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Blues Junior sounds like a phaser.

Discussion in 'Amp Tech Center' started by dustintnicholson, Jan 10, 2021.

  1. dustintnicholson

    dustintnicholson TDPRI Member

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    First of all, hope everyone is having a great start to 2021.

    I recently bought a Blues Junior III from a local pawn shop for cheap. I’ve had it for months and have been playing it with no issues. I recently purchased a Eminence Swamp Thing and installed it. Now when playing at a low volume there is what I can only describe as a very light digital clipping sound in the amp. Also when playing at a regular volume (Vol: 4, Master: 4) if I play a single note and let it sustain, it begins to make a phaser like sound at the end of the decay. Does anyone have any ideas? I had the clipping sound as being a defect in the speaker, but I really can’t explain the phaser sound.
     
    Chiogtr4x likes this.
  2. corliss1

    corliss1 Friend of Leo's Platinum Supporter

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    Did this only start after the speaker swap? If you have the old one, hook that up and see if the behavior is the same.
     
    JRapp likes this.
  3. dustintnicholson

    dustintnicholson TDPRI Member

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    Only after the swap. I haven’t put the old one back in yet, but that was my next step.
     
  4. strat a various

    strat a various Friend of Leo's

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    1. Try it with an outboard speaker (or swap the speaker again).
    2. Swap out the preamp tubes one at a time.
    3. Built in phaser ... feature or bug?
     
  5. Chiogtr4x

    Chiogtr4x Doctor of Teleocity

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    There are only 2 things I know how to do with my tube amps ( my buddies and I all go to the same great amp tech in DC-area for maintenance) :
    - replace speakers

    - swap out tubes to troubleshoot or replace ( and I actually have my bias adjusted if power tubes are replaced)

    Have you tried a new 12AX7 in that #1 spot, farthest to the right?

    I would just take one new 12AX7, try it in each of the 3 preamp tube spots
    and hear for differences?

    * it's just a cheap ' do no harm idea'
    ( unplug or OFF before swapping> test> OFF> try another spot

    Equally try a new matched set of EL-84's in the power tube slots...

    I have an old Blues Jr. ( now my ' big gig' amp), which has been a good friend since 1999 ( some parts replaced/ modded)
     
  6. Mark the Moose

    Mark the Moose Tele-Afflicted

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    Might be a malfunctioning speaker. Could also be that in the wrestling around of changing speakers a marginal tube was pushed into the realm of an audible problem.
     
  7. dustintnicholson

    dustintnicholson TDPRI Member

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    Welp.... it’s the speaker. While I was pulling it out to put the old one back in, I decided to throw it in an external cab I had. Same results through three different amps. I’ll contact Sweetwater tomorrow to figure out the next step. Thanks for all of the help guys.
     
  8. Munchie99

    Munchie99 Tele-Meister Ad Free Member

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    Basic troubleshooting for the win!
     
  9. dustintnicholson

    dustintnicholson TDPRI Member

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    Completely forgot I even had the cab lol. I was dreading having to install it in all of my amps.
     
  10. strat a various

    strat a various Friend of Leo's

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    Great you solved that.
    Question ... I have a Blues Jr and I have a Swamp Thang in my Princeton ... I probably wouldn't put it in my Blues Jr, the Fender speaker in it sounds real good. Was the speaker in the BJ when you got it damaged, blown? Is there something else about it you don't like?
     
  11. Digital Larry

    Digital Larry Friend of Leo's

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    Glad you solved the mystery, but by "phaser" did you mean "phase shifter" or Star Trek kinda phaser?
     
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