High Efficiency Speaker Asylum: Good design/plans/idea for a 100-500Hz front loaded horn? by Erik F.

Now, since I have solved my D54 horn problem I'd like to
build some new stuff:

Intention is to cover a frequency range from 100Hz (better a little
lower like 85 or 90Hz) to 500Hz with a front horn.

I've heared a lot about the straight Edgar 80/100 horns.

Found on http://www-user.uni-bremen.de/~carnivor/horn/hornfolds.html :

The 100Hz Horn is: 22" x 22", Horn Length: 16", Curve Type:
Exponential (m factor 0.6 i guess), approximated in two steps.
Mouth Area: 21" x 21", Throat Area: 9" x 9"
Back Chamber Volume: "enough to enclose driver"
(obviously this is a secret, as back chamber volume is essential
for proper reactance anulling which enhances response near cutoff)

Somewhere else I found:
The 80hz horn is 25H x 19W x 32D according to my dimension for building a box around it.
That gives you a mouth opening of about 23 1/2 x 17 1/2 with the
length being around 22". Yes, it is front loaded. The mounting
plate will take a 15" driver and then there's a box around that
in the rear.

What I don't like is to spent DM 550,- which is approx.
US $ 240 per EV EMV-15L or EMV-12L speaker. An other fact is
that I was not able to find out anything precise on the back
volume of the named speakers.

But, if one of you guys out there has achieved some good results
with "cheaper" speakers and/or other designs, I would be happy
to hear from you (or maybe just a little tip like: x liters back
volume for a 100Hz horn with a y speaker).

TIA

Erik

Btw.
Any comments on links where to see Edgar horns?