Diagnosing DSL40C hissing noise

Discussion in 'The Workbench' started by Alex P, Sep 19, 2020.

  1. Alex P

    Alex P New Member

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    I have a DSL40C with a bad hissing noise. I've tested for microphonic tubes and even just replaced the V1 preamp tube with a new one, which according to other people who had the same issue, fixed the hiss. I also moved the tubes in different combinations but the noise remains. I'm not sure what the noise could be now, any help? Thanks a lot.
     
  2. Chris-in-LA

    Chris-in-LA Well-Known Member

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    We need more info. Is your guitar plugged in or not? Effects? Does the hiss get louder when you turn the amp up? Etc.
     
  3. Alex P

    Alex P New Member

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    The amp makes the noise without a guitar being plugged in and it does get louder as I increase the gain/volume. It's especially prevalent in the high gain channel but it's abnormally loud. I'm not running any effects currently, so I know the noise is from the amp. I found a video that demonstrates the issue but the solutions I read in the comments did not work for mine:
     
  4. Chris-in-LA

    Chris-in-LA Well-Known Member

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    Your video title says the amp is new, if so, return it. I wouldn’t even have that fixed under warranty unless that was my only option.
     
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  5. Alex P

    Alex P New Member

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    It's not my video, my amp is used.
     
  6. Chris-in-LA

    Chris-in-LA Well-Known Member

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    I was afraid of that. Have you looked inside to see if anything is burned?
     
  7. Alex P

    Alex P New Member

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    No I haven't, I'm not really confident enough with electrical work to open up the circuit, though I can say I've never smelled something burning within the amp.
     
  8. Chris-in-LA

    Chris-in-LA Well-Known Member

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    It sounds like you’ve done most of the things that you are comfortable doing. I don’t know why other forum members haven’t offered any advice by now, I’m not familiar with your amp. If you have an effects loop you might try using a patch cable to connect those two jacks. If that doesn’t work you’ll probably have to take it to a tech.
     
  9. Chris-in-LA

    Chris-in-LA Well-Known Member

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    You’ve swapped out preamp tubes, have you tried new power tubes?
     
  10. Alex P

    Alex P New Member

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    I haven't tried power tubes as I wanted that to be the last resort since I'd have to pay a tech and buy more expensive tubes. I think I may have to take it to a tech since I've tried everything. What would a patch cable in the effects loop do?
     
  11. Chris-in-LA

    Chris-in-LA Well-Known Member

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    Some loops have oxidation on the jacks and the cable bypasses them. Not sure how to explain.
     

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