My 1st ELS build - first question! - 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 17th December 2012, 12:16 AM   #21
fperra is offline fperra  United States
diyAudio Member
 
Join Date: Jan 2008
Location: Lakewood, WA
I got 1.8% tension on my build (1/4 mil mylar) and I didn't dare to go higher although I did give some thought to try for 2%. I'm happy I stopped at 1.8.
  Reply With Quote
Old 17th December 2012, 01:39 AM   #22
bdjohns is offline bdjohns  United States
diyAudio Member
 
Join Date: Feb 2010
Location: Iowa
Thanks for the encouragement and direction, everyone.

Jer, if I put the 120 vac terminals between the transformer input and output, I'll be good?

I definitely will test for arcs before final assembly. Do I need to incorporate the HV supply to test, or only what you suggested by putting the stators together and supply amplified signal to the transformers?

I now understand why folks go for the VHB tape method - fixturing and applying the epoxy is tedious! First half of one panel is curing now.

Bruce
  Reply With Quote
Old 17th December 2012, 03:12 AM   #23
diyAudio Member
 
Join Date: Feb 2008
Location: Jackson,michigan
Set the stators up just as if it was completed with some plastic spacers in between them and run them with the bias and the amp with a source just like normal.

It would be safer to have the inputs more separated although having the 120v in the middle will add some protection.
But, If it arcs over to the 120v line you can First blow the bias transformer and/or it can travel up the line and take something else out.
Just like Lightening can do !!

My computer will sometimes reset from arcs off of my Variable HV supply to just the ground side as it travels up the ground side and interrupts the either the CPU or power supply.
Up the ground side of the line (Green wire) !!!
It hasn't done it lately but it has in the past though.

I just completed this test with my new stators and it passed.
Although I didn't use the transformers because my supply puts out 13.61Kv.

jer
Attached Images
File Type: jpg Test Mock Up.jpg (61.0 KB, 180 views)
  Reply With Quote
Old 8th February 2013, 09:18 PM   #24
bdjohns is offline bdjohns  United States
diyAudio Member
 
Join Date: Feb 2010
Location: Iowa
Default Update - panel resonance frequency?

I got my panels arc tested with 30 volts on the transformer inputs, at various frequencies. I sure learned the value of the 10 watt current limiting resistor. I must have momentarily left the input frequency at an extreme and that resistor started smoking! At first I thought it was transformer. Luckily my amp and transformer are fine. Kind of fun to hear them quietly sing with no diaphragms!

I got one of my panels with Mylar applied, 6 um, 1.5% stretch, though I had an accident while taking it off the flat gluing surface and tore one of the four 5" x 11.5" cells. I took the opportunity to hold the panel near one of my main speakers at different frequencies. It resonates at approximately 135 +/- 10 Hz. Is this too high? Do I need to stretch it less? I think I will be crossing over at around 300 Hz. Maybe up to 500. Need some help soon, as I'd like to keep going. I am using epoxy - great shear strength, but it pulls up pretty easily. Thanks, Bruce.
  Reply With Quote
Old 9th February 2013, 12:20 AM   #25
Bazukaz is offline Bazukaz  Lithuania
diyAudio Member
 
Bazukaz's Avatar
 
Join Date: Nov 2005
Location: Vilnius
Send a message via Skype™ to Bazukaz
Quote:
Originally Posted by bdjohns View Post
I got my panels arc tested with 30 volts on the transformer inputs, at various frequencies. I sure learned the value of the 10 watt current limiting resistor. I must have momentarily left the input frequency at an extreme and that resistor started smoking! At first I thought it was transformer. Luckily my amp and transformer are fine. Kind of fun to hear them quietly sing with no diaphragms!

I got one of my panels with Mylar applied, 6 um, 1.5% stretch, though I had an accident while taking it off the flat gluing surface and tore one of the four 5" x 11.5" cells. I took the opportunity to hold the panel near one of my main speakers at different frequencies. It resonates at approximately 135 +/- 10 Hz. Is this too high? Do I need to stretch it less? I think I will be crossing over at around 300 Hz. Maybe up to 500. Need some help soon, as I'd like to keep going. I am using epoxy - great shear strength, but it pulls up pretty easily. Thanks, Bruce.
Hi,

What is the slope? An active 24db/oct. filter at twice the resonance or so should be adequate. However if you use some light damping(even a light covering material does some job) requirements could be relieved.
High tension also can result in residual resonances up to higher frequencies.
So if the design allows(sufficient d/s spacing for width) it's desirable to have less tension. For this reason some people use heat shrinking. This has it's own caveats as you may end with not sufficient tension and diaphragm collapsing into the stator.
Read this whole thread , IMO it's valuable:
ESLs have bad decay plots

The epoxy is good for the purpose but it's important the surfaces are very clean(wiped with alcohol or acetone). It usually tends to increase bonding to mylar over the months. Another nice property of epoxy is it's usually possible to scratch it off the plastic spacers via knife.
How did you manage to rip the mylar off? If a stretching frame is used then it's quite easy to put it over the panel and cut mylar with a hot soldering iron after curing. Difficult to do wrong. Also the mylar is pressed into by weight of the frame and bonding surface becomes extremely flat. Some vegetables could be used for higher downwards force but it's not really necessary .

Regards,
Lukas.
Attached Images
File Type: jpg Gluing_small.jpg (101.4 KB, 122 views)

Last edited by Bazukaz; 9th February 2013 at 12:22 AM.
  Reply With Quote
Old 9th February 2013, 04:29 AM   #26
bdjohns is offline bdjohns  United States
diyAudio Member
 
Join Date: Feb 2010
Location: Iowa
Thanks for the link to thread on decay plots Lukas - good stuff. I have a DCX2496 crossover, so I will use at least a 24 dB slope.

I tore the Mylar when lifting the panel off the stretching table, where I had not cut completely through the Mylar. It was easy enough to get the old epoxy off the frames. I have been using alcohol - probably just need to give it more cure time. Thanks for the great tip on using a soldering iron!
  Reply With Quote
Old 9th February 2013, 07:22 AM   #27
diyAudio Member
 
Join Date: Feb 2008
Location: Jackson,michigan
I have been messing with transformers lately again.
With the 100watt version I can get as low as 330Hz to 370Hz with a 40Vrms input just before the onset of core saturation and distortion starts to rise considerably.

The 50watt version should have similar performance as they are designed with the same frequency and voltage parameters in mind.

This should give you an idea of how low you can go with your crossover vs how big your amplifier is.

If you are using a amplifier only capable of 28Vrms (100watts) you may be able to get down to but no lower than 233Hz or else you have core saturation and sever distortions below this frequency.

jer

P.S. Lukas, Your stretcher setup looks very nice !!!

Last edited by geraldfryjr; 9th February 2013 at 07:26 AM.
  Reply With Quote
Old 9th February 2013, 02:13 PM   #28
Bazukaz is offline Bazukaz  Lithuania
diyAudio Member
 
Bazukaz's Avatar
 
Join Date: Nov 2005
Location: Vilnius
Send a message via Skype™ to Bazukaz
Quote:
Originally Posted by geraldfryjr View Post
P.S. Lukas, Your stretcher setup looks very nice !!!
Hi,

Thanks, but this frame has had some flaws.So I have redesigned the stretcher to be significantly larger and pull all four sides with wing nuts.
Making the stretcher wider and longer has one advantage : highly stretched areas at corners which could form partial resonances are just cut off.
I have been able to achieve about 2-3% Fs accuracy through mechanical stretching now; however there are some steps , like gluing mylar with glue and not double sided tape which lets it go over 12 hour period through which epoxy cures. Also it's very important to stretch the film lightly but evenly prior to gluing to the frame.
Concerning core saturation : LR crossover cross at -6db output. This means at crossover point the trafo is already receiving only half of the input voltage - assuming no clipping. If heavy clipping occurs at either amplifier or DSP then even DC can be fed into the transformer.
So a cutoff frequency could be lowered somewhat. Furthermore, most of peaks in music material occur below about 200-220Hz. So core saturation is much less likely above this frequency unless excessive active EQ boost is used.

Regards,
Lukas.
  Reply With Quote
Old 15th March 2013, 01:00 AM   #29
bdjohns is offline bdjohns  United States
diyAudio Member
 
Join Date: Feb 2010
Location: Iowa
Default Panels Completed!

Well, I finally got these panels put together several weeks ago and thought I'd update with a few pics. I ended up with 1.25% stretch. With the setup shown, I was able to measure fairly accurately to 1/64". The stretched Mylar is so fragile, that it broke once when I nicked it lightly with my magnifier!
Attached Images
File Type: jpg Stretched Mylar 2.jpg (747.9 KB, 67 views)
File Type: jpg Stretch measurement 2.jpg (502.9 KB, 65 views)
File Type: jpg Stretch Measurement 3.jpg (742.9 KB, 63 views)
  Reply With Quote
Old 15th March 2013, 01:27 AM   #30
bdjohns is offline bdjohns  United States
diyAudio Member
 
Join Date: Feb 2010
Location: Iowa
Default Panels Completed!

I used 1/16" Lexan for spacer material. It is 3/4" wide, leaving 1/8" beyond the edges of the stator to block high voltage. I ripped it into strips on my table saw, deburred and sanded it. After aligning the glued front and back stator holes, I notched the Lexan, as a gauge point for re-alignment on the final glue-up. Also 3/8" wide aluminum extrusions were epoxied over the internal Lexan spacers.
Attached Images
File Type: jpg IMG_0421.jpg (855.5 KB, 30 views)
File Type: jpg IMG_0420.jpg (781.5 KB, 27 views)
File Type: jpg IMG_20130202_141238_745.jpg (995.4 KB, 34 views)
File Type: jpg Alignment Notch (2).jpg (936.5 KB, 34 views)
File Type: jpg Epoxied aluminum stiffeners.jpg (1.01 MB, 31 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
1st build suggestions MarkL1 Tubes / Valves 13 6th January 2012 02:42 AM
1st post what can i build with this? turnthetable Tubes / Valves 10 7th February 2011 12:02 PM
1st build done. bloozestringer Tubes / Valves 8 14th January 2009 01:22 AM
Going to build my 1st GC DolbyR Chip Amps 9 4th January 2006 07:07 AM
1st build, what do i need? ChaseMe Subwoofers 2 30th September 2005 09:12 PM


New To Site? Need Help?

All times are GMT. The time now is 04:02 AM.


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