Speaker Sensitivity?

[Aric M L]

Could someone do me the favor of explaning to me how much the speaker sensitivity reading matters? Do a few numbers difference there really make a audible difference? I am looking at a pair of tannoy mx-2's and the rating is 88dB (2.8volts @ 1 meter) and I suddenly realized this is latin to me and trying to compare these numbers will do nothing. If it has a lot to do with what you drive them with I'm going to use an HK AVR-40.

[msrance]

Could someone do me the favor of explaning to me how much the speaker sensitivity reading matters? Do a few numbers difference there really make a audible difference? I am looking at a pair of tannoy mx-2's and the rating is 88dB (2.8volts @ 1 meter) and I suddenly realized this is latin to me and trying to compare these numbers will do nothing. If it has a lot to do with what you drive them with I'm going to use an HK AVR-40.

Aric, sensitivity is the Sound pressure level that a speaker can generate when played with 1 Watt of power at a point 1 metre away. 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. 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.

Now the important part, specially if you want to play music that your neighbours really enjoy and besides you are aiming at having your friends in the far end of the city listen to what you play at your house. To increase the volume by 3 db, you must double the power. So, using the example of 90db, to make 93 db you would need two watts, and to make 96 decibels, four watts. Hence the lower the sensitivity rating, more powerful an amplifier you need to double the SPL.

And I would say the Tannoy's are a good choice, I auditioned a pair long back - dont know what model - but they sounded good, though I was looking for a floorstander and besides they didnt fit my budget.

[topspeed]

Could someone do me the favor of explaning to me how much the speaker sensitivity reading matters? Do a few numbers difference there really make a audible difference? I am looking at a pair of tannoy mx-2's and the rating is 88dB (2.8volts @ 1 meter) and I suddenly realized this is latin to me and trying to compare these numbers will do nothing. If it has a lot to do with what you drive them with I'm going to use an HK AVR-40.

Your Tannoy's are producing 88dB's of sound pressure when being fed 1 watt (2.8v) measured from a distance of 1 meter from the speaker. This is the standard method of showing speaker's efficiency and it is important. To understand why, you first must realize that to increase sound pressure levels (i.e. volume) by 3 dB's, you must DOUBLE the wattage. That's right, a barely noticeable increase in volume requires TWICE as much power. Therefore, a speaker that is more efficient at say 93dB/1w/1m will be considerably louder with the same amp than the Tannoy's and will produce the same level of volume that the 88dB speakers do with lower levels of distortion due to less strain on the amp, theoretically at least.

Hope this helps.

[92135011]

I find the ratings kinda funny.
I listened to a paradigm (forgot what it was) rated at around 90dB
then listened to a quad rated at 86dB

The volume control was the same.
EXCEPT. They sounded similar in terms of loudness.
So, it's either that testing standards are different, or the 4dB difference is negligible?

[Geoffcin]

Your Tannoy's are producing 88dB's of sound pressure when being fed 1 watt (2.8v) measured from a distance of 1 meter from the speaker. This is the standard method of showing speaker's efficiency and it is important. To understand why, you first must realize that to increase sound pressure levels (i.e. volume) by 3 dB's, you must DOUBLE the wattage. That's right, a barely noticeable increase in volume requires TWICE as much power. Therefore, a speaker that is more efficient at say 93dB/1w/1m will be considerably louder with the same amp than the Tannoy's and will produce the same level of volume that the 88dB speakers do with lower levels of distortion due to less strain on the amp, theoretically at least.

Hope this helps.

Here's a good website to determine the ratio of power to volume in room.

http://www.myhometheater.homestead.c...alculator.html

There's one parameter in the formula that's not exactly correct, and that the fact that all speakers do not drop off at the same rate to distance. Planars have very little dispersion in the vertical, so the drop off in SPL is nearly 1/2 of conventional speakers. Also most Planars are dipoles that radiate out as much sound out the back as the front. This is not taken into account when the sensitivity measurements are made.

I'm not sure that I agree that an 88db speaker would cause an amp to distort more than a 93db speaker. Most SS amps have flat distortion curves right up until they get very close to clipping. Some eve dip in the mid-power range. Even if you take the "average" receiver's amp @ 100 watts, it should drive this pair of 88db speakers to 104db or so before clipping. That's pretty loud!

[markw]

This chart kind of aproximates what loudness levels you cah obtain with an 88db sensitivity speaker. Distance from the speaker, room acoustics and the testing methods used may lower this somewhat.

Keep in mind that a 3 db increase in loudness is barely audiable.
Also, an apparant doubling of loudness requires a tenfold increase in power.

1 watt = 88 db
2 watts = 91 db
4 watts = 94 db
8 watts = 97 db
16 watts = 100 db
32 watts = 103 db
64 watts = 106 db
132 watts = 109 db
264 watts = 112 db
528 watts = 115 db

Using this as a rough guideline, if you moved to speakers with a 3 db gain in efficiency (91 db), then you would 1/2 the power to attain tha same loudness as an 88 db speaker. Likewise, another 3 db increase in sensitivity (94 db) would require only 1/4 the power that your 88 db speaker needed.

This is why many with low power amps go out of their way to search out the most efficient speakers they can find. This does limit their choices drastically.

I would recommend you search out the speakers you like and then look for a receiver/amp that can drive them to adequate levels. There's more of a selection of powerful amps than there are highly sensitive speakers. Plus, speakers are more critical in determiining the overall sound of your system.

Granted, most listening normally is done using less than one watt on a continous basis. Where the extra power comes in is when deep bass is called for and occasional peaks in ths sound, like special effects, crescendos and the like.

The good news is that subwoofers can alleviate the need for the internal amps in the receiver from dealing with power sucking bass, assuming your kit is set up properly. Loud gunshots from the corners are another story. They will hit up your main amps.

enjoy...

[92135011]

I notice that some companies have 2 sensitivities.
one is anechoic an the other is 2 speakers in a room
from the companies that list these, I notice a 3dB difference between the two

what is anechoic?

[RGA]

The anechoic is used as a measuring test - it's a measuring chamber not a real world listening room.

Most amplifiers will be fine driving 88db which is fairly sensitive. Where it really matters is if you ever plan on using a tube amplifier. But even here you'd be more concerned with knowing the speaker's minimum impedence over sensitivity.

88db is loud. You can achieve loud with one watt. Most average listening you won't see the amp go past 2 watts. I have heard tube amps played at deafening levels than never went past 10 watts on the meters and they were rattling walls. It's the quality of the first watt that matters most.

A 10 watt amp will drive most speakers to an acceptable level provided that it's a good quality amplifier. Then there are some rated at 120 that are complete disaster areas.

If you like the Tannoy when you listened chances are you liked the whole system...so get the whole system. People need to listen to the whole set-up. I would suggest you take your amp with you when you listen to compare.

[skeptic]

Speaker sensitivity is one way of looking at efficiency, the relative degree to which the speaker converts electrical energy into sound energy. The rate at which electrical energy is delivered is expressed in watts. Most audiophiles don't know this but the rate at which sound energy is produced is also rated in watts. One watt of sound energy is an enormous amount. Another way to look at it, the way most commonly used is to mesure how loud a speaker plays at a given distance when a specific amount of electrical power is fed to it. It is usually measured at 1000 hz at a distince of one meter (39.37 inches) in an anechoic environment (echoless) environment. The same speaker will have different numbers at different frequencies, in different environments, and at different distances. 80 decibels is a loud sound. 100 decibels is a very loud sound. 120 decibles is the threshold of pain. Each time you go up 10 decibels, the sound energy is 10 times greater but because perception is not linear, it will not seem ten times as loud.

What this number is telling you of practical value is how much amplifier you will need to make a particular loudspeaker sound loud in a given room. A speaker having a 90 db sensitivity may do quite well in most rooms with a 50 watt per channel amplifier. It is moderately efficient. Some people prefer certain types of amplifiers which cannot produce much power generally and they look for speakers having a higher sensitivity, say 95 db. Some speaker designs generally have a very low sensitivity and requrire a great deal of amplifier power, say 100 watts per channel or more. Generally high sensitivity models include folded horn designs like Klipschorn. Low sensistivity designs include most electrostatic designs and some acoustic suspension designs. The overwhelming majority of designs on the market are inherently fairly efficient however, many of them are made less efficient because of losses in their crossover networks. When you see a ported design (not a sealed enclosure) with a sensitivity of 86 db, its a good guess that this is the reason.

There is absolutely no correlation between speaker sensitivity and sound quality. There are both excellent and poor performers at both extremes of sensitivity and everywhere in between. The best advice usually given to audiophiles is to choose the speaker you like first and then pick an amplifier or receiver suitable to drive it. A 200 wpc amplifier is not a good choice for a klipschorn. An 8 wpc amplifier is not a good choice for a Magneplanar either. BTW, many speakers now come with built in amplifiers for dedicated bass units called subwoofers reducing the power required for the rest of hte system substantially.