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Old 29th March 2004, 07:15 AM   #1
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Default estimating max continuous spl of a speaker

https://secure.wilmslow-audio.co.uk/...Fort__114.html

the drivers in this speaker have continuous power handlings of 100/w, 100w, and 75w.


ignoring the excursion limits,

how can you estimate the max continuous spl the pair can achieve?

Is it 108DB @ 1 metre, or around 111Db?

............................

another question,

given the sensitivities of the separate drivers in a speaker, how do you estimate the overall sensitivity of the speaker?

.....................

What is the difference between nominal power rating and max power handling(or max input power/music power)? As stated here: http://www.warco.com.au/waraudio/dri...al/7w4411.html

In here:
http://www.solen.ca/ue4.htm

This speaker can produce 130+ Db SPL and rated at 300RMS. How can they acheive it when one of the drivers used is only rated at 75W and 91Db/1m?
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Old 29th March 2004, 12:00 PM   #2
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do the log table

91db ----1watt
94db-----2watt
97db-----4watt

etc

assuming your speaker is linear youl attain that spl :P

ofcourse efficiency /sensitivity is easy to cheat (measuring it)

RMS(root mean square) is the real measurement. Those other ones id have to look up to remember exactly what theyve decided them to be.

dont forget that numbers dont reveal how a driver sounds :-)
it maybe 110db of yuck distortion...not pure nondistorted audio.
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Old 29th March 2004, 12:23 PM   #3
tiroth is offline tiroth  United States
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It's hard to agree on what the standard should be for "max" power. Reasons for stated power to be higher than expected:

1. Music power could be assumed, which means the maximum peak power the drivers could withstand is assumed, since RMS will be 5-10 times lower.

This results in interesting terms such as "continuous peak power".

2. In multi-way systems, weight the efficiency based on the percentage of power each driver is expected to contribute, rather than limiting total SPL to the weakest link.

3. Don't consider linearity.

4. Assume room gain.

I think 1 and 2 are very reasonable considering that none of us listen to sine waves...yet at the same time they hide some of the information. I don't think we can agree on any one number; it is best to do the math yourself and decide how you wish to characterize the SPL capabilities.
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Old 29th March 2004, 12:48 PM   #4
Previously: Kuei Yang Wang
 
Join Date: Nov 2002
Default Re: estimating max continuous spl of a speaker

Konnichiwa,

Quote:
Originally posted by tech.knockout
https://secure.wilmslow-audio.co.uk/...Fort__114.html

the drivers in this speaker have continuous power handlings of 100/w, 100w, and 75w.


ignoring the excursion limits,

how can you estimate the max continuous spl the pair can achieve?

Is it 108DB @ 1 metre, or around 111Db?
Well, you need to clearly define your conditions. First, you can work out what kind of level a single speaker can produce at 1m distance by simply taking the RMS powerhandling and the sensitivity, add the db between 1W and the rated power to the 1W/1m sensitivity and subtract around 4 - 6db for thermal compression. You can also estimate the ability of the speaker to cope with really short peaks by assuming an amplifier with either your given peak power limit or a power around 4 times that of the rated RMS power.

So, if you have an amplifier capable of delivering around 56V undistorted peaks to the Speaker you can expect around 26db - 2 to 4db for compression (peaks compress a little less) above 1W/1m. If the 90db/W/m is realistic (often hard to say) you could hence expect a single speaker to produce peaks of up tp 113db in 1m Distance, given an amplifier capable of delivering 56V peaks.

If you then place a pair of speakers in a normal room and play a mono signal you can expect a 6db increase in SPL. For every doubling of the Distance between speaker and listener you loose 6db in SPL. So, if you listen in 2m distance from the speaker and have a pair your net point is still 113db peak. If you have more listening distance your SPL falls further, I normally fiond that for 3m listening distance -9db on each speaker is realistic. However, the fact that your roomis not a anechonic chamber gives you 2 to 3db extra.

So for a normal room, a speaker pair, 3m listening distance and a "mono-compatible" signal your SPL at the listening position approximally is the same as the 1m SPL of the single speaker, with maybe +/-3db error budget for local conditions.

Quote:
Originally posted by tech.knockout
given the sensitivities of the separate drivers in a speaker,
how do you estimate the overall sensitivity of the speaker?
This is complex and depends on many factors. Tweeters often have lower powerhandling, but often are not required to handle much power (spectral distribution) and have a higher sensitivity, meaning their acoustic output is reduced in the X-Over which in effect increases power handling. Usually the woofer is the least efficient/sensitive item in the speaker while being required to handle the largest and most energy rich part of the musical spectrum, hence it is usually reasonable to take the woofers power handling and SPL as the "baseline" and hope the speaker designer was competent enough to make rest work okay with that.


Quote:
Originally posted by tech.knockout
What is the difference between nominal power rating and max power handling(or max input power/music power)? As stated here: http://www.warco.com.au/waraudio/dri...al/7w4411.html
Nominal or continous means the amount of power that can be applied to the driver indefinitly without damaging the driver. Music power/Max Power etc are based on what the speaker can handle with a signal that has a high crest factor and short peak durations, such as recorded music (crest factor 10 - 20db and peaks in the single to double mS range).

Quote:
Originally posted by tech.knockout
In here:
http://www.solen.ca/ue4.htm

This speaker can produce 130+ Db SPL and rated at 300RMS. How can they acheive it when one of the drivers used is only rated at 75W and 91Db/1m?
I would be carefully as to how literal you wish to take manufacturers written specs. They usually will take a "pick" of what particulary spec they pick to make their product look better.

With a 91db/W/m sensitivity you need to apply > 1,000 to attain > 130db, I find this stretching the truth perhaps a little.

Sayonara.
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Old 30th March 2004, 01:01 AM   #5
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Quote:
With a 91db/W/m sensitivity you need to apply > 1,000 to attain > 130db,
the speaker as a whole is rated 94Db/1m

Anyways thanks. The sensitivity figures are for only one single speaker not in an enclosed area, correct?
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