How do you go about measuring acoustical watts?

[JBL 4645]

I’ve read in the JBL manually I read about it on the HPS-4000 site so, how do you go about in a simple way of measuring acoustical watts, nothing over top just simple layman’s will suffice.

What means can you use to measuring this, (acoustical watts) the answer is somewhat eluding me at present.

[Ruediger]

To my opinion You can't.

You can measure SPL, calculate radiation impedance SOMEHOW, then calculate particle velocity, then calculate LOCAL intensity, then integrate intensity times area.

Ruediger

[JBL 4645]

To my opinion You can't.

You can measure SPL, calculate radiation impedance SOMEHOW, then calculate particle velocity, then calculate LOCAL intensity, then integrate intensity times area.

Ruediger
I know how to use the SPL db metre.

Please :) make a youtube to put into simpler terms of: oh, so that’s how it’s done. I’m too damn exhausted tonight with backache that is thumping me in the back! :(

[Ruediger]

I know how to use the SPL db metre.

Please :) make a youtube to put into simpler terms of: oh, so that’s how it’s done. I’m too damn exhausted tonight with backache that is thumping me in the back! :(

The receipe I gave can only theoretically be followed, not practically. Sorry that I did not make it clear enough.

Ruediger

[JBL 4645]

The receipe I gave can only theoretically be followed, not practically. Sorry that I did not make it clear enough.

Ruediger

Its Dutch to me. Even the JBL manual reads like stereo instructions. Just text no diagrams or pictures just text.

http://en.wikipedia.org/wiki/Sound_power

[Ruediger]

Its Dutch to me. Even the JBL manual reads like stereo instructions. Just text no diagrams or pictures just text.

http://en.wikipedia.org/wiki/Sound_power

Can You tell me document name and page number where You read what You are asking about?

Ruediger

[JBL 4645]

Can You tell me document name and page number where You read what You are asking about?

Ruediger

You'd have to scroll down the page a bit! On this site at HPS-4000 is where I was reading about it. http://www.hps4000.com/pages/comments_.html

The site page link has very (harsh turquoise colour) that will turn white pages to pink so watch out!

Wow. I didn't hear anything wrong in Westwood. All I know is that it was a marked improvement to the sound/picture at the Chinese! There is something like 17,000 watts of power for the various loudspeaker systems in the Village. I mean this theater is one of the preferred venues in Los Angeles for 'showcase' presentations because of its pedigree (and size). The THX trailer sounded in no way strained to my ears, no more so than the 'Broadway' trailer usually sounds anyway. I am not prepared to make a comparison with the theater in Hawaii that you speak of, having never heard it (or any other HPS-4000 theater, for that matter), but I am curious about your impressions of the Village. I don't mean to sound pompous, but I am just dumbfounded that anyone could find the Village wanting!

Any leads for where I can find HPS-4000 in the City of Angeles?

Posted by Roger on May 26, 1999 at 010204. In Reply to Re The sound at the Village pales next to Waikiki Twin. posted by Matthew A. Snyder on May 25, 1999 at 211042


Dear Matt:

Let me start again by saying that it is not at all my intention to put down the Village theatre in any way. As I stated I found the Village sounding better than most theatres. But when you compare it to a properly maintained HPS-4000 theatre like the Waikiki Twin it falls short. The 17000 watts of power at the Village that you mentioned is meaningless when it is passed through low efficient speakers that are employed at the Village. The stage speakers at Waikiki are approximately 8 times more efficient than that of the Village. That means the Waikiki can have one-eighth the amplifier power the Village has, but be able to give the same exact output. Not too many people realize that it is the speaker's output in acoustic watts which is the true measure of a systems power not the amplifier watts which you stated. The difference between the subwoofer's efficiency is even more..somewhere around 20 times. The Waikiki Twin has the equivalent power of 14 and one half symphony orchestras. The Village may have somewhere around 5 and is even a bit larger than Waikiki Twin. This difference in acoustic power is no joke and really assures that the sound will be as clear as possible even under the most highest peaks. This among other reasons is why the sound at Waikiki is a lot cleaner and fuller than the Village.

Another reason is the 4-way fully horn loaded speaker design at Waikiki. The Village uses a conventional 2-way. This creates a lot of problems with dialogue reproduction and also cannot compete with the detail and the richness which is available with the 4-way design. All you have to do is listen to dialogue or music in both auditoriums and you will realize the difference.

Sound tuning is another factor. The way the HPS-4000 theatres are tuned is also superior. Other systems including THX tune the sound based on pink noise and steady sound in the back of the theatre where there is a lot of reverberation present. Pink noise is not an accurate way of tuning the sound because it ignores sudden impulses and first arrival sounds. Taking readings in the back of the theatre is also wrong because a microphone does not recognize the reverberation present and adds it to the reading. What you get is a completely polluted response which does not represent what the human ears will hear. The HPS tuning is done towards the front of the theatre and also takes in to account the first arrival sounds. This why the sound at Waikiki is so detailed and contains nuances and effects that are absent at the Village.

I understand that Village theatre has long been hailed as the absolute finest, and like you said used for special venues and premieres. The HPS-4000 theatres have not had the fortune of being as widely recognized as THX, but when it comes to quality, I mean really true quality, they are the best. There have been a lot of audio experts that agree with me on this. Again you might say, I do not see anything wrong with the Village. Well my friend there nothing is. But if you really want to listen to a sound that is so incredible that will leave you stunned by its caliber then the HPS-4000 sound is for you.
Matt

[Ruediger]

On that page the term "acoustic power" is used but it is not claimed that a.p. could be measured easily. I think it is meant naively.

In electricity there is voltage, current and impedance, in acoustics there is sound pressure, particle velocity and acoustic impedance. The mathematics are the same. This is why we can draw an equivalent electrical circuit for a mechanical (oscillating) device such as a loudspeaker. If You really want to dive into it: Beranek explains this in his book "Acoustics".

For practical work You would not try to measure acoustic power, You would calculate it from other values.

Ruediger

[Allanvh5150]

Here is some useful info.

http://en.wikipedia.org/wiki/Sound_power

Allan.

[JBL 4645]

Ruediger
Cheers for reply I’ll go with SPL db, and leave it at that.

Al

That’s the same link I posted a few pages up when looking for keywords, no way do I want to listen to anything like Rocket engine, much less a Chain saw I hate the loudness of those things, I’ve used them before with ear defenders and they still sound loud only muffled.

Its also one reason why films don’t sound realistic with Rocket engines, I mean who wants that in their living room, at 180db! Instant Deafness is what will happen!:(

What makes me laugh is it takes a lot of bloody noise to get into space to hear the tranquil peace of silence.

[ratitifb]

Here is some useful info.

http://en.wikipedia.org/wiki/Sound_power

Allan.according to ISO standard there are 3 main methods to carry out the measurement of the acoustic power level of a sound source (generally expressed in dBA re 1pW with 1/3 oct. filter band analysis) :

1/ in an anechoïc room by envelopping (spheric or parallepipedic surface) the sound source with measuring microphone
2/ in a reverberation room (olny few points of measurement inside the diffuse sound field)
3/ in a semi-anechoïc room (equivalent to anechoïc room with a reflective plane floor) by envelopping (hemispheric or parallepipedic surface) the sound source with measuring microphone

See acoustical power measurement on ISO standard 374x ;)

[timc]

according to ISO standard there are 3 main methods to carry out the measurement of the acoustic power level of a sound source (generally expressed in dBA re 1pW with 1/3 oct. filter band analysis) :

1/ in an anechoïc room by envelopping (spheric or parallepipedic surface) the sound source with measuring microphone
2/ in a reverberation room (olny few points of measurement inside the diffuse sound field)
3/ in a semi-anechoïc room (equivalent to anechoïc room with a reflective plane floor) by envelopping (hemispheric or parallepipedic surface) the sound source with measuring microphone

See acoustical power measurement on ISO standard 374x ;)


This i correct. You could also do a polar measurement of the sound intensity at a given distance from the acoustical center.

In either case, this is not a trivial matter, and lots of equipment, and knowledge is needed to get an accurate result.

If you want to make a quick estimate, you could just look at the sensitivity of the speaker, and then calculate the effectivness of the speaker in %. If you then make an asumption concerning the directivity, you could get a rough estimate of the radiated acoustic power at a given frequency.