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Stretched Wire Hybrid ESL Build
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Old 16th May 2018, 12:26 AM   #11
DriedChalk is offline DriedChalk  United States
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Quote:
Originally Posted by AVWERK View Post
Hard woods have high Q resonances and should be damped any way you can manage when assembled
Attachment 680702
Could you elaborate on this? Is it the stator frame or the speaker as a whole I should be worried about?
I plan on attaching the panel to the frame with velcro-easy install and removal-is this the type of damping you're referring to?

Thanks
Ben
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Old 16th May 2018, 12:38 AM   #12
DriedChalk is offline DriedChalk  United States
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Here's the latest for today:
Finished making all of the stator lattice pieces. I plan on assembling it as a whole tomorrow, then spraying it with lacquer for stability, then gluing the wires in.
I cut all of the MDF pieces for my bass cabinets and started assembly. If there's spare time tomorrow I will finishing assembling them and start putting veneer on.

Just for fun I cobbled together the main parts of the speaker and put them arranged them together (I can almost see it coming together finally)
As much as I enjoy this project, it has also consumed almost every waking moment of my life these past two months and I can't wait to be finished!
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Old 16th May 2018, 12:43 AM   #13
DriedChalk is offline DriedChalk  United States
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Originally Posted by chinsettawong View Post
Very nice work so far. You're almost there. Keep going!
Thank you for your words of encouragement! I'm too far in now--no turning back!

Ben
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Old 16th May 2018, 02:48 AM   #14
AVWERK is offline AVWERK  United States
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The Velcro would be an excellent way to decouple the stator assembly from the hard wood frame.

With those hardwood posts you will more than likely be generating “tuning fork “ frequencys up the frame and maybe the top joining piece should have a pocket area to be filled with sand and lead shot to counter that possibility.

Regards
David

Last edited by AVWERK; 16th May 2018 at 03:05 AM.
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Old 16th May 2018, 05:03 PM   #15
CharlieM is offline CharlieM  United States
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Quote:
Originally Posted by AVWERK View Post
The Velcro would be an excellent way to decouple the stator assembly from the hard wood frame.

With those hardwood posts you will more than likely be generating “tuning fork “ frequencys up the frame and maybe the top joining piece should have a pocket area to be filled with sand and lead shot to counter that possibility.

Regards
David
My stators and frame are quite similar these, and I recall when building mine that I had much anxiety about their low mass, which is much lower than any of the perf metal panels I was used to. Knowing that heavier perf panels vibrate significantly, the much lighter wood/wire panels were sure to vibrate even more. So; I was exceedingly worried about vibrations and resonances coloring the sound.

My stators are isolated in the frame by gaskets front & back, formed by 1/8" x 1/2" medium density foam speaker gasket tape from Parts Express. The gasket tape is applied to the mating surfaces of the frame and back moldings which secure the panel into the frame.

(I think the best way to mitigate resonances would be to bond the panels into the frame with RTV silicone, which would couple the frame's mass to the panels and let the mass dampen the panels-- but then; that would permanently bond the panels to the frames which is definitely not a good idea, should you ever need to service the panel)

So when I fired up my panels for the first time and cranked up the volume I was awe-struck at how good they sounded. And then I placed my hand against the wooden support lattice and felt it vibrating like crazy-- even so, it doesn't seem to matter-- the panels sound fabulous!!!

Moral of the story: DON'T WORRY ABOUT IT :-)
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Old 16th May 2018, 07:05 PM   #16
CharlieM is offline CharlieM  United States
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Old 23rd May 2018, 05:04 AM   #17
bolserst is offline bolserst  United States
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Quote:
Originally Posted by CharlieM View Post
Ö I placed my hand against the wooden support lattice and felt it vibrating like crazy
Do you happen to know if the vibrations were caused by the woofer? Or the ESL panel. If the panel was the source, any idea what frequencies? I did some accelerometer measurements on my panels and the only vibrations in the lattice were related to the diaphragm modes at low frequencies. Rapping the lattice structure with a screw driver did show the expecting higher frequency structural resonances, but the ESL itself just didnít excite them even when driven hard.

Adding acoustic damping dramatically reduced the vibration caused by the diaphragm modes, although like you I didnít notice an audible problem to begin with. Most likely this is because the radiating area is small compared to the diaphragm, and the lattice just isnít an efficient radiator at low frequencies.
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Old 23rd May 2018, 04:49 PM   #18
CharlieM is offline CharlieM  United States
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Originally Posted by bolserst View Post
Do you happen to know if the vibrations were caused by the woofer? Or the ESL panel. If the panel was the source, any idea what frequencies? I did some accelerometer measurements on my panels and the only vibrations in the lattice were related to the diaphragm modes at low frequencies. Rapping the lattice structure with a screw driver did show the expecting higher frequency structural resonances, but the ESL itself just didnít excite them even when driven hard.

Adding acoustic damping dramatically reduced the vibration caused by the diaphragm modes, although like you I didnít notice an audible problem to begin with. Most likely this is because the radiating area is small compared to the diaphragm, and the lattice just isnít an efficient radiator at low frequencies.
I'm not equipped to determine the frequencies at which the lattice vibrates, or what portions are excited by the woofer or diaphragm-- I suspect both.

My stator lattices are likely less massive than most, insofar as the stator side rails are just 3/8" thick x 3/4" wide. The surrounding speaker frame provides vertical support, and it's quite stout.

The panel is isolated in the frame by 1/8" x 1/2" med density foam rubber gaskets on both sides. I would guess the lattice vibrates predominantly alone without transferring much of its energy to the frame. In any case, it sounds really good.
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Old 1st June 2018, 10:11 PM   #19
DriedChalk is offline DriedChalk  United States
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Speakers are done and functional, and just gave my presentation on them today!
The dispersion of sound is very impressive; much smoother and wider than the curved panels I previously made. There is still definitely a sweet spot, but I still am able to enjoy the music throughout the whole room.
The Mylar is stretched roughly to 1.25%.
The bass cabinets work well, but some bracing may be a thought for the future. In the sealed box, they're much quicker than I would have expected.
I'm glad I designed these with subwoofers instead of woofers, as external subs would have been a pain and it's nice to be able to EQ them out and get very low bass with a great thump in kicks and a soothing rumble on bass notes.
It's possible I'm missing some detail in the mids, but I have set the crossover at a point where most of the detail is handled by the panel.
The crossover is set at 220Hz, with a 48dB/Octave slope.
The MiniDSP is incredibly useful, and I can't even imagine the nightmare that passive crossovers would have been.

I'm very satisfied with the whole system, although I bet that they could still use a few tweaks.

If I were to do another system like this, the frame lattice would be made of some kind of laser cut acrylic or some other material that could be made to have a low profile.

Of course, I need to thank CharlieM again for not only his great website which has incredible information, but also his willingness to share his plans for the wire stretcher and lattice frames with me. (I also stole his Mylar stretcher idea). I probably wouldn't have been able to complete this project had it not been for him.

Feel free to ask questions or give feedback!

Ben
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Last edited by DriedChalk; 1st June 2018 at 10:19 PM.
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Old 1st June 2018, 10:38 PM   #20
CharlieM is offline CharlieM  United States
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OUTSTANDING !!!!

You've done a super job with your design and execution. And you needn't worry about over driving or damaging those panels-- short of poking a stick thru a diaphragm, I really don't think you can hurt them. And I have a pretty good idea of how they sound :-)

Enjoy!
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