Hybrid ESL, suitable x-over frequency? - diyAudio
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Old 8th August 2010, 09:03 PM   #1
markusA is offline markusA  Sweden
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Default Hybrid ESL, suitable x-over frequency?

I'm toying with the idea of a hybrid esl.
To keep the D/S spacing down in order to keep efficiency up I guess bass is handled "best" by a conventional woofer.
The question is where to put the x-over frequency?

300Hz would make it easier (150-200Hz would make it really easy) to build a bass modul but I've seen recomendations to keep it between 500-600Hz in order to keep the SPL up?

How would you do it?
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Old 9th August 2010, 07:01 AM   #2
Calvin is offline Calvin  Germany
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Hi,

I´d say it depends....
.....on panel dimensions in first place. The lower the panel can reach down in frequency the lower You can place the CR-frequency. So it´s a matter of area and stator-stator distances and the mechanical tension of the diaphragm. A larger sized panel will show less drop out through phase cancellation and allows lower CR-freqs. I wouldn´t place the CR lower than the frequency where the dropout reaches -3dB, maximum -6dB, otherwise you need too much equing, hence too much power and You run into excursion problems and decreased dynamic range. If the panel can accept the high power, because it is built very precise and with a tightly tensioned diaphragm You might test the -6dB-point. If it is built just mediocre and with lower tensioned film You might rather take the -3dB-point.
Sonically I like the lower CR-freqs better. With very precise built large panels You may reach down below 200Hz (and some special features which I´m not allowed to disclude here) and still can have an outstanding dynamic range.
- CR-frequency may also be dependant on the choice of bass system. Dipoles are probabely the best partners for ESLs sonically but their upper bandwidth limit stays typically below 400Hz and the useful freq-range rarely exceeds 300Hz.
Closed boxes et al don´t face the upper bandwidth limit problem, but don´t integrate in such a smooth and seemless way with the ESL as dipoles can.
To give You an idea.
My ´small´ system features a panel of 3.000cm² area, accompanied by 6x 6.5" bass-drivers in a dipole bass tower, crossed over at ~250Hz.
The ´big´ system features a panel of 6.000cm² area, accompanied by 8x 6.5" drivers in a dipole bass tower and a 2x15" Subwoofer in CB, crossed over at ~170Hz and 50Hz. Dynamic range reaches ~110dB@4m.

jauu
Calvin
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Old 9th August 2010, 10:59 AM   #3
markusA is offline markusA  Sweden
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You give me hope.
Of course I am comfident in my ability to keep up the building quality.
My initial thoughts were something along the lines of a 8"x48" (2400cm^2) panel , pretty close to your small system but not quite. (Phase cancellation will start early)

I get what you mean when you say your big system...

The larger options doesn't have the same WAF as the small one and I imagine the difficulties increase when you opt for big screens?
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Old 9th August 2010, 01:16 PM   #4
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Hi Markus,
My hybrids have 12”x 48” panels mated to a 10” transmission line bass and they are bi-amp’d using an active crossover with 24db slopes. The panels are sectioned with 3.5” span between the diaphragm supports, 1/16” d/s spacing and the diaphragm is mechanically tensioned to just over 1% elongation. For my setup, a 275hz crossover frequency works very well without excessive EQ'ing.
Good luck with your project!
Charlie
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Old 12th August 2010, 12:02 AM   #5
markusA is offline markusA  Sweden
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What kind of sensitivity would one expect from a ESL with a <300Hz crossover frequency?
Lets say 2'x5'? Or 12"x48" like you already have CharlieM.
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Old 12th August 2010, 02:28 AM   #6
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Quote:
Originally Posted by markusG View Post
What d/ of sensitivity would one expect from a ESL with a <300Hz crossover frequency?
Lets say 2'x5'? Or 12"x48" like you already have CharlieM.
I will have to defer to others to answer that question, as I don't have the means to actually measure the output of my panels. My impression, however, is that a 4ft2 panel with 1/16 d/s spacing and 1:70 or so step up ratio driven by moderately powered amps will easily play loud enough to suit most people.

I'm bi-amping my hybrids with a pair of 225W/channel Carvers and 1/3 throttle is about all I can stand (they'll blow women's panties right off).

My friend Mavric has similar hybrids bi-amp'd with a pair of 100W/channel Adcoms and they rock n' roll pretty good.

If you look at Sheldon Stokes' ESL 1.0's, his panels are almost certainly less efficient than mine, since he's using twice the d/s spacing (1/8"), yet he powers them with a pair of 30W tube amps and they apparently play loud enough to suit him.

When I was building my first set of panels I was very worried that 12x48 might be too small but my worries turned out to be unfounded, as they are much more efficient and dynamic than I had imagined. In fact, my 4ft2 panels can easily overpower the 10" woofers past a certain volume level so I later augmented them with subwoofers for when I want to play my jazz really loud.
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Old 12th August 2010, 04:01 AM   #7
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I just finished my latest pair of ESL. The diaphragm size is 120x20 cm. The bias voltage is around 2.6 KV. Using step up transformer ratio of 1:90, I can play mine loud enough with a 6 watts 6528 single ended tube amp. I make them full range this time and they sound wonderful.

Wachara C.
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Old 12th August 2010, 12:50 PM   #8
markusA is offline markusA  Sweden
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That's just awsome.
120cmx20cm is "tiny", if I could build them this small it would fit my initial ideas just perfectly.
Of course larger will be better but it wold be nice to make a small one the first time.
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Old 12th August 2010, 02:30 PM   #9
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Hi MarkusG,

120 cm x 20 cm is the diaphragm size. The actual stator size is around 125 x 25 cm. I don't think it's tiny. If you can hear the sound, you will know what I mean.

By the way, my spacer's thickness is 2 mm.

Wachara C.
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Old 12th August 2010, 03:14 PM   #10
markusA is offline markusA  Sweden
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I guess it's in the eye of the beholder.
Fair enough though, ESL's are never small but it sounds like the perfect size for me.
I was thinking 2mm D/S spacing myself and it really does sound like you have built the speaker I was thinking about building.
Great to hear you're happy with it.

It sounds like the perfect beginner size. If needed one can always build larger later on.
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