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Accelerometer Testing of Loudspeaker Drivers
Accelerometer Testing of Loudspeaker Drivers
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Old 16th December 2016, 09:47 PM   #31
gdan is offline gdan  Greece
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Accelerometer Testing of Loudspeaker Drivers
The photo of the previous post.
Thanks Murilo!
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File Type: jpg Accelerometer amp.jpg (166.4 KB, 334 views)
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Old 6th April 2017, 07:42 PM   #32
gdan is offline gdan  Greece
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Accelerometer Testing of Loudspeaker Drivers
Another reminder for those that are interested to build the accelerometer amplifier.

More info here:
http://www.diyaudio.com/forums/swap-...plifier-2.html
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Old 21st September 2017, 09:07 PM   #33
gdan is offline gdan  Greece
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Accelerometer Testing of Loudspeaker Drivers
I have used the ACH accelerometer with its pre-amplifier to measure the distortion of a woofer and its peak displacement in relation to the input voltage.
I used the STEPS part of the ARTA software (STEPS Main Menu --> Record ---> Distortion vs. amplitude) with the output of my accelerometer amplifier (set to "Exc" to measure displacement) connected as an input to the software.
The accelerometer is attached to the center of the woofer's cone and the microphone very close to the cone.
In the attached photo you can see such a measurement of a 12" subwoofer placed in a box of about 30 litters.
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File Type: jpg Cone Displacement measurements at 20 Hz.jpg (94.3 KB, 258 views)
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Old 10th July 2018, 05:50 PM   #34
skn is offline skn  Denmark
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Hi George,

Just to let you know.
The Accelerometer preamp. arrived this morning and everything looks fine.
And thanks for building the unit and doing the calibration.

Steffen
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Old 11th July 2018, 01:53 PM   #35
Pano is offline Pano  United States
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Accelerometer Testing of Loudspeaker Drivers
Quote:
Originally Posted by gdan View Post
In the attached photo you can see such a measurement of a 12" subwoofer placed in a box of about 30 litters.
Interesting graph. The displacement vs voltage looks very linear. Why is THD so high?
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Old 12th July 2018, 09:56 AM   #36
gdan is offline gdan  Greece
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Accelerometer Testing of Loudspeaker Drivers
If you consider that the woofer is driven at 20 Hz by 15.5 Vrms (almost 44 V peak to peak) and the excursion is 14 mm peak to peak, I would say that a distortion of 10% is not so high.
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Old 17th September 2018, 02:07 PM   #37
gdan is offline gdan  Greece
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Accelerometer Testing of Loudspeaker Drivers
I found also the measurement of the same woofer at the frequency of 30 Hz.

Much better the results here.
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File Type: png Cone Displacement measurements at 30 Hz.png (88.7 KB, 114 views)
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Old 23rd September 2018, 09:40 PM   #38
head_unit is offline head_unit  United States
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So is there a speaker-usable accelerometer that one can just BUY? I see a Mouser part but it looks huge (I couldn't find dimensions)
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Old 24th September 2018, 07:49 PM   #39
gdan is offline gdan  Greece
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Accelerometer Testing of Loudspeaker Drivers
Yes, there is, at least for the woofers larger than 8".
The ACH-01 accelerometer has a weight of 3 grams and could be used without serious effects on drivers that have a cone mass weight greater than 25 -30 grams.
I have used it also in smaller woofers with acceptable results.
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Old 25th September 2018, 02:28 AM   #40
trobbins is offline trobbins  Australia
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MMA7361L on a pcb are available for use up to 400Hz.

FXLN837XQ up to 2.7kHz.
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