Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: JKRamsey1991 on November 20, 2019, 09:01:19 am
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So recently I got a wild hair and dimed my twin reverb and played for a bit. And well I ended up blowing a speaker lol.
So swapped out the speaker and now I have an unpleasant distortion occurring. Doesnt sound like blocking distortion but rather like a really crappy distortion pedal on a low setting. Distortion occurs with volume low like around 2-3.
Any ideas what to test for? No visible signs of any failures. Amp has been completely rewired with new circuit board due to the original board becoming conductive just an FYI. Both channels distorting as well so I assume phase inverter or power amp. I swapped the PI tube with a known good one and there was no change. Just looking for ideas on where to start testing for this.
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TRs have 2 speakers, if only 1 replaced maybe the other is dodgy?
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+1 definitely check 2nd speaker n "seat" on new one
I got a wild hair and dimed my twin
:think1:
one of the things I DIS-like working on twins, that final dime-it test, IN MY HOUSE!!
I've found that previous techs have messed enough with bias, that you ALWAYS want to check, or have checked prior to that experience :icon_biggrin:
they came new biased typically cool, but time n tinkering.....
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I tested the amp through an extension cab I have and the problem persisted. The amp had a 50 watt eminence and a 150 watt eminence in it. The 50 watt one was the sacrificial lamb of that test.
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OK, start with a voltage survery on the power amp and compare to the schematic.
Power tube plate / cathode idle current? Preferably per tube.