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-   -   Accelerometers to measure panel vibrations? (https://www.diyaudio.com/forums/multi-way/364441-accelerometers-measure-panel-vibrations.html)

head_unit 14th December 2020 02:01 AM

Accelerometers to measure panel vibrations?
 
Where can I buy one of those? I can find a lot of information, but all old. And I don't have time go get into some DIY construction project about it.

I plan to make some cabinets, and want to experiment with damping, bracing, coating. Therefore it would be really handy to have an accelerometer of some kind (I'd hope connectable to Mac or iPhone) to quantify improvements or lack thereof

puppet 14th December 2020 02:14 AM

I've used half a glass of water or coffee. ... wouldn't connect that to a Mac or iPhone though.

jjasniew 14th December 2020 02:17 AM

The absolute cheapest way would be "Guitar Pickup Piezo Contact Microphone" off ebay, for < $15, shipped.

It wont have the infrasonic response a real accel might have and you wont be able to calibrate it to compare measurements with someone else. But it should give you relative indications of the effectiveness of your damping applications, i.e. brace / no brace, coating / no coating, etc.

nezbleu 14th December 2020 02:18 AM

Siegfried Linkwitz used a phono cartridge for the purpose in some of his early experiments.

head_unit 14th December 2020 07:23 AM

Quote:

Originally Posted by puppet (https://www.diyaudio.com/forums/multi-way/364441-accelerometers-measure-panel-vibrations-post6448219.html#post6448219)
I've used half a glass of water or coffee. ... wouldn't connect that to a Mac or iPhone though.

But on the side panels...won't the coffee spill out?!?! :eek:

head_unit 14th December 2020 07:28 AM

Quote:

Originally Posted by jjasniew (https://www.diyaudio.com/forums/multi-way/364441-accelerometers-measure-panel-vibrations-post6448224.html#post6448224)
The absolute cheapest way would be "Guitar Pickup Piezo Contact Microphone" off ebay, for < $15, shipped.

Ya just stick that one with...what the heck DO you stick it on with? I've read Atkinson's measurements for years, and is it Vance Dickason? But I don't remember the details.

My idea is have a professional build the cabinet shells, and then I experiment with all the internals. Like how about a rigid brace, versus a brace under compression but with a gel pad at one end. Well, something more durable than gel but with some vibrational elasticity which I someone opined was more effective than total rigidity.

Flaesh 14th December 2020 08:05 AM

Can a smartphone be used as an accelerometer?

markbakk 14th December 2020 08:06 AM

The accelerometer method is either tedious or quite inaccurate. Tedious: you will have to measure every other square inch (way of speech) of the panel involved and next calculate the integral to get a reliable impression of the actual sound production of the panel. Inaccurate: if you only measure on a few spots, you will not have a clue about the mechanical-acoustical transmission of the vibrating panel.

Furthermore, don't worry too much about panel vibrations, as a decent cabinet will do fine in domestic situations. With possibly one exception for the vibrations of loudspeaker units to the baffle.

MrKlinky 14th December 2020 09:01 AM

I bought an accelerometer for exactly this purpose, then realised it would tell me nothing about the Q of the resonances nor the real-time energy storage of the enclosure, both of which I consider rather important. I would tend towards a low mass, highly damped enclosure rather than an ultra-stiff (within reason - ie. not a hollowed-out 2 ton boulder) and possibly high Q option.

MrKlinky 14th December 2020 09:03 AM

Quote:

Originally Posted by head_unit (https://www.diyaudio.com/forums/multi-way/364441-accelerometers-measure-panel-vibrations-post6448377.html#post6448377)
Like how about a rigid brace, versus a brace under compression but with a gel pad at one end. Well, something more durable than gel but with some vibrational elasticity which I someone opined was more effective than total rigidity.

Sorry to stray off-topic a little, but I have been think along these lines; using a two-piece brace supporting opposite walls with a visco-elastic material joining them and operating in shear.


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