Acoustic Horn Design – The Easy Way (Ath4)

PB I agree with everything you said, it is exactly what I'm trying to say regarding the SB26's suitability: cowanaudio's statement really has nothing to do with the SB26 at all, it's really a statement about the differences in waveguides.

EDIT: okay I see you are saying any 1"+ dome will have a difficult time with the steep throat that a deep waveguide would have. From that perspective I can understand why the specific tweeter being considered is important. I don't know that that was what cowanaudio was getting at though? Still, in judging compromise, what is worse, a wiggle in the top octave, or inferior motor and smaller diaphragm having higher distortion at low frequencies? With the 8' waveguides I've done, both aspects perform well, less so with the 5". But I don't think switching to the SB19 is going to change that calculus.

John was far more patient with his explanation than I may have been. The bottom line is an SB19 in a large waveguide will outperform a 1" dome on any waveguide. Put the 1" dome in a large narrow waveguide and the high frequency polars fall apart. Your waveguides don't suffer from this because they have very wide patterns, but your waveguides don't achieve what I am trying to achieve, that is tight pattern control down to 500Hz. I appreciate that this is not your goal and I also appreciate that in many applications your waveguides will work very well.

You said that the 1" dome will have lower distortion than the 3/4" dome. Well at 1KHz and 110dB the 3/4" dome has H3 that is 50dB down. Exactly how low do you think it is important to push down that third harmonic?? My customers are happy with the results I produce and that's what counts to me. Most speakers have bigger anomalies to deal with than -50dB H3 at 110dB.
 
Again, from your comments it wasn't clear to me that your issue with the SB26 was due to your use of a deep waveguide with a steep throat. I took your comments as having an issue with the SB26 itself, in any waveguide. Which didn't make sense to me.

I agree with everything else you said, so I think this is a miscommunication.
 
Again, from your comments it wasn't clear to me that your issue with the SB26 was due to your use of a deep waveguide with a steep throat. I took your comments as having an issue with the SB26 itself, in any waveguide. Which didn't make sense to me.

I agree with everything else you said, so I think this is a miscommunication.

The SB26 is a spectacular driver, way better than its low cost would suggest. It appears to work well in your wide waveguides too. My designs have different priorities and the larger domes are a poor choice. I'd feel a bit better if the SB19 cost more :eek:
 
PB I agree with everything you said, it is exactly what I'm trying to say regarding the SB26's suitability: cowanaudio's statement really has nothing to do with the SB26 at all, it's really a statement about the differences in waveguides.

EDIT: okay I see you are saying any 1"+ dome will have a difficult time with the steep throat that a deep waveguide would have. From that perspective I can understand why the specific tweeter being considered is important. I don't know that that was what cowanaudio was getting at though? Still, in judging compromise, what is worse, a wiggle in the top octave, or inferior motor and smaller diaphragm having higher distortion at low frequencies? With the 8' waveguides I've done, both aspects perform well, less so with the 5". But I don't think switching to the SB19 is going to change that calculus.

Agree 100%.

It's similar to discussing a 18" woofer in a sealed box, versus a 12" woofer in a horn. If you look at the leader board over at Account Suspended, sealed boxes are shockingly competitive IF the driver has a lot of displacement. But most people would assume that a 12" woofer in a horn would walk all over an 18" woofer in a sealed box, because horns are so efficient. The "trick" is that the 18" woofer in a sealed box is going to need a LOT of displacement.

At the same time, the smaller driver has some inherent advantages when it comes to playing high frequencies.

A similar calculus happens, when we're talking about 3/4" domes on deep waveguides, versus 1" domes on shallow waveguides.
 
You said that the 1" dome will have lower distortion than the 3/4" dome. Well at 1KHz and 110dB the 3/4" dome has H3 that is 50dB down. Exactly how low do you think it is important to push down that third harmonic?? My customers are happy with the results I produce and that's what counts to me. Most speakers have bigger anomalies to deal with than -50dB H3 at 110dB.

And this situation was funny to me, because I'm dealing with the exact same issue in the past couple months:

I've been tinkering with a bunch of waveguides using Mabat's software here :

Metlako: A Small, Affordable Two-Way Unity Waveguide

After five or six iterations, I broke down and stopped using a NE19 dome tweeter, and switched over to a compression driver.

I had to "pad" the compression driver down a HUGE amount, something like 15dB...

But even with a humongous reduction in the input voltage, I noticed something funny, which was that the NE19 sounded a little bit smoother and cleaner.

Yes, I'm definitely splitting hairs here, they're both wonderful drivers. And if they both cost $20 I wouldn't lose any sleep over it. But the BMS 4552ND costs $600 a pair! BMS 4552ND 1 Inch High Frequency Neodymium Compression Drive 8 Ohm

I won't rule out the possibility that mine are beat up; I bought them off of Danley Sound Labs, so it's very possible they've seen some abuse, and need new diaphragms.

I would try a different ring radiator if I had one, but all of my other ring radiators are screw-on. (JBL 2408H-1 and BMS 4540ND.)

And on a side note, I hate to open this can of worms again, but if you REALLY want to see what a 3/4" dome can do, try putting one on a Paraline. I did that for a goof, using a Paraline I built but never documented. Because the diaphragm is so small, the Paraline actually worked really nicely. But the surprising thing was the efficiency; something that we often over look with the Paraline is that the efficiency can be significantly higher than a conventional waveguide. This is because horns raise the efficiency by narrowing the beam, basically it's the same energy constrained to a smaller area. And the Paralines have a vertical beam of zero degrees (1), so the on-axis output can be fairly ridiculous. I was seeing gains of 3-6dB over a "conventional" horn.

(1) this can be varied by messing with the geometry btw
 
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So the first horn is printed. It is meant as a replacement for the old horn in a cheap 15" + 1" box with around 3 kHz crossover. A wrong concept from the beginning, but I see definitely some improvement. The blue line is the old black horn, the green lines are the new horn and new horn some 25 deg off axis. All measured without a baffle. I definitely see improvement:)
 

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Hi!

I can't get this ATH software to work. I got right gmsh-4.3.dll on the program folder and whole program is located on desktop. First it just opens black window for couple of seconds and any tries after that just quickly flash the same window.

I'm running Win10, but i'm on the insider preview version. Would that cause the issue?

EDIT: Never mind. Found the answer. Run CMD first and keep running the software on that window. From all the pics i assumed it to have graphical user interface.
 
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