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LM386 and 4 Ohm 3W speaker poor audio quality

feyen206

New Member
I have an LM386 and a 3w 4 Ohm speaker, and I've tried every possible schematic, and nothing seems to work. The sound quality is poor when I make the speaker audible, by turning the volume up. What should I do?
 

Nigel Goodwin

Super Moderator
Most Helpful Member
Give more details - like how have you built it, what are you putting through it etc.

The LM386 is a well used and reliable component, so it's pretty well down to what you're doing.
 

ronsimpson

Well-Known Member
Most Helpful Member
The sound quality is poor when I make the speaker audible, by turning the volume up. What should I do?
Man goes to the doctor; "Every time I do this it hurts".
The doctor: "Then stop doing that".
Stop turning up the volume. Or choose a pleasant kind of music. I am the funny man.
We need to know much more information. Pictures? Drawings?
 

audioguru

Well-Known Member
Most Helpful Member
What is your power supply voltage and is it stable?

The datasheet for the LM386 shows that with a 4 ohm speaker then it produces more power heating the IC than power in the speaker.
When the power supply voltage is 9V to 12V then the maximum low distortion power in a 4 ohm speaker is 0.26W. With an 8 ohms speaker the power is 0.45W when the power supply is 9V and the power is 0.54W when the power supply is 12V.
 

audioguru

Well-Known Member
Most Helpful Member
Instead of the low output power and high heating of an old LM386 in a 4 ohm speaker, why not use a modern PAM8403 Stereo amplifier? Each output produces 2.5W at low distortion in a 4 ohm speaker when its power supply voltage is only 5V. An assembled amplifier is available cheaply on ebay but the IC might be a fake.
 

unclejed613

Well-Known Member
Most Helpful Member
looking at the [data sheet] something that's missing are any distortion or power measurements for 4 ohm operation. when this happens in a data sheet (it also occurs in spec sheets for AV receivers and other audio amplifiers) it usually means "you can use a 4 ohm speaker with this amplifier but it might not give good performance". i know this is somewhat "reading between the lines" on a data sheet, but omitting performance data for edge cases is very common, especially with audio. AG is correct, if you must drive a 4 ohm speaker and expect better performance, use an amplifier IC that is designed for it, and has performance data for 4 ohm operation. the LM386 was originally designed at a time when almost all small low power speakers were 8 ohms. handheld AM/FM radios, walkie-talkies, portable cassette players all used small 8 ohm speakers between 3 and 5 inches in diameter. these days there are surround sound speakers that are 4 ohms, and are almost as common as 8 ohm speakers. manufacturers do this because with 4 ohm speakers it gives the advertising department higher wattage numbers to publish in the spec sheet.

you still haven't posted a schematic or description of how you are using the LM386. if you have the gain preset at 200, and a line level input signal (like what you get out of a phone or a DVD player) then you will get nothing but distortion. if you knock the gain back down to 20, you will get more headroom before the LM386 goes into clipping.
 
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