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Old 7th June 2011, 12:57 AM   #21
jcx is offline jcx  United States
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maybe your assumptions are wrong - transducer efficiency ultimately has a trade off against bandwidth - although most speaker diver's efficiency is way below that limit

also electrostatic drivers look horribly inefficient when driven from conventional amps because they are a mostly reactive load - if you used a bidirectional switching topology amp you could recover the stored charge each cycle

at a single frequency you can cancel the esl reactance with a series inductor for good electrical drive efficiency at that frequency

horns have limited bandwidth, possible nonlinearity due to high pressures in the throat

Last edited by jcx; 7th June 2011 at 12:59 AM.
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Old 7th June 2011, 01:04 AM   #22
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Quote:
Originally Posted by jcx View Post
if you used a bidirectional switching topology amp you could recover the stored charge each cycle
You mean like class D/T ? I'm not making any assumptions just giving my conclutions based on incomplete info. Keeping an open mind is the only way to make breakthroughs.
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Old 7th June 2011, 01:18 AM   #23
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You can use class d to counteract the low impedences at high frequencey's but your not going to get the 25kv p-p required to get maximum performance without the use of a transformer effeciently with today technology yet.IMHO

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Old 7th June 2011, 01:28 AM   #24
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but you can probably improve efficiency by optimising the transformer for the application and not using standard audio standards. (maybe) I like the idea of designing custom systes with the whole chain in mind, including the room. I guess I don't understand where the 4-16 Ohm standard for speakers came from. It doesn't seem to be optimised for any amplifier technology ever used.
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Old 7th June 2011, 01:41 AM   #25
jcx is offline jcx  United States
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the amplifier switch topology needs to support bidirectional current flow at both positive and negative output V - bjt switches won't


there is an old JAES paper on a multi-section esl driving a horn - possibly this could be upped in vertical dimension to a line source AES E-Library Horn-Loaded Electrostatic Loudspeaker
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Old 7th June 2011, 02:11 AM   #26
brsanko is offline brsanko  United States
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I don't understand peoples interest in line arrays they seem to amplify the shortcommings of the drivers used. I.e. limited dispersion, frequency cancelations, etc, what exactly are the advantages? It seems like a horn with one wide frequency driver far exceeds the performance of a line array with like 8 of them.
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Old 7th June 2011, 05:38 AM   #27
jcx is offline jcx  United States
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you misunderstood the dimension I was suggesting you "stretch"

the planar drivers use elements the height of your room - the horn becomes "2-d", flaring only in the horizonal plane

this avoids the interference/comb filtering with multiple drivers

floor, ceiling reflection just look like an extension of the line source

with more radiating area, slower roll-off with distance you can get higher spl with less displacement = better linearity


a inherent problem is that cylindrical wave propagation is dispersive although you are probably listening "near field" so frequency balance would be fine



if you can afford the space for 2 coffin sized speakers in your room line sources may be a good option

Last edited by jcx; 7th June 2011 at 05:40 AM.
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Old 7th June 2011, 06:21 AM   #28
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Here's my fantasy-physics: fabulous idea.

A strength of ESLs is that the impedance of the Saranwrap diaphragm in making sound waves is vastly closer to air than shaking big blocks of cardboard (AKA cones) is. With a horn transforming this a lot further, aberrant behaviour of the ESL diaphragm begins to vanish* and only the motive power (which is clean electric waves coming from the amp and transformers (if any)), defines the very very clean sound output.

Yes conventionally, the parameters of horns and ESLs don't seem to work together. But the concept sure seems worth exploring.

*Really due to negative feedback from the air load.
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Last edited by bentoronto; 7th June 2011 at 06:23 AM.
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Old 7th June 2011, 02:04 PM   #29
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Okay that was helpful info, but then it would seem to me that electrostatics should be very efficient but it seems that the opposite is what I've heard. Why is it that electrostatics are known for their almost problematic inefficiency?
Efficiency is the acoustic output power divided by the electrical input power.
Sensitivity is the acoustic output power divided by the electrical input voltage.
They are related, often confused, but not the same.
Compared to dynamic drivers, ESLs are very efficient, but generally a bit less sensitive.
When you hear people say that ESLs are less efficient that usually mean they have to turn up the volume to obtain the same acoustic output level as a dynamic speaker. Since the volume knob is controlling the output amplitude of a voltage source, this is lower sensitivity, not efficiency.

A related limitation that is unique to the ESL is that of maximum output. ESLs are limited in the amount of force they can generate per unit area of diaphragm. Trying to exceed this limit results in ionizing the air in the gap between stator and diaphragm. Depending on the construction method and materials arcing, corona, and ozone generation may result. What this means is that if you want it louder, you canít just keep increasing the voltage levels. The only way to increase the peak SPL output capability is to add area, or operate the ESL in a gas that has a higher ionization threshold.

Last edited by bolserst; 7th June 2011 at 02:10 PM.
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Old 7th June 2011, 04:09 PM   #30
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snip The only way to increase the peak SPL output capability is to add area, or operate the ESL in a gas that has a higher ionization threshold.
The Dayton-Wrights were designed to be capable of powering movie theaters, at least with multiple sets.

If I am not mistaken, the same arithmetic that magically multiplies the peak power capability of the amps in a music system when you bi-amp also applies when you divide the tone compass with speakers.

Having said that, playing my D-W speakers 5 octaves wide, I can still blast over 100 dB in my modest-sized music room.
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