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Discussion in 'Troubleshooting and Repair' started by rosa, Feb 11, 2012.

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  1. rosa

    rosa

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    Dec 12, 2011
    I am repairing an old mixer and it uses 5meg pot for the volume control of each channel. Would a 2 meg pot work instead? Also, how can I be certain that these are logarithmic pots and not linear?


    thanks
     
  2. Rleo6965

    Rleo6965

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    Jan 22, 2012
    Try using 2meg pot. If not satisfied with sound result. Series 3meg resistor to 2 meg pot.
    You can try these combination 3m then the pot or 1.5m - pot- 1.5m or pot - 3 m. depends of volume you of preamp you need.


    Buy 2 meg pot with same for letter written on original pot body. ( A or B)
     
    Last edited: Feb 11, 2012
  3. davenn

    davenn Moderator

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    Sep 5, 2009
    and failing that mesure it with a multimeter in resistance mode.
    a log pot will change in reading quickly as you turn the shaft, a linear one will change in value "evenly" as you trun the shaft

    Dave
     
  4. rosa

    rosa

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    Dec 12, 2011
    cool, thanks
     
  5. rosa

    rosa

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    Dec 12, 2011
    If a pot in the half way position gives half the resistance value of its total 50k resistance, can I assume it is linear?
     
  6. Rleo6965

    Rleo6965

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    Jan 22, 2012
    Probably. But it's much better if you take the advice of Davenn . Connect your multimeter probe to terminals of potentiometer and observe multimeter reading corresponding to the shaft movement. This more accurate to determine correct type of pot.
     
  7. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Jan 21, 2010
    Almost certainly.

    In fact that was what I was going to suggest earlier, but I noticed you already had plenty of suggestions and I didn't think it was worth adding to any possible confusion. :)

    edit: there are some really weird tapers that may exhibit this, but be non-linear either side of it, however the chance of finding one of these is pretty unlikely. davenn's suggestion is a generalisation that will work, but you do have to know what you're looking for. Confirming it's linear or not is the easiest option though.
     
    Last edited: Feb 12, 2012
  8. Rleo6965

    Rleo6965

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    Jan 22, 2012
    I think most Linear pot was use for volume control and balance control for audio equipment. Non-linear is for Tone control? or the other way around?:confused:
     
  9. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,490
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    Jan 21, 2010
    Log pots are typically used for volume controls.
     
  10. Raven Luni

    Raven Luni

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    Oct 15, 2011
    I discovered that when I put linear pots in my bass guitar - now I have a tiny useful zone :p
     
  11. rosa

    rosa

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    Dec 12, 2011
    two more questions

    It seems that they are linear.

    how are audio or logarithmic potentiometers built to achieve their function? physically, what is the difference with the linear pot.

    also, I have disassembled the pots, cleaned and reassembled. they are well built so it was easy to do. Is it OK to apply a dab of mineral oil. Can anyone recommend something to lubricate them? I have read answers to this in other forums, but there seems to be a confusion between cleaning and lubing.

    thanks
     
  12. shiekh

    shiekh

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    Oct 11, 2010
    I have been know to use silicone oil, but I would avoid mineral.
     
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