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#1
04-05-2011, 06:55 AM
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Replacing tubes in an Amp.
Hey, I have a Bravo 112, 25watt tube amp.
Ive had this amp for about 12 or 13 years and I bought it used. It seems like its not as clean as it used to be, so Im assuming I need to replace the tubes. Im sure its long overdue Also, the reverb is messed up. When i turn the dial on the reverb and play the guitar, the reverb slowly starts to feedback until i turn it off. I checked springs and the tank and they look fine. Could this be a tube or something? Is a tube job something I can do by myself or do I have to take it to a tech?
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2008 Fender Stratocaster VG 1997 Squier Stratocaster Pro Tone 1988 Guild F112 Twelve string 2009 Norman B18 2011 Larrivee L-03 Last edited by SwimTrunks; 04-05-2011 at 07:01 AM. 
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#2
04-05-2011, 08:27 AM
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Sure you can replace the tubes yourself but to do it right you'll need an oscilloscope to bias them. Were it mine I'd take it into a shop (although I'm not familiar with Peavey's.)
I used to have a vintage Ampeg V4 and it cost about 240 bucks (just for a quartet of power tubes) to re-tube it back in the 90's but then it had about 20 other rare tubes in it too. It ran strong for about 15 more years of hard gigging and rehearsing before I sold it. Last edited by arie; 04-05-2011 at 08:42 AM.
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#3
04-05-2011, 09:15 AM
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great thanks arie.
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2008 Fender Stratocaster VG 1997 Squier Stratocaster Pro Tone 1988 Guild F112 Twelve string 2009 Norman B18 2011 Larrivee L-03
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#4
04-05-2011, 03:05 PM
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You only have to bias the power tubes,the two large ones your 25watter likely has. The preamp tubes aren't biased. There's usually 3 to 5 of those that control input gain stages and reverb so your reverb problem might have to do with a bad preamp tube. Also depending on the power circuit, biasing may not be needed if it uses what's called cathode biasing. If you've still got a manual you might find out or a tech could tell you, or possibly internet research.
Latif
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#5
04-05-2011, 09:00 PM
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Quote:
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2008 Fender Stratocaster VG 1997 Squier Stratocaster Pro Tone 1988 Guild F112 Twelve string 2009 Norman B18 2011 Larrivee L-03
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#6
04-05-2011, 09:22 PM
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Call teh guys at Eurotubes (www.eurotubes.com), tell them what you have and what kind of sound you want out of the amp...they'll set you up....
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#7
04-05-2011, 09:30 PM
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Quote:
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Will
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#9
04-06-2011, 10:09 AM
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Quote:
 "Cathode bias" amps are the ones that do not require bias adjustment. They are self-adjusting in the sense that the bias voltage is derived from the current flowing from the cathode. "Fixed bias" means that the bias voltage comes from a fixed source - they still need to be adjusted for optimum results.
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Go for the Tone, George
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