How many watts can the STK4221II IC output at 4 ohms?

[techgeek72]

The STK4221II IC can output 80 watts at 8 ohms.

How many watts can the STK4221II output at 4 ohms?

 

[KatieandDad]

The datasheet only specifies the output at 8 Ohms = 80W.

I would summize that it can't go as low as 4 Ohms.

 

[FoMoCo]

Most likely it will run out of current, so a good estimation is one half rated power into half the impedance. You'd also want to use the lowest supply voltage possible as the extra voltage only produces extra heat.

While it's not true that it can't handle a 4 ohm load, it will be severely limited in power output. It may even die if not fully protected and you do something dumb with it. You'd be better off with a better match to your load.

 

[KatieandDad]

Can you substantiate how it will handle a 4 Ohm load ?

 

[AudioSan]

as long as one don't know the current limit, this will all be guessing.

 

[KatieandDad]

Unfortunately the datasheets are very poor. The STK4122 II was specified at 80W / 8 Ohm. There might be other information available with user instructions from units that used these chip amps.

 

[FoMoCo]

as long as one don't know the current limit, this will all be guessing.

Very true. But a safe assumption is that maximum output into 8 ohms is also close to current limit. It's probably a bit more, but short of measuring it, we don't know.

Can you substantiate how it will handle a 4 Ohm load ?

Yes. Just take a course in electronics.

 

[KatieandDad]

I've got a degree in electronics.

As AudioSan stated, you can only suppose.

If the output devices are running at maximum current iaw with the datasheet then the maximum power will be halved.

You could always add your fuses to see what blows first.

 

[FoMoCo]

If the output devices are running at maximum current iaw with the datasheet then the maximum power will be halved.

I'm pretty sure I already said that before you made your remark about me needing to substantiate my claim.