Ohms is only a measure of resistance when you are dealing with DC
electricity. When you are talking about an amplified sound signal, that is a
type of AC. Ohms within the realm of AC may be resistance or reactance or
both. In either case, DC or AC, ohms is an opposing force to the flow of
current. That much is correct. Think of it this way... Voltage is pressure
that pushes electrons through a circuit. Impedance (that's the general term
for resistance or reactance or both) is the opposing force to this pressure.
It regulates the flow of current (Amps). If you put voltage into a dead
short, (an impedance of nothing) there is no regulation of the flow and the
circuit will do its best to pass infinite current. Something that won't
happen for very long before something burns up.

Ohm's Law says that E = IR. Voltage is equal to current times resistance.
Power is P = IE. In other words watts equals amps times volts.

A stereo power amplifier usually has a fixed maximum voltage that it can put
out. That's the pressure. If your speakers have a high impedance, then you
are not going to get so much current to flow through them, resulting in less
power transferred to the speaker. On the other hand, if your speakers have a
very low impedance you might pull too much current from the amp, either
damaging the amp or causing it to distort.

The overall volume of the sound you hear from a pair of speakers has
everything to do with the efficiency of the speakers. How much of the
electrical power that is sent to them actually gets turned into sound that
you hear? All the rest of that power is turned into heat. Speakers are
horribly inefficient devices. You are lucky if 1% of the power that goes
into your speakers comes out as sound. One pair of speakers with 10 watts
going into them might sound much louder than another pair of speakers with
150 watts going into them.


"ScottW" wrote in message
news:Iy0Ae.31634$up5.19238@lakeread02...

"KLA" wrote in message
...

hi guys

regarding ohm rating, according to my studies, ohm means resistance to
the current. is it low ohm better or higher ohm?

Assuming you mean speaker ratings... if all things equal (and thats a big
if) a higher ohm rating usually means the speaker will be easier for an
amp
to drive. It will take less current at a given output level.

Usually one needs to consider the speakers efficiency as well as impedance
for fundamental amplifier compatibility.

But if you have a cheap amp... or simply don't know.... higher ohms is at
least safer for your equipment.

For most stereo amps, 4 ohm or 8 ohm speakers are fine.

ScottW