This clarifies a lot.
Throughout (t)his thread camplo has set out his objectives clearly and precisely.
Like camplo, we all have our own personal set of objectives and preferences, even though these are not always as well defined.
camplo's quest, may not be everybody's cup of tea, but it's an interesting endeavor nontheless.
In this thread about the construction of a multicell horn, the builder made an interesting comment:
"A Kugelwellen multicellular horn would be kind of cool to try build due to better coupeling to the free air at the horn mouth."
This is a nice follow-up to Pano's post.
In order to reproduce signals as true to source/reference quality as possible, it seems wise to opt for a horn that takes the Axi2050's potential to the max.
The question remains: "Can camplo make it work?"
I think it's SAFE to say: Yes, he... (click!)
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drba_swh_160_sq_pe_rb - BEM sim
This is an ABEC sim of the horn from post #4288 Is it possible to cover the whole spectrum, high spl, low distortion with a 2-way?
I understand from @docali that this does not have constant flare rate. Its has progressive T factor to force shorter axial length so its a compromise.
The simulation model is for 4Pi space and accurate to about 6Khz. The mesh resolution was reduced so this model could run in a reasonable time.
This is an ABEC sim of the horn from post #4288 Is it possible to cover the whole spectrum, high spl, low distortion with a 2-way?
I understand from @docali that this does not have constant flare rate. Its has progressive T factor to force shorter axial length so its a compromise.
The simulation model is for 4Pi space and accurate to about 6Khz. The mesh resolution was reduced so this model could run in a reasonable time.
Attachments
I wish I could spend some cash to buy these: HIFI4ALL.DK | Køb Salg Bytte | Bms horn (for English, please use Google translate, it works good enough for me). Although with a bass unit, it would be three way.
OK so, regarding the horn above, it is based off of a 160hz model but with the progressive T it is expected to not load as low as the original of this file. Equally important, the original 160hz horn model dimensions aren't known (to the spectators of this) so, as well, we cannot know whether the horn is following the practice of using axial throat length to translate Fc at 1/2WL.
Compromise will have to take place! This whole thread is based off pushing an objective and exposing where the compromise will be. With the purchase of the AXi I have compromised my pocket book lol!
When looking into the points that you have brought up, first I looked at the horns (Musique Concrète J321 Le Cleac'h horn) suggest Fc, the area where the decay is cutting sharply above 3ms, and the only decay measurements I could find of the AETD15M. So the AE has much tighter decay than this horns lower response...at 200-300hz we are verging on the nominal schroeder frequency, which is somehow relevant, and contending with the single point source concept. I think that crossing within the transition of the schroeder frequency generalized to say 200-300hz for the average room?...is a good idea. In the idea of being a signal purist a higher decay from a driver is never acceptable right? but if you had to compromise on that would you not want to have that happen where the rest of spectrum in that area is likely to agree? So potentially this would cause me to perceive a form of exaggeration in that area....I'll eat that, I dislike 250-290hz lol!!!
A pattern I think I see is for this tightening of decay to be ~156% above the fc of sperical and the jmlc horn in that review. That would put me at 128hz if I ran with that theory for a 200hz horn. Before the decay increases dramatically, appears to be at 420ish..which ~131% of 321hz which would be 153hz for 200... if that math is even logical, then 160hz is not a crazy place to land, given that the trend holds true for round horns of similar shape. I would like to believe that the schroeder frequency is going to help hide some of the blemishes. Also I think there is a connection between the tightening of decay and the point where a horn begins to be strongly directive based on is diameter so if that were true a larger horn has benefits there, as well if its not true, there are still the benefits of having directivity in general, at a lower frequency than a smaller horn use for a higher crossover.
So in short, I think 160hz is already the compromise I am looking for, if the width is what I think it is...somewhere near 30"?
Compromise will have to take place! This whole thread is based off pushing an objective and exposing where the compromise will be. With the purchase of the AXi I have compromised my pocket book lol!
When looking into the points that you have brought up, first I looked at the horns (Musique Concrète J321 Le Cleac'h horn) suggest Fc, the area where the decay is cutting sharply above 3ms, and the only decay measurements I could find of the AETD15M. So the AE has much tighter decay than this horns lower response...at 200-300hz we are verging on the nominal schroeder frequency, which is somehow relevant, and contending with the single point source concept. I think that crossing within the transition of the schroeder frequency generalized to say 200-300hz for the average room?...is a good idea. In the idea of being a signal purist a higher decay from a driver is never acceptable right? but if you had to compromise on that would you not want to have that happen where the rest of spectrum in that area is likely to agree? So potentially this would cause me to perceive a form of exaggeration in that area....I'll eat that, I dislike 250-290hz lol!!!
A pattern I think I see is for this tightening of decay to be ~156% above the fc of sperical and the jmlc horn in that review. That would put me at 128hz if I ran with that theory for a 200hz horn. Before the decay increases dramatically, appears to be at 420ish..which ~131% of 321hz which would be 153hz for 200... if that math is even logical, then 160hz is not a crazy place to land, given that the trend holds true for round horns of similar shape. I would like to believe that the schroeder frequency is going to help hide some of the blemishes. Also I think there is a connection between the tightening of decay and the point where a horn begins to be strongly directive based on is diameter so if that were true a larger horn has benefits there, as well if its not true, there are still the benefits of having directivity in general, at a lower frequency than a smaller horn use for a higher crossover.
So in short, I think 160hz is already the compromise I am looking for, if the width is what I think it is...somewhere near 30"?
Attachments
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I agree. Have you built the horn yet and taken measurements? I've done a 600Hz biradial that you may be interested in...
Joseph Crowe's DIY Speaker Building Blog: ES-600 Biradial Horn
Next week a 290Hz version goes on the CNC made from bamboo plywood. Still not 160 Hz.
I think that I have found the right horn for camplo and his size restrictions. If I remember well the exponential horn has a terminated mouth and it is terminated at 45 deg. For this angle the reflecting waves from mouth to throat from it's real and imaginary part should theoretically cancel. Therefore, this is a horn of this type derives from spherical wave horn with T=0.7. the length s about 90cm:
View attachment drba_swh_147_T07_Jericho.zip
View attachment drba_swh_147_T07_Jericho.zip
and here a second version which has a slightly larger mouth diameter because of expanding T and lower base cut-off. Btw, the cut-off has not the same meaning as for the typical swh. The construction vector is determined by the cut-off value.
View attachment drba_swh_120_T07-T20_Jericho2.zip
View attachment drba_swh_120_T07-T20_Jericho2.zip
Now you are just showing off
But do not complain if someone would later say " beam me up camplo"
I was just thinking, These in one setting are a one mans show, or tools for sound engineering, or at least a custom tool for me. Nothing stops me from changing my set-up at any given time. I mean the horns are not permanently attached to the driver.....When I wanted to approach things from the other side of the spectrum, going completely wide dispersion, couldn't I just run the drivers without a horn and raise the crossover? Someone once made the comment that the best tweeter they heard outside of a horn was a compression driver without a horn. So I have no idea how that works but if that was a not the way then sure'y I would have another horn/waveguide to switch to for entertainment time with the family, which by my guess would be some type of (CD) waveguide or biradial, geared towards a 630hz crossover.
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I have a hard time believing that to be the case. Maybe this person hasn't heard a good horn. A good horn will not introduce any more resonance than other resonances in the system. Here is a TAD TD-2001 on a 'good' horn. There's no resonance to speak of except for some room reflections starting to be introduced at 2kHz.
https://1.bp.blogspot.com/-QSZ6YcSh...cSHew8Cso7w9QCLcBGAsYHQ/s1600/Burst+Decay.JPG
- maybe I didn't say it right. All they meant was, of all the drivers they heard that were not in horn (dome, ribbon, etc), a compression driver without its horn sounded awesome to them. They were in favor of tweeters in a horn but the discussion was about non horned drivers.
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oops, yes it's obvious now that I read it correctly! It would be easy to try. I suspect the phase plug could be removed in this case and vented into a damped chamber. Some of the diaphragms look cool too.