Loss of volume?

Discussion in 'Amps [BG]' started by YellowCarLuke, Feb 13, 2014.


  1. YellowCarLuke

    YellowCarLuke

    Joined:
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    Hey! I recently switched on my Mesa mpulse 600 head/Marshall 4x10 for some jamming and was concerned when the volume was rather low (even when turned up full).

    Is this just an issue with the tubes? They haven't been changed since I purchased the head. They don't appear to be glowing (from what I can see through the small grating at the front) either.

    I don't mind buying new ones but I was just worried if there might be something more sinister at play, any ideas pals?

    :bag:
     
  2. Downunderwonder

    Downunderwonder

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    Slow morning. Check the battery in your bass?
     
  3. teemuk

    teemuk

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    It is impossible to know. Loss of volume can also be the result of intermittency somewhere, like worn out / dirty potentiometers or switches in things like FX loop jacks. Practically there are dozens of other scenarios besides bad tubes. ...like the aforementioned battery.

    But bad tube is definitely easy to rule out, right?

    This may not mean anything. Not all tubes glow very brightly to begin with and much of it has to do with the internal construction of the tube. In some tubes the filaments are almost hidden from sight (and such tubes have almost no discernible glow at all) while some tubes have their filaments much more visible. Do note that many tube amps have LEDs or other lamps to illuminate the tubes to give a more prominent impression of glowing. The designers do this because today people expect to see distinctive glow in tubes and the glow of the filaments alone isn't usually bright enough for their tastes. If it doesn't glow like sun people think it doesn't work properly, despite the amp actually working and emitting sound as usual.

    For example...
    [​IMG]
    Both these preamp tubes operate normally. Their internal architecture is different though, which means the other tube seems not to glow at all in comparison to the other. But this just shows how little importance the magnitude of the filament glow actually has. Both tubes in this case work just as they are supposed to.

    Obviously you are more interested in whether the glow has reduced from what it was earlier or not, as that would be the only real pointer that a tube has started to malfunction in some way.
     
  4. RickenBoogie

    RickenBoogie

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    FX loop jacks, battery in bass would be more likely than tubes. Plug a short cable from send to return, see if that helps.
     
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  6. YellowCarLuke

    YellowCarLuke

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    I don't play an active bass so it couldn't be a battery problem. I plugged into an old ampeg 4x10 combo that was lying out there and it was grand for volume.

    I suppose you're right about the tubes but like I say I just wanted to know the other possibilities, it just sounds like a total loss in volume, no difference in tone as such.

    I'll give that a go too thanks. :)
     

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