Eden WT405 hum

Discussion in 'Amps and Cabs [BG]' started by tchristian, Sep 24, 2018.

  1. tchristian

    tchristian Supporting Member

    Nov 18, 2011
    Missoula, MT
    I'm hoping some of you might watch a short video and come back with your thoughts. Eden WT-405 works fine and sounds great but has a nasty hum/hiss. It's hooked up to an 8 ohm floor monitor for the video. The other end of the instrument cable you'll see me insert into each input is plugged into a passive Fender Jazz. The poking I do at the end is directly on the input jack connector where it plugs into the preamp board.

    When I replaced the fan in this amp last year I had the preamp out on the bench where I treated the switches and pots with Deoxit. I also treated the Amp In/Preamp Out and Send/Return jacks, and I've tried jumpering each pair. None of it helps.

    I ordered new input jacks today; I'll install them when they arrive. I've loosened and tightened all of the direct-to-chassis grounding screws.

    Seems to me the "hand job" I gave it at the end of the video is, um, revealing. :)

    Thanks for looking. theo

  2. sissy kathy

    sissy kathy Back to Bass-ics Gold Supporting Member

    Apr 21, 2014
    Arbutus, MD
    Did it hum before the fan replacement? Eddy currents are generated in motors, make sure the fan housing is grounded. Try reversing polarity of the fan.
    Last edited: Sep 25, 2018
  3. tchristian

    tchristian Supporting Member

    Nov 18, 2011
    Missoula, MT
    Thanks for the reply. The hum began a few months after the fan replacement. Annoying at first, eventually intolerable. Always worse on input #1. Also, I shot the video with the fan disconnected.
  4. tchristian

    tchristian Supporting Member

    Nov 18, 2011
    Missoula, MT
    It's fixed. Replacing both input jacks did the trick. Works excellent now with only a very quiet hum which, according to many posts here and on the Eden forum, is normal for this series of amps. The parts went on backorder and took weeks to arrive. That's why I'm only just now posting the results.

    Funny, in all that time only a single reply to my question. Same thing happened when I was servicing an Ampeg SVT II. Had to go it alone. Good to have friendly advice, just not sure why I look for it on talkbass.
  5. JRA

    JRA my words = opinion Supporting Member

    sorry you were all alone on this one...i didn't notice the thread until today! :)

    but hey: you got it fixed and eliminated the hum! good for you! :thumbsup:
  6. Oh man, I have similar issue with my WT300. The fan was disconnected, so A tech reconnected it and now have a similar noise.... maybe I should disconnect the fan and see it that fixes it!

    He also mention some diodes of something were lose and pushed them down with to re-seat them. I thought that maybe the issue all this time. The amp has been sitting on my self for about 4 years waiting for someone to help fix it. I have had it back twice with different tech to avail. The original guy is gone now. Last guy told me all amps make noise....
  7. tchristian

    tchristian Supporting Member

    Nov 18, 2011
    Missoula, MT
    Thanks, appreciate it. Next time I'll bump the thread a couple times before getting discouraged. ;)

    I hope you find someone you can trust to give it a go-over. I've had to learn this stuff on my own since there are literally only a couple of techs in my town, neither of which are people I trust. For me it wasn't the fan at all. I probably didn't emphasize enough how very loud my hum was, even with the fan disconnected. It was loud enough to overwhelm moderate playing level. Now, though, it's on par with my other solid state amps. Good luck with yours.
    munkeyfish and JRA like this.
  8. MrLenny1


    Jan 17, 2009
    New England
    Good fix. That is a very nice amp.
    I had a WT-400 for 10 years and it also had a
    bit of a hum. No working issues.
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