A "hidden" horn sub

[Fuling]

My latest project:


A 2,2m long horn with 2 x 8" drivers, shielded since I plan to use this thing as a stand for my TV and VCR/DVD.
Mouth size is 45 x 61cm.

[AndrewT]

Hi,
the mouth area of your horn will cut off at about 90Hz if you use both floor and rear wall loading.
The actual mouth area (Sm)=0.27sqm.
Wall + floor loading gives an effective area = 4 * Sm = 1.1sqm.
The circumference of the equivalent area is 3.71m and this equates to 92Hz.
However your length will allow some output down to about 50Hz but because you have truncated the the horn early I think the ripples in the low end response will be quite severe.
If you can achieve corner loading then that will extend the response down to 65Hz. In this case rear exit from the horn could use the corner as part of the horn expansion and could give an effective doubling again in the mouth area. Some experimentation here I think?

[Fuling]

Thanks, lazy as I am I´m always happy when someone else does my maths

The term "sub" was a bit optimistic in the first place, the idea is to add just a little bit of bottom end to a pair of tiny BL horns with FE107E drivers that I already have (my own design but quite similar to Buschorns.)

I´ve ordered a pair of (cheap) drivers (Qts 0,36 Fs 44Hz) but I haven´t started cutting any wood yet, so there is still time for changes. I must admit that WAF is of major importance here, thats why I bother to design the horn in such a way that it can be used as a TV bench.

Maybe a double horn that couples to both floor and back wall would be better?

[Fuling]

Here:

A bit shorter hornlength, bit the mouth area is increased to 0,405m^

[zobsky]

Originally posted by Fuling
Here:

A bit shorter hornlength, bit the mouth area is increased to 0,405m^

when i saw this post, i was having the same thoughts about double horns.

also consider that you will get bass from the sealed box behind the driver

[AndrewT]

Hi,
the bass from the sealed box, how does it get out?

[zobsky]

Originally posted by AndrewT
Hi,
the bass from the sealed box, how does it get out?

through the horn.

i should have been more explicit, .. the volume of air behind the driver loads the driver like a sealed system

[PeteMcK]

how about porting the chamber to the front of the box?

[Fuling]

how about porting the chamber to the front of the box?

PA bass bins often has ported back chambers, so I guess it would work fine.

[Bjohannesen]

Hi Fuling (nice name)

I have made a TL sub with a very good SAF, which might give you some ideas. I am writing on an article about this design. The geometry ends up with a tuning frequency of 25 Hz, and as both the opening and the driver is at the floor, I am very satisfied with the performance.

Hi from Wonderful Copenhagen