Twin reverb 65 reissue. Ratty buzz..

Discussion in 'Amp Central Station' started by Randybobandy09, Jun 21, 2021.

  1. Randybobandy09

    Randybobandy09 TDPRI Member

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    Hello all, picked up a 65 reissue twin reverb couple weeks ago. When I got it. It had a ungodly loud hum from the power section. Took it to tech. 1 filter cap was bad, and 2 preamp tubes aswell. When I got it back hum totally gone. Now with humgone, i have more power. But a new issue. With amp on 3 and picking certain notes, particularly higher register ones. And the high notes in full chords I get this ratty buzz on top of those notes. Louder amp gets worse it appears. On 6 full chords roar with the ratty buzz and turn to mush. Light picking sorta fixes that. I'm confused as to where to start. It has the original groove power tubes from 15 years ago, but tech said they tested fine. Tho he didnt recall where bias was, but it was "checked" crossover distortion? Bad power tube,? Speakers? Bias? It's a nasty roar of a ratty buzz. And always remember twins staying clean till about 7ish with singe coils.. dont know where to start.. but think bias should be first in line. All 4 power Tubes are all super purpleish. But I'm color blindish aswell.. I allerciate any direction and apologize for such basic questions. Gotta learn more..
     
  2. 24 track

    24 track Doctor of Teleocity Ad Free Member

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    I have one as well, and got some ungodly noise the tubes sounded like garbge so I took a chop stick and while the amp was on I tapped gently on all of the tubes one of the 6L6 tubes went microphonic, so I replaced the full set of 6L6's , this also works for the smaller tubes as well.

    considering you just got the amp back I would take it back to the tech to have him recheck it out

    I do some amp repairs for a large music retailer and have worked on these amps for other people. One i got was a complete mess internally so much so that i took mine apart to see if i had any of the same quality issues , I did not , it was a quality issue for one this one particular unit
    these amps are 85 watts that is a ton of power

    best of
     
  3. schmee

    schmee Doctor of Teleocity Ad Free Member

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    Sounds like the vibration is causing something, so yeah, I would check those pre tubes by tapping etc while it is on. Try both channels and see if it does it in both to help narrow the issue down. I hope your tech didn't just replace one filter cap, when one's gone it's time to replace all. But I doubt filters are your issue. No loose speaker connections? Try it with the reverb tank unplugged also.
     
  4. Randybobandy09

    Randybobandy09 TDPRI Member

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    He did just replace one.. yes, this nasty ratty buzz happens in both channels. Havent tried it without reverb plugged in. Will do that tonight. I'm going it's just a very cold bias? But a loose speaker connection is worth looking at too. It was a hard task to endure, but with vol on 3 to 5, I out my ear down by speakers, it wasn't appearing to originate from the left speaker(when facing towards front of amp) it appeared to be more located by the power tubes or the right speaker..
     
  5. 24 track

    24 track Doctor of Teleocity Ad Free Member

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    its wierd that he only replaced one cap I always replace both, fender always use IC brand caps which are not the beat for quality there are far better ( I always use F&T) and have had tremendous success with these.
     
  6. corliss1

    corliss1 Friend of Leo's Platinum Supporter

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    Chasing rattle is always a pain - there's no easy way around it except to isolate the issue. You can hold the power tubes with a rag so you don't burn yourself to see if that's the issue, and then press or hold various other parts to see if you can affect the rattle.
     
  7. Randybobandy09

    Randybobandy09 TDPRI Member

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    Yes, I wasn't happy. But was happy the original issue is gone.
     
  8. Randybobandy09

    Randybobandy09 TDPRI Member

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    Definetly. I just dont know if it's a rattle, because it kinda sounds like a ratty distortion sorta like rectifer tube sagging.. but it didnt appear to come out of left speaker.
     
  9. Fret Wilkes

    Fret Wilkes Friend of Leo's

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    If it does it in both channels, and doesn't appear to come out of one speaker, I'd say a voice coil rub on the speaker in which it does happen. I had some nice Weber Neo 12s in my 68 Twin a few years back. I got this "ratty distortion" as the notes decayed. I shipped them back to Weber and replaced with their ceramic California model. No more "ratty distortion". Just a guess, but it sounds like what I heard with mine.
     
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