Will S4580P work for a gainclone?

[KrisWood]

Hi everyone,

I'm new to diy audio and looking to build a replacement for my dying stereo. In the interests of not spending any more money than absolutely necessary on my very first amp project I'd like to reuse any parts I can before buying new ones.

I've got some S4580P opamps that came out of my old sound card and I'm wondering, would they work in a gainclone to power 8ohm 20w speakers?

Here's the datasheet:

http://www.datasheetcatalog.org/data...auk/S4580P.pdf

Also, how do you tell if an opamp will be suitable or not?

[pacificblue]

An op amp is not a power amp, so no, the 4580 won't work for you. Whether an IC is suitable to drive speakers will be stated in its datasheet. A Gainclone is built around the LM3875.

[KrisWood]

Thanks for the reply. I guess my question was more, how do you tell? The datasheet just looks like a bunch of numbers to me with none of them meaning anything. Which numbers do you look for to know if it can or cannot drive speakers?

[Mooly]

Originally Posted by KrisWood

Thanks for the reply. I guess my question was more, how do you tell? The datasheet just looks like a bunch of numbers to me with none of them meaning anything. Which numbers do you look for to know if it can or cannot drive speakers?

The physical size of the device is one clue. Anything that can deliver "power" into a low impedance load (speaker) will have some means of clamping it to a heatsink to help get rid of the heat.

The data sheet gives a max output current for the device... 50ma was it ? That tells you it's for small signal work. Speaker current are in the amps region.

Maximum power dissipation of the device, again that tells a lot. 800mw is tiny. Anything up to 100 watts for a power chip is seen.

The devices used in gainclones are in a way just "power opamps" but if you study the data sheets you will see they mention high supply voltages, high output currents, also a minimum load impedance of say 4 or 8 ohms (as against 600 ohms minimum for most opamps).

You need to do a lot more reading I think but keep asking the questions.

[pacificblue]

They usually have something like "Audio Power Amplifier" in the datasheet title.
And there are output power specifications.

[KrisWood]

Thanks Mooly, I'm learning a lot from answers like yours. Each one gives me clues for what to read up on next!