Here is a little horn just designed:

I got in a true 3meter path length (right down the center - see dotted line in diagram) and the mouth is 2558cm^2. The mouth rapidly opens up in the last 15cm so my guess it will 'seem' more like a 2200cm^2 mouth or so, which is just fine. Expo flare.

It uses TWO 10" drivers, using two can get a smaller size and deeper bass extension. I modelled up the Peerless CSX 10" 850146 and here is the response curve with 100W input power (drivers wired in parallel):

So it reaches 27Hz at its low end. At 26Hz it is only 1db lower in gain so you could say it will do 26Hz actually - not bad for the size. The crossover at 70Hz~80Hz to the mains will smooth out the slightly rising response but it isnt' an issue anyway, only about a 3db 'shelf' and will definitly get rid of the peaks.

I choose to model the dual CSX 10" because:

*Peerless is a high quality manufacture from experience with their products
*Has a shorting-ring in magnetic structure to reduce distortion and improve linearity
*Extended 4-layer high power VC, 200W each or 400W total
*Works for my application

Horn size is 108cm high, 60cm wide, and only 80cm deep - all external dimensions and MDF is 25mm.

Now all I have to do is build it :P

It will be sad to stop using my big 18" driver but the benefits are probably worth it. The basshorn can do 120db with 30watts compared to 500watts for my vented 18" sub - huge difference! And the horn can still do much more than 120db!

Anyway ~~ any comments?

BTW: probably a variety of other drivers that will work with it too

Adrian

I would assume the ripples would be due to mouth size, but if there is enough excursion in the drivers, a little EQ should be fine.

I have been thinking about a home use subhorn using 10" drivers myself, and am toying with the idea of going straight up the wall to ceiling height, using the horn as the rear of an entertainment unit (ie TV etc in front of horn as it goes up the wall - TV would sit on mouth opening section on floor).

Cheers
Graeme

I'd make part of the side panel removable, just around where the driver is, on both sides of the box (to access both drivers) which should be easy enough. The CSX 10" drivers I modelled are only 10.8cm deep, and I have 19cm in the rear chamber - so about 8-9cm between magnet and back wall, should be a pretty easy job to get drivers out this way + have the complete 19cm clearance around the drivers to get to the screws on the other side of the driver.

I thought about zig-zagging the folds too, it ended up making the box higher though which was not acceptable for my constraints (well the only height constraint is ugliness! but thats reason enough).

That subhorn sounds interesting, I'm not sure I can visualize exactly what you mean though - so rear chamber and start of horn would be at the ceiling and it runs all the way down, kinda like a completely straight horn or maybe with one fold?

Adrian

The second woofer is unnecessary; you don't need it for power in a home environment and it's only giving you an additional 3dB of output so I'd lose it. The space devoted to it coud be reassigned to the horn, allowing either a smaller box overall or a longer pathway for an even lower Fc. Don't underestimate what you can accomplish from a small box. This SPL chart is my Tuba 18, a 45cm cube driven by an eight. It doesn't go as low as your design but it sure goes a lot lower with more SPL than anything else in its size class. You can get what you want in a far smaller package or get even more from the same size box by bagging that second woofer.

How could I get a smaller volume by using just one woofer? In the horn I posted, I planned to have the woofers side by side (hence 60cm width or 55cm internal for two 25.7cm drivers + a few cm of wiggle room). If I dropped one of, the width could obviously go down to even 30cm, but to get the same mouth area and area along the whole horn the height and depth would have to be increased to make up for the area lost in the width... or do you use a more fancy method which could take up less space with 1 woofer?

After Wayne had a little snicker at my use of the word 'small' to describe my horn plan I posted I went away and refolded it totally different. I came up with this:

Its again for two woofers... but I managed to get height down from 109cm before to 95cm - had to decrease mouth area to 2000cm^2 but length is the same (well it was 3m now its 2.93m, practically nothing), no matter though its what I had originally wanted in the first place and doesnt change response curve barely:

Im still going at it, Im trying to find a way to get the height even less now that I've got the depth pretty small.

Adrian

Cheers

(Sorry 'bout my snicker. You know I think your designs are excellent. It's just that I get a grin out of basshorns referred to as "little" basshorns, even those built by Mike for his car. I surely wasn't ridiculing the design, so I want to make sure you know that.)

Compare to mine,~422L total ,1driver
99x97x44 total\

Note that adrians horn is ~1cube smaller,cos i have ~ 1cube too much vrc :-p

I hate his angles though!

200cm Throat
2600cm mouth
expo 299cm

this little woofer has a shorting ring! awesome! + i trust peerless more than any other 150$ 10" woofer company!

Im gona CAD up 2 drivers now ,superb performance!

2drivers vs 1 driver. same horn apart from Throat and Vrc adjusted.(so bigger)

The one thing I might change on Adrian's layout is the position of the throat in relation to the cone. Having it offset to the side will make cone movement resistance greater on the bottom than the top, which will make a tendency to rotate and torque the cone and voice coil at high levels. I think I'd modify it slightly so the throat cutout was centered over the cone.

im going to try a wider horn in the morning,at the moment its 480L and 42cm wide so its rather big.

Or i could just make it 40hz F3 :-) il try one of those woofers somehow :-D

Cya!