Twin Reverb [UL]- rebuild help.

[J M Fahey]

Just for the benefit of others who may read this thread in the future:

1) agree that UL is not a magic power enhancer by any means; "UL Fender" *did* have more power (nowhere near 135W by the way) *because* +V voltage was raised to scary high levels,´period.

2) as a safety concern: 2 x Jensen C12Q are *absolutely unsuitable* for a Twin Reverb.
In fact even originally fitted C12N (twice as heavy as C12Q) did not last long if amp was used full blast.

FWIW I have made a small fortune selling replacement speakers to Twin Reverb users, go figure.

To boot Master Volume was removed from this amp, so power amp is unrestricted, so ...

[olddawg]

It was mentioned before.. but have you simply tried to dry it out? Seriously, a blow drier on warm pointed at the board and left to run for a couple of days in a dry room. It costs nothing to try. You may or may not want to remove the speakers first. It's worked before.

[Leo_Gnardo]

Just for the benefit of others who may read this thread in the future:

1) agree that UL is not a magic power enhancer by any means; "UL Fender" *did* have more power (nowhere near 135W by the way) *because* +V voltage was raised to scary high levels,´period.

2) as a safety concern: 2 x Jensen C12Q are *absolutely unsuitable* for a Twin Reverb.
In fact even originally fitted C12N (twice as heavy as C12Q) did not last long if amp was used full blast.

FWIW I have made a small fortune selling replacement speakers to Twin Reverb users, go figure.

To boot Master Volume was removed from this amp, so power amp is unrestricted, so ...

1) In fact it's not even a "real" UL circuit. The tap ratio isn't what it needs to be for proper ultra linear operation. It's called that because it resembles one somewhat, like a chimp resembles a gorilla. This subject has been beaten to death in another thread a couple years ago.

2) Agreed, the life of a C12Q will be seconds if this amp is played at high volume.

Besides the OP has already stated he's ignoring your suggestions. Since we're going to be identified as muppets anyway, I suggest we take a couple of comfortable seats in the balcony and observe the unfolding tragedy at our leisure. Doubtless it will go on for a few hundred more entries. Here, have some popcorn Juan.

[olddawg]

1) In fact it's not even a "real" UL circuit. The tap ratio isn't what it needs to be for proper ultra linear operation. It's called that because it resembles one somewhat, like a chimp resembles a gorilla. This subject has been beaten to death in another thread a couple years ago.

2) Agreed, the life of a C12Q will be seconds if this amp is played at high volume.

Besides the OP has already stated he's ignoring your suggestions. Since we're going to be identified as muppets anyway, I suggest we take a couple of comfortable seats in the balcony and observe the unfolding tragedy at our leisure. Doubtless it will go on for a few hundred more entries. Here, have some popcorn Juan.

This made my day... nothing like a dose of reality! Lmao!

[Sea Chief]

No its a decent suggestion apparantly, but with childish silly replies like this then I'll not be reading yr suggestions either/ ignored.

[Sea Chief]

ok ignored then lee- wasting yr time/ grow up

[Sea Chief]

Mistake: C12N's in.. not C12Q's sorry. I'm worried the bias runaway/ ott current thing might have damaged the spkrs..

can s'one say whether I can determine if I have dmgd them, definitively? they read 3.5ohms in parralel (not series then- a typo) as they should be I believe, & I get sound from them.. but did notice some odd noises, after on for a while, whilst using I think from a 5f1 champ.

[Chuck H]

Probably noises from the Champ? Speakers can't make any noises on their own. Further, you're putting about as little stress on them as they will ever see with a Champ. Not exactly the acid test.

[Sea Chief]

Chuck, may very well be it (maybe a 6n6, 6v6 russian thing I had in there).. but I was worried that with the inherrant 'excessive bias runaway issue thing' in the TR, that this might > have transferred to the delicate spkr coils/ ie heat damage.

[Chuck H]

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?

[pdf64]

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)...

Chuck, I don't see any way that a bias issue could, in itself, damage speakers that were adequate for the amp's regular output.
Only way may be collateral damage, eg if the OT overheated significantly and shorted primary to secondary, thereby sending HT current through to the speakers.
As the OT has not been flagged as faulty in the report of the tech's findings, I think it reasonable to assume that the speakers have not been damaged, recently at least.

...Doubtless it will go on for a few hundred more entries...

I suspect kiloposts may be more realistic.

[Chuck H]

Lol...

Well, Sea Chief is one of those that hears a crackle in a guitar cord as it's dragged across a carpet and wonders if the static could have damaged his input circuit. He might even convince himself that things sound different since the event.

Sorry Sea Chief. I can't say "no offense intended", but it's really just ribbing. You do tend tend to worry and fuss (for better or worse?). The important thing is that we all get our tone in our own way. However we get there.

[Sea Chief]

Lol...

Well, Sea Chief is one of those that hears a crackle in a guitar cord as it's dragged across a carpet and wonders if the static could have damaged his input circuit. He might even convince himself that things sound different since the event.

Sorry Sea Chief. I can't say "no offense intended", but it's really just ribbing. You do tend tend to worry and fuss (for better or worse?). The important thing is that we all get our tone in our own way. However we get there.

If I buy a dead dog of a twinR, with current issues & incorrectly matched speakers (to the amps wattage).. & I hear the spkrs sounding rough.. yes I worry & fuss already! its perfectly sensible & reasonable to put the 2 Q', I have up here re. the spkrs, but I don't really expect sarcasm in reply (well yes, from the ignored gaggleoftwats- but not from you tbh).

[Leo_Gnardo]

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.

[Sea Chief]

Thanks for help- I know where I'm at now with the plan rebuild, & the usual childish trolls with nowt better to do have popped up from under the bridge/ sigh, so thread done.

I'll defo do another once its built- I'd imagine I might need a bit of your good help again then.

Ciao. SC