A couple of posts got me to thinking. Rather than hijack their posts (and then slapping my hand) I figured I'd start this one.

Audio amplifier circuits are going to be with us always. They are one of the logical first circuits any beginner would make. They would likely also be stereo.

So what is a good minimum speaker for a beginner? I have a box of cheap speakers, including the ever popular 1½" special transistor radios used to use. Because it was available when I was growing up I tend to lean toward 8Ω.

What would you guys suggest?


While I am on the subject lets go over good specs for a amplifier. It should have 600Ω input impedance (a common standard) and a minimum gain of 100, possibly 1000?

I am starting this thread to help folks new have a rule of thumb to work with. This is not for any specific project.

 

Not many beginners have an expensive 600 ohms Shure dynamic (coil and magnet)performers microphone.
Instead they have a cheap electret mic that needs a preamp with a gain of about 50 and an input resistance of 27k or more.

Most line level sources need a power amplifier (1W or less into 8 ohms) with a gain of about 30 and an input resistance of 10k ohms.

When the total gain is too high then the amplifier is very sensitive. A volume contol can reduce the output level if it is too high.

There are some inexpensive good-sounding 4" speakers available.

 

So these 4" speakers, 8Ω?

I've seen my share of 2Ω and 4Ω besides.

For those who want a mic, electret should have a preamp. I would define it as a requirement.

 

Most home speakers are 8 ohms. Car speakers are 4 ohms and 2 ohms.