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Discussion Starter · #1 ·
I am building two sono subs and I am not sure what port size and length I should go with . My speakers are XJ15'S from DIY cable, they are 15 inch and the parameters areT/S from a production sample broken-in for 3-4 hours at 50% excursion. Measurements are with VC in parallel.

Re: 3.95 ohm
Qts: 0.578
Qes: 0.673
Qms: 4.095
Fs: 24.5hz
mms: 130g
cms: .300mm/N
BL: 11
Vas: 284L
Xmas 27mm one way
I am going to use a 24 inch tube 12 feet long cut in half ,So 6 foot long per speaker . It would be about 7 1/2 cubic feet per sub, I was considering a 6" port tuned to 17.2 hertz at 30 1/4 . My room is a whopping 12 by 15 and 7' ceiling, I have an Ep 2500 on order . Also should I use poly-fill inside sub?:scratch: thank you for your help.

171 Posts
Hi Jake
I'm certainly not the guru on sub building but I think the Qts of your driver (which is on the high side ) may lend itself better to a closed box system. The group delay will probably be very high if you use a ported box (will sound slow and with "delayed " bass) Have you modelled the response on a winISD programn. I'm assuming you can get hold of this, a great starting point.You may be able to use a very large enclosure with a very low tune, say around 15 hz. to avoid hearing the group delay. But this drivers lack of damping would better suit a sealed enclosure. I have'nt entered your drivers specs into my programn (having trouble with it at present) maybe someone else can.

Hope this is of some help

Discussion Starter · #3 ·
Thank you for your response jason I tried that program and got a model for group delay. But I don't know how to save it and post it and I really don't understand what it means I apologize for my lack of BASSic- knowledge But you do give me a good idea. I will start off with the enclosure sealed and not glue on the end caps and try it. Then I will go ahead and try it ported to around 15 Hz Just to see the difference. I really have nothing to lose except a little scrap MDF, I guess there is no test like the hearing test, also. Does anybody know if the DSP might help with the group delay? Oh yeah, I just read something in the new pro Alpha ver. And I quote : If you are wondering why the group delay of vented box is very different from WinISD version 0.43 and below, the reason is that it calculated it wrong. Current versions produce correct results.
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