Some questions on ESL dimensions - Page 3 - 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 11th July 2007, 05:27 PM   #21
diyAudio Member
 
Join Date: Nov 2005
Location: Southern Germany
Hi Vitalstates,

the plot is taken in a large room (10x10x3,5 m). The ESL is placed 80cm from the bottom. Distance of measurement is 1m. Obviously the graph is smoothed by 1/3 octave.

The red graph corresponds to the speaker in the picture. it is the "Element 160", which is a fullrange ESL with 0,3 squaremeter area.

One customer wants to modify the ESL by adding baffles left and right made of transparent acrylic.

As you can see, the baffles improve upper bass/lower midrange significantly (black graph)

Capaciti
Attached Images
File Type: jpg kunde-e160-1.jpg (46.5 KB, 304 views)
  Reply With Quote
Old 11th July 2007, 05:41 PM   #22
Calvin is offline Calvin  Germany
diyAudio Member
 
Calvin's Avatar
 
Join Date: Nov 2004
Location: close to Basel
Hi,

"I would suggest that you try this experiment yourself. Seeing and hearing it is better than 1000 words."
Guess what? Did that years ago, measurements included.
Started my ESL Life with panels of Audiostatic-like types.
The tension with audiostatics is low and fs is raised by the dots against the value of a ´undotted´membrane.


jauu
Calvin
  Reply With Quote
Old 11th July 2007, 07:42 PM   #23
diyAudio Member
 
Join Date: Apr 2005
Location: Utrecht
Quote:
Originally posted by Calvin
Hi,

"I would suggest that you try this experiment yourself. Seeing and hearing it is better than 1000 words."
Guess what? Did that years ago, measurements included.
Started my ESL Life with panels of Audiostatic-like types.
The tension with audiostatics is low and fs is raised by the dots against the value of a ´undotted´membrane.


jauu
Calvin

Hi,


Didn't you measure a lower amplitude of resonance???, or decay time?
It really sounds like less resonance to my ears.
If the only advantage of the dots would be raising Fs, than it is a silly thing because you could achieve this also by higher mechanical tension. Since audiostatic used 6 micron and even 8 micron these higher tensions are not a problem. Also a mechanically division into two smaller segments would also raise Fs.
Maybe the area around a dot has a higher Fs, while at a larger distance, between the dots, it becomes gradually lower as the influence of the dot decreases. So it is distributed.
__________________
drs M.J. Dijkstra
  Reply With Quote
Old 12th July 2007, 11:34 AM   #24
Calvin is offline Calvin  Germany
diyAudio Member
 
Calvin's Avatar
 
Join Date: Nov 2004
Location: close to Basel
Hi,

one should let loose of the thinking, that professionals do what they do solely for better sound purposes.
The reason why Audiostatic uses the dots is simply easier manufacturing and less costs with an accaptable result in technical and sonical regards.
You can build the panel quickly and easy as a framework on which the membrane is glued and (low) tensioned with heat. Afterwards You press in the flexible silicone material. Thereby raising the tension, raising overload treshold, fixing the membrane and centering it between the stators. This is much quicker and easier as glueing several spacers into the framework before fixing the membrane and it gives a similar precision with regard to centering.
Too, You can test the frame+membrane before putting spacers in. In case of a problem You save at least the effort of glueing the spacers.

jauu
Calvin
  Reply With Quote
Old 12th July 2007, 01:32 PM   #25
diyAudio Member
 
Join Date: Apr 2005
Location: Utrecht
Hi Clavin

I don't know if they used the heatshrink method.
Anyway, as I remembered correctly, Ben Peters of audiostatic patented the silicone dots long ago, so if I have time enough I may search for it.
Please note that audiostatics are full range esls which can go very low, so raising Fs a lot is not what they want.

I used the heatshrink method, than added the dots. But it didn't prevent collapsing the membrane to the stators in rest. After mechanically tensioning the membrane and the dots, it worked as it should do.

I've made several esls without dots in the past, but they needed heavy damping (BAF/grill cloth) to give acceptable bass.
So I prefer the dots.
__________________
drs M.J. Dijkstra
  Reply With Quote
Old 12th July 2007, 06:16 PM   #26
diyAudio Member
 
Join Date: Nov 2005
Location: Southern Germany
Hi Folks,

independent from individual preference the invention of the silicone dots by Ben Peters is one of the major ones regarding ESL.

I use them as well for following reasons and experience:

1- With dots you can easily set the resonance of a given ESL size to a desired range
2- The loss of driven area is significantly lower than by using long vertical or horizontal spacers.
3. As the dots divide the longitudinal resonances of panel width and length, spectral decay can be optimized. Overall spacers increase issue with spectral decay since they add new borderlines and as a result increase longitudinal resonances.

I made a hell of prototypes in my career to compare dots to spacers. At least to me it is no question which one to choose.

There is a simple test to evaluate: make two panels same size, one with dots,one with spacers. Both need to be burned in perfectly. By playing music and using reflecting light into the membrane,you will recognize the dot supported membrane acting perfectly, means the mebranes moves as if it is one stiff surface. Watching the spacer one one you will see resonances (membrane moves like waves), more or less depending on frequency range.

You can discuss a lot of theoretical arguments, but if you see both membranes moving, you might recognize the better approach.

Capaciti
  Reply With Quote
Old 12th July 2007, 07:47 PM   #27
BillH is offline BillH  United States
diyAudio Member
 
BillH's Avatar
 
Join Date: Mar 2005
Location: Wisconsin
Hi, Capaciti.

Quote:
I made a hell of prototypes in my career to compare dots to spacers. At least to me it is no question which one to choose.
Do you have any guidelines for placement and spacing of the dots?
  Reply With Quote
Old 13th July 2007, 07:42 AM   #28
Calvin is offline Calvin  Germany
diyAudio Member
 
Calvin's Avatar
 
Join Date: Nov 2004
Location: close to Basel
Hi,

Yeah the dots are indeed a very clever thing Though the membrane does of course not act perfectly. If so it would move as a piston. It can´t do that. As soon as the membrane has to move one can clearly see the ´dead rings´ around every dot and the bowing of the membrane. The method using a light source and music just prooves that the membrane is vibrating. You might recognize effects with very low tones, but raising the Fs with dots (lowering the amplitude thereby too) would make it rather impossible to see real effects. The light source could be strobed and the feeding signal a sinewave. Than You could see differences.

The best use for a light source is imo to use it to determine the right angle of both panels while setting the system up .

jauu
Calvin
  Reply With Quote
Old 13th July 2007, 07:55 AM   #29
diyAudio Member
 
Join Date: Apr 2005
Location: Utrecht
Quote:
Originally posted by BillH
Hi, Capaciti.



Do you have any guidelines for placement and spacing of the dots?

Hi,

The membrane has the dimensions: 25 cm width , 100 cm long.
Across the length, every 10 or 10,5 cm a dot is placed right in the middle of the membrane, so around 9 dots total. This is the way audiostatic did and this works good. You may experiment with the amount of dots in this or other esls.
__________________
drs M.J. Dijkstra
  Reply With Quote
Old 13th July 2007, 10:58 AM   #30
diyAudio Member
 
Join Date: Nov 2005
Location: Southern Germany
Hi,

Martins guidelines are OK, but the positioning of the dots are suject to investigation for each panel size.

Even i tested dots which are positioned asymetrically and thus got further means to control fundemental panel resonance, but this is still a learning procedure. By FEA you might be able to calculate the effects, but defining the right parameters should be the problem.

Calvin is right to mention that there are still dead sections without movement of the membrane, but those are very limited adjacent to the dots. Long spacers result in much more dead area.

Finally it is a question of the option you have, which method to use. With bended Panels like ML no choice but spacers, with flat panels spacers or dots. Thats it.

Capaciti
  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
How important are dimensions? Lewis Moon Subwoofers 1 16th February 2009 03:44 PM
ESL dimensions Few Planars & Exotics 2 24th February 2008 05:47 PM
Speaker design questions: dimensions sfhseric06 Multi-Way 11 17th January 2008 10:17 AM
Box dimensions hewlew1 Subwoofers 1 6th November 2007 11:07 PM
Box dimensions Vivek Multi-Way 10 16th September 2001 08:02 PM


New To Site? Need Help?

All times are GMT. The time now is 08:44 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