DIY weighted diaphragm stretcher (pic) - 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 29th September 2007, 10:49 AM   #1
diyAudio Member
 
Join Date: May 2006
Location: Netherlands
Default DIY weighted diaphragm stretcher (pic)

Click the image to open in full size.

The picture shows the weighted diaphragm stretcher being used on a diaphragm for a Quad ESL bass panel.

I finished the build of this tretcher a couple of days ago. The results are outstanding!

The hard part was sourcing all the components and finding solutions to some of the parts that were custom made on the original Quad stretcher. The most critical parts are the clamps that need to have a firm grip on the film but not tear it, and the belt wheels - you can't have much friction at this point.

It is quite a thrill to have a diaphragm tensioned while suspended in air. Everything should be nicely balanced, when you pull one of the cords softly the whole diaphragm moves in the same direction.

I build it to refurbish Quad ESL diaphragms. On the stretcher is a bass panel film ready to be coated. The weights are made from PVC plumming pipe filled with leadshot and can be opened and adjusted to experiment to get the right tension. Each weight consist of two parts - the primary weight is tuned for tensioning bass panel diaphragms and the second part can be attached to the bottom of the first to increase the tension for the treble panels.

In the middle is the stator table which can be adjusted in height with a car jack. I wanted to build something a little more sophisticated but it proved difficult to make a nice lift mechanism. The car jack get's the job done.

I've tried a lot of different tensioning methods and this is the best by far. Apart from some unique features that this type of stretcher offers, it also has excellent consistancy (the resonance frequency is stable within 1 Hz between panels) and it is a breeze to use. Tensioning a diaphragm takes only a couple of minutes.
  Reply With Quote
Old 29th September 2007, 10:26 PM   #2
diyAudio Member
 
Join Date: Sep 2004
That really is cool!!!Well done!I wondered how much you need to tension a diaphram?
  Reply With Quote
Old 29th September 2007, 11:00 PM   #3
diyAudio Member
 
Join Date: May 2006
Location: Netherlands
Hi daz,

I'm not sure if I understand your question correctly, but if you're asking about the size of the weights then I'm sorry but I won't tell. Not in public anyway.

Thanks for the compliment!
  Reply With Quote
Old 30th September 2007, 12:15 AM   #4
SY is offline SY  United States
diyAudio Moderator
 
SY's Avatar
 
Join Date: Oct 2002
Location: Chicagoland
Blog Entries: 1
Will you whisper in my ear at ETF?
__________________
And while they may not be as strong as apes, don't lock eyes with 'em, don't do it. Puts 'em on edge. They might go into berzerker mode; come at you like a whirling dervish, all fists and elbows.
  Reply With Quote
Old 30th September 2007, 12:47 AM   #5
diyAudio Member
 
I_Forgot's Avatar
 
Join Date: Jan 2005
Location: Phoenix, Az.
Beautiful!

I_F
  Reply With Quote
Old 30th September 2007, 09:38 AM   #6
diyAudio Member
 
Join Date: May 2006
Location: Netherlands
SY: if you buy me a beer
  Reply With Quote
Old 30th September 2007, 12:32 PM   #7
SY is offline SY  United States
diyAudio Moderator
 
SY's Avatar
 
Join Date: Oct 2002
Location: Chicagoland
Blog Entries: 1
Consider it done. A nice Leffe.
__________________
And while they may not be as strong as apes, don't lock eyes with 'em, don't do it. Puts 'em on edge. They might go into berzerker mode; come at you like a whirling dervish, all fists and elbows.
  Reply With Quote
Old 1st October 2007, 06:45 AM   #8
diyAudio Member
 
Join Date: Nov 2005
Location: Southern Germany
Hi Arend-Jan,

outperforming !! Congratulations.

Its funny, you experienced the same issues i did. Especially the clamps are tricky. You are right, this is the best and the most reproducible way to stretch an ESL membrane.

But i wonder that you just do mechanical tensioning. Quad implemented a thermal treatment to the process and i do as well.

Capaciti
  Reply With Quote
Old 1st October 2007, 08:54 AM   #9
diyAudio Member
 
Join Date: May 2006
Location: Netherlands
Quote:
Originally posted by Capaciti
Hi Arend-Jan,

outperforming !! Congratulations.
Thanks!

Quote:

Its funny, you experienced the same issues i did. Especially the clamps are tricky.
Cool, you build a stretcher too! I'd love to see it. Can you post a picture?

Quote:

Quad implemented a thermal treatment to the process and i do as well
send me a PM.


Arend-Jan
  Reply With Quote
Old 4th October 2007, 05:33 PM   #10
diyAudio Member
 
Join Date: Aug 2007
That's off-limits on my coolness scale!

I wonder if you could have done with just half the weights though. Of course the "other side" of a weight should then have been clamped with a spring between the clamp and the supporting frame.

Come to think of it, when fitting a primary mirror to a (newtonian) telescope, we (amateur telescope builders) use a "floating support" (a pressure equalizing mechanism) to ensure that the mirror is supported equally on all contact points.

Like this: http://home.scarlet.be/~tsc84361/atm/my14inf5.html

(About half way down the page)

To improve on your design, something similar could be done with a lever system like in the annex. That way you would be guaranteed that the force pulling on each clamp would be the same. At least if the distances between AB and AC are equal and between DB, EB, FC and GC. Same for the opposite side.
(It goes without saying that you would need it for all sides.)
Attached Images
File Type: jpg stretcher.jpg (28.7 KB, 866 views)
  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
Christening a new ESL wire stretcher Few Planars & Exotics 12 20th August 2009 08:31 AM
HDPE diaphragm Coffee Planars & Exotics 11 6th March 2007 02:00 PM
Pneumatic Diaphragm Stretcher Performance I_Forgot Planars & Exotics 15 3rd December 2006 02:45 PM
rd-75 diaphragm replacement poor_lackey Planars & Exotics 0 7th November 2006 03:36 AM
conversion from A-weighted to flat RMS tschrama Everything Else 18 3rd November 2003 10:47 AM


New To Site? Need Help?

All times are GMT. The time now is 03:50 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