Looks good, just doesn't go nearly low enough for many movies, even the ~24 Hz sims I did need to be tuned lower, though really need a driver with < 20 Hz Fs.
GM
GM
Can you please share the dimensions of the enclosure? How far from corner /back wall/ side wall you use them?
Thanks!
If one took BFM's little T18 and directly scaled it by 2.25X (also, I scaled the late Ernst Beck's California horn by 1.2X to see)
both corner loaded - both pretty darn big
2.83v Rg = 0.4 ohms
T18 for "18" does 102dB@16Hz 2.83v. The back chamber volume
could be reduced somewhat.
both corner loaded - both pretty darn big
2.83v Rg = 0.4 ohms
T18 for "18" does 102dB@16Hz 2.83v. The back chamber volume
could be reduced somewhat.
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a simple 20Hz tuned 343 liter reflex in a corner with 3dB boost @20Hz looks pretty good
BUT it could be of advantage to cut volume to 250 liters and raise tuning and the 3dB boost
to 22Hz - output is good at 105dB/23Hz/0.5 pi and about 2.2 watts input at tuning
BUT it could be of advantage to cut volume to 250 liters and raise tuning and the 3dB boost
to 22Hz - output is good at 105dB/23Hz/0.5 pi and about 2.2 watts input at tuning
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A 300L sealed gives you an F3 of 42 and an F10 of 24Hz, that can be enough. And a huge 750L cabinet can even do better with an F3 at 40Hz and an F10 at 23Hz. With room gain you should be where you want with that.
And it easely can be loud enough without loosing bottom by overexcursion.
A 450L vented tuned to 20Hz will not do it, the box is too small for that. You need a 1200L vented box to get there. The 450L will have an F3 of 31Hz and a fast slope down.
And it easely can be loud enough without loosing bottom by overexcursion.
A 450L vented tuned to 20Hz will not do it, the box is too small for that. You need a 1200L vented box to get there. The 450L will have an F3 of 31Hz and a fast slope down.
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bump. I am thinking of using this woofer from 300Hz down to the abyss. Just see if OP and others can provide more feedback. I probably pick 300L sealed over 250L reflex, as I don't really need the SPL.
On paper, 20 W gets you > 115 dB/30 Hz-up/1pi, tapering off to 90 dB/10 Hz with full power only netting you another 5 dB/10 Hz, so not worth the extra VC heat on those low B organ notes. 😉
OK, you asked for < 300 Hz performance.............regardless, based on published specs; at 300 Hz, a > 2nd order XO is desired to drop its breakup modes in its 1.5-2 kHz BW down to where our hearing acuity is all but gone and with no info on the mids, layout, can't speculate further.
300Hz and above will be handled by a unity horn. The horn will be sitting on top of the bass bin, similar to your Altec A2 user picture. I think the horn (conical horn with an around 16-18" diameter opening) is a bit small, so the horn does not fully load down to 300Hz. Active DSP crossover, so can use any order crossover.
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Fb = 0.39 x (30hz/0.35qts) = 33.28hz.
Vb = 14.76ft3 × (0.35qts ^2) = 1.81ft3.
Shoot, that's EXCELLENT for an 18" driver in car audio! The 2 Polk Audio MM1540DVC shallow mount 15's I had in my F150 SuperCrew required 1.8ft3 sealed per driver.
Vb = 5.7 x 14.76ft3 x (0.35qts^2) = 10.31ft3.
Fs = 0.38 x (30hz/0.35qts) = 32.57hz.
THAT seems typical for an 18" driver.
Vb = 14.76ft3 × (0.35qts ^2) = 1.81ft3.
Shoot, that's EXCELLENT for an 18" driver in car audio! The 2 Polk Audio MM1540DVC shallow mount 15's I had in my F150 SuperCrew required 1.8ft3 sealed per driver.
Vb = 5.7 x 14.76ft3 x (0.35qts^2) = 10.31ft3.
Fs = 0.38 x (30hz/0.35qts) = 32.57hz.
THAT seems typical for an 18" driver.
Thanks, but I don't see how it relates to the Fb = 0.81 x Fs formula. My question was to GM is why the 0.81 multiplier and why Vb = Vas? He don't receives PMs, that's why I asked here.
The OP posted
so tuned lower to increase low bass BW and take advantage of the wall gain.