“Blowing wind”/crackling noise in DSL40CR

Discussion in 'The Workbench' started by Ethan Webb, Oct 22, 2020.

  1. Ethan Webb

    Ethan Webb New Member

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    Hello I’m new to this forum. I purchased a second hand DSL40CR and I love the tone and everything about it. However I get a weird wind like sound and an sometimes I’ll get popping noises.The master volume and volume are all the way down. It sounds like blowing in a microphone kind of. I tested the tubes and no noises came out of the speaker and the sound didn’t increase. However one of the pre amp tubes doesn’t sound like the rest. Maybe that’s the reason? Has anyone experienced this sound before? I’ve heard people say it’s something to do a resonator, caps, fuse, pre amp tube. I don’t want to spend a ton of money trying to fix it so if it isn’t a preamp tube and something bigger I’d rather take it back and get a new one. Thank you in advance. Although I am hoping it’s just a preamp tube.
     
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  2. SkyMonkey

    SkyMonkey Well-Known Member

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    You say you have 'Tested' the preamp tubes. Can I ask how you did this?

    As your 40CR is 2nd hand, there is no way of knowing the abuse the tubes have suffered in the past.
    Preamp tubes in an amp of that age (i.e. no more than 3 years old) will far more likely have developed a fault than have worn out.
    The way to isolate a bad preamp tube is first of all to have a spare ECC83 (12AX7) that you KNOW is good.
    Then swap V1 with the good spare. Fire up the amp and see if the problem has gone away.
    If not, repeat for V2, V3 & V4, each time with the good tube.
    It is best to check all four as more than one may have failed.
    New preamp tubes do NOT need re-biasing.

    Power amp tubes wear out faster than preamp tubes, so there is a chance they are on their way out already.
    Power amp tubes are best replaced as a set if one is failing.
    Again, the best way to check is to have a KNOW good spare EL34 to swap in one at a time.
    But as they are best purchased as a balanced pair (or quad) you really should have a balanced set in your toolbox for such an occasion (same with preamp tubes).
    If you do change the power amp tubes the amp WILL need re-biasing.

    Here is a vid of some cheesy guy on re-biasing the DSL40CR.

    And welcome to the MF @Ethan Webb :welcome:

     
    Last edited: Oct 22, 2020
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