Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Platefire on May 18, 2010, 11:16:02 pm
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When I first turn on the amp here lately the reverb continually splashes for a couple of minutes and then goes away. My first guess is it is either the reverb driver or recovery tube. This is a AB763 circuit with bias tremolo. Anybody had this before? Plate
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Happened to me too. It was a reverb tube in my case. I don't recall which one.
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I would guess that its the driver tube. How have you been old friend?
Dave
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Probably a tube. This amp has been working for a long time, hasn't it? What changed right before the problem showed up?
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Recovery amp crackles.
If the crackle is reverberated-ed-ed.... it's before the tank, driver etc.
Smack it. Clean sockets and pots
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Thanks! Looks like it's unanimous, the tubes have it! Well I kinda thought so--maybe! I like PRR suggestion to clean the pots & sockets first and give that a try, if not then replace the tubes-one at a time. The amps been doing great. The amp always worked great but had been sitting up a while and I decided to use it--so a little corrosion is suspect maybe with a little contact cleaner might fix. The mid/raw control is a life saver on this amp as far as giving it a little flex at low volumes. It's a little stiff at low volumes when not turned up to "Raw" setting. So I just leave that mid/raw control dimed out--works for me.
I work for the governement/Army and they blocked the Hoffman site on my work computer. I've had very little time lately for getting on my home computer--so I haven't been able to visit the site much lately. I'm putting in my paperwork for retirement with tentative date 02 Sept 10. So when that happens I'm hoping to have a lot more free time. Good to talk to you guys! Platefire
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I tried cleaning the pins/sockets and it seemed to help but it was still a little noisey. I went ahead and changed the 12AT7 driver and 12ax7 recovery and it seemed to do the trick. I'll let it sit a spell and really cool down and fire it up to see what it does. Thanks, Platefire :undecided: