I'm planning to build an enclosure with 2x12's for home audio. I've been looking around for some info regarding the best direction of subwoofer & port placement for best bass response & quality. I'm thinking of 2x downfiring with front or rear ports or 2x in front and rear firing. What's the best config other than these? Also I have a hard time understanding port length calc for 2x ports. The punched out # is a bit more than 2x the length for 1x port, so do I take that # and divide it by 2 to get my 2 ports or each port is the punched out #. thanks.
Best choice is to port to the same side as the driver, whether front-firing or down-firing. Alternative is to port in another direction, and this is dictated by the amount of space available for the port structure. All the sound will come out into the room, so it's not that big of a deal.
If you want to convert one port to two, and keep the same tuning frequency (of course), each (equal in diameter) vent's length will be slightly more than twice the length of the original single port. This is due to the fact that doubling the number of ports greatly increases the port opening area. If the dual ports are made to be smaller in diameter than the original port size, you will need to calculate port opening area in square inches. Port calculators come in handy for this, as well as box building programs such as WinISD Pro.
https://www.subwoofertools.com/forum/portlength.htm
https://www.subwoofer-builder.com/freesoft.htm
https://www.mhsoft.nl/spk_calc.asp#top
https://www./help2/Articles.cfm?id=31
...and to the left side of this page under "port length calculator"...
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Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.
I've always taken the sub and fired the port into the corner of the room. It seems to roll up the wall and back over the room, in my opinion... As far as ports, I know that the length of the port is what determines the frequency, I believe If you take the diameter of the port and divide that by two, but keep the same length, that will give you what your looking for. If this was me, unless I was going to put a divider between the subs, I'd just run one single port.
Home audio and car audio are somewhat the same, but yet pretty different in the same aspect. What type of sound are you going for, because I've seen some excellent sounding surround sounds with a single 8" sub....
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...don't crush the weasel...
Thanks for the info guys. I've been busy remodeling around the house so it took awhile to respond. I'm not sure whether to use 1 or 2 subs because I want deep bass, but not to over crowd the speakers. I'm using 4x bose IV 301 for fronts, rears, and some old technics for center and mid centers but planning to upgrade when I have $_$. I think my best choices are front mounted, rear firing. Or front mounted and design the port into the enclosure. The reason I chose to down fire due the cosmetic design of the facings, but hell seeing the woofers pound would be great too.