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Post subject: Replacing the tubes on my amp?
Posted: Fri May 27, 2011 5:20 pm
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Hi!
So I recently bought a Peavey Bravo 112, I wanted to upgrade a little, and my previous fender mustang wasn't cutting it volume-wise. So I picked up this amp real cheap, used of course, apparently from the 80's. Anyways, since it is a tube amp, I was wondering if it was possible to change the tubes for another "type". I'm guessing that, like everything else associated with electric guitars (pickups, bridges, strings, pedals, amps, jeez, even patch-chords) there are alot of different types and brands of tubes, and they make a real difference in the sound. According to the specs that came with the amp, this guy has 2 different types: "12ax7's" and "el84's", assuming I'm reading the schematic right, I don't know the symbol for tubes. I noticed that the marshalls I've looked at have "el34's" as one of their tube types.
Any input on what types of tubes I should be looking at and what kind of job it will be to replace them? -I find the current tubes get distorted too early, at around volume setting 5 of 10 on the *clean* channel

Thanks!!

ps I don't care about changing around the distorted channel, the clean one is the only one I plan to use

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Post subject: Re: Replacing the tubes on my amp?
Posted: Fri May 27, 2011 6:07 pm
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If you get intouch with the author of this page, you'll likely get somewhere.

Firstly though I'd look at replacing V1 (furthest away from the power transformer) to a Ecc82 valve. You can't really go swapping EL84's for any substitute valve too easily. So just look at getting the bias for the power section lowered.
That will likely get you somewhere nearer where you want to be. There's undoubtedly other things that can be done. However without seeing the schematic, I can't suggest any.
The schematic for this amp isn't easy to locate. I'll carry on looking though.

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Post subject: Re: Replacing the tubes on my amp?
Posted: Fri May 27, 2011 6:45 pm
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I have 2 different schematics that came with the amp, i'll scan them at some point and post them
Thanks for the help!

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Post subject: Re: Replacing the tubes on my amp?
Posted: Sat May 28, 2011 2:06 pm
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EL84s, I would look for 1970s Saratovs; these are from Russia. I have them in my Trainwreck Rocket colone; great cleans and mean crunch. I got mine for Terry Kilgore, AKA Sgt. Overdrive. e was the guitarist for David Lee Roth and is super knowledgeable on all things tubewise. He can also suggest replacement 12AX7s.
http://mhuss.com/sgtoverdrive/ click on the link to email him directly.
Tell him Serge Small sent you

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Post subject: Re: Replacing the tubes on my amp?
Posted: Sat May 28, 2011 2:38 pm
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yep. the whole tube thing confuses the bejeezuz out of me. i've heard SO MANY differnt' opinions on it and i'm still confused. one sales guy tells me if it isn't a boutique (spelling) amp, it don't matter what you put in but they need to be matched (?). other folks say it will completely change the sound of the amp.
i look forward to seeing many posts on this one. i'm sure there is already some good threads on the subject. but i'm also sure that some opinions may have changed since then. Mr. Nik always has some good stuff to say on these and all other subjects. someone else will chime in and confuse me even more. i'm looking forward to it.


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