Question for Geddes and John K

[Borat]

At my current level of understanding of Audio reproduction i have to conclude that the optimum system would have to consist of the following:

ESL section covering approximately 300 hz - 20 khz. this can be either a single curved section or a 2-way with a curved HF driver and flat LF driver. some sort of foam attenuation can be used to attenuate the backwave.



Dipole Array section covering approximately 50 hz - 300 hz.



Multiple Distributed Sealed Subwoofers 50 hz and down.

the 50 hz crossover point to subs is approximate. in actuality it would be about 50% higher than the frequency at which room pressurization starts so room dependent.

So question is - aside from size, cost and the obvious need for at least three amplifiers - can you give me a reason why this wouldn't be optimal ?

of course anybody else who thinks they know why this wouldn't work is welcome to share your opinion as well.

[badman]

The premise of this thread is rather ludicrous. Why should these gentlemen respond when it's obvious you either haven't read their work, OR disagree with the fundamentals of it?

[Borat]

Originally Posted by badman

The premise of this thread is rather ludicrous. Why should these gentlemen respond when it's obvious you either haven't read their work, OR disagree with the fundamentals of it?

what does their work have to do with this ?

just because neither of them are involved with ESLs for example doesn't mean they can't appreciate the advantages of this technology. most likely they simply find it boring because it needs little improvement.

i understand that working with horns is very exciting because so many things can go wrong. but i don't want anything to go wrong in MY system. i also understand that building a transient perfect 3-way using passive components may be fun too but an ESL doesn't need a crossover to begin with.

i am asking John K and Geddes because i trust their judgement in general, not because i am interested in any particular niche technology that they happened to be involved with. i trust that, unlike you, they would be open minded enough to consider ideas outside their field.

besides - why would i ask Linkwitz whether dipoles are the way to go ? that would be retarded.

[planet10]

An ESL will always have the problem that the waveform from the ends will arrive at a time delay greater than the threshold of time delay detection by humans. They will therefore always have an associated time smear thru-out their bandwidth.

dave

[Borat]

Originally Posted by planet10

An ESL will always have the problem that the waveform from the ends will arrive at a time delay greater than the threshold of time delay detection by humans. They will therefore always have an associated time smear thru-out their bandwidth.

dave

you're speaking as if there are two distinct waveforms here rather than a continuum. this is not an array but a panel - i don't think your logic applies here.

[planet10]

It matters not whether it is a line array or its limit, a continuum. The waveform from the top of the panel or the bottom of the panel takes longer to get to your ear than the stuff from the middle -- at least in any but a HUGE room with a listening position in the far-field.

dave

[Borat]

Originally Posted by planet10

It matters not whether it is a line array or its limit, a continuum. The waveform from the top of the panel or the bottom of the panel takes longer to get to your ear than the stuff from the middle -- at least in any but a HUGE room with a listening position in the far-field.

dave

so tell me Dave - doesn't that mean that high frequencies must be almost completely GONE due to all the cancellation from time delay ?



this isn't something easy for humans to understand. even i have to think about stuff like this to understand it. the good news is that his brilliance ( me ) is willing to help humans in this endeavor.

ps: i am taking a nap ...

[thadman]

Originally Posted by Borat

so tell me Dave - doesn't that mean that high frequencies must be almost completely GONE due to all the cancellation from time delay ?



this isn't something easy for humans to understand. even i have to think about stuff like this to understand it. the good news is that his brilliance ( me ) is willing to help humans in this endeavor.

Borat,

Planet10 is correct that a linesource will always experience time smear. However, I do not believe the effect is due to cancellation or because the sound radiated from the ends reaches your ears later. Indeed, the panel launches a wave. A cylindrical wave to be precise. These wavefronts are inherently dispersive.

HOWEVER, due to the way the panel interacts with the fluid, the panel launches dispersive waves which experience group delay. Higher frequencies travel faster than lower frequencies (ie phase distortion). This is why time smear is observed in linesources. It is dictated by the size of the radiating surface and is unavoidable. It is also non-linear, so electronic equalization is not an option.

The only non-dispersive wave function (transient perfect) is the sphere and an ESL definitely doesn't launch a spherical wave.

[thadman]

http://www.aes.org/tmpFiles/elib/20091125/14889.pdf

[Key]

Originally Posted by planet10

An ESL will always have the problem that the waveform from the ends will arrive at a time delay greater than the threshold of time delay detection by humans. They will therefore always have an associated time smear thru-out their bandwidth.

dave

There is no 6 microsecond threshold for time distortions which arrive equally at both ears. The test you keep referring to determined that threshold by messing up ONE channel of a stereo set not both.