Notes
The outer extent of the phase plug is part of the magnetic circuit (pole piece) that delivers flux into the voice coil gap. Typically it is made from a specialized mild steel know as 'Swedish Iron'. In ALE and Goto Unit drivers, the pole pieces are made from the exotic steel called Permendur [1]. Once these components become saturated, they limit the flux density that can be delivered into the magnetic gap. Reducing carbon content and alloying with cobalt are the methods used to elevate the permeability of the steel. Bottom line: consider plug modification to be one step away from designing a compression driver from scratch.
References:
[1] Permendur - Wikipedia, the free encyclopedia
The outer extent of the phase plug is part of the magnetic circuit (pole piece) that delivers flux into the voice coil gap. Typically it is made from a specialized mild steel know as 'Swedish Iron'. In ALE and Goto Unit drivers, the pole pieces are made from the exotic steel called Permendur [1]. Once these components become saturated, they limit the flux density that can be delivered into the magnetic gap. Reducing carbon content and alloying with cobalt are the methods used to elevate the permeability of the steel. Bottom line: consider plug modification to be one step away from designing a compression driver from scratch.
References:
[1] Permendur - Wikipedia, the free encyclopedia
O.S. Horn Sans Lips
Lips are added to mitigate the abrupt transition to free space that outbound waves 'see' when they exits the horn. Response ripple is induced by the attendant wave reflectance and diffraction.
Regards,
WHG
Lips are added to mitigate the abrupt transition to free space that outbound waves 'see' when they exits the horn. Response ripple is induced by the attendant wave reflectance and diffraction.
Regards,
WHG
Hi J-M,
Short Comment Follows:
The aberrations in wave front shape occurring in phase plug annuli and at their confluence, can be attributed to the viscosity of air at differing frequencies, surface roughness of the phase plug boundaries, and the high acoustic pressures that occur within these confined spaces, as well as the slope of the annular passages. Here air rarefaction and compression are taking place far outside domain of the linear elasticity of air. Thus a coherent plane wave front is impossible to achieve no mater what geometry might be used. The best that can be expected by a design effort is to minimize the effects of these short-comings. That may turn out to be just polishing the phase plug surfaces of an otherwise good design.
Regards & Cheers for the Coming Holidays
WHG
Hello Pano,
Electricity, paint, fixing leaking taps Inside the apartment rented by an american-swiss friend before she'll come back.
Not a minute for myself. As the aprtment is inside the marina, I can see the yachts through the window and from the attic I can see all along the beach and the casino on the left but the only walk I'll be taking will be to try to get my train to get back to Paris on the afternoon...
(BTW when the friend will be in USA, the apartement which is on 3 floors (+ attic on the 4th floor) and possess 2 bedromms and 2 bathrooms with bathtube + 2 toilets will be rented for 1 week to 3 months... )
Here is a link with pictures of the marina :
Port-Deauville, le port privé - Portail officiel de la Ville de Deauville
Best regards from Deauville, Calvados, France
Jean-Michel Le ClLéac'h
Hello,
Here is few pictures of Iwata - Le Cléac'h horns that I use to calulate.
http://s108.photobucket.com/user/i_should_coco/media/ETF2013/IMG_7608_800.jpg.html?sort=3&o=0
http://1.bp.blogspot.com/-ZrFxRRN3yfo/Uo8uarChHaI/AAAAAAAAGMs/IWHI3jJLaIU/s1600/Sytsem1.jpg
http://3.bp.blogspot.com/-Hg1o8kFac_g/Uo8usvNUuGI/AAAAAAAAGNU/ULvFM-NvLIE/s1600/Speaker1.jpg
http://www.audiohagel.dk/index/details.php?image_id=1689
http://www.audiohagel.dk/index/details.php?image_id=1697
The cloud of 40000 points was processed by Nicolas Davidenko who derived the data for the 3D machining tool.
Franck Delbauve built those magnificent horns using his 3D milling machine.
Best regards from Paris, France
Jean-Michel Le Cléac'h
Here is few pictures of Iwata - Le Cléac'h horns that I use to calulate.
http://s108.photobucket.com/user/i_should_coco/media/ETF2013/IMG_7608_800.jpg.html?sort=3&o=0
http://1.bp.blogspot.com/-ZrFxRRN3yfo/Uo8uarChHaI/AAAAAAAAGMs/IWHI3jJLaIU/s1600/Sytsem1.jpg
http://3.bp.blogspot.com/-Hg1o8kFac_g/Uo8usvNUuGI/AAAAAAAAGNU/ULvFM-NvLIE/s1600/Speaker1.jpg
http://www.audiohagel.dk/index/details.php?image_id=1689
http://www.audiohagel.dk/index/details.php?image_id=1697
The cloud of 40000 points was processed by Nicolas Davidenko who derived the data for the 3D machining tool.
Franck Delbauve built those magnificent horns using his 3D milling machine.
Best regards from Paris, France
Jean-Michel Le Cléac'h
Hello Rewind,
Those Iwata-JMLC horns provide the same acoustical load on the driver as the axisymetrical Le Cléac'h horns of the same cut-off and T value.
They also provide very low diffraction at their mouth, which is a feature that all Le Cléac'h horns have.
The quality of the sound is very much the same as with the axisymetrical Le Cléac'h horn, but due to the shape, the rate at which the radiation angle decreases with frequency in the horizontal plane with the Iwata-JMLC horn is half than with the axisymetrical Le Cléac'h horn, thus doubling the width of the sweet spot.
Due to the shape, the treble would benefit sometimes of some equalization, even if with good compression drivers as the TAD TD2001 the slightly decreasing response in the high frequency (over 3500HZ roughly) aproximates the desired frequency response curve for small auditoriums.
Best regards from Paris, France
Jean-Michel Le Cléac 'h
Jean-Michel,
We have already discussed this before, but would it be possible using your spreadsheet(s) to design a horn of a given hypex flare that would have an OS horizontal profile (with some form of mouth termination) ?
What I am looking for is good loading (hence the hypex flare) and almost constant horizontal directivity control up to at least 8 or 9kHz (hence OS or quadratic).
Of course the vertical directivity control would suffer a lot, but my guess is that the vertical profile would have to form some sort of slot (narrowing) at some point in the throat of the horn to keep up with the target flare, and that would probably help vertical directivity as well.
We have already discussed this before, but would it be possible using your spreadsheet(s) to design a horn of a given hypex flare that would have an OS horizontal profile (with some form of mouth termination) ?
What I am looking for is good loading (hence the hypex flare) and almost constant horizontal directivity control up to at least 8 or 9kHz (hence OS or quadratic).
Of course the vertical directivity control would suffer a lot, but my guess is that the vertical profile would have to form some sort of slot (narrowing) at some point in the throat of the horn to keep up with the target flare, and that would probably help vertical directivity as well.
Hello Pooge,
Analogy with (let say) "anatomical parts" is a long story concerning Le Cleac'h horns.
The shape of Le Cleac'h horns is never a choice of esthetical préférences but derive from technical choices.
So more often than thought, the anatomical comparison is very revealing of some characterstics of the mind of the person who emits that comparison.
Romy the cat used to compare the E-Jmlc horns to vaginas...
Best regards from Paris, France
Jean-Michel Le Cléac'h
Hello Pos,
I don't want to use someone's copyright for my own créations.
But it is interesting to note that if I calculate a horn using my method but forcing it on the first half of its length to keep a constant thickness (of the air duct seen in a vertical axial plane), then the horizontal profile is very similar to an OS waveguide, without any intention to copy that profile...
See as an example the 3D schematics of that horn who provide a controlled directivity Inside the horizontal plane :
http://i307.photobucket.com/albums/nn281/AudioVoice/new_cd_horn.jpg
(Here again I wait fro anatomical comparison, several used to compare to Rolling Stones "red lips sofa"...
Best regards from Paris, France
Jean-Michel Le Cléac'h
Well in my mind, I'd like to polish a pair. Would make for a nice threesome!
But Romy needs help for other reasons.
Hello, I am thinking of better control of expansion rate, minimizing diffraction points, and better matching of exit angle to the particular horn I design.