B
btw, by continuously stating "read Kolbrek book" is nothing else than a "KO argument". First, the authors are Kolbrek + Dunker. Second, the book has a large number of pages. Just give us a page reference to what you refer in each case, or better put it here in the forum.
For raw polars, it's of course fine, certainly better than nothing. For a DI, it's simply wrong.
I used these as reference. It does not interest me much if this is wrong or not: I use this only as a guideline for my optimizations.
For a given reference axis, the DI is always only one (since there's only one total radiated power). That you get two, pretty different ones, should alone tell you that something is wrong. As a guideline use whatever you want, but please don't call it Directivity Index.
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I can give the page but of course I will not scan a page and put it here, it will create copyright problems and be not very respectful.
Dunker works mainly on history part if I remember well, I stating Kolbrek because it's him that write what I have explain, he pass sometime to study bi-radial btw.
But well If you talking about midrange beaming and midrange narrowing you can find public resources or even simulate it, just make a basic horn without any roundover or return and you will see it, on my link I explain it with true polar, to demonstrate the utility of roundover/return/smooth profile.
But you know it I thinks, as mabat, Joseph and others that take it in consideration in their design.
Of course "original" A290 or TH4001 are full of midrange beaming and narrowing.
Fair enough. The vertical PDI could then be probably taken as the worst-case DI, although I'm not absolutely sure about it - depends on how bad are the diagonals 🙂
I'm the one with the problem!
No available and proven horn with minimal beaming and narrowing. Looks like the ES450 or ES290 is the best that I can hope for any time soon, at least by year's end.
I thought about the AH425, but that's even more beamy.
Please describe these benefits. Would they also be equally realized via rolled back mouth edges, like those in this horn?
https://josephcrowe.com/products/3d-cad-plans-for-es-290-biradial-horn-horn-no-1670
Soft termination or rolled back mouth edges reduce edge diffraction.
As Joseph Crowe puts it:
"severe edge diffraction effects the off-axis consistency as well as all time domain aspects (step response, burst decay) which would result in a blurring of transient detail across it's bandwidth."
It is easy to see those effects in a comparison of a horn with severe edge diffraction to a smoother edge bi-radial similar to the one you linked:
https://croweaudio.blogspot.com/2020/05/altec-811b-with-tad-td-2001.html
Since the rolled back mouth already mitigates diffraction effects, a soft termination using damping material like terry cloth, foam or felt would make little difference.
Art
I thought Altecs might/ would have got diffraction better sorted than that.
I’d just started looking for a pair of 1003s. Based more than anything else on the great endorsement of a friend who’s owned a few when he lived in America.
Here in Australia they cost way more than in America. So few, they’d probably need to be imported - you can imagine the cost of that
I’ve only ever heard Altec multi-cells once, for about 20 minutes
My friend was in raptures about Altecs when young, and probably hadn’t heard many good systems of any type. You’ve got me thinking a lot of his unequivocally very positive attitude stems from inexperience, and or the quality of the drivers.
Do you think all their multi-cells are similarly bad?
Are their other flaws behind the Altec multi-cell’s generally high reputation?
I’d just started looking for a pair of 1003s. Based more than anything else on the great endorsement of a friend who’s owned a few when he lived in America.
Here in Australia they cost way more than in America. So few, they’d probably need to be imported - you can imagine the cost of that
I’ve only ever heard Altec multi-cells once, for about 20 minutes
My friend was in raptures about Altecs when young, and probably hadn’t heard many good systems of any type. You’ve got me thinking a lot of his unequivocally very positive attitude stems from inexperience, and or the quality of the drivers.
Do you think all their multi-cells are similarly bad?
Are their other flaws behind the Altec multi-cell’s generally high reputation?
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As Art said in his post. For me the benefit was audible and easily measurable in the FR, even with the crude tools I had at the time. It's posted on the forum somewhere, but a long time ago. Subjectively I remember it simply being "cleaner" sounding.
I do NOT think they are bad - in fact I have given up on all other horns, because the multis do what I want them to do and better than any other horn type I have used in the past 40 years. So why would I bother with anything else? 😉
I have not used or heard the 1003s, that's a big horn. I still have a pair of 803s and have owned and used the 1005 and 1505s. I've seen, but not heard (alas) the mighty 1803 horns. People will repeat all sorts of stories about the faults of multi-cell horns, I don't believe any of them - because I have tried to find those flaws and never have. IMO the only reason they fell out of favor is because they are difficult and expensive to build.
Could they be better? Certainly. I would love to spend my retirement researching and building mult-cell horns to see what could be improved. But I don't think that is going to happen.
Thanks Pano
A very informative reply
Pano said:
Could they be better? Certainly. I would love to spend my retirement researching and building mult-cell horns to see what could be improved. But I don't think that is going to happen
Wow: Openness the inevitable limits to knowledge; the common scenario of the retired audio enthusiast.
Concluding with the realist
I love it. If only I had such insight etc … decades ago
In just three sentences you’ve captured a LOT of wisdom
much appreciated
Respect
A very informative reply
Pano said:
Could they be better? Certainly. I would love to spend my retirement researching and building mult-cell horns to see what could be improved. But I don't think that is going to happen
Wow: Openness the inevitable limits to knowledge; the common scenario of the retired audio enthusiast.
Concluding with the realist
I love it. If only I had such insight etc … decades ago
In just three sentences you’ve captured a LOT of wisdom
much appreciated
Respect
In reference to @Pano 's post #376, cf also https://hifihaven.org/index.php?thr...s-associated-with-good-multicell-horns.12581/
Kindest regards,
M
Kindest regards,
M
3.5 years later, I have to say that the A-290 despite the problems I have had have proven themselves in room. The adapters were problematic (drilling error) and probably could be optimized from a geometric perspective for better performance.
I’ve only had time for a skim over the thread, but (wow!) looks very pertinent. With 60 posts if there aren’t several with information that would be new to me I’d be amazed
Much appreciated!
Otto