A good resource to study dispersion of various transducers is Visaton or Tymphany homepage, the datasheets show response at 0¤, 30¤ and 60¤ (up to 120¤ coverage)
The cone profile, stiffness and surround contour are important contributors to cone driver's dispersion. More about this at www.klippel.de and www.loudsoft.com Spesifically this link http://www.klippel.de/fileadmin/kli...ure/Papers/KLIPPEL_Sound_Radiation_Poster.pdf
The cone profile, stiffness and surround contour are important contributors to cone driver's dispersion. More about this at www.klippel.de and www.loudsoft.com Spesifically this link http://www.klippel.de/fileadmin/kli...ure/Papers/KLIPPEL_Sound_Radiation_Poster.pdf
Accurate post & interesting links
Good posts Juhazi,
Thanks for the links, they have good information and are food for thought.
I am not sure what you mean by " BMR limits are also much lower and tighter "
but I think you might be meaning off axis frequency response?
I agree that the standard OEM BMR driver (4.5 inch Neo) "only" covers 120 to nearer 130 degrees if plus / minus 3dB is used as reference in an Anechoic chamber scenario.
I have found that things change ( for the better!) when you flush mount a speaker on wall or have a very shallow cabinet & curved sides on wall.
In addition my version of the driver has a different spider and surround and cone coating (applied to both sides of the inner cone and internal surface of external cone) as well as a few other minor changes.
All my R&D is focused on optimising the BMR for small sealed box on wall / in wall designs and so far all my measurements are done in situ ie on wall in real rooms.
Later this year ( October if all goes to plan) I will spend the money to get an independent acoustic engineer to carry out a full suite of anechoic measurements.
This really is only to satisfy my own curiosity (and throw a bone to the geeks & watch the sparks fly!) as I regard most anechoic measurements as irrelevant at best and often misleading, when designing a range of on wall / in wall loudspeakers
In my case, the A C measurements are a consequence not a goal....
Cheers
Derek.
Good posts Juhazi,
Thanks for the links, they have good information and are food for thought.
I am not sure what you mean by " BMR limits are also much lower and tighter "
but I think you might be meaning off axis frequency response?
I agree that the standard OEM BMR driver (4.5 inch Neo) "only" covers 120 to nearer 130 degrees if plus / minus 3dB is used as reference in an Anechoic chamber scenario.
I have found that things change ( for the better!) when you flush mount a speaker on wall or have a very shallow cabinet & curved sides on wall.
In addition my version of the driver has a different spider and surround and cone coating (applied to both sides of the inner cone and internal surface of external cone) as well as a few other minor changes.
All my R&D is focused on optimising the BMR for small sealed box on wall / in wall designs and so far all my measurements are done in situ ie on wall in real rooms.
Later this year ( October if all goes to plan) I will spend the money to get an independent acoustic engineer to carry out a full suite of anechoic measurements.
This really is only to satisfy my own curiosity (and throw a bone to the geeks & watch the sparks fly!) as I regard most anechoic measurements as irrelevant at best and often misleading, when designing a range of on wall / in wall loudspeakers
In my case, the A C measurements are a consequence not a goal....
Cheers
Derek.
"Low and narrow" can be read as rather Limited max spl and narrow frequency band - comfort zone. But because I have not seen extensive and easily comparable measurements, this is just an educated guess.
A cone behaves very badly off-axis by nature, because of geometry. Flat and dome transducers behave much better in this sense. Problem with flat/planars is stability at high excursion.
BMR is fascinating and I hope that you will make it's best virtues to sing! I don't think that it will ever be a high-end device, but your goals are reasonablyl set for it.
A cone behaves very badly off-axis by nature, because of geometry. Flat and dome transducers behave much better in this sense. Problem with flat/planars is stability at high excursion.
BMR is fascinating and I hope that you will make it's best virtues to sing! I don't think that it will ever be a high-end device, but your goals are reasonablyl set for it.
"stability at high excursion"
Hi Juhazi,
Yes I agree " stability at high excursion" is more of a problem with flat cones than cones / domes and I believe I have solved this problem.
The honeycomb structure for the flat cone really is a great advantage, a very rigid but light and non resonant structure is attainable.
It has proved impossible to achieve the same performance with a curved cone or dome.
Also having 4 faces of the cone is very useful as this allows one to vary the coatings and damping performance...Each material has a different effect and damps different frequencies, this "widens the net" of damping performance.
Also a fundamental advantage of line arrays helps solve the "stability at high excursion" problem:
To achieve a given SPL, One driver pumping plus / minus 10mm will sound horrible ( or blow up!)...
10 drivers pumping plus / minus 1mm will sound sweet!
Thanks again for your input and kind words.
Cheers
Derek.
Hi Juhazi,
Yes I agree " stability at high excursion" is more of a problem with flat cones than cones / domes and I believe I have solved this problem.
The honeycomb structure for the flat cone really is a great advantage, a very rigid but light and non resonant structure is attainable.
It has proved impossible to achieve the same performance with a curved cone or dome.
Also having 4 faces of the cone is very useful as this allows one to vary the coatings and damping performance...Each material has a different effect and damps different frequencies, this "widens the net" of damping performance.
Also a fundamental advantage of line arrays helps solve the "stability at high excursion" problem:
To achieve a given SPL, One driver pumping plus / minus 10mm will sound horrible ( or blow up!)...
10 drivers pumping plus / minus 1mm will sound sweet!
Thanks again for your input and kind words.
Cheers
Derek.
Basically just to be able to cross in the 700-1200Hz range in a cheapo 2-way while retaining at least some HF performance. Maybe you're right, maybe something like the Aura would always be better for that. Depends on whether you can get better SPL (and/or sensitivity) without giving up too much HF by using a larger BMR, I suppose?
I would be interested to see a polar comparison of a 4" bmr and the tangband flat cone 4"er.
Id doubt much difference in dispersion, but a huge difference in dynamic capability.
Just my 2 pence
The right wide band 3" will get you 500hz or lower and to 20k pretty darn well. Like the neo w3 1285sg for example. I'm confident even the 2" w2 800sl would manage 600-20k with the correct filter.
Id doubt much difference in dispersion, but a huge difference in dynamic capability.
Just my 2 pence
The right wide band 3" will get you 500hz or lower and to 20k pretty darn well. Like the neo w3 1285sg for example. I'm confident even the 2" w2 800sl would manage 600-20k with the correct filter.
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Here's a comparison for you: Soundstage's measurement and FaitalPRO's measurement on the same graph.
Attachments
Hi guys,
over the past 30 months I have become a huge fan of the Q-Acoustics BMR speakers and have used two of the units of an LCR-50 array as full rangers (from say 200Hz up) in my 2.2 config open baffle boombox speaker. See its 1st test here on YouTube if you are interested:
YouTube DIY OB Boombox Sound Demo
I have also recently replaced my main hifi in my home-office with a similar surround pair in a 2.1 config and use single Yamaha JA-6001 doing lower bass duties.
The absolute clarity I get with these setups are truly astounding. Just as reference, some of the previous speakers have been (in order of ownership):
Infinity Kappa 9.2i Series II (ribbons)
Linn Nexus LS250
Kef LS50
Peiga Premium 3 (ribbons)
Piega Premium 5 (ribbons) still have these
Magnepan SMGa
I cannot imagine parting with my BMR’s - ever!
over the past 30 months I have become a huge fan of the Q-Acoustics BMR speakers and have used two of the units of an LCR-50 array as full rangers (from say 200Hz up) in my 2.2 config open baffle boombox speaker. See its 1st test here on YouTube if you are interested:
YouTube DIY OB Boombox Sound Demo
I have also recently replaced my main hifi in my home-office with a similar surround pair in a 2.1 config and use single Yamaha JA-6001 doing lower bass duties.
The absolute clarity I get with these setups are truly astounding. Just as reference, some of the previous speakers have been (in order of ownership):
Infinity Kappa 9.2i Series II (ribbons)
Linn Nexus LS250
Kef LS50
Peiga Premium 3 (ribbons)
Piega Premium 5 (ribbons) still have these
Magnepan SMGa
I cannot imagine parting with my BMR’s - ever!
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Meanwhile here is another BMR maker I stumbled on: BMRs - Tectonic | Tectonic
but while they all tout wide dispersion most of the data sheets have no dispersion data at all. One that does has a polar plot which I don't mentally "grab" as quickly since I don't see as many, but it does not appear shockingly amazing.
I do carry an interest in flat cones from many ages ago when I was moved from design engineering into research. One of the things I was experimenting with was flat honeycomb-you could indeed get some startling dispersion, really close to on-axis even at 60 degrees.
Another contender is the Bertagni/B.E.S.T./Sound Advance Invisible technology, with a "hammer" driving a flat polystyrene diaphragm. Expensive due to low production volume.
but while they all tout wide dispersion most of the data sheets have no dispersion data at all. One that does has a polar plot which I don't mentally "grab" as quickly since I don't see as many, but it does not appear shockingly amazing.
I do carry an interest in flat cones from many ages ago when I was moved from design engineering into research. One of the things I was experimenting with was flat honeycomb-you could indeed get some startling dispersion, really close to on-axis even at 60 degrees.
Another contender is the Bertagni/B.E.S.T./Sound Advance Invisible technology, with a "hammer" driving a flat polystyrene diaphragm. Expensive due to low production volume.
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