Lets say speaker number 1 has a rating of 2-50 watts RMS, and number 2 is like 2-30. Does this mean speaker number 1 needs to have close to 50 watts to play properly, or does that just mean it can handle up to 50 watts? Thanks any info.

 

It means that speaker 1 can handle 50 continuous watts and speaker 2 can handle 30 continuous watts. Both speakers will be able to handle peaks in excess of their ratings. For instance (if I remember correctly) the Infinity Reference Series components I used to have were rated at 90 watts continuous and 270 watts peak.

 

Alright, so if my head unit gives out 22rms, if I run them from the HU, would both speakers will still play properly, I mean would the 30 watt speaker be a better choice for me because i'm more so pushing it's limit? Thanks.

 

Either set of speakers will work with your HU. There's no need to try and match your HU's power output to the speakers rated RMS wattage.

 

In most cases, peak power is twice RMS. You don't need to worry about getting the numbers close, as long as the sub can handle it, you should be fine.

 

Would a 85 watt speaker play at the same loudness at the same volume level as a 30 watt speaker would, considering all other aspects of both speakers are roughly the same? Thanks for the help guys.

 

The amount of wattage that the speaker can handle has nothing to do with how loud it will be. For that you need to compare sensitivity specs. Most speakers spec something like this...

87dB @ 1 watt from 20-20kHz @ X% THD

The higher the number the more efficient the speaker is at turning the signal into sound.

 

RMS is strictly what a speaker can handle continuouslly. Cool, thats bascially what I needed to know. Do you happen to know which brands tend to have a higher sensitivity spec. Thanks again help.

 

Considering that there is no standardized way of achieving these numbers, you can usually assume that most of them are crap anyway.

A head unit will NEVER have that kind of power output unless it's got a DC-DC converter that's capable of raising the amplifier rail voltage. Without it, you get a best-case scenario of 17 watts RMS regardless of what they say. Some of the newer ones do have higher rail voltage and may produce a little more power, but the difference between 17 and 22 watts is barely audible.

As for speaker ratings... those are even more worthless than power amp ratings. Power handling is a function of the content being driven through the speaker. The type of signal, and the frequency range where most of the energy is contained all plays a role. Find a speaker rated at 50 watts RMS and play a 50 watt 20hz signal through it and see how long it lasts. Play a 50 watt 2khz signal through it and it'll probably last all day.

My point is, power ratings can be used as a very loose guideline only.

 

Power ratings and sensitivity ratings are not very good guides to indicate how loud something will get. Power ratings don't indicate how much power it will take to achieve a given SPL, that is dependant on a lot of other things, Efficiency, sensitivity, power and BL compression, suitability for a given box.... etc.

. Some companies list the sensitivity of the speakers, some list the efficiency there is a big difference, and some companies just rate it using a system they pull out of thin air...
lets take three common subs for instance.
Adire Shiva rated at 84.2 db
Infinity Perfect 12 rated at 96 db
Alpine Type R 12 rated at 87 db
At first you would think that the Infinity would be the loudest with little power since it is rated at the highest sensitivity, but this is not the case. The first is the Shiva then the Infinity and alpine. The infinity and the alpine are actually very close to the same sensitivity, it is just due to the fact that infinity chose to use a bogus in car response number for the rating. For the rest of the comparison i will just use the Shiva and the Alpine. First of all with low power the Shiva being the most efficient will absolutly stomp a mud hole in the Alpine (and the infinity) at 100-300 watts, but at higher power (around 550) it will be a very close comparison because the alpine was meant to take a bit more power, and the shiva starts to suffer power compression after 350 and severely after 450. Even tho the shiva is capable of taking 650 watts thermally it is useless to run more than 400 because of its power compression. It will gain very little from 450 to 650 watts. There is no published specs that will tell you this.

 

Granted, sensitivity specs can be misleading. But they are the only thing consumers have to go by. And those specs also need to be quoted as I said above. ie X dB of sensitivity @ 1 watt from "A" Hz to "B" Hz @ X amount of THD. Without those other numbers the sensitvity spec means next to nothing.

 

http://www.adireaudio.com/tech_papers/spl.htm

 

It's nice to see that somebody else understands what power compression is. Day in and day out I listen to banter on some of the other boards and all people do is throw specs back and forth. It's even worse than magazine 1/4 mile comparisons. Thank you for that breath of fresh air.