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gat474

Speaker sensitivity comparison

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I wouldn't read into those figures. A lot of non reputable (and some reputable) manufacturers blatantly lie. Also for car speakers, they can use the on baffle or in an enclosed car sensitivity figures, which will be fairly different

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I suspect that all of these "measurements" from almost everyone are either dodgy or are the best possible figure under the most conducive of conditions.

 

Most nominal 4-ohm speaker manufacturers use 2.83volts because that secretly equates to 2 watts not 1, thus giving an inflated (better) sensitivity number.  The corresponding 1 watt @ 1 metre is 3 dB less.

 

Then, of course, is how and where they have been measured.  My 4-ohm mains are advertised as 86 for 2.83v, but that is really 83 for 1 watt.  Compare that with a German magazine that measured them at 77dB.  What's going on there; sumpin' just ain't right.  I can't believe either number.

 

In the OP, the 92dB speaker is much more sensitive ...

92 - 81 = 11dB = approx 10 times more sensitive

 

(dB is a logarithmic ratio; dB = 10 log(p1/p0)).

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17 hours ago, gat474 said:

This might be simple but a quick google search revealed various opinions and even arguments.

In short, this is due to people not fully understanding what they are talking about.    When two people who "kinda" understand it, explain it in different ways - they seem at loggerheads and don't know how to "explain" it.

17 hours ago, gat474 said:

I'm trying to work out which is the most sensitive speaker comparing the two different measurement values.

The issue here is typically "what do you mean by sensitive?"

 

Typically - people define sensitive to mean, how much voltage does it take to make the speaker move X.     Termed "voltage sensitivity".

Alternatively.... There is also efficiency.  This is how much power (energy, watts) needed.

 

The fact that they are both stated in dB confuses people.

17 hours ago, gat474 said:

4 ohm speaker with a sensitivity of 92 db at 1 watt at 1 metre vs

4 ohm speaker with a sensitivity of 84 db at 2.83 volts at 1 metre.

It's all math, but it's no so hard once you understand what you're trying to do.

 

You need to scale one of these to the same units as the other.

 

We know that:    power = volts squared divided by impedance.

 

So, for the second speaker, we know that:    power = 2.83 squared divided by 4

So, we know that for the second speaker power = 2 watts.

So.... now we have:

 

17 hours ago, gat474 said:

Speaker 1 (4 ohm) makes 92 db from 1 watt

Speaker 2 (4 ohm,) makes 84 dB from 2 watt

We know that for every doubling (or halving) of power applied we get 3dB more (or less) output.    So we know that:

 

17 hours ago, gat474 said:

Speaker 1 (4 ohm) makes 92 db from 1 watt

Speaker 2 (4 ohm,) makes 81 dB from 1 watt

 

 

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Posted (edited)
17 hours ago, Muon N' said:

No difference between '1 watt at 1 meter' and '2.83 volts at 1 metre'.

2.83 volts = 1 watt of amplifier power.

Not a great start for "arguments and opinions"   😕   Perhaps an edit?

Edited by davewantsmoore

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17 hours ago, gat474 said:

Yeah, we’ll I doubt the accuracy of the specs to be honest. Who would sell a car speaker that was so inefficient and expect people to buy it against something with a much higher rating?

Soinds like some marketing magic to me.

We need to know more about the drivers first.

 

Imagine if .....   These are woofers, and....

 

The more sensitive driver has low power handling and low excursion capabilities.... that result in it being limited to 90dB at 80Hz.

The less sensitive driver has high power handling and high excursion capabilities ..... that result in it being limited to 110dB at 80Hz.

 

For use in a "room filling hifi system", nobody would buy the higher sensitive driver....  as running out of puff at 90dB @ 80Hz is not loud enough.

 

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4 hours ago, aechmea said:

Then, of course, is how and where they have been measured.  My 4-ohm mains are advertised as 86 for 2.83v, but that is really 83 for 1 watt.  Compare that with a German magazine that measured them at 77dB.  What's going on there; sumpin' just ain't right.  I can't believe either number.

The only way forward is to understand why they are different .... which involves understanding their methodologies (or at least one of them).

 

 

Any large driver manufacturer will provide (or be able to provide) information on how they got their numbers....

 

I think headline "sensitivity" (or "efficiency") .... is often over-evangelised by people using the "nimble racecar" analogy.    Sensitivity (or "efficiency") in a speaker only becomes a problem when you do not have enough.... otherwise the stand-alone generalisation that more efficiency will do more "good things" doesn't really hold so much.

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20 hours ago, gat474 said:

This might be simple but a quick google search revealed various opinions and even arguments.  I'm trying to work out which is the most sensitive speaker comparing the two different measurement values.

 

4 ohm speaker with a sensitivity of 92 db at 1 watt at 1 metre vs

4 ohm speaker with a sensitivity of 84 db at 2.83 volts at 1 metre.

 

Both are car speakers.

 

Is there a simple answer or is it all in the maths?

Are the drivers from the same manufacturer? If they aren't, it's not a safe assumption that they are comparable.

 

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Just to finish up this thread I got my answer today.  So, in answer to Red Spade's question the speakers are from different manufacturers.  The speakers spec'd at 92db at 1 watt at 1 metre were a pair of Polk DB6502 component 6" car speakers.  They are (were) fitted to the front doors of my car and powered from a Sony head unit with has probably 20 wpc rms.  I paid good money to get them fitted, should have done it myself as the fitters didn't seem to know about phase of tweeters and mid bass, didn't know about connecting all wires to the crossover box and didn't seem to care too much about fitting the speakers to the door frame so there wouldn't be any gaps.  The phase and crossover problems have consumed me for a few months now, given they were all messed up it took me a few goes to correct it all.  In the end I hated the speakers anyway, didn't matter how they were configured they sounded average.    The tweeters mounted in the car original dash locations sounded like honky midranges, very annoying and there was no top end, just lots of midrange.

 

I was that frustrated that I went to another car audio store and had a listen to a couple of other pairs of speakers.  Hard to make any valued judgments on a sound board but in the end it came down to some Morels which were made specifically with a high sensitivity for systems without car amps and a pair of Pioneer D65C whcih are another two way 6.5 inch component speaker.  To my years the Pioneers sounded the best to me but had a lower sensitivity than the Morels at 84db at 2.83 volts at 1 metre.  The Morels being up at about 94 db.   The Pioneers were the catalyst for my question about sensitivity.   I was starting to get buyers remorse thinking that the Pioneers would not be sensitive enough and that I should have bought the Morels which were made for my application.

 

Anyway, bought the Pioneers and finally got around to fitting them today.   This is when I discovered that the professionally installed Polks were leaking a little air around the mount.   The installers hand't even bothered to make sure that they were sealed.   The Polks are a 6"and the Pioneers a 6.5.   The Polks have a separate crossover with a 12db slope on both mid and tweeter whereas the Pioneers have a 12 db slope on the tweeter in line and the mid bass just a 6 db coil attached to the midbass itself.   Off to Autobarn to buy some spacers as the Pioneers were around 30mm deeper.   After a few hours and double checking all the wiring they're all working.

 

The answer to the sensitivity question?   Looks like the Polks are exaggerating the measurements as the Pioneers play just a little louder and also have a much fuller sound with the bigger mid bass driver.   The Pioneers sound very good too.   I'm glad I finally got it sorted.  Shame I spent good money on the Polks and paid some dunce to fit them but that's the way it goes I guess.   

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