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Thread: Subwoofers and valve amps

  1. #1
    Join Date: Apr 2016

    Location: Bishops Stortford

    Posts: 565
    I'm Chris.

    Default Subwoofers and valve amps

    A general enquiry.

    Subwoofers like REL benefit most by being fed a high output signal from the speaker terminals of the main amp in order to best match the character of the overall system.

    But, in my experience most valve based systems have that distinctive very low level hum in the main speakers if you place an ear up close to the drivers.

    So will installing a sub as described above amplify this hum to the point of distraction?
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  2. #2
    Join Date: Apr 2012

    Location: London

    Posts: 280
    I'm james.

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    That hum should be mostly at 100Hz in the UK, so assuming most speakers have adequate output at that level it should make no difference. If it's 50Hz hum then that's a different matter, but that should only be from directly heated valve type circuits and there should be a humbucker to minimise it.

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  3. #3
    Join Date: Apr 2016

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    I'm Chris.

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    Quote Originally Posted by Jazid View Post
    That hum should be mostly at 100Hz in the UK, so assuming most speakers have adequate output at that level it should make no difference. If it's 50Hz hum then that's a different matter, but that should only be from directly heated valve type circuits and there should be a humbucker to minimise it.

    Sent from my GT-I9195 using Tapatalk
    Thanks James, part of the hum (50Hz) does come from the DC heated triodes, but that is well minimised with the humbucker. So its probably a residual 100Hz hum and I guess its possible to minimise that in the subwoofer by reducing the value of the sub crossover.
    Last edited by bumpy; 14-04-2018 at 16:15.
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  4. #4
    Join Date: Apr 2012

    Location: London

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    I'm james.

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    I'd say the amp should be designed not to have too much hum as designers surely assume that their amp will be used with full range speakers. Also a sub shouldn't exagerate the bass, just reinforce or extend it.

    My experience has been that I barely had it running, such that with only the sub running (at normal listening volume) it was barely audible, yet it still made a heck of a difference in my room!


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  5. #5
    Join Date: Apr 2016

    Location: Bishops Stortford

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    I'm Chris.

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    Quote Originally Posted by Jazid View Post
    I

    My experience has been that I barely had it running, such that with only the sub running (at normal listening volume) it was barely audible, yet it still made a heck of a difference in my room!

    Sent from my GT-I9195 using Tapatalk
    With Hi Fi this has always been the way to set it up. With surround-sound one tends to be that bit more exaggerated with the bass.
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    Silver mains cables, interconnects and speaker cables by SW1X

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