1973 Super Reverb - cap questions.

[Leo_Gnardo]

When looking at a re-cap, it depends what you want. Is it an assurance of reliability for a gigging or working amp?

I'd have to say, reliability for the next 20+ years is always a good thing. Who wants to take a chance their amp will fail mid-gig or at that important audition or expensive recording session.

Over the last year or so, just for curiosity, I've been measuring the caps I swap out of old amps. Sometimes the ones that look perfect, aren't. Good ol' Mallorys & other "reliable brands" that read near zero microfarads. Both in hi voltage filter OR cathode bypass functions. If you insist on leaving in your vintage caps, I'd suggest you test them and make sure they're reading reasonably close to their claimed value before continuing to run them.

As for chewing cables, I'm with the dog. Who could resist? That plastic insulation feels like gristle to the teeth. Bit of a hassle when you get down to the wire though, don't swallow any, it gets stuck in the throat, very uncomfortable. And I hope Scummy was kidding - dog won't learn anything by being beaten.

[Mick Bailey]

Some guys just play at home and will forgo reliability in favour of originality, dealing with any future problem when it actually arises. From a repairman's perspective perhaps not an ideal choice. I like this situation to old cars - lets say you bought a '73 car with original plug leads and tyres. You may want it as a daily runner and replace those items. If you want to show it or just do a few miles in it you may want to keep them. It does surprise me sometimes just how long those Silverface Fenders will hold up on all of their original parts. I'd like to think that there will always be amps out there that keep 100% originality. Museum pieces, if you like - to act as a reference point for the future.

[Fretts]

Jim Seavall, owner of Scumback Speakers, used to post at The Axhouse (a private invitation only forum) using the screen name "Scumbag." I was there during the time that he was doing research on pre-Rola Celestions, prior to his taking the project commercial with his Scumback speaker company.

His choice of monniker seemed appropriate; Scumbag once posted about whipping his dog with speaker cables because he chewed on them.

I'd rather not use my speaker budget to support a Scumbag who boasts about abusing animals.

I have to weigh in on this...
I have known Jim personally since 1999. We spent a lot of time together up until 3 years ago when he moved; we still get lunch together now and then. Jim adores animals, he is a total softie where pets are concerned and is a total sweetie with his dog and cats. He is also prone to hyperbole when telling a tale, maybe that's the source of the impression, especially when you can't hear the tone of voice when you read something. That remark about whipping "Bear" with a cable is a real stretch compared to how I have seen him heap affection on the dogs & cats and treat them like little princes and princesses. I'm sure that any of the people that have spent any time at all with Jim would bring the same report to the table. Jim IS loud and brash and it rubs some people the wrong way until they "get" him, but he's no dog-beater by any definition.

The Scumbag name is an ironic twist on an incident involving a belligerent night nurse, which I'll illuminate in some other post but it's tongue-in-cheek, I can guarantee you that.

I have a lot of speakers from Celestion, Jensen, CTS, Eminence, Oxford and so on; if that golden period Celestion is your thing, he has nailed it, he's a perfectionist in that regard. I have several SB's in use alongside the others and they are exactly what they are advertised as. Even the rep from Celestion conceded that Jim's were better recreations, they just don't have the motivation to invest any great resources into a tiny niche market when they are making Bank off their Chinese factory.
Bottom line - after 18 years of personal observation, I can say Jim does not whip his dog and makes very good guitar speakers.

[Fretts]

I share your sentiment but chewing cables is a really dangerous behaviour, so perhaps his actions weren't malicious?

I couldn't get behind anybody who treated animals with cruelty either. Fortunately, that is not Jim.

[Chuck H]

Not to drone on about a slightly off topic subject, but...

Dogs are my favorite people. My wife and I are dog owners at our core. We train with positive reinforcement and have always enjoyed smart and well behaved canine companions. But I have hit my dogs on a couple of occasions when it seemed appropriate. Of course I'm talking about utterly intolerable behavior that the animal has to learn offends you so badly that you would use corporal punishment when that isn't the norm. Like snapping at a child or attacking other household pets. In fact those are the only two occasions when I've done it. And then it was considered, instant and timed to be well understood by the dog. Remember that even mother dogs bite their pups when they misbehave. Children and dogs will forever do some of their learning based primarily on the physical discomfort associated with different outcomes. You can nearly always let them make their own mistakes. Nearly.

[J M Fahey]

dog won't learn anything by being beaten.

They will learn, actually, BUT only if 2 conditions are met:
1) dog MUST see that there is a direct relation between action and discomfort
2) in any case it must be done well within 10 minutes, otherwise they will not connect cause and effect, their short term memory erases after that time *or* focuses on something completely unrelated so lesson won´t be such.

Both learnt from a dog trainer who also happened to play Guitar with my stuff, so we had long talks while I finished his.

[Leo_Gnardo]

They will learn, actually, BUT only if 2 conditions are met:
1) dog MUST see that there is a direct relation between action and discomfort
2) in any case it must be done well within 10 minutes, otherwise they will not connect cause and effect, their short term memory erases after that time *or* focuses on something completely unrelated so lesson won´t be such.

Both learnt from a dog trainer who also happened to play Guitar with my stuff, so we had long talks while I finished his.

OK, I'll agree with *most* of that. 10 minutes? That's an eternity for dog brain. Even 10 seconds is a bit long. One of my crustomers is a dog expert - I'll leave the training to him, he knows what he's doing. Funny he used to be a Wall Street bond trader. Training his clients must have been similar. Gotta go bite a cable now...

[keithb7]

My 1971 Super Reverb recap:



Cathode and bias caps too... Do it!

[g1]

Are those big caps from 'Just Radios' Keith?

[keithb7]

The large F&T caps in the B+ I bought from www.tubesandmore.com
The large orange caps in the vibrato circuit were a rookie error, but they worked just fine.

[g1]

I bought a 'kit' of orange drops like that so I would have a few each of many values. They work just as well as anything else, I don't care if people think I bought into some orange mojo.

[frankeg]

Nice job Keith! I just finished up a Super using the F&T's. I had to change those cc resistors in the supply too. I also used a little RTV to secure those smaller 20uf caps in the doghouse. Left all the coupling & tone caps original. I usually don't check or replace the coupling or tone caps unless it's still noisy after changing the electrolytics, cleaning the pots & biasing. My amp sounded very weak and all the pots needed to be cleaned. After that it sounded awesome! It has full range sounds from bass thru mids to highs. Some folks still argue over replacing the electrolytic caps but not me! BTW, where did you leave the dc bias voltage at? I've seen different #'s on different schematics and am curious.

[bob p]

An OD kit makes sense if you need to stock a lot of different values. I like OD caps, though I have to admit that I've used them in places where they made no sense, just because I had them on hand... like the tremolo oscillator. That's one place where cheap caps make sense and there's no real benefit from using more expensive film caps.

[pdf64]

... BTW, where did you leave the dc bias voltage at?...

I suggest to set the bias voltage to whatever is required to achieve a suitable plate / cathode current at idle (eg 30mA) in the 6L6s.