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Ampeg SVT 4 Pro XLR Issue

Discussion in 'Amps and Cabs [BG]' started by devo1, May 11, 2015.

  1. devo1


    May 6, 2010
    Hello All,

    Over the past few months I started getting complaints from sound guys that my signal out of the XLR outs had a low hum. I guess EQing out everything under 10 HZ would solve the problem. Then the XLR outs completely stopped working. Only noise would come out. I had this issue at two different venues before taking it in to my tech. When I picked the amp up we tested both XLRs in to the PA and it worked. A few days later I took the amp to the gig and had the issue where nothing came out of the XLRs other than noise.

    Has this happened to anyone? I have a pad under my rack so I am doing everything I can to protect from vibrations. Any advice would help! Thank you!
  2. beans-on-toast

    beans-on-toast Supporting Member

    Aug 7, 2008
    Maybe the problem is intermittent.

    If nothing is coming out, the first thing that I would do is clean and reseat the connector pair, J22 and J23, that go from the XLR to the transformers. If that doesn't help then look at the next connector pair back, J16 and J17.

    Also, the line out jacks could be oxidized, there is a path to ground through the jack switches (shunts) that could be causing an imbalance in the XLR signal. If inserting a dummy plugs in the ΒΌ" line out jacks reduces the hum on the XLRs, clean the shunts.
    Last edited: May 11, 2015
    devo1 likes this.
  3. devo1


    May 6, 2010
    Thanks beans-on-toast! I'll those things out. I suspect the issue might be oxidation.
  4. beans-on-toast

    beans-on-toast Supporting Member

    Aug 7, 2008

    At least those are relatively simple things to try before digging deeper. Deoxit is a good product for cleaning oxidized contacts.

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