18 watt Tone Control Problems

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by wavey63, Jun 12, 2008.

  1. wavey63

    wavey63 Member

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    I just built a Weber 18 watt kit and love it exept for 2 problems I am now having with her. First, the tone controls on the tmb side do nothing. Well, the bass does a bit but treble and mids are fr show only. What should I check to fix that? Also, with 12AX7's in V1, V2 and V3 the gain is too much. I have swapped V3 for a 12AT7 and that seemed to help a bit but is there anything I can do to the boarsd to lower the gain? I have a few mods I wanna try but want to get all things in order before I procede. Thanks!:Spank
     
  2. phsyconoodler

    phsyconoodler Member

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    You have something mis-wired.Recheck your work and see what's amiss.
    Try the 12AT7 in V1.Or try a 12AY7 or 5751 instead.
     
  3. PRNDL

    PRNDL Member

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    I'd recommend checking grounds, which can be a problem when bolts are used on painted chassis.
     
  4. Mastervolume

    Mastervolume Member

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    You can also change the PI values to lower the overall gain try changing the 470K 820 470K 47K to 1m 470 1m 56K

    You do have a wire in the wrong place if your tone controls aren't working. retrace everything and check to make sure all of your grounds are connected.
     
  5. awallace

    awallace Member

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    Don't worry about the gain until you get the tone controls working correctly... it sounds like the tonestack may be bypassed somehow hence the increased gain. Go over your work carefully a section at a time comparing with the schematic- you'll find the error.

    regards,

    gtrguy
     
  6. Nolatone Ampworks

    Nolatone Ampworks Silver Supporting Member

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    +1 on this and also what PRNDL said.

    A lot of what the tone stack does is dump certain frequencies to ground based on pot settings. If you have a bad ground, the desired parts of the signal aren't getting to ground as they should be and the gain could be affected by that.
     

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