ESL woofer- anybody game?

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I would like to build an ESL woofer that works below 200 Hz. I currently have ESL panels that work to that frequency and am using dynamic woofers. I think it could be better.
My initial inquiries have indicated much bigger spacing betwen the membrane and the stators, and very high voltages. Another problem seems to be the standoff voltage of the coating on the stators. Most panels use conventional powder coating processes, which seem to break down at about 2-3 Kv.
I have been told that Nylon is the better coating, but it appears to be very expensive.
Anyone out there game for this?
 
I am game, the most important questions are:

1) How large
2) Do we go double membrane like CLX, I did that already 30 years ago by the way on a headphone (still have that thing)
3) Do we use side ears to reduce front/back cancellation?

I don't think we need that large of a spacing 4-5mm should be more than enough as a 1m^2 membrane is capable of moving at least the same amount of air as a 15" subwoofer. The front/back cancellation in my opinion is the largest problem.
 
I have been contemplating that for quite some time,
and I might have a drive system idea that might work.

But the one thing that I can tell you is you will need lots of surface area.
Displacement,Displacement,Displacement,Displacement !!!!

Compounded ( isobaric panels) may be the ticket to getting a controlled large excursion from such a system.
Otherwise your stuck with a D/S of not more than .125" to be practical.

One Idea that I have been tossing around since 2005 has been a AMT style ESL system.
I had just read through that thread again last night.
Bolserst did a great study touching on such a system and seems quite feasible but it will be very labor intensive process to build.

When you are talking about a dipole subwoofer system you need to move a lot of air to make it worth the while.

But I think that it is a great subject and is one of my many goals to try out.

Just a few of my thoughts on such a system.

jer :)
 
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A 15" woofer with a useful excursion of say 5mm can move 0.57 liters of air (please check my math). An ESL with 1m^2 area and say 2mm excursion can theoretically move 2 liters of air.

Since an ESL is supported at the edges and does not exhibit pistonic movement the amount of air moved is going to less than theoretical , say only 1 liter. This is still more than a regular woofer so in my opinion displacement is not the issue, the front/back cancellation is.

When a sub-woofer can move 10mm it is just equal to an ESL. with respect to air movement. A regular sub does have the advantage of a larger force.
 
The front/back cancellation won't be too bad, especially if you keep them far-enough from the wall (five feet or so). And angling them, relative to the wall, also helps, especially if it's the long wall. Some kind of "baffle" does help, too, especially along the "center" side of each speaker (at least in my room).

My little Magnepan MG-12s give me below 45 Hz, with only 369 sq in of mid-bass panel (according to Speaker differences , although my measurments say flat to below 40 Hz). And if I place something large up along the inside side of each one, and angle them just right, I can actually get too MUCH bass amplitude.

They are planar-magnetic, not electrostatic. But they are dipole panels so they should be comparable as far as the front/back cancellation effects are concerned.

As far as size goes, look at the link I gave, for what Magnepan was able to do with panels of various sizes. I don't know how it would correlate with size for an ESL, but it's something at least: It looks like they used 620 in² a lot, to go down to 32 to 37 Hz. But then I see a 537 in² that goes down to 34 Hz, too. And they have 786 in² and 800 in² models that go down to 25 Hz. Then again, they have a 1254 in² that only goes to 30 Hz. Most or all of those that I just mentioned are bass-only panels, not mid-bass combined, like mine.
 
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Yes I agree,
It is because of the front to back cancelations it takes much more displacement to make up the difference of that of a single driver in a monopole configuration can produce.
It is not really on issue of how low can you get it to go,But how loud for a given size.

For instance some examples of the 8' tall Acoustats can do the low frequencys rather well as there is alot of surface area.
But it was also stated that a subwoofer is still sometimes used as well.

Here are a few charts that I found while digging around in some old threads the other night that may be of some use.

And a zip file of two Linkwitz Labs Excel spreadsheets that I find most useful for determining ESL sizes and Dipole vs Monopole displacement per frequency and maximum SPL

jer :)
 

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I have now a pr of Acoustats M3 for 300hz down an a ML panels12"w by 48"L....an i still use what we call subs two ea.... 12" with there on amp.....my room is 18'w 25'L 14h....I am just playing with this setup....I use the subs with all my the speakers i have....If it Magnepans or ESls or all pistons....Two subs makes life so much ezer.....the Acoustat give good bass....but so big...the ML with the 10"pistons sound vary close....An i have done the Magnepan MG2cs, just for the 300Hhz down....for me... not sure it worth it..As for flat are crived ESL panels.... I think ML got it right... I like the sound of the flat for bass...crived for the highs...But the CLX only gos down to 55hz..subs are need
Good luck....Thanks for this post
 
WOW! I hadn't expected this much interest! OK, some of my thoughts. Dynamic speakers, including Maggies have quite a bit of mass. Dipole dynamics have the box resnoance free response, but they have difficulty with tranients due to the cone mass, and it's the transient response that endears me to electrostatics.
Arnie Newdell (dale?) at Infinity used servo techniques to overcome this to an extent, but if I am not mistaken, he only servoed one driver in each array. Servos are also very tricky to build, and one minor misstep in tuning them can be disasterous.
Of course, the radiator would have to be large, and probably need side panels to reduce cancellations. For some of you, this aggravates the WAF.
Peter Walker of Quad fame used a "woofer" in the original design. Several things were at work- larger holes in the stators, greater membrane to stator distance, thicker membrane material with a different charge dissipation coating, and much higher voltages with commensurate higher ratios in the step-up transformer.
Some of you have mentioned some very intersting stuff, and I'm hoping you'll share your ideas more completely with us.
I'm hoping we can figure out and actually build some viable ESL woofs.
Thank you all for contributing
Jay
 
Two things I forgot to include- Dynamic loudspeakers need some type of controlled air mass behind them to control their transient response.
To offset the higher voltages involved, Walker used perforated fiberglass PC material for his LF stators. I'm guessing he had the conductive surface on the outside of the panel.
They guy to ask here is Sheldon Stokes- He repairs Quads on the side.
 
Why???????? (I ask because I can't think of any good reason and I'm a big fan of ESLs.)

One of the oldest threads in the universe is how to match dynamic woofers and ESL speakers. I personally think there's virtually no difference among the sounds of woofers (like the silly talk about "fast" and "slow" woofers), except the really obvious differences of basic parameters, and even less so with crossovers below 140 Hz.

Dayton-Wrights play down to 50 Hz fine and provide a quite convincing bass (no kiddin'... in case there are people who don't think a clean 50 credible as a woofer). Know where to find 39 lbs transformers? Welder's gas? Sealed boxes? Mike Wright thought his speakers would be grand in movie theaters esp. in multiple sets.

Ben
 
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Hi,


Yes, maybe, but certainly not with an ESL panel.
An ESL is no good bass!
...go to the black board and write this sentence down 100 times.... :D

Try with dynamic bass drivers in dipole cabinets instead. Its easier and performs way better.

jauu
Calvin

+10... :)

I have heard really big ESL's and they play big bass, it is not the same as dynamic drivers and i prefer mine in enclosers thank you ..:sing:


Speed is an function of size and xover frequency, ( phasing is another) then matching is not an issue if you get them right , seamless. I had developed powered subs for My quad 63's .. no issues you couldn't tell unless i turned them off.

regards,
 
I personally admire people who do not take the easy road!

I’m running 4 x 12” dynamic woofers in H-frame my self, but would like to use ESL-elements instead.
As my panels are the size of a small doors, I have reached my WAF and going bigger would result in divorce I’m afraid!
My panels play down to 35-40Hz and at “normal” listening levels the bass they produce is the best I have ever heard.
I found that the most difficult part of producing ESL-bass was finding/winding transformers that would not saturate.

I hope you build your ESL-woofers and keep us posted on your progress! :)

Roger
 
I have Had Acoustats for years......3ea 9"w 48"L panels well give a good 35hz....great base.....you can buy these panels used for $50.ea US.....thay well 28" wide when put to gather for each side .....I think that the Acoustat best base ever....but if there ran full rang...TO ME.....the Highend is rolled down....As you would think....tradeoff....there a lot of fun...
As SM7UYJ said good luck with the Tranfourmers...the panels is not The prob.....goodluck




SM7UYJ Do you think the stepup Tranfourmers you are using can be found in the US....your ESL are the coolest i seen...
Thanks for any an all info on ESLs
 
Roger
Thanks for your time...
I have 4-5 of the Acoustat Base tranfourmers here.....an what i have found that if i just run them on panels with just 1-2ohms on the pos input an dont use the center tap on the panels side an gound the back side of the panel an one end of the winding an use the other end of the winding to drive the front of the panels it not as eze to saturate. Have you ever setup you xfourmers this way...if not why?
 
On paper it looks that way....but

Forgive the Art....i have posted this in the past..i came across this with ML in 96....
An got in touch with Mr powers At ML to get more info and a schematic...
an when i got the schematic it was as you see in all there schematic... the nom. setup with the centap grounded....an one end of the winding going to the back an one going to the front of the panels..just like all ESL i had ever seen...Acoustats,Soundlab,so....i called to see what was up an was told that thay had came up with this setup to sale in UK...thay had to ground, well the neg input from the amp to the front panel...Safty.. thay even ran two wires from the same place to the same place...what i siad..thay have some panels with 4 wires... an two run to the front ....well i got to looking at the set an siad just what you have... can be right... but it work an whin i took out the setup an put in the one on the schematic from ML...i lost output??
so whin i put the SE I call it... setup back in with the back panel gronded not the front i got even more output....so then i move on to my Acoustats an it did the same thing .....;sound great an gave more output....so thin i move on to my soundLabs A3s an got the thing...great sound an more output....so i pass this on to Moray....an he look at it an tride it an it workt for him all so...

So i gess that as we no, the paper is not right all the time...
I think it helps with the mismach in the tranfourmers windings...an it stops a fulx back an forth that come with the back of the panel that has no bias feed coting...all i can say is after trying it bouth ways ...i alway endup here At whats in the art... give it a try...you can always go back!....an i have never found any one that thinks more output out of a ESL is a bad thing...
To me how it sounds is the same way a SE tube amp sounds vris a pushpull
faster an sweeter....just one mans o-pine

Thanks for your time an all years of info on esl you have given
 

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Call it just ego, but let me explain about how Dayton-Wright did it.

The speakers are a meter square and 300 cm deep.

The diaphragms are roughly across the middle, and the middle assembly holding the diaphragm panels is sealed side to side and top to bottom.

The front and back are sealed with film across the whole meter square.

The inside is filled with heavy welder's gas.

So, the diaphragms drive (1) the heavy gas and then (2) the larger external films.

A clever concept for bass and no owner I have ever talked to has complained about the rest of the range playing through the gas, etc. (The later models with the tweeter are a different story.)

Oh, did I mention the 39 lbs transformers?

Do I understand that someone has actually measured Acustats playing 35 Hz?

Ben
 
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