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Old 6th June 2007, 03:15 PM   #11
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Default ESL and Horns

I used a Klipsh corner horn for bass, a front loaded horn for 90-500 hz using 3 8" drivers and ESLs above that. The system could play LOUD!
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Old 6th June 2007, 03:58 PM   #12
tade is offline tade  United States
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so, sound energy falls off quite rapidly above 500hz?
That makes sense. so, i was thinking that 500hz or so is an OK crossover point because it is high enough that the energy levels are falling but it leaves the majority of harmonics etc coming from a single source. those three eights are in a FLH, is it a straight horn, how were they wired? was your esl diy? if so what were the stator spacings and bias voltage.
Was the midbass horn fairly long, and was it time aligned with the esl? I like the idea of using an esl because they beam and so you can mount it far and above behind a largeish midbass horn without terrible diffraction effects from the lip of the horn. Also the beaming keeps the efficiency up.

etc... surely all things that have crossed your minds.

btw, could beaming be adressed with vertical slats on the top and bottom with the middle section left alone. that might create an MTM like effect with little hf coming forwards from the top and bottom but being redirected to the sides.
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Old 6th June 2007, 04:23 PM   #13
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I think you missed the whole point of ESLs. They reproduce a wide frequency range at very low distortion. They also produce very sharp imaging. But they won't do any of those things very loudly.

When you start mucking about with horns, crossovers, and to a lesser extent, bass drivers, you'll destroy the imaging completely.

Why go to the trouble of using an ESL for a tweeter? There are plenty of competent tweeters available and they are usually much lower cost and a lot less trouble to use and much lower maintenance than an ESL. You'll end up with a loud, mediocre speaker that has an ESL tweeter just like some of the old commercial speakers that used ESL tweeters as a marketing gimmick.

If you want high volume, don't use an ESL. That isn't what they do well. Now if you were to devote some energy to figuring out a way to make an ESL produce high volume along with all its other wonderful qualities, THAT would be special...

I_F
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Old 6th June 2007, 04:37 PM   #14
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Default mid bass horn

My mid bass horn was a straight exponential horn about 24 inches square at the mouth and around 36 inches long. The three 8s were mounted vertical on a board and I think about a 2 inch slot for the throat. I wired the drivers in parallel, so about 3 ohms.

No crossover is really necessary since the horn has built in mechanical crossover. I remember the top end rolled off fairly fast all by itself. I mounted the diy ESL panels on top of the horn and could not tell any differnce with moving the position of the panels.

My panels were made of the cain metal about 60 thousands thick with 3KV bias. My system could blow away anything commercially made in the 70's.
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Old 7th June 2007, 08:19 PM   #15
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I was going to use tensioned wire stator so i could decrease spacing and bias in the tweeter section.
I would think a 8"x84" panel with 2mm spacing could be very loud to 300hz. If the mylar was close to touching the stator at 300hz the displaced air would be equal to 7.6mm excursion of a 15" dynamic. At 300hz 8mm of excursion on a 15" woofer would be loud, very loud.
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Old 8th June 2007, 09:23 AM   #16
Calvin is offline Calvin  Germany
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Hi,

2mm is far too much for coupling from 300Hz on with such a big panel! 1mm is enough and with a safety margin of +50% because of acoustic coupling You end up at 1.5mm maximum! It is a very common mistake and it seems each and every beginner falls into this trap, that the spacing is chosen too wide! You donīt improve dynamics with a greater d/s, but itīs just the other way round!!...You loose! You need much more drive voltage, drive power, higher transformation factor, etc, etc. All this degrades the capabilities of the panel seriously technically and audibly! To build a panel thats capable to quite hornlike dynamics its of prime importance to understand, that You need a efficient panel as possible. What the panel canīt supply for, You wonīt achieve with more drive power! Best example are imo the Quads. They are relatively easy to drive, thats true. But the panels themselves are terribly inefficient and are driven with trannies featuring factors well above 1:200(!!). The result is that they perform poorly with regard to dynamics.
If You want it seriously loud, rather use more panel width (10"-15") and less height (50" -70"). Than You have more reserves at the lower end. Set the resonance as high as possible (>150Hz) by using strong mechanical tension and approriately placed diaphragm supports (with a flat panel of the suggested size and d/s You can e.g. place horizontal spacers every 100-120mm. Such a panel would present a capacity of ~2nF (80kOhms@1kHz, 4kOhms@20kHz). So a transformer with something between 1:50 and 1:75 could be ok for fullsize driven panels. With segmented panels You could go up a bit in transformation factor (~1:100).
1.5mm will allow for a max. signal-voltage of ~3kVp-p (1kVrms). So the amp should be able to produce at min. clean and stable 20Vrms (100W@4Ohms).
As transformers You could than use a pair of simple power toroids 6V/230V/ >50VA, giving ~1:65-68). For a segmented wire panel You could use a quad of 4.5/230V (giving ~1:90-1:95). This way SPLs of >110dB@4m will be possible above 300Hz with very low distortion. This should be enough to satify even horn afficionados.

jauu
Calvin

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Old 8th June 2007, 11:44 AM   #17
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My first panel arrangement was 20 inches wide and 50 inches tall. Ran them from around 450hz up. With .60 panel thickness they played good and loud. Later with the mid bass horn I rearranged the panels to about 36" square amd set them on top of the horn. That worked very well too. Calvin is correct that more panel width will improve the low end response. Been a while since I did the math on all this stuff.

I was experimenting in the 70's following the Hermeyer/Sanders articles in the Audio Amateur. Lots of fun.
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