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Electrostatic sound propagation

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Posted on February 2, 2017 at 14:57:03
George S. Roland
Audiophile

Posts: 1464
Location: N W Pennsylvania
Joined: March 20, 2004
Here is a "dumb" question about electrostatic speakers. I have been a lover of Quad ESL-63s for many years and have just gotten a nice pair of USA Monitors back from Electrostatic Solutions. They sound fabulous!
So, as I understand it, the diaphragm sits in between the stators and vibrates there. The stators are perforated with holes and are, in turn covered over with dust covers of solid film. So my question is how does the sound get from the diaphragm through the holes in the stators and through solid plastic dust covers and sound so good? It seems they would be muffled somehow with all those components blocking the flow of air.

 

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RE: Electrostatic sound propagation, posted on February 2, 2017 at 18:59:26
Byrd69
Audiophile

Posts: 2875
Location: East Syracuse, New York
Joined: August 23, 2004
I have several pairs of electrostatics. I've never heard of this solid film dust cover you speak of.


Your interest may vary but the results will be same. (Byrd 2020)

I can't compete with the dead. (Buck W. 2010)

Cowards can't be heroes. (Byrd 2017)

Why don't catfish have kittens? (Moe Howard 1937)

 

Dust cover..., posted on February 2, 2017 at 20:22:20
Jonesy
Audiophile

Posts: 3149
Location: Winnipeg, Manitoba
Joined: September 1, 2005
Contributor
  Since:
March 1, 2018
The gent in the video shows installation of the mylar dust cover. There's a cover on both front and back. After this comes a metal grill front and back. Then of course the final fabric dust cover or "sock".

Cheers!

Jonesy


"I know just enough to get into trouble. But not enough to get out of it."




 

RE: Electrostatic sound propagation, posted on February 3, 2017 at 07:24:36
Jonesy
Audiophile

Posts: 3149
Location: Winnipeg, Manitoba
Joined: September 1, 2005
Contributor
  Since:
March 1, 2018
And don't forget the honeycomb frame the stators are mounted to.

My guess is there is enough surface area to produce sound versus area that blocks sound. I have some old literature that I'll try and dig out to see how Peter Walker came up with the mechanics.

Lots of layers indeed.

back grill cloth
back metal perforated protective grill
back thin solid mylar dust cover
back honeycomb stator frame
back perforated stator
middle mylar diaphram (electrostatically moved by voltage in back and front stator)
front perforated stator
front honeycomb stator frame
front thin solid mylar dust cover
front metal perforated protective grill
front cloth grill cloth

Interesting indeed.

As a test, you'll find any physical sound you make yourself, like clapping behind the speaker, is heard on the other side almost as if there is no speaker there at all. Talk about transparency.

Hope Kent can chime in.

Cheers!

Jonesy



"I know just enough to get into trouble. But not enough to get out of it."




 

RE: Electrostatic sound propagation, posted on February 3, 2017 at 07:43:35
Mendel
Audiophile

Posts: 1207
Location: GTA
Joined: January 17, 2009
My Acoustats sound much better with the socks pulled down. I have been running them "naked" for years. Don't think they have any dust cover, I can clearly see the mylar through the plastic louvers and stator wires.

 

RE: Electrostatic sound propagation, posted on February 3, 2017 at 08:00:19
fredtr
Audiophile

Posts: 1973
Location: Phoenix
Joined: January 4, 2005
Yes, they all muffle the sound. After I glued mine, I listened to them for days before putting the dust covers etc., on and they sounded a lot better. I have seen pictures of people that leave everything else off except the dust covers.

 

Agreed. Socks down on Quads sound better too., posted on February 3, 2017 at 09:17:29
Jonesy
Audiophile

Posts: 3149
Location: Winnipeg, Manitoba
Joined: September 1, 2005
Contributor
  Since:
March 1, 2018
Then removing the protective grill would further improve the sound on the Quads. But then your are in "lethal" shock territory.

Jonesy



"I know just enough to get into trouble. But not enough to get out of it."




 

RE: Electrostatic sound propagation, posted on February 3, 2017 at 16:34:23
josh358
Industry Professional

Posts: 12327
Joined: February 9, 2010
It's a fortunate truth of wave mechanics that if the spacing of holes is small compared to the highest wavelength being reproduced, the sound will join back together on the other side to recreate the original wave. Not intuitive, but true. In fact, hole spacing is mathematically analogous to sampling rate in digital audio -- you need a minimum of two holes per wavelength at the highest frequency to be reproduced -- if you have fewer and you'll get lobing.

There's another angle to this as well, namely, that for best peformance, you actually need something to impede the air flow in order to damp the diaphragm. Sometimes planars use small holes to this end, sometimes fabric or even paper, or some combination of them. Too much damping and you'll deaden transients, too little and you'll get too much ringing.

Not that everything in a speaker makes a positive contribution to the sound -- some things are just necessary and cause unwanted effects -- resonances, absorption, reflections. Dust covers, grille cloths, support structures, etc. all tend to be deleterious to various degrees.

 

RE: Agreed. Socks down on Quads sound better too., posted on February 4, 2017 at 05:37:03
Removing the protective grills from my ESL 63s made an audible improvement, so they play that way now.

I am careful not to stick my finger through the dust cover.

But...mine are in a dedicated room than is free of cats and kids.

I do run Kent's almost not there socks, which are essentially inaudible.

 

Great Info!!!! (nt), posted on February 4, 2017 at 07:21:58
Jonesy
Audiophile

Posts: 3149
Location: Winnipeg, Manitoba
Joined: September 1, 2005
Contributor
  Since:
March 1, 2018
nt


"I know just enough to get into trouble. But not enough to get out of it."




 

RE: Electrostatic sound propagation, posted on February 7, 2017 at 11:25:37
Zombie
Audiophile

Posts: 772
Joined: March 5, 2002
I had a pair of ESL-63s without the grilles and dust covers, and sometimes I took the socks down (no difference), maybe more detailed, but I like the sound of my stock ESL-988s better, mellower, yet detailed. Sold the stripped 63s to a detail onanist.

 

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