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Post subject: Should I change the caps/preamp tubes in my '73 Fender Twin?
Posted: Sat Sep 03, 2011 11:06 pm
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Hey everyone! I picked up (what appears to be, based on all the info I could find) a '73 Fender Twin Reverb in a Pawn Shop with a slip cover for $145 a few years ago. I slapped some new power tubes, since some were done and others were completely missing. I used a matched quad of Ruby Tube's 6L6GC's.

Now here's the problem. It hums. A lot. When I use my Strat or LP, I still get the hum. And you can forget about using the 1/3/5 postions on the strat because it gets crazy hum! I'ved tried it at home with a pretty clean power supply and at church and I get the same results.

Also, when you hit the front of the amp with a hot signal, it breaks up. But it's not a sweet, sexy tube break up. It's actually a pretty harsh distortion that sucks. I accidentally turned the volume up on my Tone Press compressor and it cranked the signal and it sounded horrible!

One more thing is that the vibrato clicks when it's engaged.

So my questions is, does it sound like this amp needs a cap job? How about new preamp tubes? I originally wanted to do both, but the tech I talked to wanted an un-Godly amount for the cap job and then told me that the amp "is more valuable with original caps and preamp tubes." I personally think that's a load of crap but whatever...

So what do you guys think? Should I give it a cap job? Sound like it needs new tubes?


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Post subject: Re: Should I change the caps/preamp tubes in my '73 Fender T
Posted: Sun Sep 04, 2011 12:32 am
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Your amp -- any amp, for that matter -- isn't worth jackfuckingshit if it cannot perform the task for which it was designed and built. Find another amp tech.

It sounds like decades of neglect have taken their toll and it's time to either pay the piper or find another dance partner. I don't know what you think constitutes "un-Godly" but five bills wouldn't be beyond the pale to bring this amp back to spec. Count on replacing all of the filter and biasing caps, V1 through V6, all four screen resistors, and anything else that looks wonky once a competent tech sticks his head "under the hood" and inspects the innards. A quality overhaul should yield a decade or more of reliable service, often substantially longer than that.

HTH

Arjay

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Post subject: Re: Should I change the caps/preamp tubes in my '73 Fender T
Posted: Sun Sep 04, 2011 2:05 am
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" then told me that the amp "is more valuable with original caps and preamp tubes."

You know, I wonder how this tech makes a living--- if he's discouraging ppl from simple maintenance? Proper restoration, at this point, will save you from future agony and grief. Done right these amps can perform righteously for a LONG, LONG time. At least, that's my experience.


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Post subject: Re: Should I change the caps/preamp tubes in my '73 Fender T
Posted: Sun Sep 04, 2011 6:01 am
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Yes " it is more valuable with original caps" .......

But the amp should work properley first . A '73 amp is not very collectable for discuss longtime if you should keep the caps or not .

Follow what Retroverbial and BMW write


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Post subject: Re: Should I change the caps/preamp tubes in my '73 Fender T
Posted: Sun Sep 04, 2011 6:54 am
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Dayumn! I want to whip all those so called "techs" with the power cord of a vintage amp till they feel like they've "been tied to the whippin' post". :roll:
Look around and find who works on the amps of the pro musicians in your area,I'll garaun-damn-tee there's a competent one around somewhere,and they don't work for free,but at least you won't be paying him to reconstruct a hack job.
Good luck!


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Post subject: Re: Should I change the caps/preamp tubes in my '73 Fender T
Posted: Sun Sep 04, 2011 9:23 am
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Rebelsoul wrote:
Look around and find who works on the amps of the pro musicians in your area,I'll garaun-damn-tee there's a competent one around somewhere,and they don't work for free,but at least you won't be paying him to reconstruct a hack job.
Good luck!


Good amp techs detest "broom-and-dustpan" jobs (cleaning up some other asshat's mess).

Find one in your area who knows WTF he's doing.

Arjay

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Post subject: Re: Should I change the caps/preamp tubes in my '73 Fender T
Posted: Sun Sep 04, 2011 11:53 am
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So do these symptoms sound like a cap problem? I just want to know before it pay to have it fixed. And I know it's not that collectable, but I like the way it sounds for the most part. It just when it's got too hot of a signal or when the preamp is cranked too high it come out with some harsh distortion.


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Post subject: Re: Should I change the caps/preamp tubes in my '73 Fender T
Posted: Mon Sep 05, 2011 4:01 am
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Yup. Hum and funky overtones are dead give-away for dried out filter caps. Now, there maybe other issues, but they should be attended to AFTER replacing the main filter and bias filter caps. And replaced with QUALITY 'lytics. Like Sprague ATOMS or F&T's.

The 5% tolerance resistors hanging off the grid of the power tubes and the phase inverter stages should be check for drifting too far out-of-spec. And I like to double check the grid stopper and screen resistors on old amp power tubes. Just because they perform a vital stability and even "fuse" function that can protect your precious tubes and output tranny.

Believe me, a little good maintenance is worth it. Esp if you plan to put this amp through its paces (and knew doesn't? It's a Fender, after all). And not have to worry about unpleasant surprises. :( :( :(

Plus, once reliable---you can sell the thing for a better price. You won't lose $$$ with basic service. IMHO.


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Post subject: Re: Should I change the caps/preamp tubes in my '73 Fender T
Posted: Mon Sep 05, 2011 10:33 am
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jwblant wrote:
So do these symptoms sound like a cap problem? I just want to know before it pay to have it fixed. And I know it's not that collectable, but I like the way it sounds for the most part. It just when it's got too hot of a signal or when the preamp is cranked too high it come out with some harsh distortion.



Welcome to the world of older tube amps. You got what you paid for - the money you saved buying the amp can go into maintaining it and bringing it back to working order. Filter caps are a must - expensive? Not as much if they explode and then a transformer is taken out.

If you give your location, you'll get multiple recommendations on who to go to that is a competent Fender amp tech that won't give you moronic advice like keeping it stock. Keeping it stock and playing it is a recipe for the amp being damaged more, as well as you potentially getting an electric shock.

For those oddball folks, have whomever works on your amp save everything he takes out. It may be worth something to someone, but having your amp in a playable condition is worth the investment.

For $650 (your $145 + $505 in parts, labor) you'll have a really sweet sounding Twin. And that's still as Arjay said a deal.

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Post subject: Re: Should I change the caps/preamp tubes in my '73 Fender T
Posted: Mon Sep 05, 2011 11:21 am
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nedorama wrote:
For $650 (your $145 + $505 in parts, labor) you'll have a really sweet sounding Twin. And that's still as Arjay said a deal.


+1

Preach it, Brutha Ned!

Arjay

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Post subject: Re: Should I change the caps/preamp tubes in my '73 Fender T
Posted: Mon Sep 05, 2011 7:39 pm
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AMEN!! :D


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