Ever seen this on a Black Face Super Reverb?

[Randall]

I have a what I think is a '65 or '66 Super Reverb in for service from a recording studio. No date codes on the speakers, and some of the tube chart torn away. He says he wants to tune it up and "make it stock", and that it sounds great as is. One of the original 70/350v reservoir caps is blown, the others look to have been replaced at some point, I think? Did Fender put the silver Mallorys or the gold 20/500v filter caps in these at all? And notice the piggy back resistor on the 4700R, was this done to raise the preamp plates V's?



On the inside I find this big red hot dog on the B+. Surely this can't be stock? Ever seen this done? Notice the bias supply ground has been moved due to a broken PT lug. The 100R filament ground R's are moved to the first output socket. And what about those non-polarized bias supply caps? Any reason to change them out to polarized?

[Justin Thomas]

Well, in the cap pic, the one all the way to the right is from the 34th week of 66, by Mallory. Those copper jobbies? 188 is listed as a EIA code for GE on the Triode pages under Cap manufacturers. Dated 13th week of 66. The silver one I can't see, maybe you could remove it & check? The hot dog seems to be from 45th week of 66, thoughI couldn't find a EIA code. So, all possibly original, and maybe your amp is an early 67, or they failed very early in life. With Fender, almost a ything is possible.

Did Fender WANT to put a C10N 50W speaker in a 66 Princeton Reverb? I don&t know, but I've got one with a period-correct speaker. A little nice for a "student" amp of the time, but if it's a small sacrifice to get the amp out the door and sold, Fender would make it, rather than wait.

Justin

Edit: didn't look at the resistor... I do think tjis amp was worked on at so.e point VERY early in its life... that CF resistor is somethong I would expect in an Ampeg of the period, but never seen those in a Fender.

[Enzo]

Don't make it mysterious, it is just an amplifier. treat it like you would any other. If someone put weird caps on the bias supply, they seem to work, so it can;t be that bad. But for the price of a 50 cent cap or dollar or whatever it is, replace it and it will be off your mind for good.

Why did someone do any of this? WHo knows? Maybe they had a grand purpose, or maybe they were lame and these parts were as close as they could come without ordering stuff.

He wants it stock? Make it stock.

[Justin Thomas]

Or, the hot dog is the first reservoir cap... you could draw a schematic & compare... there's a lot of parts in it that look not-original. But I do think the repairs are quite old. I also do like to use one part instead of two if one will do the job. I bet it was repaired in a hurry, worked fine, and was forgotten about.

I like the mysteries, myself... I just think it's more of a fun exercise than to try to poke holes in something or get obsessive about originality. Stock? Use the last schemo before the AC568, I bet that's it...

Justin

[The Dude]

There are many times someone brings something into my shop and they need it RIGHT NOW. Not uncommon with gigging road musicians who are leaving town and can't wait. They have shows to do and need something working ASAP. I've done plenty of repairs where I used whatever I had in stock that was close to get something going- paralleled or series resistors for odd values, radial caps instead of axial with leads extended, pots with a parallel resistor to get a reasonably close value and working range, etc. It's not what any of us would consider and "optimal" repair, but the customer is happy. He has his gear working and is back to gigging. I ALWAYS explain that exact replacement parts were not used and in some cases they may want to have their "whatever" looked at again when they have more time. If I do something really odd, I'll even leave notes inside so the next tech knows what was done and how to put it back to original. I often wonder how many of these "on the quick" repairs are still out there never having been opened up again. As far as I know, Rick Nielsen's Rivera built Fender Deluxe could still have radial caps from an old television in it.

[g1]

Yep, even that added on resistor may have been a quick fix to bring the value back to spec.
And that cap on the bias pot isn't stock either.

[gui_tarzan]

I guess that's a benefit of not having done this as a profession for most of your life, seeing things like this in amps I work on is interesting. It's like anything else from the past, we have a natural wonder about who did it, why they did it this way and so on. At least I do. But I was raised around a family with a lot of history, or longevity if you will so we have a lot of life history to share. I've got a picture of my great-grandfather fishing in a remote Tennessee river with his bibs and a straw hat on from around 1905 or so. He lived long enough that my kids remember him from when they were very young.

The point is, it's easy to become jaded if you do something long enough, I certainly am with IT after doing it for over 25 years. The mysteries may be irrelevant to some but these amps that were made back in the 50's and 60's were produced during a tumultuous time and part of the fun, at least for me, is doing the research and discovery. Some of my customers appreciate the history of their amps and I certainly do. It's becoming a lost art and very very few young people I know even care about it.

From a repair standpoint, and I think this is where you're coming from Enzo, yes it's just an amp. To effectively repair them we have to separate ourselves from the coolness (or lack thereof) of it. But to some of us it's more than that. I'd love to have some of your experience from years long ago when these amps were just becoming popular. I missed living through some of that history having been born in 1963 even though I played around with tube radios when I was a kid. Maybe it's just me, I don't know, but I like to know all the whys and whens and whats and hows. It helps me get into the minds of the people that built these things.

[Enzo]

Please enjoy your efforts, I would not want to get in your way.

The only thing on my mind when I said don't think mystery was not to let said mystery get in the way of fixing the amp. For example, that odd mish mash of bipolar bias caps. I got the impression - right or wrong - that you might be concerned there was some reason it ought to be done that way. I didn't want you sitting there worried there was something special about the amp that it needed odd bipolar caps. I wonder "geez, how did this happen" all the time.


I used to work with a guy who was convinced that all the parts we used were specially selected. SO we'd have a common part like a 4558 IC, made by Texas Instruments, and he'd order them from Peavey for Peavey amps, and from Fender for Fender amps and from Crate for Crate amps and so on. There were little part drawers for Peavey 4558s and another drawer for Fender 4558s and so on. They are the same part, nothing special about them, those companies never took 28 cent op amps and did special things to them. But our guy was so convinced they did, if an amp came in needing a "Peavey 4558" and we were out, he'd let the repair sit, waiting for new Peavey ICs to arrive instead of picking one from the Fender drawer and completing the repair.

That is what I meant by it is just an amp. I may be jaded after 60 years of electronics, but I think it is more a matter of interest evolves. I see notations on schematics now and then that DO specify using one particular brand of IC. Now I find that interesting, and want to know why it might be. I just wrote here the other day about a Marshall amp that used old 1458 op amps, and that slapping in the more common 4558 or even newer types could cause trouble with instability in that amp. Usually a 4558 works just fine in place of a 1458.


I think too it pays to learn what does make an amp special, which you hint at. That is fine.

COffee cups. A lot of restaurants will use one color coffee cup for regular and another color for decaf. That help the waitress refill you without having to ask. That is an interesting thing to notice, first time you do. Or was to me anyway. Now another restaurant I go into one day, all the mugs are green, except mine, which is blue. They don't appear to be doing the decaf thing. There was probably some reason, like maybe the last few of the old ones had not yet gone away, but I shouldn;t think my cup of coffee was somehow special for it.


I have here a bunch of surplus precision resistors, they tend to be odd values, like 1485 ohms. I use them. You might follow me in a Fender amp, and find a 1485 ohm cathode resistor in a preamp stage. When that happens, I hope you wonder, gee, why is that odd resistor there? But at the same time, if it is bad, I hope you don;t go looking for another 1485 ohm resistor, but instead think, it is just an amp, and install the 1500 ohm resistor the schematic asks for. That is my message.

[Leo_Gnardo]

That red "dynamite stick" looks more at home in a B-15. Looks like someone wanted to augment the main B+ filtering to try & knock down hum. Same in the bias supply. Non-polarized is a non-issue. You can replace 'em for freshness' sake if you like.

[gui_tarzan]

Enzo, I didn't mean that in a disparaging way, please don't take it that way. I appreciate everything you do for so many of us here. Without your willingness to help and share your many years of experience, a lot of us would be stuck in some situations. Maybe you didn't intend that comment about "it's just an amp" to sound "jaded", but that's how I perceived it. That's my fault, I apologize.

[Justin Thomas]

Hi all,

Maybe we can all agree that while it is certainly fun to solve the mysteries, let's not lose sight of the fact that it is after all, an amp. Amd what's an amp to do? Make loud noise! There's a store here in VA a friend and I went to. They had about 50 tweed amps all lined up around the store, on a shelf by the ceiling. Fenders, Gibsons, Gretsch, all kinds of really nice old amps. I asked if any of them were for sale, and the reply was, basically, " they're all broken, but all of them are completely original. So we just leave them on display." I bet what Enzo was emphasizing is, don't let cool interesting quirky things about any particular amp discourage us from helpingbit do what it was made to do: MAKE GLORIOUS LOUD NOISE!!!

I don't think Enzo is jaded at all. I just bet time and time again he's seen too much great old gear lose its purpose by getting forgotten about. Anybody remember the Dunbassbob Bandmaster? It took way too long and way too much e pense to get that thing rocking again. The really good part is, that amp is still out there makong noise. Too many like it are not!

Justin

PS I'm hpusesitting. I went to the kitchen to get a soda, and on my way back to my seat, I see a wall hanging: "Wisdom is knowing what to overlook." I think that sums it up nicely! And Enzo, apologies - I'm not trying to speak for you... Sorry if it seems that way.

[Enzo]

Hey, it was all philosophical anyway, and i wasn't feeling negativity.

Yes, maybe not this one, but I see too many guys obsessing over which brand of resistor is "better" or worse yet "correct" for some amp. I see too many people with an amp not making sound and worried that their 100k triode plate resistor measured 112k and was that maybe the cause. So along with preaching troubleshooting, I try to preach that these things are not super critical lab equipment that might be upset at the tiniest little alteration. We are not trying to find the weight of an electron, just trying to make Stairwell to Heaven come out loud.


And I do hope they find that Higg's Boson, so Higg's can sail off on his boat.

[g1]

I'm not dyslexic, but somehow I always see that as Hogg's Bison. But I know it's Stairway, not well. Or was that a jest? .

[Randall]

Enzo. You are amazing! I've learned so much from you. AND you make me laugh!

[Enzo]

yes, everyone has to have his own take on Stairway, but when I play it, it sounds more like a stairwell.


Yes, OF COURSE it was a joke...


And do you know the difference between a bison and a buffalo?