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Silver Member Username: Sploosh56Post Number: 378 Registered: May-04 | I've been making custom subwoofer enclosures for a lot of people lately who live by me. I've only recently began to make slot ported enclosures for people. They have all been tuned to 35 hz and sound pretty good. Just curious if I would notice any difference in SQ if I tuned a box at 29 hz instead of 35 hz. Would the box still add the 3 db efficiency? |
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Silver Member Username: InsearchofbassPost Number: 381 Registered: Jun-04 | my guess is that you would lose spl because it would require more power to achieve the same excursion (as you get further away from your tuned frequency) but if you had room for extension of the suspension you could theoretically make this up but ultimately again more power is needed |
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Silver Member Username: Sploosh56Post Number: 379 Registered: May-04 | alright thanks |
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Gold Member Username: Jonathan_fGA USA Post Number: 1472 Registered: May-04 | You'll get the 3 db, but lose a little output around the tuned frequency (will still be 3 db higher than sealed). 3 db is a general increase, some ported boxes can add 6 db at tuning, it's just in the design. You'll be able to drop lower, and SQ will be better with a lower tune. |
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Gold Member Username: Jonathan_fGA USA Post Number: 1475 Registered: May-04 | By the way, 3 db is a general average within the subs range, the tuning frequency, if the box is the correct size and it's what your after, will add even more db. |
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Silver Member Username: Sploosh56Post Number: 380 Registered: May-04 | will it still sound as good as a sealed box or no? |
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Gold Member Username: Jonathan_fGA USA Post Number: 1491 Registered: May-04 | It can. Key is to make the slot port large enough so there is no port noise, and tune low. Run WinISD, and aim for a rolloff similar to a sealed box. It'll just be free power, basically. |
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New member Username: MattellermetsDanville, IL US Post Number: 3 Registered: Sep-04 | hey guys sorry if I'm interrupting a smart thread with a dumb question... but someone once said the only dumb question is the one you dont ask... anyway how exactly do you tune a box to a certain frequency? i have built 3 sealed boxes for my extended cab s10, with great results, as long as the windows are down.. so anyway i sold the latest box, and am looking into two 12's in the 100-200 range possibly... anyway i was going to port the box, either slot or round.. anyway heres my thinking so far, let me know if it would work, and how i would do it. *external dim. somewhere around 15" deep, 36" wide, 24" tall -maybe slanted for seats to recline, the actual space back there is more like 24" deep at the bottom, angle to 12" deep at 24" height, then up to ceiling... and the whole thing has about 44" width *about 3 cu ft for each forward firing 12" *a slot port for each, side by side in the middle of the top of the box, with a fabricated sealing cover for the ports, with something like glorified toolbox latches holding it tight -this way, for everyday use, or windows down, the ports can be shut, and then for windows up SPL tests, or cold weather, the cover can be removed...tell me if this is a silly idea or what, just thought of it while sitting in calc class for some reason? hehh annyway let me know on which speakers you recommend, and i'm not stuck on 12's, they just tend to be a good balance on response and volume... i could go three of them, or four 10's or 1 or 2 fifteens, i dont care.. just tell me what you think for under a few couple hundred |
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Silver Member Username: InsearchofbassPost Number: 397 Registered: Jun-04 | you could do port covers yes but i did it a different way ....i used a brace inside the box with square coutouts on the back of the box one to seal it then one to fit with a 4 inch pvc hole and made the ports to different frequencies to find the best one for my car then i could leave that one in and go sealed or ported any time all flush mounted (no air leakage either when sealed) |
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New member Username: MattellermetsDanville, IL US Post Number: 6 Registered: Sep-04 | thats a good idea sean. i might try it on mine. but hey i'm still in the dark on one thing, please explain how to tune a port to a specific frequency. are there certain port volumes that produce certain frequencies, or is it based on port length? maybe the diameter changes the frequency, too, although i was thinkin the diameter would be directly related to the size of the driver? idk fill me in guys |
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Bronze Member Username: A3formePost Number: 32 Registered: Sep-04 | Matt, Try this site out, it might help you. http://www.bcae1.com/spboxnew2.htm |
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Silver Member Username: InsearchofbassPost Number: 459 Registered: Jun-04 | heres a site to help you understand round and square port tuning heres one step further it shows predicted port volocity so you no how to avoid port whistle but it doesnt do square ports all i do is go same size square per port for a ball park figure. There are more exact ways if you need it these guys will explain. http://www.linearteam.dk/default.aspx?pageid=ventcalculator |
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Silver Member Username: InsearchofbassPost Number: 460 Registered: Jun-04 | use the square port calculator to know the new length |
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Silver Member Username: InsearchofbassPost Number: 461 Registered: Jun-04 | by the way if you have even moderate power in the s10 extended it will slam i saw a guy hit 140 with one mtx 10 pushing 800 rms to it but he has hit 145 it was in a large tuned box about 4 cubic ft set up for one note but you could do the switchable port for everyday use too would just take less power (darn lol) and less db but still be good if you have the truck like i tested your best hit frequency will be like 59 hz thought youd be intrested to no |
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Silver Member Username: InsearchofbassPost Number: 462 Registered: Jun-04 | by the way we did measureemnts in my buddies s10 extended i think i figured out we could do 9 cf with with fiberglass insulation 2 inches thick. The box would go all the way up just below the windows |
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New member Username: StreetballVassar, Ks United States Post Number: 1 Registered: Sep-04 | Hey imma using a Mofo15 subwoofer 340oz mag 4inch voice dual 2 ohm 2600watts max im wanting to use a memphis box design the sub is rated at 40hz but memphis has a 60hz and a 50hz spl box and a streetbass 40hz which one is better for my sub??/ i want it to be loud... |
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New member Username: MattellermetsDanville, IL US Post Number: 7 Registered: Sep-04 | thanks sean. my truck is the later model (98+) with a 3rd door (grreat for sliding boxes in). anyway i'm going to check out those calculators, do some measuring, and see what i come out with. 59hz, huh? i wish i had checked that out with a freq. testing cd before i took my last sealed box out. hmm anyway i'll update whenever i find anything out |
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Silver Member Username: InsearchofbassPost Number: 512 Registered: Jun-04 | perfect 59 hz should be it for your truck that was the exact model of my buddies truck i tested third door and all he hit 132 with about 300 rms using two volfenhag 12 48 series in 1.70 cf each ported but dont worry bout those subwoofers i may have misscalculated with the measurements in the truck it might have taken 3 inches of insulation to get there instead of two (speaking of the 9 cf box comment) |
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Silver Member Username: InsearchofbassPost Number: 513 Registered: Jun-04 | the woofers we tested were firing almost straight up at the ceiling of the truck with slight angles in a part fiberglass box |
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Silver Member Username: InsearchofbassPost Number: 515 Registered: Jun-04 | by the way that 132 db was with a low tuned everyday port with those volfehag 12's |