U Frame can go a bit closer to wall than H frame
Ha? Why?
Thanks, I'll look it up.
I'm about 1m (3') off the back wall.
Not as much as I'd want but I have space constraints...
You do not have to have woofer facing you. Remember Gradient Helsinki 1.5 speaker?
Ha? Why?
It exhibits more of a cardioid polar response, so there is less radiation from the rear than an H frame which gives a true dipole response.
Here's some info that might be of help:
http://www.quarter-wave.com/OBs/U_and_H_Frames.pdf
I built a pair of the Goldwood H-Frames as mentioned in this article below.. Surprisingly nice for the money.. I use them crossed at approx 70Hz 24db slope.. Really nice sq. Using bookshelf 2 way cabs on top..
http://www.quarter-wave.com/Project08/Jordan.pdf
http://www.quarter-wave.com/OBs/U_and_H_Frames.pdf
I built a pair of the Goldwood H-Frames as mentioned in this article below.. Surprisingly nice for the money.. I use them crossed at approx 70Hz 24db slope.. Really nice sq. Using bookshelf 2 way cabs on top..
http://www.quarter-wave.com/Project08/Jordan.pdf
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
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?
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
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
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..
H and U frame may have slightly different side cancelation, but to the front and back, they are completely unrestricted
If you want to learn about cardioid bass, study kimmo saunisto web pages
You will find how a U-frame can produce a cardioid-like pattern here:
DIY-dipole-1
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...
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...
Last edited:
With approximately I meant something like +- 30%. The effective radius of a square is somewhere in between half the diagonal (11" in this case) and half the width (8").Wouldn't that be 8" then?
Why would MJK use 9"?
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
- Home
- Loudspeakers
- Subwoofers
- H Frame designer