46266
From: unicknn, [host-69-59-64-244.nctv.com]
Subject: noob needing help with box port
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Hey yall im needing help figuring out how big my port should be on my new box. Im running 2 alpine type r 10s. The tech sheet says my port dimensions should be 11 square inches, 22 inches long, and displace .237 cubic feet. Thats for each. I went to my local audio store and the guy told me that i need to double the dimentions cause its 2 subs. so 22 square inches for the opening. He also told mt that it would probably be best to tune the box to 45hz instead of 35. My box will have a volume of 2.9 cubic feet for both subs. Im just getting this off of all the online calculators so im not 100% they are correct. I put in my measurement and the calculators tell me if i want 45hz my port length needs to be 6.2 inches long and if i want to tune to 35hz it should be 12.8 inches long. Why is this so much different then the tech sheet? How long should my vent be in this situation? Ive probably confused everyone lol. Moderated By: brian@diysubwoofers.org |
Responses:
[46267] [46268] [46269] [46280] [46270] [46272] [46273]
46267
From: Brian, [72.22.155.163]
Subject: Re: noob needing help with box port
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If you using two subs, (1) make the box twice the size as recommended, and (2) use TWO ports with the same dimensions given for the single port in Alpine's recommendations. Here, the advice from the audio store is correct, as increasing the cross-section of the vent to 22 sq.in. is basically the equivalent of using two 11 sq.in. vents. A port of 11 sq.in. will have an effective diameter of about 3.75 in. If you use two such ports to achieve an Fb of 35 Hz with a 2.9 cu.ft. box, they'll each need to be about 14 in. long. Alpine's suggested vent length looks like it will tune the box around 30 Hz rather than 35 Hz. The suggested tuning of 45 Hz is ridiculous, unless you're planning to enter SPL competitions and you want a boomy-sounding subwoofer. |
46268
From: unicknn, [host-69-59-64-244.nctv.com]
Subject: Re: noob needing help with box port(NT)
| (NT) |
46269
From: unicknn, [host-69-59-64-244.nctv.com]
Subject: Re: noob needing help with box port(NT)
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well im not used to these forums so i typed my questions up and nothing got posted cause I forgot to put my name in lol. Where are you getting these numbers from? Ive put them in 2 different calculators and get nowhere near what you get. Is there some actual formulas out there that I can use? I trust my math over an online calculator any day lol. Also if I wanted to brace the box some would I be ok using some 2x2s or is there something out there thats better? thanx for all the help so far man. I apreciate it. |
46280
From: andrewt, [host86-151-119-181.range86-151.btcentralplus.com]
Subject: Re: noob needing help with box port(NT)
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the formulae are posted in this Forum. Have you looked at them yet? |
Responses:
None
46270
From: Brian, [216.110.126.104]
Subject: Re: noob needing help with box port(NT)
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I used the equations at the link above :-). 2x2s can work for bracing, if you use enough, of course. |
46272
From: andrewt, [host81-156-58-77.range81-156.btcentralplus.com]
Subject: Re: noob needing help with box port(NT)
| download the fee simulator: winisd pro. |
Responses:
[46273]
46273
From: unicknn, [host-69-59-64-244.nctv.com]
Subject: Re: noob needing help with box port(NT)
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I got that but I have no clue how to work it and my subs arent even in it. Moderated By: brian@diysubwoofers.org |
Responses:
None
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