New Analog Devices MEMS vibration sensor

GroupDIY Audio Forum

Help Support GroupDIY Audio Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

zapnspark

Well-known member
Joined
Feb 17, 2005
Messages
107
Location
Midwest
See the video demo here:

http://tinyurl.com/59gzft

Unusual for a vibration sensor, because the response extends
to 22 kHz.
Uses? Speaker compensation?
I just thought this was interesting.

ZAP
 
[quote author="zapnspark"]See the video demo here:

http://tinyurl.com/59gzft

Unusual for a vibration sensor, because the response extends
to 22 kHz.
Uses? Speaker compensation?
I just thought this was interesting.

ZAP[/quote]
Caught your url on micbuilders as well, thanks.

I'm not too familiar with the ins & outs of such sensors, but what determines the limit ? Being MEMS based, you could have quite a bit of freedom w.r.t. dimensioning structures I assume.

Bye,

Peter
 
I'm not too familiar with the ins & outs of such sensors, but what determines the limit ? Being MEMS based, you could have quite a bit of freedom w.r.t. dimensioning structures I assume.

Accelerometers have been used on sub-woofers in a feedback arrangement (can't remember the brand right now)
Accelerometers are usually limited to lower frequency ranges.
These new AD ones are very tiny and very flat up to about 10 kHz with a 22 kHz resonance peak.
They could easily be mounted to a speaker cone.
However, I don't know if it's practical to use them to feedback compensate midrange or tweeter speakers.

ZAP
 
[quote author="zapnspark"]
I'm not too familiar with the ins & outs of such sensors, but what determines the limit ? Being MEMS based, you could have quite a bit of freedom w.r.t. dimensioning structures I assume.

Accelerometers have been used on sub-woofers in a feedback arrangement (can't remember the brand right now)[/quote]
Dunno about eventual (or likely) others, but at least there was the Philips MFB-speakersystem
(motional feedback, woofer only, active speakers).

http://www.mfbfreaks.nl/


However, I don't know if it's practical to use them to feedback compensate midrange or tweeter speakers.
That's beyond me as well. It sure might be nice from a technical point of view, but whether it brings real benefits these days I couldn't tell.

Bye,

Peter
 
I think Velodyne is the prominent accelerometer-based motional-feedback subwoofer company.

I think the low frequency driver compensation is the only fairly practical application of accelerometer feedback stabilization/compensation. One of the problems at higher frequencies is the fact that the cone is not really that rigid, so you've got all kinds of wave effects. Trying to sense one region and use it to provide feedback, even if the mass of the accelerometer were completely negligible, would likely lead to serious errors. I don't know, it might work at up to 500-900Hz or so, depending on the cone rigidity.
 
bcarso,
Thanks. Velodyne it is.
What you say makes sense. Too many multi-modal vibrations to make it very practical.

I wonder if anyone is working on a MEMS based microphone?

I found this in Wikipedia 6-26-2008
MEMS microphones
The MEMS (MicroElectrical-Mechanical System) microphone is also called a microphone chip or silicon microphone. The pressure-sensitive diaphragm is etched directly into a silicon chip by MEMS techniques, and is usually accompanied with integrated preamplifier. Most MEMS microphones are variants of the condenser microphone design. Often MEMS mics have built in analog-to-digital converter (ADC) circuits on the same CMOS chip making the chip a digital microphone and so more readily integrated with modern digital products. Major manufacturers producing MEMS silicon microphones are Akustica (AKU200x), Infineon (SMM310 product), Knowles Electronics, Memstech (MSMx)and Sonion MEMS.
 
[quote author="bcarso"]Ahh---actually quite a few manufacturers, I see.[/quote]
Indeed many companies doing it...

You could also imagine the various possibilities with an array of such mic-elements: localization, noise cancelling etc

Regards,

Peter
 
[quote author="clintrubber"][quote author="bcarso"]Ahh---actually quite a few manufacturers, I see.[/quote]
Indeed many companies doing it...

You could also imagine the various possibilities with an array of such mic-elements: localization, noise cancelling etc

Regards,

Peter[/quote]

Lots of that going on too. Here's a book Springer is pushing, for one reference; a mite pricey for the number of pages but so it goes: http://www.springer.com/engineering/signals/book/978-3-540-78611-5?cm_mmc=AD-_-enews-_-PSE1888-_-0
 
Yup I recall the Phillips woofer using feedback back in '70s(?) and then there was Servodrive with the actual servo motor woofer.

Ironically cleaner bass isn't universally perceived as better since we are so familiar with the distorted sound.

JR
 
[quote author="JohnRoberts"]Yup I recall the Phillips woofer using feedback back in '70s(?)[/quote]
FWIW, the article from Philips Research that I found is from 1968:

http://www.mfbfreaks.nl/artikel/oorsprong/1/index.html

The full article is there, but note it's in Dutch.

So indeed the products on the market in the seventies; a service-doc from the first series dated Nov 1975.

The sensor-unit:

pxe.jpg



Regards,

Peter
 
[quote author="JohnRoberts"]Ironically cleaner bass isn't universally perceived as better since we are so familiar with the distorted sound.
JR[/quote]

When Wolfgang Klippel was at Harman he demonstrated his mirror filter with a little woofer. The relatively undistorted bass energy was impressive, but Marshall Buck rejected it as not useful for computer speakers since it didn't sound as loud as the distorted version.
 
Back
Top