LM386 audio amplifier
LM386 audio amplifier
(OP)
I'm trying to make a small audio amplifier using an LM386N-3 IC from National. 700 mW max output.
I have a small loudspeaker, 4 ohm, 700 mW max power.
I connect the IC like indicated in the datasheet, with a gain of 20. I get lots of distortion, even at low levels.
I'm using the schematic indicated in the datasheet as 'Amplifier with gain 20 minimum parts'.
I found out that with earphones (135 ohm) there is no distortion, so I put a 56 ohm resistor in series with the load and it works ok, but the sound level is dramatically reduced. If I go lower then 56 ohm I get distorsion.
Any idea?
I have a small loudspeaker, 4 ohm, 700 mW max power.
I connect the IC like indicated in the datasheet, with a gain of 20. I get lots of distortion, even at low levels.
I'm using the schematic indicated in the datasheet as 'Amplifier with gain 20 minimum parts'.
I found out that with earphones (135 ohm) there is no distortion, so I put a 56 ohm resistor in series with the load and it works ok, but the sound level is dramatically reduced. If I go lower then 56 ohm I get distorsion.
Any idea?
RE: LM386 audio amplifier
What are the frequencies that you are trying to reproduce? The 250uF cap with the 4-ohm load creates a high-pass filter with a knee at about 160Hz, so your gain below that is going to drop off rapidly.
Have you scoped the power supply pin to see if it is being pulled down by the load?
Glenn
RE: LM386 audio amplifier
RE: LM386 audio amplifier
Anyway, glad to hear you solved the problem.
Glenn