Tech Quest

Systems

I was wondering if you could answer a couple of questions for me. First Off what are ohms? Second- Whats RMS mean? and is a good sub gonna have a high sensitivity (db) level? any help appreciated.

AustinKP

1. Ohms - Measurement of Resistance or Impedance. They don't really matter in that 2 isn't necessarily better than 4. Just have to make sure that the amp you buy supports the impedance level of your sub or lower, i.e. if you have a 2 ohm sub, your amp has to be 2 ohm stable. Generally, amps will give you more power at lower impedance levels. If an amp is 2 and 4 ohm stable, they're usually rated like this: 250x1 @ 4 ohms, 500X1 @ 2 ohms.
2. RMS - Root Mean Squared. power an amp can put out constantly, as opposed to peak wattage. From now on, Peak Power ratings are WORTHLESS. All higher-end amps give their ratings in RMS power. Most don't even advertise peak power ratings any more. When comparing amps, ALWAYS compare RMS power, not peak.
3. Good subs generally have high sensitivity ratings. The higher the sensitivity rating, the more volume output, given a certain input power. The better the sensitivity, the more sound per watt. Lower sensitivity isn't necessarily bad, it just takes more power (more money) to get them loud.

exalted512

just adding to what he said...sensitivity doesnt mean a sub is better than the other, or really even mean it makes it louder
sensitivity ratings are measured different by different companies...they do this so they can put bigger numbers because many people believe subs with a higher sensitivity will be louder, but in reality theres much more than just the sensitivity rating that will determine how loud a sub will be
-Cody

bknauss

Just follow companies that use the CEA2006 guidelines... they're the standard, and companies like Polk are using them even though they're not required at this point (JBL is another... not too hard to tell since the plaster it all over their web pages).

neomagus00

i believe that alpine also posts certified specs for their amps

MacLeod

Yeah they do and here is another neat little thing they do that pisses me off.

Take the V12 T420. Its a 2 channel rated at 110x2. Not bad. But click the "more information" tab and scroll down to the power ratings and the 110 is from 20-200 Hz! Most amps are rated at 20-20,000 Hz which takes a lot more power. So this would put that amp at around 90x2 I would guess. This is kind of shady to me. I wish they were a little more honest in their ratings. Still, they are awesome amps.