Is it possible to cover the whole spectrum, high SPL, low distortion with a 2-way?

If you aren't listening in the sweet spot, you are using these types of horns improperly...thats called user error. This is a pure signal elitist type tool, I'd say.
The German horn is actually the size of the autotech 350hz, its diameter is 60cm.
I think hes giving the throat cutoff (250hz), where as autotech is naming (350) by mouth cutoff.
His dept should be about 13.5 inches if what I say is true.
 
Hmm, i remember djk saying most non constant directivity horns, even a decade is a stretch.

I'd been looking at the spherical tractrix, stereo labs 600hz to cross at 800hz, even then, 3 way would be needed.

But..........

Tractrix is natural progression of bubble of energy ?

And it is a smooth path with a nice round over.

So looking at echoes (reflections) in horns, I'd imagine it is very very clean and detail revealing.

Horn loading, i think it needs to be 1/4 wavelength deep, but 1/2 would be better.
Post 8
Is a horn phase coherent device?

But i am just repeating what I've read.

Norman
 
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It's not my dream horn but the 18s XT1464 performs a lot better regarding dispersion control over the frequency range.


I am not convinced the XT1464 is better in the top octave.
This is the horizontal polar plot (Vance Dickason).

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If you aren't listening in the sweet spot, you are using these types of horns improperly...thats called user error. This is a pure signal elitist type tool, I'd say.
The German horn is actually the size of the autotech 350hz, its diameter is 60cm.
I think hes giving the throat cutoff (250hz), where as autotech is naming (350) by mouth cutoff.
His dept should be about 13.5 inches if what I say is true.


Indeed Camplo.
Several times you have clearly stated what your objectives are.
Since this is your thread and you are aware of the limitations, your arguments are certainly legitimate.
Moreover, you're definitely not the only supporter of such horns.

Is the 13.5" depth for a 1.5 or 2" throat?
 
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Lol the output level potential of this potential system is more than I'll ever utilize. The same concept of using a product made to create high spl (compression driver) at home at hifi/studio levels, creating a very low distortion playback, was applied to the woofers is all. The unmeasured characteristic of low dynamic compression is what really sucked me, as well as an experience with a fav reference track and some altec replicas, showing casing imaging like I've never heard it before. High directivity, can negate the need for major acoustic treatment. The lack of dynamic compression characteristic, which in turn could be described as a high dynamic contrast, I would think, is inherit in most, if not all, horn designs, but is more so present, in a horn with the highest directivity. I honestly want to cover more frequency, down to 300hz would be nice. I just read this in the Jmlc thread
some time ago i made a tractrix horn with 25" ( 60cm ) mouth diameter, ( see picture below ) and tested it with the Radian 950Pb, crossing quit low, at 300hz/12db. Performance was tremendous, despite many say, to use a horn driver below Fs increases distortion dramatically. I didn't hear this.
If I had of came across this earlier I would of purchased a bigger horn!
 
In theory, the best would be one driver in one horn.

Regarding horn vs. driver, I think you're close to optimal.
The JMLC-270 would still be ok, but any bigger won't bring you much.
I am not convinced the 2451 is at its best <300Hz.
The woofers likely do a much better job in that range, even more so at high SPL.
 
The unmeasured characteristic of low dynamic compression is what really sucked me, as well as an experience with a fav reference track and some altec replicas, showing casing imaging like I've never heard it before. High directivity, can negate the need for major acoustic treatment. The lack of dynamic compression characteristic, which in turn could be described as a high dynamic contrast, I would think, is inherit in most, if not all, horn designs, but is more so present, in a horn with the highest directivity. I honestly want to cover more frequency, down to 300hz would be nice. I just read this in the Jmlc thread If I had of came across this earlier I would of purchased a bigger horn!

That is a very nice summary of what I also think is special about Tractrix horns covering as wide a range as possible. Add the ability to play with flea watt amps, and the coherence of a single very low mass driver covering such a wide range.

For me, the advantages far outweigh the negatives. If those two drivers sound like they're made of the same cloth (my only concern at this point), you should have a amazing setup. Congrats on making some progress!
 
I was thinking... a lot of intelligent opinion went into decisions made for this project, and that I'll likely be satisfied. The radian 951 and 950 in my opinion are copies of the older JBL 2450/2451 drivers. Though they may improve upon, I bet there isn't much difference. Just my bet though. In the testimonies of the 950, diaphragm model wasn't mentioned but many good things have been said about the surround material of their diaphragms. My concerns are more so about diffraction at the mouth, but I think the polar will turn out quite nice with the chosen horn. I am interested in covering a larger portion of the freq. range with a single horn but all things considered I may have done a good job choosing the middle path between high frequency performance and low.
 
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ICG

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I am not convinced the XT1464 is better in the top octave.
This is the horizontal polar plot (Vance Dickason).

That pretty much depends on the driver, too! I've seen other measurements which look a lot better than that. But even if it doesn't perform better, it's still only ~1/10 of the price!
 

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From what I gathered you always want the biggest horn you can use for the job. How true it is, I dunno.
The polar of the jmlc 350, most likely due to the driver used in the measurement, isn't flat. The polar for the 350hz tractix is super flat, and the polar for jmlc 200 is just as flat, so with the right driver the jmlc 350 should just as flat, unless you guys know something I don't.
The prices at autotech seem fair, what I paid was close to their price structure.
 
My concerns are more so about diffraction at the mouth, but I think the polar will turn out quite nice with the chosen horn. I am interested in covering a larger portion of the freq. range with a single horn but all things considered I may have done a good job choosing the middle path between high frequency performance and low.


Camplo, mouth diffraction and reflectance should not be a cause for concern.
JMLC horns were primarily developed to minimize those, hence the 270° rollback.
A JMLC beats the Tractrix in this respect, only the MinPhase is of the same level.
 
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ICG

Disabled Account
Joined 2007
From what I gathered you always want the biggest horn you can use for the job. How true it is, I dunno.

No, that isn't true. The problem with big horns on multiple ways is, they are in each others way physically. A back offset can be compensated with a dsp, however, a vertical or horizontal offset cannot. The first problem is, big distances will create interferences, which you can't fix with a dsp either. The next thing is, the great distances between them requires a great listening distance to become homogene. It's not unusual big horn systems require a minimum listening distance of 4-5m. That's not always possible and in most cases it means, you are close to the back wall and get the short reflections from there which is bad for the stage location and resolution. The difference of the dispersion angle doesn't help there much either. So big horns can pose a serious problem. I personally don't like the sound to move up and down in height with different frequencies.

We are talking about a two way system here, so it's not a critical issue here unless you want to use a front horn for the bass too.
 
First off, everything is a compromise.

If we take a look at most CD horns we will find that they are quite short. Maybe you may never recognize how your driver sounds like if until you mount it on a long horn which simply provides better loading, especially down to the resonance region of the driver/horn combo. You can see this effect by simply doing a free air impedance shot and then mounted to the horn.

I am quite sure that the driver itself prefers a long horn, especially if you wnat to go down as possible, but what I found is that most long horns are no more constant directivity. I own myself a tractrix horn which itself sounds natural but has considerable beaming. if you mostly hear music at the same position then this might be acceptable and you could equalize the system for this position. The mentioned long horns, tractrix, JMLC, Minphase can mostly be found as round versions. But a better horizontal dispersion is desirable and therefore I am working on this to stretch the horizontal part of those horns while preserving the underlying math or assumptions.

br!
 
Sounds like you want a set of elliptical jmlc's, tractrix or the iwata. At least I do, I've got a connection on a pair of elliptical Jmlc's just waiting on the asking price that came from auto-tech, I'd pay the guy listing price plus shipping to me, but it kinda sounds like hes going to ask for list price plus every other charge he incurred to get them here, which would be a no go for me lol (I'm frugal).

Also this, GeoShip - eBay Global Search search all ebay countries at once, works pretty good if you try various combinations of search terms.
 
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