ever had was a drip-edge with Jensen ceramics.
 

Frank Entele

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The ink stamp says Tech 87 stamped it ‘21st week of 1968’…or that’s how I’ve always read those chassis ink stamps.

AB568 would have ostensibly kicked off 1st week of May, 1968…that’s week #17 or so, right? So should have had the bias balance and honking 2000pf caps, as noted. But Fender prebuilt components and assembled from he shelf, as needed.

If the amp works, sounds good to you, doesnt smell, smoke, pop or fart when playing it? Seems worth $500 and you can change/improve as you go along.

good luck -
 

SoK66

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Holy Twin Sisters Batman, that's a week 21 1968 AB763 '68 Super Reverb! Probably one of the last one's made before the dreaded first gen '68 Silverpanel circuit was launched. From your photos it is a near dead ringer internally for my own week 21 '68. which I will have owned for 50 years this spring. To my somewhat informed eyes it looks very good inside, a great score for $500!

That amp has been well serviced, that's very nice looking work inside. The resistor replacements are easy to explain, beyond simply removing the hiss by swapping out the plate resistors. They used those cheap Jamaican resistors in that era and most will by now either have failed or drifted way off song. They are easy to identify, look at the three vibrato section resistors, they have that dull color. The blue Sprague Atom filter caps are correct, they used to be the go-to cap until the prices got way out of hand and techs started using the excellent German F&T brand caps. Were it mine I'd get a read on the dropping resistor values, they are the two between the positive poles of the dfilter caps. If they are original they have most likely drifted and that will throw off all the voltages downstream. Easy to replace them when doing the filter capacitors.

It would have had CTS alnico speakers originally. I'm not familiar with those Carvin speakers, but if they sound good they are good.

It should have a GZ34/5AR4 rectifier tube, which will raise the internal voltage (B+). Someone has installed the 5U4GB no doubt to drop the B+, but that does make the amp sag more and it also has a 50% greater amperage draw on the power transformer. A better solution is to use the correct rectifier tube and a "buck" transformer to reduce the line voltage going into the amp to the then common 115 - 117vac the amp was originally designed around.

Enjoy that amp! Mine was a workhorse for years, still the best amp in the house!
'68 SFSR date code stamp.jpg
 

mrface2112

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Wouldn’t the 568 have the added 2000 pf caps off the power tubes? I think it’s prob a end production 763 with factory mods before the new circuit was implemented with the changes

You are absolutely correct--an AB568 should have those big honkin' caps, and it doesn't. And I will walk back my comment about the 47Ks in the PI. The PI looks like the 100K/82K pair that was classic of the AB763. I'm gonna blame that it was early and I hadn't had my coffee yet, LOL.

I concur that it's a very late AB763.

In any regard, OP, you got a fantastic looking amp with all of the proper servicing (and none of the classic ****ery) for a really good price. Enjoy!
 

itsGiusto

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Crabby old man comment of the day:
Everybody wants nice breakup at lower volume, but nobody wants the ceramic speakers that give it up.
The best-sounding SR I ever had was a drip-edge with Jensen ceramics.
Interesting perspective, makes sense. Do you know much about these speakers that are currently in my amp? I don't know anything about Carvin speakers. I wonder if they're at all similar to Jensen ceramics. This Carvins certainly seem to have way higher power handling capacity, so I'm guessing there are likely some tonal differences just from that alone.
 
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jumpbluesdude

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I’m always amazed a how quickly people are ready to share the little information they have that is completely wrong in addition to perpetuating completely bogus information. I’m a USAF trained electronics tech who worked on military tube gear and later guitar amplifiers, specifically Fender, since 1989.

First off, nice score for $500! This looks to be a 68 AB763 as pointed out by some of the knowledgeable folks in this thread. Do not take the blue molded caps out and sell them on eBay.😖 This is a transitional model still constructed almost entirely like the blackface amps. The brown cap in the middle of the amp circuit is what Fender would transition to later. This still has mostly Ajax blue molded caps - a really good thing because they sound great and are not as prone to leakage as the predecessor yellow Astrons. They sound better than the brown turd caps like the one in the middle of the circuit.

The solder joint with the 82k is in need of being re-flowed. It wouldn’t surprise me if you were able to tug on and pull out one of the components. It’s not a bad idea for reliability to reflow solder joints. Heat the components and the brass eyelet enough to melt the solder, don’t melt it on the iron. A little goes a long way.

The Blue Sprague Atoms are great. Leave them alone. Someone did a fine job there. They also did a fine job servicing the rest of the amp from what I can see. I can’t see the power cord, but the hot(black) should go to one of the transformer black wires, solder and heat shrink. The white should go to the fuse, other side of the fuse goes to the power switch, other side of the power switch goes to the other black transformer wire. This is the safest way to run it. Green goes to chassis like it already does. The death cap BS is an internet myth that has no basis in fact whatsoever. The ground switch and so -called death cap are abandoned with a 3 pronged cord. Do people REALLY think Leo put together these great sounding reliable amps with a cap that would kill you? And furthermore that Underwriter Laboratories put their stamp of approval on an amp that was defectively lethal and was inherently unsafe? Idiots. Please do not perpetuate the idiocy. That cap was designed to reduce hum. Shock hazards in vintage amps are a whole other subject I won’t go into, but that cap was not the cause.

If you want to do something, you can check the resistors for tolerance, which you should do with one leg out of circuit. This will also give you a good opportunity to retouch solder joints. Retention the tube sockets with a small screwdriver or a dental tool that has heat shrink on the knurled area for safety. Spray a little tuner cleaner in the pots if you have it. It’s the best stuff for cleaning pots, but extremely hard to find these days. Cramolin works too. Spend time turning them back and forth 20 or 30 times after spraying. Put some WD 40 on a q-tip and rub it on your tube pins then work the tubes in and out of their sockets several times to remove corrosion from where the tube pins contact the socket pins.
If you have a cap check machine like a Sencore LC75, which I use, or an ESR meter, check the caps Most, if not all, are likely to be within tolerance and free from leakage. Run the amp. There is a reason so many of the Fender amps are still around. They are reliable
and need very little to keep going. A servicing every 20 years, which this amp had recently, and tubes is all they need. Enjoy the amp. I’ve been looking for one of these myself. I’d have felt lucky to find what you found for the price you paid.
 
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myfenderissues

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I've been on the lookout for a good deal on a super reverb for 2 years now, and one finally came up locally for $500. It was selling for so cheap ostensibly simply because the original tolex, back panels, grill cloth, reverb tank bag, and speakers are gone. But the amp is fully functional.

I've looked over the amp, and to my knowledge, I think it was a really good buy for this price - I see super reverbs from 1968 that have their tolex and grill cloth but without original speakers that sell for $1300 these days. And if they have the original speakers, I see them selling for $1900. However, I would love the opinions of some of the community folks who know their way around vintage amps, to see if there's something I'm overlooking about the functional condition of the amp.

I should note that for me, I don't ever buy vintage amps for the purpose of owning a vintage amp, or for resale value. I purchase amps like these when they're cheaper to buy and restore than it would be for me to build from scratch. I'm mostly interested in playing the amp, but not really interested in it as a collector's item. So it doesn't bother me in the least that the tolex and grill cloth are gone.

Here are some shots of what's inside the chassis.

View attachment 1071780
View attachment 1071782
View attachment 1071783
View attachment 1071784
View attachment 1071786

My first impression is that the lead dress on this seems pretty damn good compared to my two other silverface amps (a 1972 princeton reverb and a 1972 twin reverb). The the heaters are elevated significantly above the signal wires, wires mostly seem to try to cross each other perpendicularly, etc.

I do have some concern about some solder joints, and I'm thinking maybe I should solder-suck them, and reflow solder.
This picture shows some where maybe there isn't enough solder, and the connection looks tenuous:
View attachment 1071792

And this picture shows some where there seems like there's way too much globby solder, and the solder also looks really dull, like maybe it's a cold joint:
View attachment 1071793
I'm interested in your advice, should I leave these joints be, or preemptively try to fix them?


Interestingly, the amp has a Trainwreck Type-2 master volume installed. It's not something I'd choose to put on there myself, but I guess I might as well keep it, at least for now. It sounds fine.


The previous owner thought this might be an AA270, AA1069, or AB568, however, I do think that the circuit seems like it may have already been blackfaced to AB768 specs, or at least close. I'm glad about this, since that's something I would have done myself anyway.
In a cursory glance, I'm not seeing some of the telltale signs of the later silverface circuits. For example:
1. If there were power tube caps from grid to ground, they've already been removed. None exist now.
2. The input cap to the PI seems to be 0.001uf, not 0.01uf
3. I think it has a bias circuit, not a balance circuit like on later amps
However, the amp does seem to have a 5U4, not a GZ34, so it's not full AB768, at any rate.


The owner indicated that the amp had been recapped within the past decade, and this seems to hold up. I see sprague electrolytics, not original white fender ones. However, the original blue molded caps still seem to be there for coupling caps, which may be good, I know people tend to think highly of those.

The doghouse seems to also have what I think are spragues, based on them saying "ATOM". Can anyone confirm? I'm pretty sure these aren't original at any rate, so it's unlikely I'd need to swap them out.
View attachment 1071794


One slightly concerning thing is that there seems to be something melted on the power transformer:
View attachment 1071796

However, I didn't see any sign of this in the chassis. Maybe it got too hot at some point? Advice would be useful!


The cabinet is one that has screws to keep the baffle on, which I like! It's not one of the glued-in kinds.
View attachment 1071798


I guess for my next steps I plan to go through it and check some more values to see if it's really blackface specs, and take some voltages. I want to look at the PI plate resistor values, at least.
I'll install 1 ohm cathode resistors on the power tubes, and make sure the amp is biased right.
I also want to make back panels for it out of some plywood, and get a reverb pouch and make a cardboard bottom for the tank.
I will also remove the death cap, or at least disconnect it from the high-voltage end.



I also am going to swap the current ceramic Carvin VL10 speakers for something closer to CTS alnicos. I have 2 eminence made fender 10" blue alnico speakers from the 90s (which I hear are pretty similar to CTS), and 2 Jensen 10" alnicos. I'll put those in for now, but I may want to swap the jensens out later for something more CTS-like, if anyone has any suggestions.


I'd love to hear your thoughts! Do you think this was a good purchase, or is there something big I'm overlooking? Please let me know if you see anything that I should address in the amp, I'd like to try to spruce it up, get it in great functional shape!
Looks like a good deal for 500. Main thing is if it works if transformers are good no shorts. Maybe you like the tone as is don't start changing things around to match some alleged vintage design on the internet. amps generate heat and the amp is 50+ yo so any crust and brown stuff doesn't mean tubes and stuff are messed up and have to get replaced right away. Seems your anticipating more of an electronics project. just enjoy how it sounds before messing with the components
 

schmee

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Nice amp and great price with the BF style cabinet!
I like ceramic speakers in the Supers, but the alnicos are nice also.
Those Carvin speakers look to be Eminence from the grey labels on the side of the magnets. maybe 1058's... which you are correct, may be adding big bottom to the sound, maybe too much in a 4 x 10 setup, hard to say. But good speakers. And at today's prices if you sell them you may get half your amp cost back!

Nothing wrong with the transformer, looks typical to many out there.

Make it AB763 or keep it that way if it is. I wouldn't add the cathode caps on the power tubes.

The Atom/spragues in the dog house are good and expensive!
That amp looks fully serviced and you are ready to rock!

Does the baffle have the aluminum trim on it?
 
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