I had a similar idea of soongc , and presented this horn flare last year at the Geddes on waveguides thread, post 790, at page 32
here Earl's comment :
Your intermediate curve does not follow the OS contour. Of course sound will propagte down it, it will no matter how its shaped, but there will be more diffraction if its not OS.
it would be interesting to know which is a bigger advantage : to have a larger radius at the throat, and a slight better loading, or at the mouth, and less diffraction.
Angelo
here Earl's comment :
Your intermediate curve does not follow the OS contour. Of course sound will propagte down it, it will no matter how its shaped, but there will be more diffraction if its not OS.
it would be interesting to know which is a bigger advantage : to have a larger radius at the throat, and a slight better loading, or at the mouth, and less diffraction.
Angelo
It's really hard to tell what is better until it's built, listened to, and measured. I just spent lots of time trying to simulated using AxDriver BEM software to simulate starting from the driver diaphragm, adjusting the curves till I gradually zeroed in what looks good. Adjustments really are a few mm each case, looking at the results, and figuring out how to shape the contour in a succedding run. No magic, just intuition and hard work. I don't even know whether it will sound good or not yet.
soongsc said:
Yes - very good overall tracking of my measurements (though *no* normal axisymmetric one sided app) and your BEM simu !
I guess I have scaled the contour a little bigger than what you intended - hence the peak at 15kHz we don't see in your simu .
Can you confirm that its simply a down shift or did you stop simulation at 20kHz?
Michael
angeloitacare said:
Quantifying HOM has not even been doen and still is work in progress (other thread)
So no one can tell the difference between the HOM-less - which actually is "only" the least possible HOMming horn - and any other contour by numbers.
Maybe its not that much of a difference and also the diffraction at the mouth is not taken into account in this simple comparison AFAIK - great concept of Jean-Michel in this point.
As far as I can speak for the LeChleach contour: its presentation simply is great (without foam).
No such HOMmin as sparsly described as increasing nastiness over long time of listening or increased SPL - at least to my ears.
Bottom line - don't get demoralised - just give your thoughts a try.
Michael
If you have looked at my previous waveguide measurements in the Geddess thread, all have the same thing at around 20KHz regardless of the size and contour. This is something that just doesn't show up in the sims. I will have to study the situation a bit more to figure things out. I think it has somthing to do with matching the driver with the waveguide.mige0 said:
soongsc said:
Are referring to this?
http://www.diyaudio.com/forums/showthread.php?postid=1772631#post1772631
It shows sort of the same effect but in reverse.
Meaning the peak is largest at 0 deg - which would - if you equalize for flat on axis - as is with my 0deg ref measurements - turn into a deep notch for any other angels than 0 deg.
Michael
Now that the school year has ended, I'm looking forward to actually building something!
Although I still plan to use the AH-425 and GPA 288-8H, I have abandoned the idea of using the Petit Onken enclosure for the 414. Instead, I want to try the 414 in a small (~1.8 cu ft) sealed enclosure (F3 about 80 Hz), and use the AE TD15M below. The 288/414 combination will be run from my PP 300B amp. The TD15M will be powered separately, its response optimized with a DCX2496.
Another alternative will be Lynn's previously-mentioned "minimalist" system, a 2-way using just the TD15M in a bass-reflex cabinet and the 288/Azurahorn combo. We'll see.
First step will be to work up a crossover so I can listen to the 288/Azurahorns over the Klipsch Chorus bass boxes. If the horns sound promising, then I will build some boxes for the 414's and try working them in. Hopefully the TD15M's will have arrived by that time...then things will get really interesting!
Gary Dahl
Although I still plan to use the AH-425 and GPA 288-8H, I have abandoned the idea of using the Petit Onken enclosure for the 414. Instead, I want to try the 414 in a small (~1.8 cu ft) sealed enclosure (F3 about 80 Hz), and use the AE TD15M below. The 288/414 combination will be run from my PP 300B amp. The TD15M will be powered separately, its response optimized with a DCX2496.
Another alternative will be Lynn's previously-mentioned "minimalist" system, a 2-way using just the TD15M in a bass-reflex cabinet and the 288/Azurahorn combo. We'll see.
First step will be to work up a crossover so I can listen to the 288/Azurahorns over the Klipsch Chorus bass boxes. If the horns sound promising, then I will build some boxes for the 414's and try working them in. Hopefully the TD15M's will have arrived by that time...then things will get really interesting!
Gary Dahl
Actually building something
I built something as a direct result of this thread. The Tone Tubby 12 Alnico/PM6A that I showed at RMAF and VSAC are from this information. Plans are in public domain. Not the monster giant-killer that Lynn has planned, but a lot of people liked it and have built it.
I built something as a direct result of this thread. The Tone Tubby 12 Alnico/PM6A that I showed at RMAF and VSAC are from this information. Plans are in public domain. Not the monster giant-killer that Lynn has planned, but a lot of people liked it and have built it.
VSAC 2008 Open Baffle
Hi Shane:
Here is a nice picture and review of the system:
EnjoyTheMusic.com VSAC 2008 report
Attached is the autocad drawing of the baffle. If you can't read this, write and I will send you the original.
Schematic to follow.
Hi Shane:
Here is a nice picture and review of the system:
EnjoyTheMusic.com VSAC 2008 report
Attached is the autocad drawing of the baffle. If you can't read this, write and I will send you the original.
Schematic to follow.