Economical large format bass-horn

[GM]

Greets!

You're welcome!

Eso's loft cement/stucco 30 Hz bass-horns: http://gallery.audioasylum.com/cgi/v...serImages=2348

Anyway, forget concrete construction with an Fc in the teens. There's two ways to build a speaker cab, either mass it up until its Fs is below the speaker's pass-band or make it rigid enough to be above it. This way the driver/acoustic load can't make it resonate.

Obviously, to get a cab to resonate below say 10 Hz will have to be incredibly massive, but if its HF is rolled off by say, 150-200 Hz, then building it with well braced 19 mm void free plywood is doable. The problem with using plywood scraps is that they have to be void free ($$), otherwise it may creak/groan at various higher frequencies that can't be damped/EQ'd out and particleboard, MDF, etc., will push its Fs down which will require ever more lams until it's finally as dense/heavy as concrete.

From this we see that cavities filled with lightweight material isn't going to cut it in sub bass-horn construction.

The hardwood would be good for building the whole horn, but if there's not enough, then at least do the throat/initial expansion until it's gone, then transition to suitable scrap and whatever bracing is required to keep it from 'drumming'.

The sloped roof only helps with the room's higher harmonics. The main width/depth ones will still be there, though not as strong.

You can probably sim the room extension somewhat by breaking the horn down into sections, but you'll have no way to sim the room's finite Vb/reflections, so probably best to make a horn design that looks good in pi space and any improvement due to the room is a plus.

Well, it seems a shame to expend all this effort on rinky-dink drivers, but whatever works for you.

GM

[hm]

Hello,
what do you think about a removeable bass horn system?
25-80 Hz 106 dB 1 W 1m, 1 sqm mouth.
my small big bass study
http://www.hm-moreart.de/100.htm