It would be nice to build a newer better Big Ear Listening Device. When I built this circuit I started with one LM386 with a mic but mic was never sensitivity enough to pick up sound far away then i remember experiment we did in college using a speaker as a pick up so I changed mic to speaker and it worked much better up close but still not receiving micro small sounds far away. Second LM386 was an after thought. If TL071 or LF351 or LM741 works better I will build one. I think a dish with a pickup at focal point will work better.There were plenty of opamps back then, even the wonderful 741 is a better preamp than an LM386 - although AG has a serious vendetta against them.
Gary,I tried an experiment & swapped the chinese LM386 m-53 with a 40 year old Radio Shack LM386 n-1 there is no difference in the sound. All circuits I find including data sheet says 10K variable resistor.
I know the LM386 n-1 from radio shack work excellent in the circuit I built 40 years ago. This circuit might not be correct and maybe it could be made better but it works amazing well. The big 8 inch diameter speaker from a 50 year old TV acts like a dish if I aim it a boat on the lake that is
You'd be surprised how many other things around you would swamp that audio intensity.3) Need to be able to hear a pin drop from 1/2 mile.
Notice that doesn't use an LM386 as the preamp!!!!!Look at this circuit. This used a parabolic dish with the mic.
The thing I built 50 years ago used a speaker instead of a dish, it worked good the trick was to slowly turn up the volume until it works. I think anything I build with a mic will need a dish.