Ohms.. how to measure these??

[sublime19]

Ok well I'm a bit confused, I know ohms are like resistance or whatever.. but here's my problem

My mate wants to buy an amp and it says
Max power 2 ohms = 2200 x1
Max power 1 ohm = 3000 x1

Rms power 4 ohms = 1200w x1
Rms power 2 ohms = 1700w x1

what does this mean?

[lawrencetlc]

does it have any other numbers or symbols?

That's really funny... I mean I never see such things like
power 2 ohms = 2200 X 1

hmmm, that's weird..

anyway, ask the shopkeeper, or flip through the manual and have a read on it.. but just a reminder that there's often things labeled with "300W", 500W, 800W, or 1000W", but actually you would never reach that high power to the speaker... nor you would never have a chance to turn it that high...

cheers

[Hobbsie]

dunno anything about ohms, but the max power/rms thing.. ignore Max power.. that is just a BS innacurate figure some companies use.. just a dodgy marketing technique. RMS is what you go by.

also http://science.howstuffworks.com/question501.htm

[lawrencetlc]

by the way, what is RMS??

[noccers]

by the way, what is RMS??

RMS is a measurement of power.

The RMS value is what you go by when you want to know what the average constant power output. PRMS is the Peak RMS value, which is often what manufacturers will advertise as it's usually a much higher value.

Both values are important when considering a product, or matching products, as one will tell you what you can expect the system to output, and the other will tell you what it can output/handle.

These values have nothing to do with audio quality, however. Product sound and quality will vary from model to manufacturer.[/u]

[devil2004]

Rms power 4 ohms = 1200w x1
Rms power 2 ohms = 1700w x1

what does this mean?

The ohm rating is very important when buying an amp.

Basically you need to see what sub/s your friend is running. Subwoofers have an ohm rating aswell and it's best to match the ohm rating that gives you the most power.

In your case, peak power is given at 2 ohms (assuming your amp isn't 1 ohm stable) then you need to get a sub which has a 2 ohm single voice coil or a 4 ohm dual voice coil and then wire the voice coils parrallel.

[Dr_Jones]

Ok well I'm a bit confused, I know ohms are like resistance or whatever.. but here's my problem

My mate wants to buy an amp and it says
Max power 2 ohms = 2200 x1
Max power 1 ohm = 3000 x1

Rms power 4 ohms = 1200w x1
Rms power 2 ohms = 1700w x1

what does this mean?

It means just that...when the amp is presented with a 4ohm load for example one 4 ohm subwoofer then the amp outputs 1200watts, if say he had two 4 ohm woofers wired in parallel the amp would see a 2 ohm load and output 1700watts. Less resistance equals more power from the amp but also means more heat and more current drawn from the car electrics. Dampening will also suffer more at a 2 ohm load.

Keep in mind that 1700 watts into 2 4ohm woofers for example will see each woofer with half each not 1700 watts a piece.

Does that help?

[sublime19]

ahh... that makes perfect sense

so it would be better just to run one 4 ohm sub rather than two of them rite?

[Dr_Jones]

No it's all relative, you gain heaps more air movement from two woofers but the cost is a reduced loss of quality, which is fair to say most people wouldn't notice anyway. It's like overclocking a PC I guess it's all good but there are trade offs.

[sublime19]

ah ic.. thanks for clearing that up
my mate only has the one sub, he wanted a good amp, I know his sub is decent but lets say his Sub is like.. 2 ohm, in that instance would he still get the most benefit out of this amp or should he buy a different one?

[Dr_Jones]

If he has one 2ohm woofer then that woofer gets 1700 watts.