No, you do not have to add a port. 21 litres, lined will have a Qtc of about 0.5 with the 10P. It doesn't matter whether it's a dodecahedron or not of course -the volume is the volume is the volume, assuming no significant eigenmodes. The question is really whether you want a critically damped sealed box or something else. Which comes neatly to
Which again depends on what alignment you're targeting. If you want vented, I'd probably pitch for ~42Hz for a lightly damped response assuming a voltage source amplifier; call it a 35mm diameter x 48mm long vent.
21 litres sealed will get you about 100 Hz F3. Add a vent and you'll get into what i feelare the optimum 16-20 litre vented size range and go much lower, at least an octave if not more.
dave
dave
We've got a few Alpair 10m/10p vented builds ranging from 15 to 28 litres. All work very well in their own way. Your cabinet volume should allow for a nice little vented jobbie! Sealed may be preferred if you will be using bass support, if not the bottom few octaves may seem a little thin.
@ nirvana, I'm kinda noobish myself, but the sim programs like winisd are pretty simple to play around with. Give it a try. You'll notice that with the vented it does hold the flat response lower (depending on tuning, box size). But the sealed (again depending on box size) generally has a shallower downward slope, so might actually have more response than you would think at say 30hz. It's pretty easy to build it with a vent then plug it and compare (or stuff it with straws).
One question for anyone more knowledgeable than myself (shouldn't be too hard):
I'm a little confuzled by all the F#s around here.
Lessee, Fs is the free air resonance - a TS parameter
F3 would be 3db down point.
Fb? is this the same as F3?
Mark lists Fo in his specs. Guessing this the same as Fs?
nirvana, please keep us up to date on your build, looks like fun. Maybe I'll try it after I finish remodeling my house.
One question for anyone more knowledgeable than myself (shouldn't be too hard):
I'm a little confuzled by all the F#s around here.
Lessee, Fs is the free air resonance - a TS parameter
F3 would be 3db down point.
Fb? is this the same as F3?
Mark lists Fo in his specs. Guessing this the same as Fs?
nirvana, please keep us up to date on your build, looks like fun. Maybe I'll try it after I finish remodeling my house.
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