H Frame designer

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perceval

perceval

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Joined 2014
#1
Been looking for a while on the net, but I just can't seem to find it.

Is there a program, online or standalone, that would help designing H frame or U frame for Woofers in a FAST configuration?

Mostly it's: how do I find the length of the "wings" around the woofer?
 
#12
Thanks Dave, yes I've read those. That's very interesting that you built that sub as I have the Jordan Eikona in open baffle at present. I was also torn between H frame and U frame sub, I still am. I built U frame in the end for a couple of reasons. 1- I had a couple of old speaker cabinets that were easily adapted and 2- I believed I may be able to get away with them closer to the wall. Ideally though I'd like to experiment with H frame as it seems the best solution except for the extra space they'd occupy and maybe need. I'm still not clear on that last point though
 
#14
Oh, I missed (or forgot) the Geometry part last time I read MJK's paper on H and U frames...

Ok, this looks easier than Hornresp, but what is r effective in the first equation?

The internal cross-sectional area is 16” wide and 16” tall. The depth of the cavity
was defined as 7.5”. The depth was selected to push the first quarter wavelength
resonance above the desired crossover frequency of approximately 200 Hz.

L effective = 7.5” + 0.6 x r effective
L effective = 7.5” + 0.6 x 9.0”
L effective = 12.9” = 0.328 m
f1/4 = c / (4 x L effective)
f1/4 = 344 m/sec / (4 x 0.328 m)
f1/4 = 262 Hz
Click to expand...
 
#15
It appears to be some kind of end correction on the cavity making it longer, similar to that on ports of ported boxes. I think r is the equivalent radius of the opening, so approximately half the cabinet width.
 
#17
scottjoplin said:
Thanks Dave, yes I've read those. That's very interesting that you built that sub as I have the Jordan Eikona in open baffle at present. I was also torn between H frame and U frame sub, I still am. I built U frame in the end for a couple of reasons. 1- I had a couple of old speaker cabinets that were easily adapted and 2- I believed I may be able to get away with them closer to the wall. Ideally though I'd like to experiment with H frame as it seems the best solution except for the extra space they'd occupy and maybe need. I'm still not clear on that last point though
Click to expand...


I use mine right up against the side walls on both sides of the living room. There's 7' of open space behind them and 12' open in the front.. On top are two bookshelf cabs towed in towards the listening couch.. They reach pretty low and sound really nice sq wise using a Dayton sub amp to power them.. Not a bad project and price for a couple of 18's to get some decent sq low end etc..
 
#19
I am familiar with John's pages, I am an open baffle guy...
You will notice its only cardiod-like at very low frequencies, 20 Hz and lower, which, considering cancelation has almost no output...starting 50Hz and up, it has plenty otput towards back, at 100Hz and up its like H frame...and that is only theory...
 
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