AudioNervosa

Specialists => Audiologists => Topic started by: HAL on October 04, 2019, 08:48:08 AM

Title: Fun with materials
Post by: HAL on October 04, 2019, 08:48:08 AM
Fun with materials.

What happens when you put an accelerometer on a piece of MDF and hit it with a ballpeen hammer. Lets take a look.

Audio spectrum 64K point FFT of piezoelectric acclerometer with CLIO.

Love hitting stuff and see what happens! :)
Title: Re: Fun with materials
Post by: Nick B on October 04, 2019, 09:42:47 AM
That’s an interesting and fun test.... and also useful if you’re having a bad day  :D 🔨 
Title: Re: Fun with materials
Post by: jimbones on October 04, 2019, 09:46:15 AM
Hal, I want to get some accelerometer's to start experimenting, could you recommend some?
Title: Re: Fun with materials
Post by: HAL on October 04, 2019, 03:15:31 PM
Digikey has one like the Audiomatica CLIO version that needs power to run.  Has a different connector, so will not work directly with CLIO.  It does have sensitivity data usually.

https://www.digikey.com/product-detail/en/te-connectivity-measurement-specialties/1-1001220-0/MSP1001-ND/279641

They sell a preamp, but that has a lot of gain that might not be what is needed.

Hope that helps.
Title: Re: Fun with materials
Post by: steve on October 04, 2019, 03:42:46 PM
Fun with materials.

What happens when you put an accelerometer on a piece of MDF and hit it with a ballpeen hammer. Lets take a look.

Audio spectrum 64K point FFT of piezoelectric acclerometer with CLIO.

Love hitting stuff and see what happens! :)

Thank you Hal for performing the experiment and sharing the results with us. The results are quite interesting.
May I ask the type, thickness, size of the MDF? If proprietary, I understand.

Cheers and great weekend.

steve
Title: Re: Fun with materials
Post by: HAL on October 06, 2019, 07:46:58 AM
Fun with materials.

What happens when you put an accelerometer on a piece of MDF and hit it with a ballpeen hammer. Lets take a look.

Audio spectrum 64K point FFT of piezoelectric acclerometer with CLIO.

Love hitting stuff and see what happens! :)



Thank you Hal for performing the experiment and sharing the results with us. The results are quite interesting.
May I ask the type, thickness, size of the MDF? If proprietary, I understand.

Cheers and great weekend.

steve
Steve,
Standard 1/2" MDF from Lowes.  Nothing special.  Going to try the oak I used for another baffle and see what it does. in comparison.
Title: Re: Fun with materials
Post by: steve on October 06, 2019, 09:30:22 AM
Fun with materials.

What happens when you put an accelerometer on a piece of MDF and hit it with a ballpeen hammer. Lets take a look.

Audio spectrum 64K point FFT of piezoelectric acclerometer with CLIO.

Love hitting stuff and see what happens! :)



Thank you Hal for performing the experiment and sharing the results with us. The results are quite interesting.
May I ask the type, thickness, size of the MDF? If proprietary, I understand.

Cheers and great weekend.

steve
Steve,
Standard 1/2" MDF from Lowes.  Nothing special.  Going to try the oak I used for another baffle and see what it does. in comparison.

Thanks again Hal. Comparing this to oak should be very very interesting. What L x W dimensions were used?

This is good information for those who are building their own speakers, even if dimensions are different. In this experiment, virtually no spikes except at very low frequencies, which can be remedied.

Cheers and thanks again Hal.

steve
Title: Re: Fun with materials
Post by: HAL on October 06, 2019, 12:16:02 PM
New test jig for sample testing.
Title: Re: Fun with materials
Post by: rollo on October 09, 2019, 11:36:23 AM
  A Mad Scientist you are Hal. Love it.

charles
Title: Re: Fun with materials
Post by: HAL on November 14, 2019, 05:24:49 AM
Have a new test setup built to start testing more samples sent by folks. 

Once I get it tweaked will post more data.  Also going to use some constrained layer damped materials to compare.  Should be interesting.
Title: Re: Fun with materials
Post by: steve on November 14, 2019, 08:55:47 PM
Have a new test setup built to start testing more samples sent by folks. 

Once I get it tweaked will post more data.  Also going to use some constrained layer damped materials to compare.  Should be interesting.

Yes indeed. Looking forward to your experiments and data Michael.

cheers

steve
Title: Re: Fun with materials
Post by: HAL on November 15, 2019, 04:52:21 AM
Ummm.  I am Rich not Michael.
Title: Re: Fun with materials
Post by: Guy 13 on November 15, 2019, 05:02:18 AM
Ummm.  I am Rich not Michael.


 :rofl:

 :duh

Guy 13
Title: Re: Fun with materials
Post by: AJ Soundfield on November 15, 2019, 06:59:12 AM
Ummm.  I am Rich not Michael.
I thought you were HAL???

I've been tempted to take a hammer to some of my creations on more than one occasion. Not for testing though...
Title: Re: Fun with materials
Post by: HAL on November 15, 2019, 07:32:55 AM
Stands for Hollis Audio Labs.  I am Rich, you can call me HAL.

Dave, I cannot do that...
Title: Re: Fun with materials
Post by: tmazz on November 15, 2019, 04:11:33 PM
Stands for Hollis Audio Labs.  I am Rich, you can call me HAL.

Just don't call me late for dinner.......
Title: Re: Fun with materials
Post by: dBe on November 15, 2019, 07:53:26 PM
I’ve done some impulse testing.  In order to standardize testing results I built a swing hammer out of a 1 x 2 and an old hammerhead.  I drilled holes at 3” intervals from 6” up to 24”.  Used a polished nail for a pivot.   Swung the arm from a vertical 2 x 4 from the same height every time relative to the hole placement.  Crude, but absolutely repeatable.  I set the gate for the first strike or moved the MUT back from the pendulum until it didn’t strike again after rebound.

Just a thought to standardize the impulse.
Title: Re: Fun with materials
Post by: dBe on November 15, 2019, 07:55:02 PM


I've been tempted to take a hammer to some of my creations on more than one occasion. Not for testing though...

 :rofl:
Title: Re: Fun with materials
Post by: HAL on November 16, 2019, 06:14:21 AM
My new test setup is a vice to hold the sample.  The accelerometer is attached with BlueTack to the sample.

I have a 12V solonoid door opener with a pulse generator being used backwards.  The solonoid pushes the actuator rear screw cap rapidly into the sample to tap it.  Totally repeatable as the pulse time is controlled by an Arduino pulse software pin set for output.  Built a solonoid driver circuit with diode protection to take the Arduino output. 

This is a modification to the swinging hammer or weight idea.

Hope to start testing the samples Peter sent of a bunch of materials soon.  Will see what happens.
Title: Re: Fun with materials
Post by: dflee on November 16, 2019, 07:53:42 AM
First off I just gotta say I won't get a thing out of this topic. BUT
Y'all are first off quite intelligent and second the posts are awesome.
Enjoy reading when you put your thoughts into words.
Carry on

Don
Title: Re: Fun with materials
Post by: dBe on November 16, 2019, 10:59:51 AM
My new test setup is a vice to hold the sample.  The accelerometer is attached with BlueTack to the sample.

I have a 12V solonoid door opener with a pulse generator being used backwards.  The solonoid pushes the actuator rear screw cap rapidly into the sample to tap it.  Totally repeatable as the pulse time is controlled by an Arduino pulse software pin set for output.  Built a solonoid driver circuit with diode protection to take the Arduino output. 

This is a modification to the swinging hammer or weight idea.

Hope to start testing the samples Peter sent of a bunch of materials soon.  Will see what happens.
Ahhhh. Cool. I was wondering how you are doin it.
Title: Re: Fun with materials
Post by: HAL on November 16, 2019, 01:46:28 PM
The CLIOwin 8.51 Standard measurements system is running and calibrated to Audiomatica's automated calibration system. 

The accelerometer sensitivity is being adjusted for by the software for testing.

The PC display is the peak hold and waveform displays for the test waveform.
Title: Re: Fun with materials
Post by: HAL on November 19, 2019, 04:24:26 AM
Modified the test rig as it had to much damping.  Needed to clamp the solonoid to the vise for stability.

Tested all the samples Peter J sent.  Also tried some constrained layer damping material CAE VB-2 as well.  Will be graphing the response plots and some comparisons.
Title: Re: Fun with materials
Post by: HAL on November 19, 2019, 01:52:56 PM
Did some comparison plots of the impulse response measurements with the test setup of samples sent by Peter J.

First is the comparison of MEDEX and Ranger Board, The second is the comparison of MEDEX to MEDEX with CAE VB-2 constrained layer damping material applied.

Constrained layer damping needs more investigation.
Title: Re: Fun with materials
Post by: HAL on November 20, 2019, 12:54:59 PM
Did the comparison plots of the impulse response measurements with the test setup of material samples sent by Peter J. 

Here are the samples sent with the material listed in the bottom of the graph,

Green is always the MEDEX sample for comparison.
Title: Re: Fun with materials
Post by: HAL on November 20, 2019, 12:56:47 PM
Next set:
Title: Re: Fun with materials
Post by: HAL on November 20, 2019, 12:59:21 PM
Next batch:
Title: Re: Fun with materials
Post by: HAL on November 20, 2019, 01:00:54 PM
Last batch of measurements:
Title: Re: Fun with materials
Post by: dBe on November 20, 2019, 01:43:40 PM
So, Rich:  what are your determinations at this point in testing?  From my end, it looks like the quartz countertop material is the most linear in decay and in my way of thinking that would be THE desireable characteristic.

Should I send you constrained layer material that I use when I build cabinets?  Ah, yes.  I think I should.  It will be coming to you in a few days.
Title: Re: Fun with materials
Post by: HAL on November 20, 2019, 06:06:44 PM
Dave,
The Quartz has a nice decay vs frequency, but it also has the largest undamped resonance at 11.5KHz.  Might be a candidate for constrained layer damping trials.  It is just very heavy!  :o
Title: Re: Fun with materials
Post by: dBe on November 20, 2019, 10:06:46 PM
I’ve never seen (or heard) 11.5K be an issue in cabinets.  Granted, this resonance will probably shift downward with larger sizes. Even so it has been my experience that cabinet materials with their resonances are the most problematic below ~ 800Hz.  Cabinet hoot is really bad at about 400Hz.
Title: Re: Fun with materials
Post by: HAL on November 21, 2019, 08:46:47 PM
Yep, lower in frequency is worse for cabinet vibrations.  Having the accelerometer makes them easy to find.  Just run a log sweep on the speaker and measure the response on a panel with it attached.  Then you know what to work on to damp.     

Now to try some constrained layer damping materials and see what happens with other samples.   The CAE VB-2 from Parts-Express is already posted on the MEDEX sample. 
Title: Re: Fun with materials
Post by: steve on November 22, 2019, 06:44:04 AM
Yep, lower in frequency is worse for cabinet vibrations.  Having the accelerometer makes them easy to find.  Just run a log sweep on the speaker and measure the response on a panel with it attached.  Then you know what to work on to damp.     

Now to try some constrained layer damping materials and see what happens with other samples.   The CAE VB-2 from Parts-Express is already posted on the MEDEX sample.

Thanks for all your time and efforts Hal. Much appreciated. A couple of questions I would like to ask.

What was the thickness and L x W of the samples tested?

If these are small pieces, is it possible with your setup to perform a test on a larger piece, say 20 inches by
35 or 40 inches?

Thanks again Hal.

steve
Title: Re: Fun with materials
Post by: HAL on November 22, 2019, 11:42:48 AM
The samples are all 1" x 3" x stock material depth cut from the raw stock.

The Dremel vise is to small for larger panels to be tested. 
Title: Re: Fun with materials
Post by: steve on November 24, 2019, 05:53:23 AM
The samples are all 1" x 3" x stock material depth cut from the raw stock.

The Dremel vise is to small for larger panels to be tested.

Thanks for providing the information Hal. I, personally, found the info. interesting and useful indeed.

cheers

steve