sub sensitivity question

[colemanyoungerinalaska]

can someone explain why most speakers that can handle alot of power have lower sensitivity. older cerwin vegas have pretty high sensitivity and i dont hear about people using them very much anymore. like the cerwin vega xl 18 100db @ 1w 1m 400 watt rms speaker. i know they have lower xmax then newer subs
what is gained with the lower sensitivity and higher xmax?

am i just wasting money on new higher powered lower sensitivity subs.

sorry if this has been answered elsewhere i couldnt find it and this has really bothered me for a while

[solacedagony]

I'm not sure exactly what correlations there are, but I'm betting that the higher power handling subs have heavier cone assemblies than the lower power handling ones, lowering the sensitivity. These days power is so cheap that it's not a huge deal to make speakers with low sensitivities in exchange for other neat trade offs such as super xmax.

[smoker]

well you ve go tstronger magnet assemblies. stiffer heavier cones, dual spiders, everything to make one handle a shitton of power and get loud enough to retract your testes is what decreases sensitivity at 1w/1m

[colemanyoungerinalaska]

that doesnt explain why theyve made them less efficient
i dont understand why theyve made them take so much more power and not equally more efficient. its probably a cost thing.

[smoker]

sensitivity is measured at 1 watt at 1 meter. so a sub that will take an enormous amount of power has to have a stronger motor, that means its not doing as much at lower power. a lower powered sub will do more at 1w/1m because it doesnt have as strong a motor, as stiff a suspension and whatnot

[GlassWolf]

Speaker Sensitivity and Efficiency.

Speaker sensitivity

Speaker sensitivity is a specification provided by all manufacturers of high-quality speakers. The sensitivity rating has no relation to sound quality, as some of the very best speakers have low ratings. Sensitivity ratings simply tell you how much sound a speaker will produce for a given power input.

Sensitivity ratings are given in decibels per watt at one meter, or db/Wm. So, with an input of one watt (usually white noise), a speaker with a sensitivity of 90 db/Wm will produce 90 decibels of sound at a distance of one meter. A sensitivity of 90 is considered average, with ratings of 87 and below considered low sensitivity and above 93 considered high sensitivity. To increase the volume by 3 db, you must double the power. So, using the example above, to make 93 db you would need two watts, and to make 96 decibels, four watts.

Most of the time your system is cruising along producing only a few watts. You need extra power for loud bass passages, crescendos in classical music, and other highly dynamic passages. Your speakers may need more than 10 times the average power to re-create these dynamic passages accurately, and if you are playing loudly to begin with, you may need an awful lot of power if you have speakers with a low sensitivity rating.

So, when you are buying an amplifier, consider your speakers, your vehicle size and how loudly you want to play. If you have sensitive speakers, you probably will not need as much power -- even 20 clean watts would probably be enough. If your speakers are only moderately sensitive, your vehicle is large or exceptionally noisy at highway speeds and you want to play loudly, you will need more power in order to faithfully reproduce dynamic passages.

"Sensitivity," which is expressed in dB, should not be confused with "efficiency" that is expressed as a percentage of power out relative to power in. Efficiency data for loudspeakers suffers from many problems such as failure to consider variations in frequency response.

Speaker efficiency is the ability of the speaker to do work or use power. The more efficient the speaker; the less power is required for the speaker to produce sound. Voice coil design, type and size of the magnets, speaker cone design and material, speaker size, etc. all play a critical role in determining speaker efficiency. However, speaker size is a good general method for guessing efficiency.

Typical speaker efficiency (for physicists) is about 5%. Meaning that for 100% power input, you get about 5% acoustical work back.

Keep in mind that when considering subwoofers, or any speaker that will get more than ~100 watts RMS of power, these measurements are affected by other factors that make this specification less than useful when choosing between speakers.

[breakjunki]

I love it. I hate when I'm trying to find someting specific out and get no where. You always come thru with some full on M.I.T. dead specific answer. Not trying to sound like a fanboy, but damn some of the stuff you come out with is pretty damn impessive, even if I only understand about 75% of it, ok.. maybe 50%

[CaptainPioneer]

well he did stay at a Holiday Inn last night ...

[colemanyoungerinalaska]

thanks
i figured i was misusing the word efficiency