Kind of pedantic - no constant directivity designs exist then. They are all deficient to some degree.
Its a matter of degree and being an absolutist does not improve the discussion. Mine are far better than most that I have seen.
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I have talked with Floyd about this exact point and he does think that very early reflections are not a problem because they add to spaciousness. I never said anything about "strong early reflections" whatever "strong" means. Very early reflections and diffractions diminish image, stronger just makes matters worse. Floyd claims that people prefer "spacious" to "image" hence his results, which are based on preference.
I don't agree, and Greisinger says this as well, that vertical reflections are worse that lateral early reelections. Greisinger states that our hearing simply ignores vertical reflections, but it gets confused by lateral ones. I would agree that there is a certain amount of coloration from vertical reflections, but there cannot be an effect on image from these. So they are not ever "good" things, like later lateral reflections, but they are not as damaging to image as the early lateral ones. Hence the need for higher DI.
I think that between us, I am more the realist 🙂.
I do not make any assumptions about the room, High DI is not as important below about 700 Hz as it is above, in any room.
A well designed room is simply always going to be better than a poorly designed one. What is wrong with that?
That is an odd statement. The pro catalogs are full of constant directivity designs. All the JBL CD horns hold d.i. plus or minus 2dB and many plus or minus 1dB. They may use diffraction slots that you don't approve of but they are truly constant directivity.
The low HOM designs of yours and JMLC, and others, may have smooth response with low reflections but they have smooth rather than constant directivity.
David S.
My waveguides are at least as good as the JBL stuff, but without diffraction slots.
JMLC are not low HOM and they do not have a flat DI.
I don't know where you get your comparisons sometimes.
JMLC are not low HOM and they do not have a flat DI.
I don't know where you get your comparisons sometimes.
I don't agree because the proximity of a speaker to boundaries negatively affects frequency response. It's also an effect that can not be corrected with EQ. So having high directivity in that region to mitigate the problem is desirable.
Nothing wrong with that but as I've already said, most people don't have such rooms.
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Joined 2003
I agree that it might be desirable, but being the realist here 🙂, I find it impractical and less important than above 700 Hz.
It's not that impractical, really. You can get pretty good constant directivity down to about 100 hz from a small speaker. Yes, you have to sacrifice bass-output, but that doesn't really matter because for good bass you need separate bass-speakers anyway.
I could write several papers to answer this question - wait a minute, I have!
Basically whenever the contour recedes from a straight line drawn from the throats center, then HOMs are created to facilitate the wave moving out to fill this space, i.e. the wave is diffracting around this curvature.
That is the simple answer - the details of which can be found in several of my publications on this topic.
Yes, a dipole, not truly constant, but I agree with your point. I have done some study along this line and I have built some dipole designs. "Practical" is relative. It adds a lot of cost to the design and its benefits appear to be pretty small. I am sure that some might find this tradeoff desirable, but I haven't.
Better than a dipole IMO would be a cardioid with two separate woofers independently driven with DSP. This could be made to work very well, but again at what cost? I don't think that the marketplace would support it, but for DIY it may be reasonable.
In my mind there is a big difference in what is "practical" for a thought experiment; what one might build for themselves with no consideration for cost; and what the marketplace would "buy into". The first is easy, and I might consider the second, but not the third.
You should let people decide themselves what they find practical or not. Doing structural changes to their rooms and/or attaching absorbers to walls is most often not an option, so a speaker that addresses those response problems I was talking about is more practical, even if it makes the speaker expensive.
Greisinger agrees with you? Is this by direct correspondence with him or by inference from your interpretations of his publications?
Earl, actually I wasn't thinking about dipoles, but cardioids. A resistance enclosure can yield a quite effective cardioid-like dispersion pattern. It loses less in terms of efficiency than a dipole and in combination with a waveguide you can use it to make a very CD speaker. Like Markus says such a speaker would be far easier to place in practical rooms and it would still sound great.
By the way, I recently noticed that your forum was down and I read the message on your website that you'll soon stop manufacturing speakers. I understand your decision but I think it's a pity. I wish you had been able to grow your speaker business to a more substantial level. Will you continue your work as as consultant?
By the way, I recently noticed that your forum was down and I read the message on your website that you'll soon stop manufacturing speakers. I understand your decision but I think it's a pity. I wish you had been able to grow your speaker business to a more substantial level. Will you continue your work as as consultant?
By the way, did you send Earl measurements of your cardioid for inclusion in his polar app?
Yes I did, back in May 2011. Some time later Earl included the data in his polar app. That speaker worked pretty well, but the most recent version is quite a bit better.
From what I can tell a resistance cardioid does not work nearly as well as the dual driver one does. IF I were to do this then I would do it the "premier" way, but that's not likely.
The fact is that I just do not find any flaws in my system when I compare to any other that I have heard. If I did then I would truly be interested in improving it. There were a bunch of my customers who went to RMAF and none of them found anything that they thought I should be doing.
Actually consulting has always been the better option for me and still is. I have two clients in patent cases and they pay well without the hard work (and no audiophile nonsense to deal with.) I am mostly just tired of cutting, sanding and painting - that's not why I went to school. (That and at 63 dirty work just does not appeal to me.) There is some interest in someone taking over the work and I will likely still make the new Summa (at an outrageous price of course) as I recently got an order for a pair of new ones of those. But the lower priced stuff is just not worth my time and trouble. Kind of statement about the whole industry actually. There are two kinds of audio products - mega bucks and Best Buy sales. Anything in the middle lacks a sound business case.
Something like the Gradient Helsinki?
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http://www.gradient.fi/Gradient/Helsinki_1.5.html
I was impressed by the midrange and treble when I listened to the Helsinki at a show some years ago. The bass is however IMO placed wrongly as well as a 15" dipole really doesn't give sufficient bass response alone.