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Old 29th February 2012, 10:05 AM   #31
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Join Date: Feb 2008
Location: Jackson,michigan
Not sure,lduarte1973,
But you can check here maybe or give them a call.

MCM Electronics | Help Center - Shipping

jer
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Old 29th February 2012, 06:41 PM   #32
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Join Date: Feb 2008
Location: Jackson,michigan
I did some more efficiency measurement and it was very hard to get some accurate figures using the calaculator.

I do get 118db at 500hz and 1000hz at 1 watt flush with the driver.
I have found that by entering the distances in feet seem to give a better reading than meters.
For instance if I have 118db at 1cm I also measure 112db at 10cm and not 98db like the calculator depict's. ???

So by using values of greater than .5 for my initial distance values for a measurement point I seem to get better results.

Therefore if I am getting 112.5 at .5 foot I do read about 106.5 1 foot, So in the calculator this works out and according to the calculator I should be getting 95.76db at 3.25 feet or 1 meter at a level of 1 watt.

This is much higher than the advertised figures for this driver at 89db.
I could tell when I first set the levels that 89db at one watt could not have been right!

Considering that I had just got done testing my little 8" sub that is rated at about 88.5db.

Being that I am using less than adequate anechoic conditions and my room is very cluttered, I manged to position the driver so that I could get a reading from 1 metter away.
I had verified the results at 500Hz and 1000Hz at about 95.4db at 1 watt with it sitting in its packaging box in order to help dampen the backwave at those frequencys.

Thanks for putting me up to this as the advertised figure of 89db did have me a little bummed out.
But now I am very very happy the the results !!!

Here are some pictures of the driver.

enjoy !!!!



jer
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Old 1st March 2012, 05:52 AM   #33
mdocod is offline mdocod  United States
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jer,

You can't do a sensitivity test inside a room like that. Your mic is picking up not just the sound from the driver, but all of the room reflections and loading, giving you a ton of "fake" sensitivity data.
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Old 1st March 2012, 06:29 AM   #34
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Join Date: Feb 2008
Location: Jackson,michigan
Yes, I understand that it is not the most accurate,But the numbers do line up.
118db flush with the driver is a lot louder than any reflections, and, 112.5db at .5 foot to 106.5db at one foot is exactly right.
Therefore the 95.5 db at 39 inches also coincides with what the calculator comes up with as well.
I also used a distance of .5meters at 19.5 inches and 1meter at 39 inches and the results were the same.
I think that it is pretty close.

In that particular area of the room there is alot of diffraction going on and very little direct reflections although like I said "it is less than optimum".

I did try different frequency's as well to help combat the effect of possible reflections and the results were the same.

If the weather was permitting I would have done it outside.
When it does clear up I will redo this again just to see how far off it is.
I am in no hurry to get them mounted as the cabinet is buried in the garage at the moment and I want to do an accurate measurement once I get them mounted as well.

jer

Last edited by geraldfryjr; 1st March 2012 at 06:37 AM.
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