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  1. Member
    Join Date
    Apr 2017
    Location
    Hong Kong
    Search Comp PM
    I want to use LM386 (http://www.kynix.com/uploadfiles/pdf2286/LM386M-1.pdf) to drive a 5W 8ohm speaker. But the speaker cannot make a loud sound. So I need your suggestions for making the speaker louder.

    And here are my guesses:

    1.Add a transistor to LM386
    2.Reduce the power of the speaker through the circuit?
    3.Or should I choose another IC to replace LM386?

    I used TDA2005 before, but the 7805 chip was easy to burn during the process. Also it makes a terrible noise.
    Now the sound quality is better by using LM386, but it cannot produce a loud sound...
    I really need your suggestions. Much thanks if you can help me!
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  2. What gain are you using? What supply voltage? It looks like the max output is 250 mW to 1000 mW depending on the version of the chip and the supply voltage. what about using a MAX9737 instead (7 W)?

    Are you doing this as a learning experience? You can buy 5W stereo amps for $5.
    https://www.amazon.com/PM2038-Stereo-Audio-Amplifier-Adjustable/dp/B01NABJTDJ/
    Last edited by jagabo; 21st Apr 2017 at 07:56.
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    • Power the chip with the highest voltage it's rated for (12 or 18 depending on model)
    • Give it a heat sink to make sure it's not thermal throttling
    • Your speaker may be limited in its physical travel by design, & therefore how much sound it can generate.
    • There is a wide range of efficiency between speakers - try as many as you can.
      Better, shop for speakers by published sound output per watt.
      As Wikipedia says here, you definitely don't want a home hi-fi speaker.
    • The right enclosure can make a huge difference. Horn types are the most efficient by far.
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  3. Member
    Join Date
    Mar 2011
    Location
    Nova Scotia, Canada
    Search Comp PM
    As jagabo mentions, if you look at the link for the amp chip, it has an output of about 200 milliwatts before the power vs. distortion curve starts going up a cliff. Just take a look at the graph for power vs. distortion.

    That isn't going to get much volume from most speakers. That driver being 5W is irrelevant to how loud it is though many seem to think that matters. What matters is the sensitivity in dB (though that spec is not very reliable) and its impedance. If you use a speaker that has too low impedance for the amp the amp will crap out easily.
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