Replacing volume pots on a Fender

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by ABKB, Jul 28, 2005.

  1. Jul 28, 2005 #1
    ABKB

    ABKB Member

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    Hello all, could use some help here. I have a Fender hot rod Deville (yeah I know it's a cheaper tube amp, but at least it's tube lol) and the main problem I am having is the volume goes from soft to ear splitting. Well I ran across this comment on a Fender board the other day,

    "simple fix... shouldn't turn you away from the amp. they ship stock with linear volume pots, you need audio taper. they do this because they can buy them cheap, and it gives the perception of more power. (wow, it's only on 3 and it's THAT loud?) the audio taper will be more smooth, but able to achieve the same volume.... it just will come later in the dial

    Problem is, I dont know which audio taper pot I need to do this. The board I found that on is a pretty deserted one, so, could somebody lend me a hand here? Thanks!
     
    ABKB, Jul 28, 2005
    ABKB, Jul 28, 2005
    #1
  2. Jul 28, 2005 #2
    unclej54

    unclej54 Guest

    look at the existing pots and see what they're rated at..on the back of them they'll say 250k, 500k or maybe even 1 meg. just buy the same rated pot in an audio taper, wire them up just like the existing ones and you're good to go.
     
    unclej54, Jul 28, 2005
    unclej54, Jul 28, 2005
    #2
  3. Jul 28, 2005 #3
    ABKB

    ABKB Member

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    Will do that. Thanks unclej54
     
    ABKB, Jul 28, 2005
    ABKB, Jul 28, 2005
    #3
  4. Jul 28, 2005 #4
    unclej54

    unclej54 Guest

    you're welcome and good luck.
     
    unclej54, Jul 28, 2005
    unclej54, Jul 28, 2005
    #4
  5. Jul 28, 2005 #5
    Normster

    Normster Member

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    I just checked the schematic for my Blues Deluxe. (Should be the same for the HRD.) It looks like it already uses a 250k audio taper. You might be wasting your time trying to replace the pot.

    If you do replace it, keep in mind that the pot is mounted to a PC board so you'll have to get the same size (16mm or 24mm?) and make sure to get the PC mount style rather than the solder lug style.
     
    Normster, Jul 28, 2005
    Normster, Jul 28, 2005
    #5
  6. Jul 28, 2005 #6
    Wakarusa

    Wakarusa Member

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    Not quite right...

    There are three volume pots on a Deville, "volume", "drive" and "master". The drive and master are only in the circuit when you select "drive" or "more drive" on the controls/footswitch.

    The volume and drive pots are already 15% audio taper, the master is a linear taper. (the other linears in that amp are, BTW, the middle tone control and the reverb mix control)

    Your issue, I would think, is the sensitivity of the volume pot. That is, when you start to turn it up, what is the minimum resistance presented to the circuit when it starts to drive things. Cheaper pots (like Fender is using these days) tend to be less sensitive with a higher initial resistance and a tad sloppy in how much their resistance changes as you turn 'em. Another option is to look for a pot with a "higher" taper (greater than 15%), but I don't think they're all that common.

    If you really want fine control, you can always replace the volume pot with a 250K multi-turn precision potentiometer ;)
     
    Wakarusa, Jul 28, 2005
    Wakarusa, Jul 28, 2005
    #6
  7. Jul 29, 2005 #7
    TheAmpNerd

    TheAmpNerd Member

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    Todd,

    Would you wouldn't be suggesting something like
    a bornes 10-turn, board-mounted, precision pot
    would you?

    I can just see it now, "hang on guys, just three more
    turns and I'm there!"
     
    TheAmpNerd, Jul 29, 2005
    TheAmpNerd, Jul 29, 2005
    #7
  8. Jul 29, 2005 #8
    ABKB

    ABKB Member

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    After looking into this some more, the post about it being on the pc board is correct, that would have to be some fine work as I have heard those break easy. Also, the 250 audio taper would be a waste as the clean volume already uses one while the master uses something else, both are way sensitive the first 1/3 of the turn. So I would need a 500K audio taper. My worry now is how much that would affect my tone as well as finding somebody I trust to do the work. It's not something I would touch. Long story short, thanks guys, between what you all have told me and what I have learned, I know what I need to do, now it's just a question of who and if. Thanks all! :dude
     
    ABKB, Jul 29, 2005
    ABKB, Jul 29, 2005
    #8
  9. Jul 29, 2005 #9
    Wakarusa

    Wakarusa Member

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    Actually, the 500KA may be less sensitive (more abrupt onset of volume) than the 250KA. Something you might consider doing is rolling your own 250KA by starting with a linear pot and using a bypass resistor to set the taper (something like 30-40% might be fun).

    If memory serves R.G. Keen has a pretty good explanation of how to do that here
     
    Wakarusa, Jul 29, 2005
    Wakarusa, Jul 29, 2005
    #9
  10. Jul 29, 2005 #10
    ABKB

    ABKB Member

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    Thanks, I will check it out.
     
    ABKB, Jul 29, 2005
    ABKB, Jul 29, 2005
    #10

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