I´ve now here the article with all of the specs that is needed to built this unit, I´m not about to translate it and post it here, but you dont know the thickness, material of the diaphragm and manner of its attachment, and I think thats the key for undestanding this driver fully. As the second fact, the compression chambers are very small and as merhaut wrote the heavy pressure caused by the loading is spread across the chamber almost uniformly because of its very small volume, because of that parts of the diaphragm are moving in piston-like manner.
thats all, believe or not, but from the point of seeing the specs of merhautofon, I must repaeat : that ESL as a compression driver is not a bad idea, but you must know how to make it properly, because you must consider all the parts again, not only make a small panel in the same way like its bigger brothers
thats all, believe or not, but from the point of seeing the specs of merhautofon, I must repaeat : that ESL as a compression driver is not a bad idea, but you must know how to make it properly, because you must consider all the parts again, not only make a small panel in the same way like its bigger brothers
Hi,
Merhaut claims alot and obviously wrote something.
The question for me is simply: "Does it make sense? Or does it work like it is claimed?"
So far we have no proof at all and it seems like we won´t get it.
The patent at least leaves too many Qs open.
Aren´t there any graphs or measurements prooving the (superior?) functionality of the device?
What I expect would be:
- higher efficiency numbers compared to an ESL of horn-mouth-area
- good measurement values with regard to distribution character (falling -but parallel to each other- SPL-curves with rising measurement angles)
- lower distortion figures compared to a ESL of horn-mouth-area
What I expect is:
- greatly reduced bandwidth, probabely not even reaching 20kHz.
- efficiency not considerably higher than a bare ESL of hm-area
- distortion figures rather higher, because of considerable stress put on the soft membrane
- distibution figures not superior hence not much different to a curved or a segmented ESL
- losses and reflections within the horn, creating distortions
If the device is to make any sense some measurements must proove a clear superiority against a good but standard ESL of same size.
But working with the given formulas alone shows that e.g. the same efficiency results as Merhaut claims with his horn can be reached by simply upsizing the ESLs membrane size!
Of course it is clear that a driver intended for usage in a compression horn has to be constructed differently than a free-air device. The question is: is it possible to design a ESL in such a way that it is capable to load a horn properly without(!) giving up on too many goodies of a standard ESL? And will this device be superior in any field to a standard ESL of somewhat larger membrane size?
Up till now I´ve nothing seen or heard that defies a clear No!
jauu
Calvin
Merhaut claims alot and obviously wrote something.
The question for me is simply: "Does it make sense? Or does it work like it is claimed?"
So far we have no proof at all and it seems like we won´t get it.
The patent at least leaves too many Qs open.
Aren´t there any graphs or measurements prooving the (superior?) functionality of the device?
What I expect would be:
- higher efficiency numbers compared to an ESL of horn-mouth-area
- good measurement values with regard to distribution character (falling -but parallel to each other- SPL-curves with rising measurement angles)
- lower distortion figures compared to a ESL of horn-mouth-area
What I expect is:
- greatly reduced bandwidth, probabely not even reaching 20kHz.
- efficiency not considerably higher than a bare ESL of hm-area
- distortion figures rather higher, because of considerable stress put on the soft membrane
- distibution figures not superior hence not much different to a curved or a segmented ESL
- losses and reflections within the horn, creating distortions
If the device is to make any sense some measurements must proove a clear superiority against a good but standard ESL of same size.
But working with the given formulas alone shows that e.g. the same efficiency results as Merhaut claims with his horn can be reached by simply upsizing the ESLs membrane size!
Of course it is clear that a driver intended for usage in a compression horn has to be constructed differently than a free-air device. The question is: is it possible to design a ESL in such a way that it is capable to load a horn properly without(!) giving up on too many goodies of a standard ESL? And will this device be superior in any field to a standard ESL of somewhat larger membrane size?
Up till now I´ve nothing seen or heard that defies a clear No!
jauu
Calvin
only graph that is at this time avalaible is the frequency response, author says that the curve falls down on 20Khz only because they stop to measure it exactly, because they werent able to measure it on such high frequencies. This claim is confirmed by guys as I told you before that said that i has a good 20us pulse response, which indicates the frequency response of the driver is sufficient.
Merhaut discussed this large range of operating from a point of influences of the acoustical transformation, which is the main cause of that.
Sensitivity and other numbers arent avalaible because of that it is patented and patent was sold, nobody from year 1972 didnt manufacture another piece of this device But I dont know this surely. But as I know it was crossed with a driver aro835, and if i think a little about it, aro835 was very sensitive 15" driver, about 98dB/w/m, and if we consider the maximum avalaible power from an amplifier at that days, its sensitivity couldnt be so low, to couple aro835.
I think that one of good points of this design is that the capacitance of this panel will be much smaller than the free air device, so the resonance of the transformers stray inductance and capacitance of the panel will be at much more higher frequency. But even free air device can be good in this point of view.
I think one point in which will be this design clearly superior, will be a waterfall test. Sadly there arent any devices avalaible.
Merhaut discussed this large range of operating from a point of influences of the acoustical transformation, which is the main cause of that.
Sensitivity and other numbers arent avalaible because of that it is patented and patent was sold, nobody from year 1972 didnt manufacture another piece of this device But I dont know this surely. But as I know it was crossed with a driver aro835, and if i think a little about it, aro835 was very sensitive 15" driver, about 98dB/w/m, and if we consider the maximum avalaible power from an amplifier at that days, its sensitivity couldnt be so low, to couple aro835.
I think that one of good points of this design is that the capacitance of this panel will be much smaller than the free air device, so the resonance of the transformers stray inductance and capacitance of the panel will be at much more higher frequency. But even free air device can be good in this point of view.
I think one point in which will be this design clearly superior, will be a waterfall test. Sadly there arent any devices avalaible.
Attachments
Calvin said:
You all seem to have some misconceptions about horns. The main practical purpose of a horn is to produce the same or higher SPL with as little diaphragm displacement as possible. Diaphragms (no mater if electrodynamic or ESL) are almost always force driven, so heavier acoustic loading does not make much difference on how stressed the materials become. On the other hand, displacement always causes stress because it involves things such as bending, breakup modes and resonances. Also, displacement is the main source of non-linearity in electrodynamics, and in ESL too, isn't it?
BTW: The reduction in membrane displacement does not only bring higher SPL capabilities with lower THD, but it also usually results in LF extension as a bonus. In an ideal system with no diaphragm displacement, all the electrical energy coming from the amplifier would be transferred directly to the air. Electrodynamic drivers coupled to horns achieve power efficiencies in the 12% to 50% range (as opposed to 0.12% to 5% for direct radiation) and this really makes a difference when listening
Hi,
Transmission Audio has one project (ongoing?) with ribbons and horns for use in PA.
They claim truly impressive distortion figures.
http://www.transmissionaudio.com/home/pasystems.html
Transmission Audio has one project (ongoing?) with ribbons and horns for use in PA.
They claim truly impressive distortion figures.
http://www.transmissionaudio.com/home/pasystems.html
As you can see the patent was filed in 1968. The longest a patent is maintained throughout the world is 25 years. In many countries it is even shorter (20 years in my homecountry for instance).
After this time it is becoming public domain. The idea behind that is that technical innovations are not obstructed too much by commercial barriers while the commercial interest of inventors being protected well enough.
Regards
Charles
After this time it is becoming public domain. The idea behind that is that technical innovations are not obstructed too much by commercial barriers while the commercial interest of inventors being protected well enough.
Regards
Charles
A few comments.
Patents in the USA run 17 years.
The ribbon based horn loaded driver clearly will work.
As long as the sound velocity/pressure in the throat area does not get close to going supersonic, there is reduced distortion compared to a similarly sized direct radiator for a given SPL level. Or put another way, lower pressures in the throat area make that source of distortion negligible. In practice this is only a problem when you get up into high PA/SR SPL levels, in home use it's likely a non issue.
Compared to the same diagphragms directly radiating, horn loading will provide "LF extension", that's part of the priniciple and benefit to horns in general.
The contention that a larger direct radiating ESL panel will equal or outperform the horn loaded version is uncertain at best. It is entirely possible that the horn can produce greater SPL and may have lower distortion specs at normal listening levels.
Much depends on the effectiveness of the phasing arrangement for these diaphragms and their effective surface area and the force that they can produce, reflected energy could be a real problem for the ESL diaphragms here. But modern horn/waveguide concepts would probably obviate much if not all of that issue.
I guess the real question is not if a large ESL is better than the horn loaded ESL, but if the horn loaded ESL will outperform a very high quality compression driver in any parameter, or in terms of sound?
_-_-bear
Patents in the USA run 17 years.
The ribbon based horn loaded driver clearly will work.
As long as the sound velocity/pressure in the throat area does not get close to going supersonic, there is reduced distortion compared to a similarly sized direct radiator for a given SPL level. Or put another way, lower pressures in the throat area make that source of distortion negligible. In practice this is only a problem when you get up into high PA/SR SPL levels, in home use it's likely a non issue.
Compared to the same diagphragms directly radiating, horn loading will provide "LF extension", that's part of the priniciple and benefit to horns in general.
The contention that a larger direct radiating ESL panel will equal or outperform the horn loaded version is uncertain at best. It is entirely possible that the horn can produce greater SPL and may have lower distortion specs at normal listening levels.
Much depends on the effectiveness of the phasing arrangement for these diaphragms and their effective surface area and the force that they can produce, reflected energy could be a real problem for the ESL diaphragms here. But modern horn/waveguide concepts would probably obviate much if not all of that issue.
I guess the real question is not if a large ESL is better than the horn loaded ESL, but if the horn loaded ESL will outperform a very high quality compression driver in any parameter, or in terms of sound?
_-_-bear
This part of the problem might probably be overcome by modern horn-modeling techniques.
One problem that I see the diapharagm movement that is caused by nearby woofers.
From:http://www.meyersound.com/support/forums/talkshop/drivers.htm
"...For example, the horns attached to the driver act in both directions - not only do they transform and radiate sound from the driver to the outside world, but they also focus external sounds on to the diaphragm, adding significantly to its stresses. ..."
Maybe not so much of a problem in a domestic environment.
Regards
Charles
phase_accurate....
I see where you are comming from and agree that in some pro siruations (ie. disco club) this probably becomes a concern. Think about a conventional baffle with a big bass driver mounted right next to a mid range driver. This is probably a situation where the impact of the bass driver on the mid unit is far gerater than with the Merhaut open back ESL comp design. While a concern in some situations most of the time drivers get along fairly well when they share a single baffle. Given the dimentions of Josef's design I don't think there will be an issue. Further if you consider that most comp driver domes fire backward into a very small closed cavity which can ony reflect the wave back out through the dome an open back system probably sounds much better. Just my two cents worth. Moray James.
I see where you are comming from and agree that in some pro siruations (ie. disco club) this probably becomes a concern. Think about a conventional baffle with a big bass driver mounted right next to a mid range driver. This is probably a situation where the impact of the bass driver on the mid unit is far gerater than with the Merhaut open back ESL comp design. While a concern in some situations most of the time drivers get along fairly well when they share a single baffle. Given the dimentions of Josef's design I don't think there will be an issue. Further if you consider that most comp driver domes fire backward into a very small closed cavity which can ony reflect the wave back out through the dome an open back system probably sounds much better. Just my two cents worth. Moray James.
I have the Merhaut article and scanned it on my old computer and have sent it to some people.
Unfortunately, that Win98SE computer's hard drive suddenly gave up the ghost and was replaced by my present XP machine.
I would scan it again except that my scanner does not have WinXP drivers, none were written. I can scan it someplace else I frequently go, though.
If you want a copy, let me know either on the board on by Email. Remember to include the Email address you want it sent to-in some cases, that is different from the Email address that is usually used.
Unfortunately, that Win98SE computer's hard drive suddenly gave up the ghost and was replaced by my present XP machine.
I would scan it again except that my scanner does not have WinXP drivers, none were written. I can scan it someplace else I frequently go, though.
If you want a copy, let me know either on the board on by Email. Remember to include the Email address you want it sent to-in some cases, that is different from the Email address that is usually used.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.