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Has anyone made an Attenuator?

Discussion in 'DIY Effects Forum' started by BDON67, Sep 5, 2019.

  1. albala

    albala Most Honored Senior Member Strat-Talk Supporter

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  2. The Ballzz

    The Ballzz Senior Stratmaster

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    Most resistive attenuation can work OK if at minimal amounts. The more level you attenuate, the more the tone and response can suffer. Also, fully variable units, such as the Weber MiniMass, etc, have "sweet spots" where it sound pretty darned good, but the settings in between are fairly lackluster. Also, on many attenuators, the impedance seen by the amplifier's output can vary widely and wildly which is not so good for the amp! Here's a long read, but details a fantastic stepped switching attenuation system that is inexpensive and easy to build and retains tone/response while keeping a very consistent impedance to the amplifier!

    http://www.marshallforum.com/threads/simple-attenuators-design-and-testing.98285/

    The guy who designed/tested these is regularly available at the Marshall forum for help and advice!

    Just My $.02,
    Gene
     
  3. garyhoos1

    garyhoos1 Huffing n Puffing. Strat-Talk Supporter

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    I have the homemade one on my HRD it's alright at 7 in the bedroom but not quite like the real power or tone of the amps master switch.
    20190907_104746.jpg
     
  4. BDON67

    BDON67 Strat-Talk Member

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    Thanks for the tip! Looks great.. I'm starting out with with a 4-position -6dB,-9.5dB, -12dB, -15.5dB with two 100W at input.. and 7 20W resistors. I can fit it in a 7"x5" box. I'll give it a test and then work on the frequency response.
     

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    Last edited: Sep 18, 2019
  5. fezz parka

    fezz parka Strat-Talk Supporter

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    Those volume boxes aren't attenuators. Its just a pot. They use the effects loop as a kind of master volume. :)

    Attenuators will go between the amp's speaker out and the speaker.
     
  6. 79olympicwhite

    79olympicwhite Strat-O-Master

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    Very useful thread. Thanks
     
    Nate D likes this.
  7. CB91710

    CB91710 This is a Custom Title Gold Member Strat-Talk Supporter

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    That looks great, but using an L-Pad will allow for infinite adjustment range, and simplifies the design/cost. Unless you're trying to tame something over 40w, they work well.
     
  8. BDON67

    BDON67 Strat-Talk Member

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    Thanks... Yeah it would be nice to have a 2ohm L pad.I couldn't find one. I should have mentioned this is for my super reverb. Hopefully attenuation settings will not affect the frequency response beyond what i can correct with tone controls of my guitar and amp..i'll have this built in a few weeks
     
  9. BDON67

    BDON67 Strat-Talk Member

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    Great article... I'm gonna try something similar. I should be able to roll off the attenuation at higher frequencies and maintain a reasonably flat input impedance with an circuit like this. R3 represents the 2ohm speaker or another resistive stage and speaker. Looks good on paper at least.. EE6124AB-9C97-4DCF-9506-1EF069951416.jpeg
     
  10. BDON67

    BDON67 Strat-Talk Member

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    I plotted the input impedance and attenuation vs frequency in excel...I just picked an L and C value to put me in the ballpark.. need to optimize a bit.. getting the parts in the mail to build a prototype.. hopefully in two weeks..
    68C200AA-D924-40DC-90EB-C8FC3F72E7B6.jpeg
     
  11. Nate D

    Nate D Most Honored Senior Member

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    No, but I can build a water impulse charge in about 2 minutes if supplies are on hand. :)
     
  12. BDON67

    BDON67 Strat-Talk Member

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    I really appreciate the comment and link... looks like a simply high-pass network needs to be built into the attenuator... do you have a "ballpark" idea of which frequencies need to pass.. 1KHz.. 2KHz.. 10KHz?
     
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