Would it be possible to downscale the midhorn to an 8", i have a pair of suitable drivers (focal axiom 8) -- somewhat similar to jbl 2118.
I see bill martinelli has used a pair of eminence 6" in a midhorn.

the tentative plan is to use them with a pair of Pi-7 (with jbl 2245 18")

Any tricks to this?

Cheers
Andreas

Since your plan is to use these with seven π-18's, I'd stick with the 90x40 aspect ratio. I think that's the best pattern for use with cornerhorns. I'd probably keep the mouth area the same, and simply extend the horn back to where it makes a 4" x 4" throat. That will look nice, making the midhorn width equal to the width of the bass bin. And I expect a horn of those dimensions will have very nice response too.

I used a 6 1/2 inch driver in the mid-horn and I'm satisfied with the results. I followed Waynes advice about keeping the mouth about the same size, the lengths close to the same as Waynes design and proportioning the entrance at the throat to the smaller speaker. I suspect too large an opening leaves the driver incapable of going as low as the horn allows it and it will flap around causing distortion. I suspect too small an opening would restrict sound. I'm sure I'll find out if I'm right ;-).

From what I've read the length of the horn and size of the mouth have a lot to do with the frequencies the horn is capable of producing. A shorter horn, or smaller mouth would be suitable for higher frequencies. Longer horn, larger mouth, lower frequencies.

Grant.

Not every driver is suited to horn use. I'm not sure what all the characteristics are, but a rising SPL level on a graph is an example of a "horn friendly" characteristic. I used a PHL driver which PHL suggests for possible horn use.

Dr. Edgar played with a lot of drivers years ago to find the best to use. I'm sure Wayne chose his drivers for specific characteristics as well which the Focal's may or may not satisfy.

Grant.

Thanks for your comments

Cheers
andreas