loudspeaker efficiency

Is 93 dB/W/m the best that current speaker manufacturers can do?

Reply to
Michael
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"Michael Dickhead "

** Posting dumb TROLLS the best you can do ??

Bloody idiot.

..... Phil

Reply to
Phil Allison

my Klipschorns are 105dB/W

Reply to
mike

No. It's typical of modern speakers especially for home use. Horn loaded systems can have sensitivities (efficiencies) of 108dB or higher but it's hard and expensive to make high sensitivity speakers flat in frequency response that don't sound "peaky" or have other faults. It's easier and cheaper to make low sensitivity speakers that sound reasonable. It's a trade off between sensitivity, money and perceived sound quality. Also, efficient speakers, like horn loaded systems are typically large and may not fit well in modern apartments and houses or pass the "wife acceptance test.".

Since the advent of high powered amplifiers, the necessity that speakers be efficient has lessened allowing manufacturers to concentrate on other factors like cost and size. In the days when a 10 Watt amplifier was about what you'd expect, speaker sensitivity was key. These days, not so much.

Reply to
Bob Eld

Wow.

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Thanks.

Reply to
Michael

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Ah, ok. Thanks for the clarification.

We bought a 10-inch Yamaha subwoofer (50W) that sounds outstanding... and it surprised me that it sounds so much better than the two 10-inch Visonik (car) subwoofers I plugged into our surround receiver (~50W/ channel). No sensitivity spec is given for the Yamaha, but the Visonik speakers are rated at "93 dB" (which I assume is 93 dB/W/m).

While shopping I saw some Pioneers at "93 dB" also and wondered if that was a max.

After posting I realized I posted by mistake to here, when I had intended to post to sci.electronics.basics. My apologies.

Michael

Reply to
Michael

"Michael Dickhead "

After posting I realized I posted by mistake to here, when I had intended to post to sci.electronics.basics.

** Just as big a mistake.

Your dumb question was not about electronics at all.

..... Phil

Reply to
Phil Allison

So what?? At least it wasn't about politics, the crap Thompson puts in here. Plus he got a couple of answers so why not?

Reply to
Bob Eld

"Bob Eld" "Phil Allison"

** It matters - fuckheads.

** So if I cut off your arm YOU will be grateful that it was not your head ??
** Trolls always get answers.

From fools like you.

..... Phil

Reply to
Phil Allison

There is the matter of "half space reference efficiency" of cone loudspeakers having some relationship to enclosure volume and low end of frequency response.

The half space reference efficiency is equal to 3.2E-8 times cube of Fs (free air resonant frequency) in Hz, times Vas in cubic feet, divided by Qts. I am not sure exactly what the constant is; I worked it backwards from figures from the datasheet of a cone loudspeaker (specifically Electro-Voice EVM-10M).

Multiply this by nominal impedance, divide this by voice coil DC resistance, take common log of the result, multiply by 10, add 112, and this is at least roughly sensitivity in dB at 1 watt, 1 meter. Sensitivity somewhere or somewhere else in the midrange is often 1-4 dB higher, and this increase is less for higher fidelity cone loudspeakers.

Qts is limited to Qms. Lowest frequency at which a cone loudspeaker in a sealed enclosure achieves -3 dB re: the reference efficiency is 70.7% of the ratio of Fs/Qts. The minimum enclosure volume that can achieve this is twice Vas times square of Qts, even with an extremely flexible surround. However, an enclosure volume of 60% of this ideally achieves about -4 dB at 70.7% of Fs/Qts.

There are ported enclosures with solid flat response down to a sharp cutoff, with -3 dB as low as around 1/3 of Fs/Qts, requiring an enclosure volume a little less than Vas times the square of ratio of Fs to -3dB point. A ported enclosure with response like that of a 4th order Butterworth highpass filter has -3 dB at .383 times Fs/Qts, and an enclosure volume 70.7% of Vas.

- Don Klipstein ( snipped-for-privacy@misty.com)

Reply to
Don Klipstein

"Don Klipstein"

** Reference efficiency sets a kind of defined upper limit on efficiency.

Typical hi-fi speakers only get to maybe 1%.

Guitar and PA bass drivers get to 10% or so.

.... Phil

Reply to
Phil Allison

It is not an absolute limit. Efficiency can be increased past that in resonances, by restricting the acoustic environment to a smaller solid angle than half space, and by horn loading.

And with an array of drivers, half space reference efficiency gets multiplied by the number of drivers.

Half space reference efficiency is 0 dB on a plot of theoretical frequency response using the Thiel Small equivalent circuit. Obviously, if the number of drivers gets this past or anywhere near 100%, then the on-axis sensitivity predicted (which often largely actually results) depends on substantial directivity. At frequencies low enough for little directivity, acoustic loading will depress the efficiency to 25% ballpark or less, translating to 107 dB at1 watt, 1 meter or so in ideal half-space with typical ratio of Znom/Re.

Fairly true, but this varies widely with woofer design tradeoff between bass response and enclosure size.

- Don Klipstein ( snipped-for-privacy@misty.com)

Reply to
Don Klipstein

I did just release in my website an old DOS program (2 versions) that I used for loudspeaker enclosure design back in the days when I was designing loudspeaker enclosures.

This software goes beyond the 5-component Thiel Small equivalent circuit, to approximately predict some real-world effects, mainly effects of acoustic loading varying with frequency. It also optionally predicts the 6 dB shelf that results from not having the enclosure against a wall (or other surface) with its axis perpendicular to that surface.

I released two versions each of the executable and the source code.

Sorry, I did develop the core of this program back in 1989, with a very amateurish software development style of my then-reckless youth, in my first months of having an X86 type computer. Among other things, I accidentally shrouded the source code. But it does work.

I decided to release this as freeware now that I doubt I will have time to manage shareware registrations any time soon.

All versions are linked from:

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--
 - Don Klipstein (don@misty.com)
Reply to
Don Klipstein

It was about the audio characteristics of an electrical transducer.

This is very likely a more appropriate group than the basics group as the knowledge here is likely higher than the basic level knowledge and that is what is needed in this case to explain it to him.

Perfectly appropriate since he thought it may have been some electrically or magnetically imposed limitation, instead of something mechanical.

You must have sold your soul and lost or something, because you have been nothing but a pissy little bitch for the last three years to every post, without even examining anything about them.

Reply to
Son of a Sea Cook

I forgot to mention: It plots a predicted frequency response graph, where zero dB is the half space reference efficiency with hemispherical coverage.

(Unless an environment choice in this program is selected where the loudspeaker axis is parallel to a reflective surface that the loudspeaker is adjacent to, in which case the sensitivity for 0 dB corresponds to twice the half space reference efficiency and coverage of half a hemisphere.)

At the right end of the zero dB line, is displayed how many dB re: 1 watt 1 meter on-axis in the far field 0 dB corresponds to, assuming a usual ratio of Znom/Re around 1.35 (I forget exactly already).

Skip past here if you are not interested in what maximum dB @1 watt 1 meter are possible with essentially no directivity, as a function of choice of operating environment.

Among the four "real world" choices of environment in my "SPKR" program, expect lack of sensitivity much-exceeding 107 or 110 dB @ 1 watt 1 meter at frequencies low enough to have lack of significant directivity, depending on environment choice. 107 dB 1W 1m corresponds to ~ 31-32% efficiency with hemispherical coverage, and 110 dB 1W 1m corresponds to ~ 31-32% efficiency with 1/4-sphere coverage.

Full-space and half-space with loudspeaker axis perpendicular to the plane have 31-32% efficiency and hemispherical coverage achieving 107 dB @

1 watt, 1 meter. 31-32% efficiency with even coverage over and restricted to a 1/4-sphere is 110 dB @ 1 watt, 1 meter. .31-.32 watt is maximum possible acoustic output when input voltage is square root of Znom and Re is 78-80.5% of Znom. (I have known loudspeakers with Re as low as around as 62% of Znom, good for 1 more dB of sensitivity.)

If the environment choice is full space, expect sensitivity in dB @

1 watt 1 meter to be largely limited to 104 at frequencies low enough to achieve essentially uniform omnidirectional coverage, 105 for Re on lower side around 62% of Znom. (A dB better than this due to slightly significant directivity is possible from directivity at frequencies barely high enough for enclosure width to be around 1/4 wavelength or so.)
--
 - Don Klipstein (don@misty.com)
Reply to
Don Klipstein

And at this point, I see a fight between one doing a good job of failing to avoid appearance of being the often-rightly-derided one of many names and often referred to as "Dimbulb", and the somewhat-similarly-infamous Phil Allison.

- Don Klipstein ( snipped-for-privacy@misty.com)

Reply to
Don Klipstein

I see yet another retarded assessment dumbfuck.

Nice retarded assessment, dumbfuck.

Reply to
Son of a Sea Cook

Hey Phyllis, Time to take your meds. Quit bothering the adults who are having a conversation. Feel free to join in but be polite dear!

Reply to
Bob Eld

Apparently, in the past, speakers were more efficient than today...

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"At one stage, professional sound reinforcement speakers were commonly around the 100dB/W/m efficiency level, but this is now rare."

In addition, most of the speaker manufacturers I saw at Wal-Mart gave only a "Sensitivity" spec in "dB" which could be in dB/btu/inch for all I know.

Thanks,

Michael

Reply to
Michael

Are you saying 107 is the maximum with arrays ?

greg

Reply to
GregS

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