Holy Grail moment

[Randall]

I have in my shop what is the cleanest 1966 Supro 2x12 amp on the planet. I mean, this thing looks like it was never used, and kept in a vacuum. Not a scratch, fingerprint or speck of corrosion on it. Still has hang tags, and extra fuse in envelope stapled in side the cab. It is immaculate. All 1964 RCA virgin tubes that look like they have never even seen any heat, pins are still bright and shiny. Jensen speakers not even broken in. Be still my heart! This my friends, is a true museum piece.

But, the customer wants to play it. He has the scratch, and he paid a premium for it because of what it is. He brought it to me before he even plugged it in. Now, this is where for me it gets into a question of philosophy. Yes, I will fit it with a 3 prong AC cord, that needs to be done. I will bring it up slowly on the Variac and monitor the current and voltages, I am most worried about the can cap since I don't even know if has ever seen HV before. If it is successful going that far, I am inclined to give it back to him and not lobby to replace the 53 year old unused electrolytics, knowing he will probably run into trouble with them down the road. But, it doesn't seem right to pay for an untouched vintage amp and then go right for replacing parts.

So I am torn.... replace the caps and feel good about their function and reliability, or leave them and wait for failure. I will of course let him make that call, but what do you think?

[Chuck H]

The most common electrolytic cap failures I'm aware of are with new caps that were never used for many years. Also, similarly, old caps that ended up sitting and not being used for many years. My vote is to replace the caps and save the old can. It will likely never be good, but you COULD cut it open and fit new caps inside to maintain the stock appearance (this may require an "artistic" approach). I expect plastic film caps in a 66, but if they're paper you will want to test them at working voltage for leakage. Use the original speakers at your own risk. 66 is sort of a crossover and I couldn't say if they're made with plastic adhesives or hide glue. Hide glue is worse, but old plastic adhesives aren't nearly as good as modern ones and they DO get brittle with age. Especially if they've NEVER been flexed. Just to preserve the customers investment I would replace them and save the originals unless he only EVER intends to play quietly and clean (?). Make sure the rectifier is silicon and not selenium. Selenium rectifiers have a shelf life like electrolytic caps. I'd replace with silicon if this is the case.

Lastly, having sat for a time might have weird effects on some things. Schedule to check it out and test caps for leakage and resistors for drift if nothing comes up to make your guy bring it in before, say, six months.?. Just seems like a good follow up appointment in this case.

EDIT: For anyone who wants to poo poo me for going TOO vintage with my considerations, I'm just being cautious because it's nothing I've seen on my bench. I know the speakers are probably made with plastic/rubber adhesives, the caps are likely plastic film and the rectifier is almost surely tube or silicon.

EDIT2: Jimi Hendrix used a Supro S6420 (produced from '64-'67) for a time. Apparently that worked out ok for him And Jimmy Page used some Supro amps in that period and later in the Led Zeppelin years also. Just a little trivia your client might enjoy.

[nosaj]

I have in my shop what is the cleanest 1966 Supro 2x12 amp on the planet. I mean, this thing looks like it was never used, and kept in a vacuum. Not a scratch, fingerprint or speck of corrosion on it. Still has hang tags, and extra fuse in envelope stapled in side the cab. It is immaculate. All 1964 RCA virgin tubes that look like they have never even seen any heat, pins are still bright and shiny. Jensen speakers not even broken in. Be still my heart! This my friends, is a true museum piece.

But, the customer wants to play it. He has the scratch, and he paid a premium for it because of what it is. He brought it to me before he even plugged it in. Now, this is where for me it gets into a question of philosophy. Yes, I will fit it with a 3 prong AC cord, that needs to be done. I will bring it up slowly on the Variac and monitor the current and voltages, I am most worried about the can cap since I don't even know if has ever seen HV before. If it is successful going that far, I am inclined to give it back to him and not lobby to replace the 53 year old unused electrolytics, knowing he will probably run into trouble with them down the road. But, it doesn't seem right to pay for an untouched vintage amp and then go right for replacing parts.

So I am torn.... replace the caps and feel good about their function and reliability, or leave them and wait for failure. I will of course let him make that call, but what do you think?

Ok lets pretend your a mechanic and someone brings you a pristine old collectable car with original tires and radiator hoses? What are you gonna do? Keep it original or recommend what really should be done?

nosaj

[Randall]

Chuck,

I am mostly concerned with the can caps. It's skinny type 10/10/20 so I wouldn't try to stuff it, I would tack them under the chassis and leave the can in place if it came to that.

Speakers? Man, these look like tight Jensens. Again this thing looks like it was stored in a vacuum. Don't think my guy will want to hear about pulling them unless they fail. And if the glue comes unhinged, that can be repaired.

The rectifier is a 5U4GB.

[Randall]

I don't have to pretend I am a mechanic. I grew up in a garage in a family of mechanics. The question depends on what the car will be used for. If it is for display, then rub some armor-all on the rubber and don't worry. If they want to drive to Hamptons with the family on the weekends, then replace the rubber.

And for what it's worth, that is an analogy I often use.

[Chuck H]

FWIW Jensen used hide glue later than any other manufacturer. Still, old Jensen's perform as well as could be hoped. Basically, if the amp is going to be cranked up into overdrive at all I wouldn't suggest doing it with those speakers. Yes, they can be "fixed" but the market is fickle and a recone is just a recone and will always be second to a working original (whether they are useful or not technically).

[Leo_Gnardo]

replace the caps and feel good about their function and reliability, or leave them and wait for failure. I will of course let him make that call, but what do you think?

I was faced with a similar situation a couple weeks ago. A customer bought himself a pristine '67 Bandmaster head. We know there's lots of Bandmasters around, so many that the price hasn't gone kookoo. But this one looked like it had been in a bell jar the last 50 years, original everything. Of course it's the customer's choice. If he chose to display it in his private museum and never switch it on, yes best that everything is left as-is. BUT this guy planned to take it out to gigs, and even proposed that I do extensive mods that would involve drilling extra holes. Hold on there Harry! I reckoned it's best to replace the AC cable with a grounded one, replace the filter caps, bypass caps too, clean controls & switches and let him evaluate how he likes it in its native form but ready for studio & stage use. He's got plenty of overdrive pedals to choose from, no point building boogie woogie channels just yet. I suggested at worst he could find a beater we won't mind punching holes in if he really wants mods, and pay for some of that by selling this beauty. That's where it stands now - he picked it up, paid for the work, he's happy so far so good, and he can take his time deciding whether his stock amp is suitable for his style. Oh I did put one minor mod in, a mid control in his vib channel input #2 jack location, can reverse that easy enough.

General advice: if it's to be a museum piece, dust it off & polish it up. If it's to be used for practice, jamming, recording, and/or concert, better swap in new electrolytics, nix the death cap, install grounded AC cable & park it right there.

And just because someone says they're going to put it in their museum, even that's no guarantee of no foul play. There's a nice brown Vibrolux 1x12 for consignment sale in a local store. I had the pleasure of working on it many years ago. It's been seldom used since than, but all the metalwork has corroded to the point where there's greenish spots on the jack mounting nuts, also a coating of grey-green powder all over the chassis. There's a road case with it, maybe it was clapped in there surrounded by deteriorating foam rubber and whatever icky gas emanated from that over the years. Dam' shame to see the metal and brightwork gone crummy like that.

[Chuck H]

We do the best we can as "service workers", technically skilled or not. But it's the same drill. Thwarting atrophy is what we do. But eventually absolutely everything you see around you will, in fact, become garbage.

Happy New Year everyone

[Leo_Gnardo]

eventually absolutely everything you see around you will, in fact, become garbage.

First hand me my bottle of antidepressants...

Yeh, you're right Chuck, then the sun will expand and turn everything on the surface of the planet into glowing plasma. Unless we manage to do the same before then. So much for "forever and ever." Guess I'll have to try and do what the shrinks recommend "live in the moment." We'll do the best we can, and not worry about the far off future too much, OK?

[Chuck H]

Sorry. I'm not always aware that some people think as dark as I do and don't prefer to be reminded. I usually come off as obtuse and ignorable. Didn't mean to poop in the punch bowl.

[Leo_Gnardo]

Sorry. I'm not always aware that some people think as dark as I do and don't prefer to be reminded. I usually come off as obtuse and ignorable. Didn't mean to poop in the punch bowl.

No worries mate, I'm usually the one amongst my friends & family to fulfill that role. Nice to know there's company!

[Tom Phillips]

I have in my shop what is the cleanest 1966 Supro 2x12 amp on the planet...

Wow - Even had the hang tags! What is the Supro Model and do we get to see photos of it? Attached is a photo of a 1965 Supro Royal Reverb that came through my shop a year ago. It was in the best cosmetic condition of any Supro I have see in a very long tiome and was dead stock. It turned out to be a lot of work to get it sounding correct and to fix original factory circuit flaws that were causing excess hum and buzz but it turned out great and the owner does use it for gigs. The work effort was one of those labors of love that included a lot of unbillable time that I donated to get it just right and for my own satisfaction.

[Jazz P Bass]

Thwarting atrophy is what we do. But eventually absolutely everything you see around you will, in fact, become garbage.

Thwarting Entropy?

[Chuck H]

Thwarting Entropy?

No! Atrophy!!! Yes, there is equilibrium. But most things do indeed dissolve. It's been said that water is the universal solvent. I've concluded that it's actually time.

[Randall]

Yes Tom, it looks very much like that amp. No Reverb though. I intend to spend quite a bit of unbillable time on the one I have for the same reasons.