I'd appreciate any thoughts from all the DIY'er out there. I picked up a Dayton Titanic 1200 from the flea market and so now what? ;)
Based on what I've read, the driver is best suited for a sealed system. The T/S parameters seem indicate it would be a poor candidate for a vented system.
PE recommends a 2-2.5 Cu ft box stuffed with an F3 of 35 Hz, with effective F3 as low as 20Hz with room gain (is this optimistic?).
Their dayton kit favoured a 3 Cu ft box.
I'm earmarked this as a project for the 2 ch. rig so I was favouring sealed already. It will see most of it's duty for classical music and some jazz and rock oldies. It would be nice if it could pull HT duties but I'm not sure how realistic this is.
I've done some preliminary calculations using the sealed XLS from diysubwoofers.org and have the following results:
Driver Dayton Titanic 1200 Original
Vas 280.280 litres Equivalent air compliance
Qts 0.407 Total driver Q at resonance
Qes 0.420 Driver electrical Q at resonance
fs 16.0 Hz Driver resonance frequency
Xmax 14.20 mm Maximum linear excursion
Dia. 30.48 cm Effective diameter
PEMax 350 watts Thermal power rating
Qtc 0.71 Total system Q at resonance
Vb 4.90 Cu Ft Net box size
Fb 27.8 Hz System resonance frequency
F3 27.8 Hz Cutoff frequency (-3dB)
Qtc 0.85 Total system Q at resonance
Vb 2.94 Cu Ft Net box size
Fb 33.42 Hz System resonance frequency
F3 28.71 Hz Cutoff frequency (-3dB)
Qtc 0.90 Total system Q at resonance
Vb 2.50 Cu Ft Net box size
Fb 35.4 Hz System resonance frequency
F3 29.3 Hz Cutoff frequency (-3dB)
Qtc 0.95 Total system Q at resonance
Vb 2.22 Cu Ft Net box size
Fb 37.3 Hz System resonance frequency
F3 30.1 Hz Cutoff frequency (-3dB)
Qtc 1.10 Total system Q at resonance
Vb 1.57 Cu Ft Net box size
Fb 43.2 Hz System resonance frequency
F3 32.7 Hz Cutoff frequency (-3dB)
My observations/assumptions so far being that I'm a newbie and know nothing about speaker design/building.
a) Qtc of 0.707 is the flatest and ideal according to what I've read.
b) I can get a smaller box (I like that idea) without giving up much on the F3 area. I'm favouring Qtc of .9
which apparently emphasizes the bass a bit.
c) Shape of the box is not as seceptible to standing waves and a cube is not the only acceptable shape for a sub box.
Anyways, if I'm total off on my numbers or assumptions, I'd like to hear it.
Anyone have experience with choosing an Fb, F3 for a sealed system? Any gottchas?
Finally, have I overlooked any other configurations ? e.g. TL, Bandpass, PR?