OK, didn't see any HR sim in the link, but know from experience that such a simple WG approximation of an expo horn only works well if broken into specific octave spreads, so please attach his HR record for us to import since yours doesn't mirror the cab's plan/section view.
@GM
I'm on the phone now so with limited capabilities. Here's his blog thread for this horn. If you scroll down a bit you will see his Hornresp screen.
https://josephcrowe.com/blogs/news/design-study-front-horn-loaded-reflex-cabinet
While the schematic shows 3 sections, the pictures show 4. He mentioned hecwas likely to add another section.
Thank you!
I'm on the phone now so with limited capabilities. Here's his blog thread for this horn. If you scroll down a bit you will see his Hornresp screen.
https://josephcrowe.com/blogs/news/design-study-front-horn-loaded-reflex-cabinet
While the schematic shows 3 sections, the pictures show 4. He mentioned hecwas likely to add another section.
Thank you!
I wonder if he measured the "physically time aligned"?
I didn't see that in the very interesting write up.
I didn't see that in the very interesting write up.
Basically you find the mean of the horn's effective* throat (St), mouth (Sm) frequencies for the 1st 'break' [(St*Sm)^0.5], then that frequency/(Sm) mean, etc., for every subsequent 'break'. I assume there's a formula to do these steps quicker, but no clue, so please post it if true.
In short, the sims are different partly due to differing driver specs and mostly due to input Vs measured
*Including any local boundaries, flared pipe end correction that increases effective axial length, which I assume HR accounts for based on 'Ang' input since actual builds ~mirrors its sims when properly inputted.
In short, the sims are different partly due to differing driver specs and mostly due to input Vs measured
*Including any local boundaries, flared pipe end correction that increases effective axial length, which I assume HR accounts for based on 'Ang' input since actual builds ~mirrors its sims when properly inputted.
Playing around with Hornresp and making some sketches, I'm liking this design. Not only because I liked what I heard but also because it's something different to build (I like woodworking).
I'm wondering what the rules, guidelines or opinions are pertaining to the mounting of the driver. If I use some compression, so have a smaller horn throat than the driver dimension, should the driver be mounted "flush" to the throat or is some spacing ok?
Some drivers like this example:
have a surround that prevents mounting it tight to the throat when the throat overlaps the cone. Would that mean only drivers with flat surrounds are suitable or is a little "chamber" between cone and throat fine (or even beneficial?)
I'm wondering what the rules, guidelines or opinions are pertaining to the mounting of the driver. If I use some compression, so have a smaller horn throat than the driver dimension, should the driver be mounted "flush" to the throat or is some spacing ok?
Some drivers like this example:
It was said in the beginning of this thread that when using compression, a driver's BL is important. Those Altec drivers used by Crowe have a pretty high BL compared to most pro drivers I looked at (20 Vs ~15)
Any thoughts on how your average pro woof would fare in such a cabinet?
Any thoughts on how your average pro woof would fare in such a cabinet?
If the Qts is around 0,20 you are fine, but those parameters are interrelated to my knowledge.
So if I understand the requirement correctly, this would be a driver that is very much suited for the kind of box we are talking about?
http://www.loudspeakerdatabase.com/RCF/L15-554K
High BL (23 Tm) , low Qts (0.24) , nice low Mms (75gr)
Or even better: http://www.loudspeakerdatabase.com/Beyma/15P80Fe_N
http://www.loudspeakerdatabase.com/RCF/L15-554K
High BL (23 Tm) , low Qts (0.24) , nice low Mms (75gr)
Or even better: http://www.loudspeakerdatabase.com/Beyma/15P80Fe_N
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Just a quick update on the time alignment, diaphragm to ear aligned, verse horn mouths aligned.
I tried the distance the sound pressure waves take as they curve following the horn sidewalls to exit, and then the distance straight up the centre of the each mouth.
Prefer the shorter straight up distance.
It's not night and day but the treble is cleaned up a bit.
Result is lower perceived distortion, particularly on complex fast music.
Many thanks to @Horneydude for enlightening me on this method of alignment, and taking the time to explain it.
I tried the distance the sound pressure waves take as they curve following the horn sidewalls to exit, and then the distance straight up the centre of the each mouth.
Prefer the shorter straight up distance.
It's not night and day but the treble is cleaned up a bit.
Result is lower perceived distortion, particularly on complex fast music.
Many thanks to @Horneydude for enlightening me on this method of alignment, and taking the time to explain it.
Thanks for the update, very nice you took the effort to find out if this way of alignment would work out for you. Inspire and be inspired, that is the magick of this forum 👍 It helps all of us to progress.
I'm pursuing a front horn loaded cabinet now for my system, and one issue I've ran into is the driver/horn interface. The throat of the horn will be smaller than the driver radiating surface to achieve compression: so, how does the driver throat/compression chamber transition to the driver? Does the interior surface geometry of the throat adapter matter? Is there a better way to do this than what I show below (a flat plane with a sharp edge facing the driver)? What about a phase plug or something similar?
These are some of the questions I'm trying to explore.
Attachments
This is not a very precise illustration but may help. The phase plug tries to eliminate the space in front of the diaphragm to extend the higher frequency response. A small gap exists only to allow the diaphragm to move. The smaller access to the horn causes higher pressure at the diaphragm, and allows the strength of the driver motor to be better exploited.
Got it - following this thinking, then, I think a phase plug would not be needed for the woofer? (looking through some older diyaudio posts on the topic also yields similar information). What I'm looking at is a 15" woofer in a 2-way system, with a low pass filter around 600hz.
If that's a no on the phase plug, what about the driver/horn throat geometry more generally? Would you want to round over that corner where the air volume in front of the woofer transitions to the horn wall? Does it matter?
If that's a no on the phase plug, what about the driver/horn throat geometry more generally? Would you want to round over that corner where the air volume in front of the woofer transitions to the horn wall? Does it matter?
For low frequencies you don't need a phase plug, but the size of the small chamber in front of the cone more or less determines the high frequency drop off. A round over does not matter i.m.o.
