Low-Mid Horn Design Help

[scotthutch]

Im currently trying to designing my own tops.

I want them to achieve 105hz-20khz

I am going to use the XT8 horn with B&C 8PE21 driver

I am yet to decide on a compression driver & horn

for the low mid section of the speaker i want to do a 2-3 fold horn.

I have been doing the calculation for a PD121 driver and got the following...

Mouth Size = 0.849m(2)

Horn Length = 0.721m

Chamber = 23.0.76L

The horn length seems reasonable to me and chamber size but the mouth size seems rather large?

Can anyone enlighten me

The calculations are all from this paper.
http://www.quarter-wave.com/Horns/Front_Horn.pdf

Regards

Scott

 

[scotthutch]

looking back over the calculations

I think that if i divide the mouth size 0.849m(2) by a size factor of 4 i get 0.212m(2)

Giving me 460mm(2) for the mouth size

Is this right?

Scott