Vox AC15H1TV combo noise

Discussion in 'Amps and Cabs' started by hw2nw, Sep 29, 2008.

  1. hw2nw

    hw2nw Member

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    Hey guys...I was tracking some stuff yesterday in the studio and noticed my amp was making two distinct noises (that it usually doesn't make).

    1- when I was plugged into the EF86 channel and hit a low chord, there was a significant metallic rattle after the chord. You can hear it a bit when you play into the top boost channel as well. I'm thinking maybe the EF86 retainer?

    2- I was playing more chords (palm mute) and realized that I was getting white noise after I played for a second. It wasn't the speaker pumping or idle amp hum, and I could could almost play rhythmically to it, just a short wash of white noise. Any thoughts?

    I'd love to take the amp in to get a service before I tour on it more, but time does not allow for a while. Any advice appreciated...when I get home I'm going to try swapping some tubes.

    Thanks for your help guys!!
     
  2. 57paf

    57paf Member

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    hw2nw:
    After I swapped my EL84s, the retainers were never quite as tight as original and they did rattle with low notes. I put silicone rings under the retainers and that stopped it.
    My EF86 also went microphonic, but it was more of a howl than a metallic rattle. I fixed that with a super heavy tube clamp (homemade, but you can buy these).
    I hope someone more knowledgeable will chime in about the white noise.
     
  3. XKnight

    XKnight Member

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    I notice some white noise as well on the EF86 channel, especially when I use single coil equipped guitars. I chalked it up to the single coil hum and electronic interference.
     
  4. soldano16

    soldano16 Member

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    Don't mean to kick you when you're down but if you look at the amp name very quickly and only catch most of the right side of it it looks like

    AC1 ........... 5H1T .......... V
     
  5. hw2nw

    hw2nw Member

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    haha! well then my amp is the 5H1T! I love this thing to death.

    57paf, where do you pick up silicone rings/clamps for the tubes?
     
  6. dave s

    dave s Member

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    It may be inherent to the amp. Sadly, you did a perfect job of describing what I hear coming out of my amp ... on either of the two channels.

    Since mine is for live work only, I don't sweat it much and only really hear the wierdness when I'm setting up tones and playing at home. The 'after chord rattle' really gets me. Sounds to me like something bleeding from the active channel through the inactive one.

    Definitely wierd and I don't like it because odd noises might mean future failure down the road. Let's hope not.

    dave
     
  7. onemind

    onemind Member

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    The metallic noise is almost definitely the ef86 tube, I've had many that had a 'mechanical' issue. first step is to swap it.
     
  8. 57paf

    57paf Member

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    hw2nw:
    I bought my silicone rings from this guy:
    http://cgi.ebay.com/8-TUBE-AMP-PREA...ryZ50598QQssPageNameZWDVWQQrdZ1QQcmdZViewItem
    There are several other suppliers of silicone rings.

    It is worthwhile to try a swap of the EF86. A friend "loaned" me his NOS Valvos and the amp got more articulate. But then this also turned so microphonic that even the above silicone tube dampers didn't work. You need a beefier tube damper like this to work with microphonic EF86s: http://www.audiotubes.com/damper.htm

    As I mentioned, I made my own heavy duty damper from copper plumbing fittings from Home Depot. Used a thin strip of aluminum flashing coiled up inside a 3/4" copper end cap to hold it tight to the tube. Drilled a hole for the glass spike on top and domed the cap as well.
     
  9. hw2nw

    hw2nw Member

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    cool! I bought some of those silicone rings from Ebay...that and some EF86 swapping might just be the ticket for this. I appreciate all your help! Not gonna let some noise rip me away from my favorite amp! :dude
     
  10. Vegas Bob

    Vegas Bob Member

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    I had the same "rattle" when I received a used one. Turned out to be the Russian power tubes. I replaced them with some Amperex EL84's and you can't get the grin off of my face. The amp is killer, too bad they ship it with inferior tubes.
     

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