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Discussion in 'Troubleshooting and Repair' started by Mr.fix it_101, Nov 29, 2017.

  1. Mr.fix it_101

    Mr.fix it_101

    30
    5
    Apr 11, 2015
    Hi everyone;
    I designed a music system using the Lm386 IC. the problem is that when I turn up the volume POT, the sound gets distorted and sounds awful. no connection is between pins 1 & 8 as shown in the diagram. I used two computer speakers and power it using a 6 volt adapter. how can I get a clean sound at high volume?
     

    Attached Files:

  2. dorke

    dorke

    2,342
    664
    Jun 20, 2015
    How did you use the computer speakers ?
    They are usually powered units.
    Please explain.

    You can't get high power from the LM386 at best it is a 1W amp.
    Powering it with 6V you can get about 0.25W at 1% distortion.
    This will very quickly rise to 10%(awful quality) at 0.4W.

    You may be able to improve what you have like so:
    Put the volume pot. at minimum volume.
    Check the DCV on the "input jack tip side" of the pot. relative to GND(with your source connected !).
    If you get any DC voltage you should use an input blocking capacitor(this I would add anyways,since you can connect various sources in the future).

    Another thing you can do is take a photo showing your actual build and post it here.
     
  3. davenn

    davenn Moderator

    13,327
    1,769
    Sep 5, 2009

    use a better audio amplifier chip

    do a search on ebay for audio amplifier modules .... there's a zillion of them to choose from
     
    Mr.fix it_101 likes this.
  4. Mr.fix it_101

    Mr.fix it_101

    30
    5
    Apr 11, 2015
    The computer speakers did not have the original circuit board when I got it. only the wires, case and speaker. but thanks for the response
     
  5. dorke

    dorke

    2,342
    664
    Jun 20, 2015
    There are a few routs to take.

    Please answer thes questions,so we can guide you:

    1. Why do you use 6V,what feeds it,why not higher?
    2. What audio wattage do you need ?
    3. What quality do you need?
     
  6. Audioguru

    Audioguru

    2,618
    593
    Sep 24, 2016
    Computer speakers are cheap little things and are not capable of providing clean sound at high volume. Of course the LM386 powered from only 6V produces distorted awful sounds when you turn the volume higher than only 0.25W which is as loud as a whisper.
     
  7. Mr.fix it_101

    Mr.fix it_101

    30
    5
    Apr 11, 2015
    1. An adapter is what currently feeds power to it. secondly, I want it to be powered from USB as well, which is 5volts.
    2. I need around 15W
    3. I need clean undistorted and crackling free sound whenever I attempt to increase the POT
    Remember that i'm not an expert so I need you guys help. Its a project i am working on
     
  8. Mr.fix it_101

    Mr.fix it_101

    30
    5
    Apr 11, 2015
    I might eventually end up going with davenn's suggestion. "use a better audio amplifier chip"
     
  9. Audioguru

    Audioguru

    2,618
    593
    Sep 24, 2016
    15W into an 8 ohm speaker is a signal that is 11V RMS or 31.1V peak-to-peak. From 5V USB? No way. When an older amplifier supplies 15W to a speaker, the amplifier heats with about 14W so the power supply must produce 15W + 14W= 29W. USB can supply maybe 200mA at 5V which is only 1W. A 15W modern amplifier operates in class-D (switching) so its heating is only about 1W then the power supply must provide 16W.
     
    Mr.fix it_101 likes this.
  10. turbogt16v

    turbogt16v

    173
    4
    Mar 27, 2015
    U can use the power from your pc case,4 pins are usualy 5v or 12v,chech from manual.
    You only need 2 wires,ground and power.
    Buy male and female chasey jack or just connect 2 wires directly.there will be ground loop on high volume.use tv speekers from old tv , they sound better or use the ome u have.if you find old tv there will be better amp chip inside then the one u have,u could use that.

    Then if you like makimg things you could end to something like this
    DSC_0139.JPG
     
    Last edited: Dec 12, 2017
    Mr.fix it_101 likes this.
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