Following my own line of thinking in one of the above posts I can show results that might be of some general interest as it demonstrates how different "termination" of a horn can improve performance.
This simple mechanism possibly could be adapted for open baffles as well.
One if the limitations of my quasi Min Phase horn is that we have parallel top an bottom plates that have to end somehow.
In order to not scarify inter driver distance there is no way to apply a round over of any useful radius. So I simply did cut them roughly where the Min Phase contour meets 180deg.
Investigating the polar wiggles at ~2500Hz showed that they can be moved in centre frequency by adding length to the top and bottom plate.
So I started to cut several "lips" and ended up with the form of a "sliced fan" of ~15-20cm / 6-8" depth.
The result is significantly better with respect to FR IR GD CSD and, as its been a "one evenings work" only, there might even be room for improvement.
One aspect of my Min Phase contour I find worth to note as nobody until now has picked it up.
Measurements shown are done *without* any equalisation.
This means my MinPhase contour provides CD behaviour *without* the nasty need of correction for a falling frequency response.
If I remember correctly, Earl has stated on several occasions that the common 6dB FR fall is "simple physics" for any CD horns.
As I claim my Min Phase horn to be as "true as CD as can be" - well – seems my results prove him wrong just another time.
Michael
This simple mechanism possibly could be adapted for open baffles as well.
One if the limitations of my quasi Min Phase horn is that we have parallel top an bottom plates that have to end somehow.
In order to not scarify inter driver distance there is no way to apply a round over of any useful radius. So I simply did cut them roughly where the Min Phase contour meets 180deg.
Investigating the polar wiggles at ~2500Hz showed that they can be moved in centre frequency by adding length to the top and bottom plate.
So I started to cut several "lips" and ended up with the form of a "sliced fan" of ~15-20cm / 6-8" depth.
The result is significantly better with respect to FR IR GD CSD and, as its been a "one evenings work" only, there might even be room for improvement.
One aspect of my Min Phase contour I find worth to note as nobody until now has picked it up.
Measurements shown are done *without* any equalisation.
This means my MinPhase contour provides CD behaviour *without* the nasty need of correction for a falling frequency response.
If I remember correctly, Earl has stated on several occasions that the common 6dB FR fall is "simple physics" for any CD horns.
As I claim my Min Phase horn to be as "true as CD as can be" - well – seems my results prove him wrong just another time.
Michael
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If I see it correctly, yours is CD within a 5dB range from 2-10 kHz. At whatever angle - you didn't state your steps.
Earls Summa is at least 15 dB from 1-15 kHz and 0-90 deg.
Sorry, but I would always accept the ''nasty need of correction'' for getting the Summa performance instead of yours.
Sorry, but I would always accept the ''nasty need of correction'' for getting the Summa performance instead of yours.
The choice is yours ! - I'm fine with that...
The traces are 0 10 20 30 deg – and - they are smoothed at 1/3 octave
One slight correction in performance analysis:
When looking at CD behaviour with respect to MP (per contra to audience coverage) it is *not* important that the traces differ in SPL at different angles.
Especially not if you are after good matching with the polar response of an OB low-mid (dipole).
What really counts is the "tracking" of FR one to the others – hence I often show *normalized* FR plots as well when this is any important.
Here you can see that the FR tracking is IMO excellent – within 1-2dB in the range of 1kHz – 10kHz *if* we let the polar wiggle - at now ~1600Hz – aside.
Above that ~3 octaves of flawless performance (again the polar wiggle due to the cylinder wave horn shape put aside), the response of my dipole horn still is smooth and easily within the (nonsense) 10 dB window of "true constant directivity" up to 20kHz
As said – this is for the window within 30 deg off axis.
Michael
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http://www.diyaudio.com/forums/multi-way/110583-fast-fun-inexpensive-ob-project-3.html#post1996185
New "sliced fan " shape isn't available yet - see last posting there....
New "sliced fan " shape isn't available yet - see last posting there....
Measurements were taken at 1m
It doesn't make sense to me to show extremely detailed data as long as there haven't been built and auditioned a bunch of these dipole MinPhase horns.
We would be drawn into an discussion of hair splitting on only some measurements of mine. Also it would be hard to keep apart what's the performance of the horn and what from the NEO3-W.
Also the cylinder wave quasi MinPhase dipole horn is not exactly the ultimate way to demonstrate my current MinPhase contour , but its fun to build (and tweak) and fun to listen to and for certain quite a bang for the buck !
So – please see it what it actually is intended for – a teaser for *DIY* – and a proof of concept with great capability to reach up into top notch designs.
Michael
It doesn't make sense to me to show extremely detailed data as long as there haven't been built and auditioned a bunch of these dipole MinPhase horns.
We would be drawn into an discussion of hair splitting on only some measurements of mine. Also it would be hard to keep apart what's the performance of the horn and what from the NEO3-W.
Also the cylinder wave quasi MinPhase dipole horn is not exactly the ultimate way to demonstrate my current MinPhase contour , but its fun to build (and tweak) and fun to listen to and for certain quite a bang for the buck !
So – please see it what it actually is intended for – a teaser for *DIY* – and a proof of concept with great capability to reach up into top notch designs.
Michael
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That's probably too close. Although loudspeaker sensitivity is specified at 1m distance, most speakers show unsteady nearfield behavior at 1m.
If one horn is working, all the others should perform the same, no?
That's why I asked for more detailed measurements. Such data would allow to discuss matters on a more objective and comparable level.
You compared your horn to Earl's Summa so it's not fair to exclude driver performance from your loudspeaker.
Best, Markus
I quite agree that when we are trying to compare against another person's design, data should be shown in perspective to avoid illusions and misinterpretations. Ultimately, I think it's good practice to avoid direct comparison.
The measureing distance is an interesting issue, because baffle edge/horn edge diffraction is going to effect the unsmoothed results somewhat.
Personally, I like to get comments back that hopefully will help me find any consideration I have missed. This keeps me in a learning mode.
The measureing distance is an interesting issue, because baffle edge/horn edge diffraction is going to effect the unsmoothed results somewhat.
Personally, I like to get comments back that hopefully will help me find any consideration I have missed. This keeps me in a learning mode.
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Actually no - if you will its a competition of "diffraction alignment device" concept against whats on top of list right now - and as it turned out that a "diffraction alignment device" actually *is* a horn - well I have to compare to the horns known.
I'm not "really" interested in Earls OS and even less in his Summa - my main interest is *whats behind* leading to this or other design decisions.
Here Earls bold "lowest diffraction ever" claim - I simply could not stand - but thats history and even overall statements that usually have came along like "carved in stone" have significantly changed to the better...
I do not remember having made comments about the performance of the Summa in *any* of my postings though - do you ?
Earl's Summa and his other speakers may work well for what they are intended for (strong toe in), even exceptional – I simply do not know as I haven't heard.
Given the two way concept with the large inter driver distance its no small surprise for me that Earl obviously has managed to get it working for home environment use at all.
That his concept has fans tells me he did a excellent job and I possibly give something similar a try one day.
Michael
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A horn that produces side-lobes is by most definitions minimum phase because it is described by both the Airy and Schrodinger equations, but you can't remove the lobes by d.s.p. only by geometry.
It would seem that some other sort of appellation is needed for your proposed device Micheal, unless the presence of side-lobes is acceptable.
As I have pointed out before a device with only a center maximum is also minimum phase and Gaussian is a more apt name for it.
rcw.
It would seem that some other sort of appellation is needed for your proposed device Micheal, unless the presence of side-lobes is acceptable.
As I have pointed out before a device with only a center maximum is also minimum phase and Gaussian is a more apt name for it.
rcw.
Oh - now I have found them
http://www.diyaudio.com/forums/multi-way/103872-geddes-waveguides-64.html#post1887771
Have to apologize - seems - I'm getting old...
Side lobes are not on my wish list - certainly true..
And yes - the discussion and your input on Gaussian beam shape was mainly here
http://www.diyaudio.com/forums/multi-way/140190-jean-michel-lecleach-horns-9.html#post1892274
and at one or two other occasions.
We (you in particular) ended by the question if it is possible to achieve a Gaussian beam that's CD as well
http://www.diyaudio.com/forums/multi-way/140190-jean-michel-lecleach-horns-9.html#post1894035
So you really think "Gaussian horn" would fit better for what I'm after and already have achieved to some extent?
It would not include the CD aspect as you outlined for the LeCleach contour ?- and that's paramount for me and implicit in EQ'ing benefits of "MinPhase" over a certain room angle
Michael
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As others have pointed out to a large extent loudspeaker systems of all sorts can be thought of as minimum phase, so calling one minimum phase just seems to be a technical sounding advertising buzz word, for a characteristic that all speakers posses anyway.
In r.f. there is a device known as a Gaussian profile horn that gives a single lobe and greatly attenuates side-lobes, for audio it probably produces horrendous amounts of higher modes and sounds terrible.
It is your device and call it what you will, but several of the heavy hitters have already commented upon the name.
I have had people comment to me that the name, "o.s. waveguide", is also in the category of advertising buzz words.
You can show that that profile gives the lowest higher mode production with an incident plane wave, just by considering the scattering relations, without resorting to exotic sounding coordinate systems.
There is also a whole literature about 'c.b.t." devices, constant beam width transducers, the two devices mentioned seem also to fit into this catagory.
rcw.
In r.f. there is a device known as a Gaussian profile horn that gives a single lobe and greatly attenuates side-lobes, for audio it probably produces horrendous amounts of higher modes and sounds terrible.
It is your device and call it what you will, but several of the heavy hitters have already commented upon the name.
I have had people comment to me that the name, "o.s. waveguide", is also in the category of advertising buzz words.
You can show that that profile gives the lowest higher mode production with an incident plane wave, just by considering the scattering relations, without resorting to exotic sounding coordinate systems.
There is also a whole literature about 'c.b.t." devices, constant beam width transducers, the two devices mentioned seem also to fit into this catagory.
rcw.
You would have to show this to me before I accepted it. You have a tendancy to make mathematical statements without any support. For example applying the "Schroedinger Equation" to acoustics. Really? That equation applies to quantum menchanical wave functions and has nothing to do with acoustics. Maybe in RF you can relate the variables to something but not in acoustics.
And just for the record, all the rest of this stuff about MP Horns and "diffraction aligment" or whatever is a bunch of hogwash. I'd much rather get back to hearing from Lynne on some useful topics.
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I have not had a lot of time to listen to that contour with the NEO3-W and therefor I can't *really* tell, but what I have heard – and what I enjoy for quite some time now with my AMT version which isn't that much different – is:
It sounds great.
No addition of "horn" sound IMO except the positives of making presentation more "dynamic" and "live like".
And yes - I quite often sit extremely out of sweet spot (outside the stereo base actually) and really enjoy the sound – though all this might be "*my* subjective" impression.
I'd second that as I think for now pretty much all has been said about my "Gaussian MinPhase" horn...
Thanks for all comments and thanks to Lynn for hosting my OT !
Michael
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JBL High output 107 1W@1m Two Way
Here looks to be a JBL Pro products "Precision Directivity" effort to make a full range product from a 1.5" HF driver and a 12" LF Driver from approx 2003...
http://www.jblpro.com/catalog/support/getfile.aspx?doctype=3&docid=1220
http://www.jblpro.com/press/pd5/pd5.pdf
Here looks to be a JBL Pro products "Precision Directivity" effort to make a full range product from a 1.5" HF driver and a 12" LF Driver from approx 2003...
http://www.jblpro.com/catalog/support/getfile.aspx?doctype=3&docid=1220
http://www.jblpro.com/press/pd5/pd5.pdf
An externally hosted image should be here but it was not working when we last tested it.
