Basic stuff -- Building an audio amp

[algernon83]

Hey there -- I'm a computer programmer starting to dabble in electronics. I recently acquired a very nice center speaker that draws too much power for my stereo receiver. Can someone please point me in the right direction to learn how to build an amplifier to let me use this thing?

 

[carbonzit]

Little more information, please? Size of speaker; impedance (in ohms); desired power level (100 mW: 1 W? 10 w?); input level; power source?

You wouldn't design a program without specs, would you? Same thing applies here.

 

[algernon83]

Unfortunately the reality of the business world very often requires programming with absent or incomplete specs!

But I don't need to subject you to that. I'll post that info when I get home from work. All I know off the top of my head is it's an 8ohm speaker with no additional power source; I don't recall its power draw or the output of my receiver -- except that the former is more than the latter. Thank you.

 

[carbonzit]

We need to know the power source you intend (or want) to use for the amplifier: batteries? wall wart? dedicated power supply?

 

[algernon83]

Oh, I gotcha. My plan is to use a wall wart, unless it would be a lot better to make a dedicated power supply.

I've got a decent collection of wall warts from 5-30v from scrounging thrift stores for parts, but I don't know how to pick which one to use. I don't know if this is a "bigger is better" scenario or a "bigger will set my house on fire" scenario.

 

[crutschow]

Hey there -- I'm a computer programmer starting to dabble in electronics. I recently acquired a very nice center speaker that draws too much power for my stereo receiver.

What do you mean it "draws too much power for my stereo receiver". Have you actually tried it or are you just going by the speaker rating versus the amp rating?

A speaker rating is just a maximum power it can tolerate without blowing and has nothing to do with how much it takes to drive the speaker. That's a function of speaker efficiency and is not directly related to the power rating. Many high power speakers have good efficiency, sometimes even better than a low power speaker.

 

[algernon83]

Yes, I've tried it, and I suppose I'm just *assuming* power draw was the problem. When I try to use the center channel, it works for about two seconds, then the receiver's protection circuit is engaged and I have to reset it. (For right now I'm just running off of the corner channels to avoid the problem.)

 

[crutschow]

That sounds like there's a short somewhere.

 

[audioguru]

Firstly you said you have a stereo receiver (it has only 2 channels, left and right).
Then secondly you have "corner" outputs for maybe surround speakers and maybe you even have an amplifier output that drives a center speaker.

If the receiver actually has an amplifier output that can drive an 8 ohm speaker then it should work fine.

 

[carbonzit]

Firstly you said you have a stereo receiver (it has only 2 channels, left and right).

They said they had a receiver, but not that it had only two channels. Just because you're stuck in the 1970s doesn't mean that everyone else is too.

 

[algernon83]

crutschow, you got it! There was a single strand from the wire at the positive terminal of the speaker touching the wire at the negative terminal. (I should really put plugs on these wires.) Thanks a lot, all!

BTW, audioguru -- I carbonzit is right; I was using "stereo" in the colloquial sense, i.e. referring to a sound system in general.

 

[audioguru]

My Reply With Quote gave an error that it was too short with not enough characters. But it was two or three fairly long sentences so I give up trying to quote.

 

[Mr RB]

AudioGuru, "Reply with quote" doesn't work properly on my old computer either.

What i do is use the button "Reply" (that is in the bottom of the person's post) which still puts the person's quote in there anyway. That works.

 

[audioguru]

All of a sudden our "old" computers don't work here anymore since this site upgraded its software?
My browser is the latest IE9 from Microsoft. It works fine on all the other electronics chat sites except at EDAboard where it has different problems lately.

This is a Normal Reply and I hope it works.

 

[crutschow]

.....I was using "stereo" in the colloquial sense, i.e. referring to a sound system in general.

In the even older days it was called a HiFi.