Hi Mike,
I played with your sealed box simulation some yesterday, using Quarter-wave mathCAD sheets from Martin King @ quarter-wave.com. Check it out, he has a lot of great articles there about single driver, open baffle and other speaker related physics. The software is very helpful in exploring how a speaker design will behave with various changes. I found that moving the driver to the center of the box makes a slight improvement in FR flatness at 400+Hz, probably nothing you would notice. But filling with stuffing at least half the volume makes a huge improvement over no stuffing. 100% stuff is even better.
The sheets have a different driver simulated as default, whose specs were similar to yours. So I left the Lvc at .9mH (I think, check your pDF) and I estimated the Sd from the drawing. But you could measure that from the peak of the surround, across the diameter to the other surround peak - the center of the moving surround. Sd is the swept area. It is close enough for this, since no ports or tuning is being done.
I also tried deccreasing the volume of the box (by stacking wood in the bottom. But since the Vas of the driver is larger than the box volume, reducing it further is counter productive. Increasing it would be the way to go, but you already have a fine box. So for sealed speaker there isn't much you can do except stuff it full with stuffing, maybe Acoustuff, from madisound. I have not used it but read people's opinions who prefer it over polyester from walmart, which is also OK and a lot cheaper. Or cut open an old pillow that says all polyester and use the wool from that.
The box frequency response of sealed cabinet is very shallow smooth slope, and remains rising up to 1kHz. To flatten out the FR between 1kHz and below, you can make a baffle step correction filter, which will lower the volume of tones above a certain frequency you choose, giving a flatter response but giving away the high efficiency at the higher freqs also. The filter would affect the sound quality to the degree you pay for nice parts and and time you put into designing it. If you use Squeezebox, Inguz room correction would be perfect for this, not affecting sound quality, while giving you the flatter FR of a hifi speaker. Quarterwave sofware has the ability to simulate a passive step filter to go between amp and driver. I can try to find a filter for you if you want, but I don't know enough to do it justice. Picking parts is the art. Since our very own miklor is Inguz expert, I would try that first, it's free.
The picture is 3 frequency curves. Top with full stuffing and driver at the top end (32") so no stand is needed. Middle is same as above with only half stuffing, and bottom is full stuffing with driver centered, and speaker would have to be on a stand.
These simulations do not include reflection cancellations from rear wall or floor. Much of the crap you saw on the first pdf I sent you was floor reflections making the FR bumpy. When you put the speaker on the floor those will exist in reality, but designing compensation for the reflections into the speaker is way beyond my ability! Your ear is already adjusted for them, but room treatment frees that brtain power up for music enjoyment... haha
I will work on the ported box next if you're interested. But if you use it you should pay Martin license fee $25 for using his software. Adjusting stuffing is also design work, but the first hit is free. haha Once you got it, you might enjoy playing with it yourself! He has some upgrades coming in Feb. to extend the frequency response prediction up to 10kHz, and speeding up the calculation by 10x. Bargain for $25.
Rich
