LM386 in series

Discussion in 'General Electronics Chat' started by lokeycmos, Apr 3, 2011.

  1. lokeycmos

    Thread Starter Active Member

    Apr 3, 2009
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    would it work to put 2 LM386 amps in series to get double the output?
     
  2. beenthere

    Retired Moderator

    Apr 20, 2004
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  3. Audioguru

    New Member

    Dec 20, 2007
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    The output power of a single LM386 amplifier at clipping into 8 ohms with a 6V supply is 0.2W. The output power of a single LM386 amplifier at clipping into 8 ohms with an 8.2V supply is double at 0.4W. Simply increase the supply voltage for more output power but above a 9V supply the output power barely increases but the heating increases a lot.

    Maybe you are talking about putting two amplifiers in a bridge to nearly quadruple the output power like most car radio amplifier ICs do.
    But an LM386 has low max output current so it results in nearly 4 times the heating in the ICs and barely any more output power.
     
  4. lokeycmos

    Thread Starter Active Member

    Apr 3, 2009
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    i built this circuit as an acoustic guitar amp for a friend. it works well, but he wanted it to be about 2 to 3 times louder. i chose this circuit because of its simplicity. i shorted pin 1 to 8 for max gain but he wants more. any suggestions?
     
  5. R!f@@

    AAC Fanatic!

    Apr 2, 2009
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    Ya !! go for TDA2030
     
  6. Audioguru

    New Member

    Dec 20, 2007
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    You don't show a supply voltage so I guess it is 9V and then its output at clipping is only 0.45W.
    Our hearing is logarithmic so we can hear a pin drop and also hear closeby jet airplanes. So 2 times the loudness needs 10 times the power. 3 times louder needs 32 times the power.
    It will probably create acoustical feedback howling.

    There are about 120 audio amplifier ICs made today. The TDA2030A produces 12W into 8 ohms when it has a plus and minus 16V supply. Its circuit can have as much gain as you want.
     
  7. lokeycmos

    Thread Starter Active Member

    Apr 3, 2009
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    darn, im out of ideas, it needs to be portable
     
  8. Audioguru

    New Member

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    Use a car radio amplifier IC that is bridged with two amplifiers. One amplifier drives one end of the speaker and the other amplifier drives the other end of the speaker. Then the power is about 3.5 times higher than the power of a single amplifier into the speaker with the same fairly low supply voltage.

    A TDA7240A IC has an output at clipping with a 12V supply (10 AA Ni-MH rechargeable cells) of 10W into 4 ohms and is 6W into 8 ohms. A recommended pcb design is in the datasheet.
     
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