Dumb Q: What voltage to speakers ?

[Peter Galbavy]

I cannot find a definitive answer but there must be some standard else amps and speakers from different manufacturers would never work.

What is the voltage range that power amps drive speakers with ?

I know that the sensitivity is quoted for a specic voltage/distance/dBs etc. but in real life how high do these things go ? And is RMS a valid way of expressing the voltage ?

Just curious... thanks.

[Dave Cawley]

4 to nearly 100 volts RMS; for 2watts to a 1K watt. Or more in peak to peak. Not really sure what the real question is though?

Dave

[Peter Galbavy]

Curiosity really.

[technobear]

Voltage = Square Root (Power x Impedance)

So for 100 Watts into an 8 ohm speaker

Voltage = Square Root (100 x 8)

= Square Root (800)

= ~28.3 Volts

[Peter Galbavy]

Aha, of course!

[Primalsea]

28.3 volts is the RMS (Root Mean Square) to work out what the amps powersupply is you times 28.3 by 1.414 which equals 40V. This means that the amps powersupply has a -40V and a +40V voltage rail.

Therefore peak output is 40V and peak to peak voltage is 80V.

RMS is useful because it is the average voltage the speakers will effectively see.

[MartinT]

Because the driver transistors cannot swing power rail to power rail, you would need more like +/- 45V DC rails to swing +/- 40V and achieve 100W RMS output.

[Dave Cawley]

Because the driver transistors cannot swing power rail to power rail, you would need more like +/- 45V DC rails to swing +/- 40V and achieve 100W RMS output.

Too true!

Dave