Twin Reverb [UL]- rebuild help.

[Chuck H]

Oh you and I have been there before too. And I've been ribbed about my particulars here on occasion. Your're skin seems to have grown sufficiently hide like.

Ok,.. There's nothing about a red plating tube or tubes that should harm speakers. 3.5 DCR seems right to me for a pair pf 8 ohm speakers in parallel, which should be what you have. C12N's might be ok in that amp. I'm not familiar with them. I know it's a repro speaker but not how repro. Since they're rated a tad under the amps claimed wattage they might get stressed if you cranked a continuous tone through the amp at full volume. Which would probably kill you anyway. Otherwise they get a lot of breaks with a typical playing situation and should dissipate heat sufficiently to survive. If they sound "rough" it could well be that they they just aren't broken in yet. Even if they came with the amp, which was dead, they may not have had much time on them or been played hard at all.

If by "rough" or "odd noises" you mean things like a distinct buzzing sound (that you know isn't the amp) or a sympathetic tone on certain notes (that you know isn't the amp) then you may have reason to suspect a bad speaker. As I mentioned, speakers will not make noises on their own. As in, the amp is sitting there after everything is warmed up and the speakers are making noises. Won't happen. That would be the amp making noises and the speakers telling you about it. Rattles and buzzes that are relative to volume can also be from the cabinet (or even the room!). Loose or ill fitted parts (or loose change on a table, etc.). This can be real PITA to track down too. All too common in old combo's. Remember that there's over a hundred watts and two 12" speakers shaking things up.

[Chuck H]

Chuck you're welcome to join Juan & me up here in the Muppet Memorial Observation Balcony. There's plenty of popcorn, c'mon up and have some.

Naw. I'm good in general admission. I tease daz and a couple of others too sometimes. SC just thinks I'm wrong about him having a certain way about him. Which I'm not. But I'm not saying it's wrong. Just different and sometimes cumbersome. I've been guilty of that myself.

[olddawg]

I’m just a curious twatwaffle... but did you ever try try the blowdryer?

[J M Fahey]

I've stressed speakers badly and come out ok many times. And I've never heard of a bias issue causing speaker damage. Not that it can't happen, but it would require something remarkable like a sustained DC offset that you would surely hear reported through the speakers (and then chose to ignore for thirty seconds).

Do you hear anything wrong with the speakers?

It may happen in DC coupled SS amplifiers, but impossible in a Tube Amp, which by definition cannot pass DC through its output tranformers.

IF it could, I would worry way more about the 300 to 500VDC at transformer primary than any insignificant (if compared to that) bias imbalance.

[J M Fahey]

Worth trying.

Leo was no fool so those amps *left* Factory working , and did so for many years (or he would have switched board materials long ago).

That they start to fail after 40/50 years actually proves they were not such a bad choice after all.

Absorbing moisture after 30/40/50/60 years? ... be my guest!!!

But water can come out easily; just heat the board to 100C where water will evaporate in minutes or, if worried, a couple hours to 60/70C which anyway is probably standard inside chassis temperature in a working Tube amp.

I might even empty board and boil it for an hour in a molten paraffin bath which will drive *all* moisture away, migrate into and reseal even the tiniest pore, and restore board to "as new" standard, ready to serve for at least 50 more years.

Because the original procedure was basically that.

[bob p]

there are probably a dozen people on this site who do most of the heavy lifting when it comes to helping people fix their amps. pissing them all off isn't a good strategy.

[Chuck H]

there are probably a dozen people on this site who do most of the heavy lifting when it comes to helping people fix their amps. pissing them all off isn't a good strategy.

Well I didn't think I was that offensive. SC already knows where some others stand and expected some grief. But I wasn't trying to dog pile him or anything. The guys he has a problem with are cooperative and well respected. Doesn't make them perfect, but they get a pass to be themselves. SC gets the same pass. He get's grief, sure, but no one is saying 'piss off chowder head'. I think my position is that he's a little quirky and get's crabby about being called on it. He's had me grumpy more than once. He may yet be back about this and he already said he'd be back when he has a new problem anyway. We might be A-holes, but we're clever ones.

[Sea Chief]

The guys he has a problem with are cooperative and well respected....

......spits tea!! cooperative as in a collective group yes, & in the case here a gaggle of children trying to impress each other with silly childish retorts just to pick at me & waste (their) time: & this is oh so helpful 'heavy lifting' too!? chrissakes- no, this is just sad ChuckH.

[Justin Thomas]

Fibsh it all...

One of the most helpful people on this board is on SC's Ignore List. I'd put that person up against any shop or tech out there and bet money he could hold his own. He asks questions and expects answers, because after decades of real-world experience in everything music electronics, from MAKING HIS OWN FRICKING SPEAKER FRAMES AND TRANSFORMERS <FROM SCRATCH!!!> to supplying the sound systems for the Earthling Invasion Fleet to Mars (okay, I made that up), he KNOWS what the heck he's talking about and knows how to find the simplest answer in the quickest way possible. Then there's another member with another several DECADES of DIAGNOSTIC and repair experience, who again, asks questions because THE ANSWERS WILL GIVE THE QUICKEST AND SIMPLEST (and often CHEAPEST) solutions. Diagnostics and repair are <NOT> black arts, voodoo, mojo, whatever. And if those two guys (and the other 10 or so) are going out of their way to help me, damn right I don't wanna piss them off or ignore them!

For cricket's sake, listen to these guys! If they ask a question or point out something foolish that was done, take it as a compliment and LEARN from your mistakes (or maybe even the mistakes of other shops!). They're NOT just in this forum to poke fun at people whose gear is busted. Don't piss away a frickin' Encyclopedia Galactica just because they might be a bit abrasive.

Okay, bye... watching from afar.

Justin

PS: posts #2 & #32. Yeah, seriously - a hairdryer. One, because Jazz P Bass & olddawg aren't dopes, either. Two, because it's FREE, EASY, and sometimes it WORKS.

[Sea Chief]

Will listen.. if they don't write childish teehee comments JT. Won't.. if they do/ will simply put on ignore (& all subsequent posts won't see).

I couldn't give a tossif they're the most knowledgeable amp builder JT. if they're rude &/ or pathetic, they're ignored. I will not waste my time reading their spiel. Pretty simple JT. One benefit of the ignore function is it should encourage these silly teeheehee kiddies to grow up in the 1st place.

Again- I'm done with this thread. Appreciate the help to the sensible chaps. That is all.

[bob p]

"One benefit of the ignore function is it should encourage these silly teeheehee kiddies to grow up in the 1st place."

I'm not sure that I understand the logic. It's like believing that if you close your eyes, then they won't be able to see you.

If you keep chiseling away at the knowledge base by putting everyone on your ignore list, then your only option will be to get advice from this guy:



Good luck with that.

[Enzo]

Ignore lists work the other way too. I long ago put someone on my ignore list, some name having to do with the ocean, and I have not since been bothered by the attitude the poster used to have.

[Tone Meister]

"One benefit of the ignore function is it should encourage these silly teeheehee kiddies to grow up in the 1st place."

I'm not sure that I understand the logic. It's like believing that if you close your eyes, then they won't be able to see you.

If you keep chiseling away at the knowledge base by putting everyone on your ignore list, then your only option will be to get advice from this guy:



Good luck with that.

There is always Soundguruman, right?

[pdf64]

As I recall, his view on biasing was ‘the hotter the better’, so the amp would be fine as it is.

[g1]

As I recall, his view on biasing was ‘the hotter the better’, so the amp would be fine as it is.

Yes, "lights out" biasing method, turn off the lights, adjust to red-plating, back off a little.