EC ZDS hum from one channel

Discussion in 'Headphone Amplifiers and Combo (DAC/Amp) Units' started by The Killer Piglet, Nov 14, 2016.

  1. The Killer Piglet

    The Killer Piglet New

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    Hi, folks

    I just picked up a ZDS, and I am encountering hum from the right side, It sounds very much like a ground loop, but nothing seems to budge it.

    I have tried the typical: lifting ground, changed outlet and cord, disconnected IC's, swapped tubes left to right.

    Nothing affects itv -not even volume- with the exception of switching from Low to High z, in which case it is much louder in High.

    Has anyone come across this?

    KP
     
  2. zerodeefex

    zerodeefex SBAF's Imelda Marcos

    Staff Member Pyrate BWC
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    New ZDS or used?
     
  3. The Killer Piglet

    The Killer Piglet New

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    It is used.

    One bit that I did notice: one of the rectifiers did not come up the first time I fired up the amp, and now I see them with the lights off and one is clearly dimmer.

    Sadly, I do not have any backups and it seems I will have to wait about 10-14 days for new ones to arrive from eastern Europe as they do not seem to be available in the States.
     
  4. Thenewerguy009

    Thenewerguy009 Friend

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    No rectifiers on eBay or any of the classifieds?

    Also does the amp physically hum? Like you can hear a humming sound directly from the amp when you turn it on?
     
  5. The Killer Piglet

    The Killer Piglet New

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    I did fine one single tube in the US (in Florida, to boot) on eBay, $20 with shipping, should get here in a few days.

    The hum is only from the headphones, the amp and ps are quiet.
     
  6. Malabargold

    Malabargold Flipper

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    I don't have my ZDS yet but from what I've read I believe it's important for the rectifiers to be closely matched
     
  7. bazelio

    bazelio Friend

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    Anything potentially electrically noisy in the general vicinity? I had some ZDS hum (through headphones of course) at the big meet. @AllanMarcus heard it. I could make the hum come and go as I waived my hand over the tubes. But after I resituated the ZDS on my table further from all the other gear, the hum was gone.
     
  8. Mr.Sneis

    Mr.Sneis Friend

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    If you swapped the tubes and it stays in that channel it seems internal imo. Was the amp moved recently? Does the headphone jack make solid contact with the plug ?
     
  9. The Killer Piglet

    The Killer Piglet New

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    @bazelio nope, no nasties.
    @Mr.Sneis yes, it was shipped to me from Canada. I am hoping it is a bad rectifier, as that would be the simplest solution but I am afraid you are probably correct.
     
  10. Malabargold

    Malabargold Flipper

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    I assume it was the one that was recently sold on Headfi. Have you spoken to the seller about the hum? I would hope that they did not falsely advertise its condition but that sort of thing happens sometimes..has it hummed ever since you received it?
     
  11. The Killer Piglet

    The Killer Piglet New

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    @Malabargold yes, that is correct. I just sent email to seller. I have been fortunate, in 20 years and hundreds of transactions in the audio world I have never had any issues from any private seller, just one dealer that tried to scam me.

    it is clear now that it is almost certainly internal, as the tube on the right side will occasionally go dark swapped tubes to confirm). Interestingly, the tube going dark does not change the effect at all.
     
  12. Mr.Sneis

    Mr.Sneis Friend

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    I'm thinking something is loose and probably just needs solder reflowed. Incredibly doubtful it's seller trying to pull a fast one, amp is point to point inside.
     
  13. The Killer Piglet

    The Killer Piglet New

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    @Mr.Sneis agreed, I have found folks in this hobby to be very honorable.
     
  14. JoshMorr

    JoshMorr Friend

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    Zds with problem from Canada.... hopefully judeus / sing sing isn't up to old shenanigans
     
  15. k4rstar

    k4rstar Britney fan club president

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    FWIW I know Bob who I assume you got the ZDS from and have spoken to him in the past, no way would he ever try to sell defective gear knowingly.

    I hope you get it sorted out.
     
  16. ButtUglyJeff

    ButtUglyJeff Stunningly beautiful IRL

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    I don't know if the seller was the first owner, and I don't know the age of the amp, but doesn't EC offer a warranty transfer for something like $100 to $200?

    At least then Craig will offer his services...
     
  17. Malabargold

    Malabargold Flipper

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    Most likely shipping damages then.

    Since it's a ZDS it's probably fairly new, although if I remember from the listing it's been through a couple of owners. I believe in the past Craig has talked people through amp repairs from their home. Worst case you have to have it sent in.

    Hopefully everything works out for you!
     
  18. Ray

    Ray Friend

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    I almost bought this amp, owner told me the amp had two tubes installed. One had a plastic center pin that must have been cracked because when he removed it, it fell inside the amp. He didn't feel confident enough taking the amp apart & it didn't seem to effect anything. I decided to pass on the deal. Hopefully you get it taken care of
     
    Last edited: Nov 15, 2016
  19. purr1n

    purr1n Desire for betterer is endless.

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    Don't worry. Craig will fix for a super reasonable fee if it needs fixing. I'll get back to you on this. Might be a loose connection. Want to confirm:
    1. You swapped rectifier tubes and right one goes dark sometimes (filament does not light up).
    2. Hum. (Assuming you tried moving the amp away from any electromagnetic fields)
    3. Do you have the original boxes (with com-formal foam for the amp and the PS), or was it a Judeus/SingSing box where he just threw everything together.
     
  20. The Killer Piglet

    The Killer Piglet New

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    @Marvey dont doubt that, I looked at EC's reputation beforehand (I have lurked here and at changstar)

    Correct, swapped all the tubes, hum will always be on right side and whichever tubes is on said said will sometimes turn off.
    Yes, it is in 'safe' area, same spot where I put all my amps for listening.
    It arrived in the original boxing, with the shaped foam, but all in one (no separate box for ps).
     

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