The SB65WBAC25-4 os a very low efficiency driver. Understandable given its size and bandwidth. Does the horn help it any?
Might the Klipsch K510 or similar sized 1.4 or 2" throat JBL CD horns have a corner frequency low enough to cross with my midwoofer, to thereby keep it from beaming and keep it out of its higher distortion range https://josephcrowe.com/blogs/news/altec-416-8b-in-100l-sealed
, like I think this horn can? https://josephcrowe.com/products/3d-cad-plans-for-es-290-biradial-horn-horn-no-1670
Unfortunately, I've yet to get a chance to hear any CD horns. Possibly one of these later this summer. https://audiohorn.net/x-shape-horn/
https://audiohorn.net/next-gen-bi-radial-horn/
I did recently hear this horn https://josephcrowe.com/products/3d-cad-files-horn-no-1994-es450-biradial-for-jbl-2446-2-throat in this three way system.
https://cdn.shopify.com/s/files/1/0...dd-831c-3f929e2e73c6_480x480.jpg?v=1708832996
But I've been told that the ES450's corner freqyency is too high for the above Altec midwoofers. Thus the ES290 horn? And given its larger size, might it also offer a very blend of direct and spacious sound?
If yes, then for a two-way would you recommend a driver like this? https://www.usspeaker.com/radian 745neoBepb-1.htm
Or https://www.usspeaker.com/radian 760neoBepb-1.htm
But would there be interactions with my midwoofers?
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The crossing frequency of a direct radiating 15" woofer to match a ~90 degree horizontal coverage angle is about 900 Hz (i.e., matching horizontal polars at the center crossover frequency is typically the criterion that is used):
So, virtually any 1.4/1.5" or 2" horn will hold its polars down to ~900 Hz.
Basically, any horn that has a one-wavelength wide mouth size at 900 Hz (i.e., 15" mouth width) will work. Some horns will work better due to being straight-sided (with tractrix mouth roll-out), so that there is no narrowing of HF polars up to the frequency of 6792 Hz--corresponding to a throat diameter of 2" of one wavelength across, or 9702 Hz--corresponding to a 1.4" throat diameter. Horns with curves walls near the throat will all experience HF polar narrowing. So a K-510 horn (2" throat) will outperform other similar sized non-straight-sided horns in this regard (non-narrowing polar coverage at higher frequencies).
If you want to use a non-straight-sided horn, that's your prerogative, but I would first ask...why would you use a non-straight-sided horn?
Generally speaking, well-designed compression drivers using Beryllium dome diaphragms will produce superior results (but usually at a higher price). I can also recommend dual-diaphragm ring radiators like the BMS dual-diaphragm drivers, but they usually need to be bi-amped and DSPed to provide time alignment of the internal diaphragms.
Chris
User @oltos mentioned two in the last link of his last post, above.
The 950BePB has been used by at least three gentlemen owning 1st-gen Jubilees or K-402-based JubScalas.
Chris
The 950BePB has been used by at least three gentlemen owning 1st-gen Jubilees or K-402-based JubScalas.
Chris
Nowadays, I think many would go the route of the Celestion Axi2050 drivers if using 2" throat horns. Note that there is a very small difference between the Axi2050s and the TAD TD-4002s that I have on my K-402s since 2009, in he amount of "air", but otherwise, there is little or no audible difference that I heard over an extended listening trial (1 month).
Chris
Chris
Would those include these drivers?
https://www.usspeaker.com/radian 745neoBepb-1.htm
https://www.usspeaker.com/radian 760neoBepb-1.htm
Or are there design or manufacturing flaws in those specific models, including issues with their phase plug, which NicoB calls "outdated"?
Again, I'm no expert, though to flatten and extend their response, at least Radian Be drivers require relatively heavy EQ, which Pierre presumably implemented successfully in his two-way system; post 15266.
Do you mean that any horn which can reproduce 900Hz with wide dispersion (no audible beaming?) will work, though some better than others and/or with other unrelated performance advantages?
And please describe single sided and non-single side horns; never heard of those terms. What are the differences? Are single sided horns mostly round horns, like JMLC horns
https://azurahorn.com/azurahorn_horns.html and/or the round kind of Tractrix horns?
https://horns-diy.pl/horns/tractrix/tractrix-350/
But in any case, why might single-sided horns be preferable, or just as appropriate to use with my midwoofers, as non-single sided horns?
And how would a horn like the ES290 fit into these design and/or performance comparisons?
My comment was, all other things being equal, Be diaphragms can significantly outperform Ti or Al dome-type diaphragms. The total advantage of Be over Ti dome diaphragms is on the order of ~7x better performance (aggregated performance, subjectively). It's a large difference. If a certain manufacturer did not use that material advantage to the extent possible to increase sound quality, that's on the manufacturer, not the material itself. This especially includes "Truextent" replacement diaphragms for JBL compression drivers (that were not designed for using Be diaphragms).
The later question was "are Be diaphragm drivers available?". There are.
I've helped dial-in Radian 959BePB 2" drivers on K-402 horns, but that is the extent of my experience with Radian Be drivers. I have heard of issues with the 950BePB drivers on K-402 horns, but I do not know the audibility of the issues, nor do I know what PEQs were used. I did find that the dial-in process wasn't as easy as the TAD TD-4002s that I've used for many years. I attribute this to perhaps better engineering design of the TAD drivers (in the US--attributed to Bart Locanthi before his passing). Nowadays, only the 4001s and 4003s are available, new, and at rather extreme pricing.
I do not own stock in any audio manufacturing company (nor am I likely ever to do so). You use compression drivers at your own risk. Nothing I've said has ever changed that.
In general, when using extended-range compression drivers of the 1.4"--> 2" variety, all require EQ, unless the old type "collapsing polars" horns (like the Klipsch K-400 series and the Smith horn types) are designed to spill their vertical polars below 2-5 kHz in order to maintain a relatively flat on-axis SPL response below those breakpoint frequencies. I don't recommend them.
I always recommend controlled directivity straight-sided horns with tractrix mouth roll-outs (without throat slots) over other horn profiles for full-range operation. I do not recommend horns that do not have large enough mouth dimensions to control their horizontal polars down to the F3 of the compression driver being used. The only exception is for bass bin horns used below the listening room's Schroeder frequency--but also placed in quarter or eighth space in-room to regain acoustic loading for frequencies corresponding to longer than one wavelength across the horn mouth horizontally.
Chris
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Chris never wrote anything about "single sided" or "non-single side" horns, he mentioned both straight-sided horns and horns with curved walls near the throat.
A round horn can have virtually any expansion ratio, parabolic, conical, exponential, tractrix, or combinations of those.
A round (or square, or rectangular) horn with straight sides has a conical expansion, the wall angle(s) roughly defining it's -6dB dispersion angle.
Chris recommends conical expansions coupled to a (large) tractrix mouth for their controlled directivity.
Horns like the JMLC with slowly expanding curved throats can load the driver to a lower frequency for a given mouth size, but the long narrow throat causes high frequency beaming.
Better (perhaps..) in terms of consistent dispersion, but using the same mouth size (area) and horn length, a conical has far less low frequency output than an exponential horn using the same driver.
The 90 degree conical horn (gray trace) has -8dB less output at ~500Hz than the exponential (black trace) in this simulation.
The diaphragm excursion at ~400 Hz would exceed 1mm (about double what a typical high frequency 4" diaphragm could achieve before contact with the phase plug), the same for both horns, the maximum level of the conical -8dB less at similar distortion levels.
Art
You present an interesting choice, horn beam widths slightly wider or narrower than a 15" speaker ~900 Hz, both a bit more narrow below 650Hz, where the 15" energy typically would dominate.
In the simulation from post #255, the choice is more complicated, the exponential simply going from wide to narrow, the conical from narrow to a series of wide/narrow bands.
In this Klipsch -6dB beamwidth chart we can see the addition of a tractrix mouth on the K-402 horn reduces the lower conical beam width "waistbanding":
But who wants what energy going where at what frequency is beyond my ability to predict 😉