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Fender princeton 112 solid state too loud!!

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  • Fender princeton 112 solid state too loud!!

    I have a friend who uses amp in a local folk band with a greek bouzouki and sometimes guitar. My friend really like this amp and wants to avoid getting rid of it

    He says the volume is too harsh. Its either off of really loud. He wants me if possible to mod it to get more control
    I aint yet had a look, But if i was change the pot value or type would that help or changing the resistor on the input

    any takers on this

    Bassman1965

  • #2
    It's quite possible that the volume pot might be a linear taper. Amp makers sometimes do that to make the amp look more powerful. You try it out in the music store, and it's rattling the windows with the volume only at 2! Imagine how loud this mighty amp is going to be on 10... The answer of course is "pretty much the same as it was on 2"

    So basically replacing it with a quality audio taper pot might well fix the issue.
    "Enzo, I see that you replied parasitic oscillations. Is that a hypothesis? Or is that your amazing metal band I should check out?"

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    • #3
      Thanks steve

      The sort of thing i can buy from cpc i guess

      Comment


      • #4
        Yeah, CPC or Farnell should stock something suitable. Pots come in dozens of shapes and sizes, so you'll have to do your homework to make sure the new part will physically fit. There are a few authorised Fender service people who hang around here and could maybe tell you more.
        "Enzo, I see that you replied parasitic oscillations. Is that a hypothesis? Or is that your amazing metal band I should check out?"

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        • #5
          The control pot is a 50K ohm 30 C type.
          Here is the description POT- BRACKET MOUNT 50K- 30C REVERSE AUDIO TAPER, SMOOTH 1/4" D SHAFT. ORIGINAL FENDER PART NUMBER 0038658000
          Used in Princeton® 112+, Bassman 25, Princeton 65 DSP/650, and Acoustasonic Jr. amplifiers manufactured from '95-'07)
          If it was mine I would ,first, verify that the control pot works properly.
          It may be faulty.
          Here is the schematic: http://support.fender.com/schematics..._schematic.pdf

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          • #6
            Further inspection of the schematic has revealed the Dirty channel treble pot is a 100K 30C & the bass pot is 250K 30C.
            Maybe try one of them in the clean volume spot.
            100K part #: 0037324000
            250K part #: 0040552000

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            • #7
              This is "reverse audio" taper, even worse than linear. :O I would definitely try replacing it with an audio (aka log) taper part.
              "Enzo, I see that you replied parasitic oscillations. Is that a hypothesis? Or is that your amazing metal band I should check out?"

              Comment


              • #8
                The dirt channel volume is a plain old voltage divider, but the normal volume and the dirt gain controls are feedback resistors around op amps, so value matters, as they work against other resistors.
                Education is what you're left with after you have forgotten what you have learned.

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