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Why does my lm386 headphone amp sound like butt?

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  • Why does my lm386 headphone amp sound like butt?

    I posted this over on the BYOC board but no one's replied. Thought I'd try my luck over here...

    In order to avoid a knock on my door while I'm testing pedal builds late at night I decided I'd throw together a little lm386 based headphone amp. It's a ruby with a j201 preamp since that's what I had on hand. The pre into my deluxe sounds nice, but the lm386 power section into my 'phones sounds awful. It's fuzzy as all get out. Could it be an impedance issue? My phones are 32ohms and only one speaker is wired up giving the lm386 a 64ohm load. Should I ditch the 386 and use a dual opamp like a 5332? Here's a link to info on the ruby,Ruby.

  • #2
    What is the voltage at pin 5 of the LM386 and the three pins of the J201?
    WARNING! Musical Instrument amplifiers contain lethal voltages and can retain them even when unplugged. Refer service to qualified personnel.
    REMEMBER: Everybody knows that smokin' ain't allowed in school !

    Comment


    • #3
      You are listening to unfiltered signal straight-to-headphone.
      Buzzy as h*ll by definition.
      Same signal into a guitar speaker will be reasonably smooth.
      By the way, if you are testing pedals, lose the FET, straight drive the LM386 with them.
      For better control replace B10K pot with A100K , much smoother and useful control range and at normal settings (not higher than 5 or 6, they will "see" a higher impedance.
      And use it in the lowest gain setting, no pot/capacitor between 1-8 pins.
      You want to listen to what your pedals do, avoid overdriving the test amp.
      Even so, always remember you are not listening through a guitar speaker.
      Juan Manuel Fahey

      Comment


      • #4
        Originally posted by J M Fahey View Post
        You are listening to unfiltered signal straight-to-headphone.
        Buzzy as h*ll by definition.
        Same signal into a guitar speaker will be reasonably smooth.
        By the way, if you are testing pedals, lose the FET, straight drive the LM386 with them.
        For better control replace B10K pot with A100K , much smoother and useful control range and at normal settings (not higher than 5 or 6, they will "see" a higher impedance.
        And use it in the lowest gain setting, no pot/capacitor between 1-8 pins.
        You want to listen to what your pedals do, avoid overdriving the test amp.
        Even so, always remember you are not listening through a guitar speaker.
        I have the get so I ca switch it out so I can get a comparison clean tone, but thanks for the advice. So how to I fiter the signal to clean it up when listened to in headphones?

        Comment


        • #5
          Originally posted by cooldude666 View Post
          I have the get so I ca switch it out so
          Sorry, what does this mean?
          Probably a typing error?
          I can get a comparison clean tone, but thanks for the advice.
          How do you listen to the "clean tone?"

          So how to I fiter the signal to clean it up when listened to in headphones?
          Once distorted you won't clean it again.
          But going through a speaker rounds/smooths it.
          You'll need a "speaker simulator" circuit.

          EDIT: and of course do not drive your LM386 so hard that *it* clips.

          Look at what Marshall Valvestate or Mesa Boogie VTwin use.
          Juan Manuel Fahey

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          • #6
            [QUOTE=J M Fahey;332645]Sorry, what does this mean?
            Probably a typing error?
            [/QUOUTE]
            My tablet autocorrected FET to get. Whoops.
            How do you listen to the "clean tone?"

            Originally posted by J M Fahey View Post
            Once distorted you won't clean it again.
            But going through a speaker rounds/smooths it.
            You'll need a "speaker simulator" circuit.

            EDIT: and of course do not drive your LM386 so hard that *it* clips.

            Look at what Marshall Valvestate or Mesa Boogie VTwin use.
            Thank you

            Comment


            • #7
              I've never experimented with an LM386 much but I suspect the output might go crazy when one of the inputs goes too far below ground (or the negative rail). I know the LM324 does this.
              WARNING! Musical Instrument amplifiers contain lethal voltages and can retain them even when unplugged. Refer service to qualified personnel.
              REMEMBER: Everybody knows that smokin' ain't allowed in school !

              Comment

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