Sensitivity of Speakers

DannyD

I always forget which is which. Is it easier to drive a speaker with 96db sensitivity rating or 89db rating. The reason I'm asking is my friend just purchased an Energy speaker system. The front tower mains have a sensitivity rating of 96 db. My polks are 89. He almost bought the polks (RTIA7's) and I'm just wondering which speaker is better and easier to push. The Energys are the CF-50 Connisseurs. Which in your opinions is the better choice?

TNRabbit

Higher sensitivity isn't necessarily "better"; some of the best speaker systems in the world aren't very efficient.

All it means is that at 2.73 volts/1 watt of sine wave input, that speaker will put out XX decibels at 1 meter.

Higher sensitivity means less watts needed to reach a given decibel level. There are MANY other variables that make a speaker "good" or "bad"....

steveinaz

The efficiency or SPL (sound pressure level) specification is the output in decibels at 1 watt/1 meter typically. So a 96dB speaker would play louder at a given wattage than a 89dB speaker.

Efficiency is not a measure of quality, nor is impedance.

DannyD

So correct me if I'm wrong...a speaker with an efficiency of 96db will play louder but sacrificing sound quality and a speaker at 89db won't play as loud but will have better sound quality. I don't think he will ever add external amplification so it sounds like the energys will benefit more from just receiver power.

TNRabbit

You've missed the point on both posts. Sound quality is entirely different from sensitivity. You can have both crappy & excellent speakers that are efficient as well as not efficient. Efficiency is not tied to how good or bad the speaker is.

kneedragger37

TNRabbit wrote: »

You've missed the point on both posts. Sound quality is entirely different from sensitivity. You can have both crappy & excellent speakers that are efficient as well as not efficient. Efficiency is not tied to how good or bad the speaker is.

Couldn't be more right. In addition, what sensitivity rating two speakers have on paper and how they actually perform in the real world are two totally different things. Remember, those sensitivity ratings are measured at 2.83V at 1 meter in an anechoic chamber. Crossovers, driver design, enclosure design, room shape, size, and layout, and many other factors will affect how your speakers use power and/or how loud they will sound when provided a given amount of wattage. Auditioning the speakers in your home, side by side if possible, is the only way to really compare which one will be louder, and more importantly sound better, for your application.

There's a great thread on the ecoustics forum about sensitivity:
http://forum.ecoustics.com/bbs/messages/1/130011.html

devani

$100 made in china, no brand, speaker with 95dB will not sound better(quality wise) than any quality made brand name speakers with 89dB.

Sure it will be louder(quantity wise)

steveinaz

Exactly. Efficiency is just subject to the design of the speaker, it has no bearing on quality. The only way you'll know which is better in the CF-50 vs RTIA7 battle, is to listen to them.

Having said that, Energy's tend to have a more laid-back treble than do RTI series Polk's--wether that's good or bad is up to your ears and personal preferences. They are both respectable designs.

cnh

Both of those speakers are good--they will sound different and some will prefer one or the other. What everyone has said is absolutely 'true'.

If I were you I wouldn't worry about it, Rti-10s are a great speaker, you have excellent amplification and 2 15" Velodynes? Wow! I think you're good! No need to worry about efficiency with that set-up.

Enjoy..

cnh

sucks2beme

In speaker design, it's a lot easier to build a 86db efficient speaker
than a 96DB efficient speaker. You normally pad DOWN to match
the tweeter, mid, and bass output. To get it back up again requires
$$$$. Cheap speaker makers don't care if it's a good balance, just if it's
LOUD. Some guys, like Audio Note, increase the DB output with
better drivers, wound with silver(big bucks!). The 4/8 ohm rating
is strictly due to the choice of drivers. Guys like B&W are famous for
making fairly efficient high quality speakers.
As always, buying a big honking amp makes this a no brainer.:D

mhardy6647

Sensitivity measures SPL output at a specified distance for a specified applied signal.
A common standard is a distance of 1 meter and applied signal of 2.83VAC (which is 1 watt if the load is 8 ohms). Thus, a "96 dB" sensitive speaker (spec'd as above) would deliver a measured SPL of 96 dB at a distance of 1 meter if fed a 2.86 V signal of, say, white noise. Note that the sensitivity may be (is) also frequency dependent. If you fed the 96 dB speaker 2 watts, you'll get (at least in theory) 99 dB; 4 watts, 102 dB, etc.

Efficiency is a measure of the percentage of electric power converted to acoustic power. Sensitivity and efficiency are related quantities, but not proportional. Many of us (myself included) sloppily intermingle the two terms.

Neither of these quantities gives much insight into how easy a speaker is to drive (i.e., how benign of a load it presents to a given amplifier). Some speakers have very complex impedance curves as a function of frequency; these might be very hard for certain amplifiers to drive. In extreme cases (e.g., Quad electrostatics) the load may drive the amplifier into instability (e.g., oscillation), with potentially disastrous results for amp and/or speaker. In general, a speaker with a broad, flat impedance curve (and frequency-dependent impedance characteristics that don't have outrageously high capacitative or inductive components) will be "easy to drive" independent of how sensitive it is. The sensitivity will give you some idea of how loud it'll get while you're doing it. The above-mentioned qualities of a load are sometimes referred to as "reactances" in AC signal jargon.

Those of us who like low powered amplifiers with little or no negative feedback (and, consequently, rather high output impedance -- aka low damping factor) worry about stuff like this quite a bit.

IMNSHO, you cannot beat good old fashioned empiricism :-)