Altec 828 horn flare without a rear enclosure

[GM]

The 825/828 horn has NO parallel panels, just the compromised original 810 and much later 816, 817.

Yes, I've periodically posted about my trials n' tribulations with trying to negate the 210/211's parallel sides with only so-so success in a HIFI app, but for prosound it's not much of an issue due to venue size, ambient noise 'floor' and acoustically long listening distances; so if a HIFI/HT app, definitely build the 825/828 horn and preferably both flat panels at an angle to make the horn symmetrical unless you plan to set them on the floor or above ear level in which case the original flare is a better choice, with floor mounting in the inverted position same as the Magnificent.

Folks so often ignore that these horns normally have a tilted down acoustic center in the XO BW designed for stage mounting, so the HF horn should be tilted down in most HIFI/HT apps since they are typically ~near field.

GM

- - - Updated - - -

now thinking of using a pair of NOS 414-16b instead of the 515 /416

The horn throat is much too big for the 414, so what little BW the horn actually loads will be cut a full octave according to HR, ergo the rear chamber needs to be reduced by a factor of 4 = 0.375 ft^3.

GM