LM386 Amp with 4 Ohm Speaker

[tubbytwo]

All schematics show an 8 Ohm speaker. Any change in parts to use a 4 Ohm speaker?

 

[audioguru2]

Hi Tubby,
The datasheet shows how inefficient the LM386 is with a 4 ohm load.
It can supply only a whopping (hee, hee ;D) 300mW to a 4 ohm speaker with fairly high distortion.
With a 6V supply. it would get hot at only 300mW output.
With a 9V supply, it would be even hotter but the max output power of only 300mW doesn't increase.

Find a more powerful amp IC. Four ohm speakers are used in cars. Philips and ST Micro make about 140 amp ICs for cars. I use a National Semi amp IC that is obsolete now but it drives my 4 ohm speaker to 4.8W at very low distortion with a 7.2V supply. ;D

View attachment 38017

 

[tubbytwo]

Hey thanks. I use 8 Ohm speakers, but was just curious. It  drives a small 4" speaker for a xtal radio. Works just fine.