Clearly you misunderstood my post Earl.
I'm perfectly fine with having an opinion with which you disagree.
You see, I'm not hung up on being correct all of the time. Also I'm open to there being other valid approaches other than yours. As all true scientists should be. Not that i am a scientist, but really who cares?
For what its worth, hifi is a folly. The science isn't used to benefit the world, unless hifi is helping the those less fortunate than us.
However, my profession does benefit others quality of life through science.
One thing is certain. As long as their are enquiring minds, there will always be another valid approach to audio that isn't the Geddes way. Whether you like it or not, you cannot possibly claim it to be otherwise.
Unless you are omnipotent now?
I'm perfectly fine with having an opinion with which you disagree.
You see, I'm not hung up on being correct all of the time. Also I'm open to there being other valid approaches other than yours. As all true scientists should be. Not that i am a scientist, but really who cares?
For what its worth, hifi is a folly. The science isn't used to benefit the world, unless hifi is helping the those less fortunate than us.
However, my profession does benefit others quality of life through science.
One thing is certain. As long as their are enquiring minds, there will always be another valid approach to audio that isn't the Geddes way. Whether you like it or not, you cannot possibly claim it to be otherwise.
Unless you are omnipotent now?
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I see you changed your post - probably best.
I was not belittling you, I was simply saying that it is not true that "opinions are neither right or wrong". Do you actually believe that this is true?
I was not belittling you, I was simply saying that it is not true that "opinions are neither right or wrong". Do you actually believe that this is true?
The problem with opinion is that it is not fact and is not description.
So if a statement expressed is not founded on fact or clear description, then it likely has truth value only by accident.
So often when an opinion is expressed, the rejoinder is, 'why do you think that?' In other words: a demand for fact or description that might buttress the opinion.
This holds for every day life and for science.
Liking something is not an opinion.
So if a statement expressed is not founded on fact or clear description, then it likely has truth value only by accident.
So often when an opinion is expressed, the rejoinder is, 'why do you think that?' In other words: a demand for fact or description that might buttress the opinion.
This holds for every day life and for science.
Liking something is not an opinion.
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Its not a question for which there is an objective answer.
I like jazz - that's a valid opinion.
I can hear nonlinear distortion in my speakers - that's not a valid opinion because it can/has been proven wrong.
In my opinion the sun did not come up this morning. 😉
My opinion, being a personal thing, and being unique to my perspective, is simply an opinion.
That was the meaning of my 'qualifying' statement. Yes deletion was necessary, the post was not representative of my person, merely that somehow my words were misunderstood, misconstrued or twisted.
Perhaps the idiosyncracies of text English, and what you guys call American English 🙄
Either way, something got lost in translation.
Anyway, back to horns (which admittedly aren't something
I know alot about)
Speed reading the 'nested horn' thread and I'm intrigued. How about that? Coaxial CD driver? Maybe ive lost the plot now ��
Thoughts on that?
That was the meaning of my 'qualifying' statement. Yes deletion was necessary, the post was not representative of my person, merely that somehow my words were misunderstood, misconstrued or twisted.
Perhaps the idiosyncracies of text English, and what you guys call American English 🙄
Either way, something got lost in translation.
Anyway, back to horns (which admittedly aren't something
I know alot about)
Speed reading the 'nested horn' thread and I'm intrigued. How about that? Coaxial CD driver? Maybe ive lost the plot now ��
Thoughts on that?
You can't get a large enough coaxial horn to be CD. CD requires a pretty large device to go down reasonably low enough to match the woofer. For a highly package size constrained situation coaxial is a very good choice, but the woofer and horn cannot match directivities except at a fairly high crossover. At this frequency it is difficult to get a smooth woofer response. Work around those problems and you have a reasonable compromise as Tannoy have shown. But it is not ideal.
By the way, there is a difference in these two statements.
"That's my opinion - it could be right or wrong"
and
"That's my opinion - it can neither be right nor wrong"
I can live with the first, but I objected to the second. Perhaps it is a subtle point in English, but it is a major philosophical point.
By the way, there is a difference in these two statements.
"That's my opinion - it could be right or wrong"
and
"That's my opinion - it can neither be right nor wrong"
I can live with the first, but I objected to the second. Perhaps it is a subtle point in English, but it is a major philosophical point.
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I invested a lot of time, research, and money in a nested horn speaker system back around 1992-1995. Called the Maltese Horn, (the HF horn sides looked like a Maltese cross) it originally was a 45 x45 x 67 inch long pyramid shaped enclosure, the outer shell the sidewalls for a 15" driver horn surrounding a 12" driver horn surrounding a 3" diaphragm compression driver horn.
The concept worked in that it made for a virtual single point source, but causes diffraction issues that can't be solved.
The nested horns put the HF driver in front of the mid driver in front of the LF driver, exactly the opposite from what is needed for phase alignment.
The picture below shows the Maltese mid/high cabinets with separate manifold bass enclosures on top- this was much more viable, and some (stolen) cabinets are still being used by a rock band that had achieved some notoriety in the 1980s.
The DSL Synergy horns and Renkus Heinz Co-Entrant horns using multiple drivers feeding a single horn eliminating the glaring problems in nested horns, and the DSL Synergy horns provide a constant directivity single point source down to fairly low frequencies.
Art
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Art
I'd love to see some more details on this as I have thought many time about designs like this but never got past the problems. Speaking of the Synergy and Renkus-Heinz designs, do you really see the idea of feeding a single horn with multiple sources novel? I mean its really the details of these specific designs that differ not the concept. I remember Brock Adamson showing me how he did this way back some 20-30 years ago when I worked closely with him. Again different in detail, but not really in concept.
These days patents are all about the details. I was recently asked to review a patent for prior art in a patent infringement case. Upon reading the patent its was so specific in its claims (although the specification was quite broad) that it would be impossible to find any prior art that was that specific. There was volumes available on the "general concept" but by the time the patent actually got allowed the claim limitations read like "wherein said loudspeaker design was started on a Thursday in October in 2012." My client started theirs on a Tuesday in March 2013, so they were good. But for some reason I was never able to find any exact prior art!
I'd love to see some more details on this as I have thought many time about designs like this but never got past the problems. Speaking of the Synergy and Renkus-Heinz designs, do you really see the idea of feeding a single horn with multiple sources novel? I mean its really the details of these specific designs that differ not the concept. I remember Brock Adamson showing me how he did this way back some 20-30 years ago when I worked closely with him. Again different in detail, but not really in concept.
These days patents are all about the details. I was recently asked to review a patent for prior art in a patent infringement case. Upon reading the patent its was so specific in its claims (although the specification was quite broad) that it would be impossible to find any prior art that was that specific. There was volumes available on the "general concept" but by the time the patent actually got allowed the claim limitations read like "wherein said loudspeaker design was started on a Thursday in October in 2012." My client started theirs on a Tuesday in March 2013, so they were good. But for some reason I was never able to find any exact prior art!
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Although I was in contact with Adamson back in 1992 trying to procure samples of his Kevlar mid drivers for use in my Maltese nested horn, I was unaware of him using anything but separate horns at the time.
As I recall, he was not interested in selling the proprietary cones at the time, and the similarity of my concept and our competition in the sound business did not promote any "sharing".
His Co-Entrant designs appear to have been patented a decade later, if I would have been aware of the concept of feeding a single horn with multiple sources in 1992 I would have gone with that.
Although I was aware of offset horns since adopting the Martin type loading in my low frequency designs around 1981, it never occurred to me to do that with a HF driver at the horn throat until seeing the Danley SH series.
And Tom Danley, as far as I know, had not considered conical horns until I talked to him through one of my Maltese horns while visiting his shop shortly after selling my sound company in 1992, after realizing the Maltese Horn was not the Greatest Thing Since Sliced Bread.
Now days many line array designs use the same horn for mid/high, but DSL has taken the concept a bit further than others, and eliminated the center to center distance problem that the first Vdosc exhibited in it's off axis response in the crossover region.
The first Vdosc design is also around 20 years old, but at the time what was inside was not widely known.
With patents and pictures available so easy to find online now, it is fun to look at history and realize how many mistakes have been made by people copying the wrong things, and then doing slight changes to make them patentable 😉.
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In this case your opinion agrees with fact. The sun didn't come up, the horizon went down!
Hi Art
Actually working with conical horns began somewhat before then, first with acoustic levitation sources
patent # US 4841495 A
And then with an array of sources trying to emulate a single source.
The Y throat was a losing proposition as it has significant interference up high.
Note the date on the patent below relative to the Vdosc patent as well. We routinely used horns like shown in the drawings below at our trade show and shop demos back in those days fwiw although most of the time I was prohibited from making any full or upper range speakers for sale by the management then.
patent #US 4845759 A
The idea for the Unity horn prior to the Synergy horn approach was driven by the interference pattern the other systems produced because of the excessive source separation, it was clear from the work above on levitation sources, one needed to make the spacing small (less than about `1/4 wl) to avoid the problems which all of the prior art exhibited.
Best,
Tom
That and the fact that I was sound asleep, so I didn't see it, hence it didn't happen.
Earl,
A common problem for coaxials that use the woofer cone as the waveguide is the discontinuity during cone excursion between the cone and the throat of the compression driver.
If the discontinuity was small enough that it was effectively invisible to the highest treble of the compression driver, would it not mean that the cone could then be designed as an ideal waveguide? If so, then what would be the maximum allowable dimension of that discontinuity, assuming one wanted a full 20 kHz out of the CD?
I could imagine a 15" cone around a 1" CD might work if the excursion were limited to +/- 0.5 mm or so, seeing as a 1/4 WL of a 20 kHz wave is 4.28 mm.
That can work...but you have to keep your head very very still. As Dr. Geddes explained, the interference pattern becomes very complex due to the short wavelengths and comparatively enormous center-to-center spacing. Subjectively, that means the treble sounds very different with small head movements. (It happens with concentric drivers too - Tannoy and KEF ruined a whole generation of their home speakers by affixing "supertweeters" atop them!)
I'm confused: why wouldn't the directivity match between woofer and tweeter in a concentric driver (using "concentric" rather than "coaxial" to distinguish drivers that use the woofer cone as the waveguide from drivers with horns protruding from the woofer cone) only work at fairly high crossovers?
For example, Tannoy's 12" midfield monitor from the mid-1990s, the System 12 DMT II, crosses at ~1.4kHz and with a fairly low order slope. True, based on your comments I suspect that is a higher crossover point than you use with your comparably-sized Abbey. But not that much higher. Also, having had the 12" Dual and the B&C woofer next to each other, the cone of the Tannoy is a bit larger, mostly due to the thinner surround. So that strikes me more as "not having" those problems than "working around them." Admittedly, as to the quality of the polars I'm asserting without data. I need to build a decent turntable and fix that!
But here's another case of a concentric driver with FR and polar data, smoothed at (I believe) 1/24 octave:
Those measurements are from desktop monitor designed around a current-production KEF concentric driver. The driver has an 8" woofer, with a 1.5" tweeter firing into a radial ("Tangerine" is the marketing name) phase plug. The crossover is fairly steep and asymmetric, with a nominal crossover point of 2kHz.
Is there something I'm missing in the directivity match there?
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