FYI, the ?standard? small VOTT flare radius is 30-31/32?, so 31? is close enough.

No throat area is spec?d so assume it?s the ?standard? 128?^2. The basic dims works out to a ~110 Hz mouth and axial length in full [4pi] space, so longer/lower if setting perpendicular on the floor. Loading the various specs into HR yields a ~127 Hz expo flare frequency. Didn?t work out its ?close enough? radius though, so no clue if it?s expo or a hypex.

For comparison, the VOTT horn is a ? size ~55 Hz horn or ~110 Hz actual, so while at a glance yours appears a larger version in comparison, it will have a more ?pinched? mids, i.e. greater directivity over a narrow BW, meaning there will probably be a hump in the mids response right where you want it ?smooth as a baby?s bottom?.

If this is your plan, then you?re better off overall shifting the horn forward to truncate it to Altec specs and adding a round-over termination out to the cab?s width, height ala Le Cle?ac?h to minimize reflections back to the throat, though only do it on three sides if ?mounted? perpendicular to the floor. That, or use a longer ~77.8 Hz flare to get to the 770 cm^2 mouth.

The way to have your ?cake and eat it too? though is to plot the 825/828?s area expansion every ?x? distance [of your choosing] and extrapolate it out until it meets your mouth dims to find the correct axial length, flare frequency and closest radius. Now it should perform like an Altec through the XO BW except with a bit more bottom end and directivity control.

As for reflex tuning, we come up with similar for an 80 Hz/4th XO, so looks like you?re good enough for fine tuning in room.

GM