How to measure diaphragm tension - Page 2 - diyAudio
Go Back   Home > Forums > Loudspeakers > Planars & Exotics

Planars & Exotics ESL's, planars, and alternative technologies

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 18th November 2006, 08:26 AM   #11
Calvin is offline Calvin  Germany
diyAudio Member
 
Calvin's Avatar
 
Join Date: Nov 2004
Location: close to Basel
Hi,

@I-Forgot
I think measuring the precise hight of the rebounce could be a bit difficult. I assume You need precise measuring here because the difference in height will be very small??!! But basically this procedure should work.
Measuring the frequency is imo easier. Even simple listening to the bouncesound, You´re ear will recognize slight differences in frequency.

jauu
Calvin
  Reply With Quote
Old 18th November 2006, 05:19 PM   #12
Bazukaz is offline Bazukaz  Lithuania
diyAudio Member
 
Bazukaz's Avatar
 
Join Date: Nov 2005
Location: Vilnius
Send a message via Skype™ to Bazukaz
Hi,
I think that it would be possible to place a dynamic driver close to stretching jig , and try to play various tones with tone generator program , and try to hear or measure the resonant frequency. Even a spectrum analyser and mic may not be needed in this case. Has anybody tried this ?
  Reply With Quote
Old 18th November 2006, 07:39 PM   #13
diyAudio Member
 
I_Forgot's Avatar
 
Join Date: Jan 2005
Location: Phoenix, Az.
Quote:
Originally posted by Calvin
Hi,

@I-Forgot
I think measuring the precise hight of the rebounce could be a bit difficult. I assume You need precise measuring here because the difference in height will be very small??!! But basically this procedure should work.
Measuring the frequency is imo easier. Even simple listening to the bouncesound, You´re ear will recognize slight differences in frequency.

jauu
Calvin
Measuring the height would be tricky, but how about measuring the time to bounce? Use a mic to pick up the ball striking the film, or better yet, a piezo electric film sensor placed on the film.

I_F
  Reply With Quote
Old 18th November 2006, 08:14 PM   #14
diyAudio Member
 
stokessd's Avatar
 
Join Date: Nov 2002
Location: Grantham, NH
Use the microphone like a guitar tuner, flick the mylar with your finger and record the damped sine wave oscillation. If you use a soundcard to record the impulse and response, you can simply FFT it and pick out the resonant frequency. You've got a bit of math head of you to determine the resonant frequency vs. tension.

Sheldon
  Reply With Quote
Old 10th May 2007, 01:30 PM   #15
volkerw is offline volkerw  Germany
diyAudio Member
 
Join Date: Oct 2004
Quote:
Originally posted by Bazukaz
Hi,
I think that it would be possible to place a dynamic driver close to stretching jig , and try to play various tones with tone generator program , and try to hear or measure the resonant frequency. Even a spectrum analyser and mic may not be needed in this case. Has anybody tried this ?
I tried this last evening, it works fine.
I layed a stator with readily glued on membrane on top of a low fs/qts woofer (25/0.25, not critical), mounted a measuring mic above it, swept a sine signal from 20 to 100Hz and watched the mic output on a scope. Panel resonance was clearly indicated. I tested 2 others complete panels and all had different fs. I think if this sort of test is done with the exciter driver mounted below the stretcher table the final resonance of ready panel will be pedictable. For correct results the stators will have to be temporary attached to the membran.
  Reply With Quote
Old 11th May 2007, 02:00 PM   #16
diyAudio Member
 
Join Date: May 2006
Location: Netherlands
Hi Volker,

If the membrane is rectangular (which I suspect since it is so common) I would not be suprised if you are able to find two primary resonances, one for the large diameter and one for the small one. Did you notice anything like that?
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Wire stators, tension, stator bending? Nevod Planars & Exotics 11 29th August 2008 12:55 PM
NTC in High Tension PSUs? Salas Parts 4 20th February 2008 11:50 AM
Change of tension in a Classe CDP dario54 Analogue Source 1 27th October 2007 06:58 PM
Marantz CD85 - tension selector kraal Digital Source 6 25th February 2007 12:58 PM
Tension on chassis eduard Tubes / Valves 35 31st July 2003 12:00 AM


New To Site? Need Help?

All times are GMT. The time now is 12:13 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright ©1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2