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Author Topic: Measurements with speakers pointing straight up.  (Read 2129 times)

Lyle Williams

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Measurements with speakers pointing straight up.
« on: December 14, 2013, 04:40:15 pm »


When measuring speakers it is important to minimise reflections and measure the speakers, not the room.  Hence the recommendation to test speakers outdoors.

I've read a couple of items where vertical testing has been used.  Speakers are pointed skyward and a test mic is installed on a tall pole.

Does anyone have any experience with this technique?  Does it produce better results than horizontal testing?
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Corey Scogin

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Re: Measurements with speakers pointing straight up.
« Reply #1 on: December 14, 2013, 07:17:08 pm »

Here's a great reference from a very reliable source that may address your question:

http://www.prosoundweb.com/article/tools_of_the_trade_how_boundaries_affect_loudspeakers/av
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Lyle Williams

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Re: Measurements with speakers pointing straight up.
« Reply #2 on: December 14, 2013, 09:10:15 pm »

Thanks.  I think from that maybe vertical testing (possibly in a hole) might be most useful for low frequencies where wavelengths are huge.
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Ivan Beaver

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Re: Measurements with speakers pointing straight up.
« Reply #3 on: December 14, 2013, 09:21:53 pm »

When measuring speakers it is important to minimise reflections and measure the speakers, not the room.  Hence the recommendation to test speakers outdoors.

I've read a couple of items where vertical testing has been used.  Speakers are pointed skyward and a test mic is installed on a tall pole.

Does anyone have any experience with this technique?  Does it produce better results than horizontal testing?
The question is "what are you trying to achieve with the measurement?"

If the speaker is on the ground (or near it) and facing up-then yes most of the reflections have been removed (assuming there are no buildings around.

HOWEVER there is the reflection from the ground at the low freq-which gives a boundary and will give a low freq boost in the response.

This is the same gain that would be had from a loudspeaker facing horizontal and on the ground.

In order to get a "free field" measurement you have to get the loudspeaker away from boundaries. 

OF course this depends on what the intended usage of the loudspeaker is, and the measurement should at least reflect some usages.

For example I always measure our monitors while on the ground in the normal position and the measurement mic 2M away.  Since this is the most common usage of that type of loudspeaker-I feel the measurement should reflect that.

Subs are always measured in half space (on the ground) since that is where they are most of the time-or against a ceiling or a wall.

Full range loudspeakers are a different story.  Since many times they are flown, the measurements are made in full space.  So if you put those speakers up against a boundary (wall or ceiling) the low freq will be louder than what the measurements show.

So the usual audio question applies  "It depends".

I feel the measurements or specifications should reflect what the customer can expect (performance wise) out of a product.  So the intended usages are considered when making measurements.  And as always-your mileage may vary depending on the particular usage.
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A complex question is easily answered by a simple-easy to understand WRONG answer!

Ivan Beaver
Danley Sound Labs

PHYSICS- NOT FADS!

Brad Weber

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Re: Measurements with speakers pointing straight up.
« Reply #4 on: December 18, 2013, 09:36:37 am »

I feel the measurements or specifications should reflect what the customer can expect (performance wise) out of a product.  So the intended usages are considered when making measurements.  And as always-your mileage may vary depending on the particular usage.
What I find interesting is how often the performance data and specifications provided by manufacturers does not define the test conditions used.  A typical full range box tested in half space would likely show enhanced low frequency response over a similar box tested in whole space but which condition is reflected in the specs and data provided?  Just another way manufacturers can manipulate the information presented without really doing anything "wrong".
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ProSoundWeb Community

Re: Measurements with speakers pointing straight up.
« Reply #4 on: December 18, 2013, 09:36:37 am »


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