As I already said a 386 will drive an 80W speaker but with only 1W.
You can always drive a speaker with a lower power but not the other way around.
Did your teacher say you needed 80W of power?
Maybe your teacher is testing you to see how smart you are.
The sensitivity/efficiency of a speaker isn't necessarily related to its maximum power rating. An 80W speaker isn't necessarily "weaker" than a 1W speaker.
An LM386 by itself should be loud enough to hear anywhere in the classroom, etc., unless there is a lot of noise in the room.
If the assignment actually requires you to boost it, it's easy to make a transistor "driver" like you'd use to drive a motor or relay for a "digital tone" like you get-out of a regular Arduino.
It's NOT so easy to make a "clean" linear boosted amplifier for speech or music. And, a driver can be driven directly from the Arduino without the LM386.
You could try All About Circuits. They can be helpful.
Or if feeling brave, Stack Exchange.
The clue is in the name, Arduino Forum.
You are just after a ready made solution for a school exercise.
If it helps, try Googling "boost output of LM386". Plenty to look at there.
Also, the datasheet https://www.ti.com/lit/ds/symlink/lm386.pdf, gives you information like what voltage to use and states that typical output is 700-mW. It's pretty clear that's way short of of 80-watts.
There's also a limit on running without adequate power dissipation.
It depends on how you interpret the question. As I look at it 80W 8Ω is a speaker specification and nowhere does it say to drive it at its capacity. Look at the data sheet and pick the optimum quality point and design for that and state in your documentation that is what you did.
Edit: lm386 is not paricukarly handy to drive a push pull transistor output. Max voltage is 18V.
So around 14V peak to peak. At 8 ohms that is less than 2 A and less than 28W...
So your teacher is preparing you for the future with a 50+ year old dinosaur chip.
This is 2025. Class-AB (post#15) is dead. Expensive parts, big (expensive) heatsinks, inefficient.
Nowadays we would use class-D amplifiers, like the PAM8403.
A 20W class-D amp would fit in a matchbox.
Leo..
The TL071 is regular op-amp with "infinite gain" before adding negative feedback (R2 & R3) to control the gain and reduce distortion.
The LM386 (apparently) also has high open-loop gain but it has internal feedback preventing open-loop operation. And that prevents you from putting the transistors inside of the feedback loop, and allowing them to introduce distortion.
I don't particularly "like" that other circuit either... But maybe the designer knows more than me and I haven't tried it. Also it's running from +/-V and you've (apparently) only got +30V.
If they are the exact words for your task, it does not say you have to get 80W performance out of the speaker.
The speaker when connected to the 385 will not "SUCK" 80W out of the 386.
The power will be what the 386 can SUPPLY to the speaker as an 8 Ohm load.
The 80W spec is how much power you can feed the speakerbefore it has overload problems.
Any circuit ideas or advice would be really appreciated.
