I woudl love to hear input from anyone on here who has box building experience- below are my plans for my first completed box . this weekend I built a rough box out of an old sterao speaker to jsut test things out a little... i dont count that. The box is for 4 string bass guitar at quiet to moderate practice volumes in a 20 x 15 x 7 foot sheetrocked & carpeted room. I used a SPL meter 3 feet in front of our amps and found that 100 to 110 db covered our level range over several practices. I will be driving the cab with an eden wt300 or hartke 5000, both pretty much 250 to 300 watts at 4 ohms. i tend to run things fairly flat, without excessive EQ-ing. Box dimensions: 19"wide x 13"tall x 13" deep EXTERNAL. Front baffle inset 1". front and back are 5/8" MDF, the rest is 1/2" plywood. 1/2" quarter round strips along each interior seam, carpenter glued and screwed with 3/4" or 1" wood screws. ( is gorilla glue better?) a shelf brace of 5/8 MDF with numerous large holes drilled in it running front to back roughly bisecting the baffle board, glued and screwed with 1/2" quarter round as described above. The woofer will be left of center, the mid centered along the same axis right of center. rear port of 3" drainpipe mounted behind and below the woofer in the lower left corner. an elbow first, with the straight portion extending along the inside of the cab for a total of 17". I estimated the speaker displacements at 90 cubic inches, and subtraced all bracing and walls to get an Overall net internal volume of 1.2 cubic feet without stuffing. I am on the fence in terms of acoustic stuffing- thoughts? drivers- peerless 831759 (len's special) 10 " : fs either 21.7 or 22.4, depending upon which publication you look at. vas=121.9L qts = .27 or 28, depending. max power = 220W Z = 4 ohm 91.4 SPL sens Re 3.6 Xmax .295" Midrange- no t ordered yet- still shopping and ... Crossover- possibly the eminence 2 way 800hz xover for 35 bucks. not purchased yet, and open to suggestions. I ran this on win pro and it seems that: 1.2 ft3 @ 29Hz (3" round port 17" long) f3 = 40hz group delay is 12.5 ms @30hz, 9.5 ms @ 40hz, and 6.5 ms @ 50 hz. I read on a speaker builder site that less is better, but that 13 ms is probably the limit of human detection. Thoughts? I dont want "mud". Cone excursion gets bad &hits max @ 200 watts @ 23 hz . (I should be running below that wattage in practice though). PLus, I shouldnt be sending a 23 hz signal into it with a 4 stringer... That said, I am on the fence about a low pass at about 30 hz to protect the speaker from "bumps". Port velocity- @ 200 watts the port velocity exceeds 54 feet/second (approx 17m/s, the value some have suggested to stay below) at frequencies below 35 Hz. (Since i am a 4stringer, I shouldnt hear too much chuffing since i have little below 40hz. ??) Fudge factor!- If i am off alittle on my volume calc's, if the box is really closer to 1.3ft3, or if i add stuffing and that effectively increases apparant volume, the vent needs adjustment a little to 15.5", f3 drops to 38.5, group delay is 13.5 ms @ 30hz, and essentially unchanged @ 40 and 50 hz, and cone excursion is exceed at 23.5 hz , and port vel is unacceptably fast at 36.5hz- All of this seem acceptable for my needs (?) If the box is really closer to 1.1 ft3, Port vel goes south at 33 hz, port length needs adjsutment up to 18.6", f3 goes up to 41.3hz, and group delay slightly better at the lowest freqs and essentialy unchanged above 40 hz. Still fine, right? SO, in summary, I went with a modified qb3 because the box size got too big (for me) to use a SBB4. the box is a hair smaller and should be noticeably lighter than the (superior) ACME low b-1... which costs comfortably more than twice as much at 400 bucks. My cab should also be more to my liking in terms of dimensions. I hope to cover it in Tweed, so it looks vintage fender-esque. Maybe not. so long as i do not push the cab hard under full wattage (250 - 300) , and stay in the practice volume range of 110 db, i think i am in the 150 to 200 watt range, and as a result cone excursion and port noise (farting, chuffing, whistling!) should be contained. (?) NOW- could anyone analyze this design and my thoughts/comments, and offer suggestions based on your real life and/or designing experiences?. Mind you, i put roughly 1,100 hours of planning into this so far, so be kind ;-) (Also, if anyone has a xover/midrange suggestion, i am open and have SOME paypal money still available. I know i will need to have an impedance compensation since most xovers are designed for 8 ohm, and the driver is 4 ohm. (I am looking at a 4 ohm mid as well on ebay, does this simplifiy things or is that irrelevant?) thank you VERY MUCH in advance.