Need Help

[houston]

if i have a sub thats 400 watt max how would i find out the rms value?

and for eg sake the rms is 100, would i need to get an amp that gives spot on 100rms or is there boundaries i can set within?

[houston]

ok to add more to this, ive got an alpine mrv-f300s amp sitting here not doin anything, what sub/s could it power? i know im prob better off gettin another sub and amp and usin this for components but im just wonderin if anyone knows a better way

[seveer unaek]

Not too sure on the rms thing, but so long as you don't have an amplifier that's more powerful than the sub you'll be ok!

[houston]

but ive heard that sometimes an underpowered sub can be just as bad as an overpowered sub!

[MarkMcQ]

Generally most audio equipment will be sold with it's output listed as it's PMP rating (Peak music power). This isn't a true measure of it's real power, more of maxed out potential output that you'd get if you really pushed the amp to it's absoloute limit for the brief fraction of a second before it blew up. It's done this way to make the equipment seem way more powerful than it is, making it more appealing to the buyer.

A very rough conversion is usually about 2:1 (Although in some rare cases the PMP can be 3 times as much as the RMS). So if the amp was listed as 200w, and it turned out to be expressed as PMP, you'd be running a 100w amp.

As an example, a 150w RMS amp (300w PMP) is more powerful than a 250 PMP (125W RMS) one.

Your 400w speaker is very likely a true figure of 180-200w in RMS.

As for an underpowered amp, this won't do any damage to your speaker in the strictest sense. What happens is that with an underpowered amp, people tend to have to turn them up louder, and eventually this causes the amp to overload and over time it kills the amp.

The one thing you absoloutely have to make sure of is that the impedance is your speaker is compatible with the amp you choose.