Designing A Sub Around 4cuft - SI 15, SI 18, HO 15 - AVS Forum
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post #1 of 15 Old 08-31-2014, 07:00 AM - Thread Starter
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Designing A Sub Around 4cuft - SI 15, SI 18, HO 15

In my family/theatre room - I've got room for two subs if I can keep them around 4 cubic feet each. I'm trying to determine what the best design/driver is, given that constraint. I understand I'm going about this backwards from what is optimal - buying a driver and then planning an enclosure around it - so please bear with me. I might be able to shuffle some things and get enough room to fit two MartyCubes with SI 18's, but that's a big IF. So for the purposes of this discussion, I'm assuming the following constraints:


1) My available space is 24x21x21.
2) I have an Inuke3000DSP


I'm relatively new at modeling in WinISD, so fingers crossed. Throw in ported designs, and things get pretty wild pretty quick. So I'm going to show all my work just in case I messed something up. I looked at three scenarios.


1) Green: Sealed SI 18 in 4 cuft. Wired for 2 ohms, 1040 watts input.
2) Blue: Ported Dayton HO 15 3.75 cuft tuned to 23. (This is Chaluga's mini-cube concept, only I made the slot port 2" high based on some commentary I saw from Bill F.) 4 ohms, 680 watts input based on the inukes 4 ohm RMS.
3) Pink: Ported SI 15 in the same box. Wired for 2 ohms, 1040 watts input.


When I look at my SPL charts, I say I want to go with the SI 15 ported first. Then the sealed 18"SI. I'm not seeing the benefit of going with the Dayton HO 15. I just don't have enough confidence in my modeling to say if this is a correct conclusion or not. Especially since I've seen comments from posters more knowledgeable than I that indicate the SI 15 doesn't do well in small boxes. So I'll take any and all comments on where I screwed up, where I'm crazy, etc...
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post #2 of 15 Old 08-31-2014, 07:02 AM - Thread Starter
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Cone excursion seems to be under control with a highpass on the ported models. Xmax = .89 on the SI drivers, and .47 on the Dayton.
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post #3 of 15 Old 08-31-2014, 07:06 AM - Thread Starter
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This is the part where coming up with a decent design got really tricky. There was a lot of trial and error and internet research involved in finding the right port height/width, etc. Air velocity is a tick high on the SI, but doesn't seem horrible. My first port resonance could be higher, but I think I'm in an OK zone? Or no?


I'll take any and all comments. I've had fun working on this and learning about ported design, but I'll be the first man to say I'm not an expert.
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post #4 of 15 Old 08-31-2014, 01:11 PM
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Why no UM-18 or UM-15?
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post #5 of 15 Old 08-31-2014, 01:27 PM
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Quote:
Originally Posted by BassThatHz View Post
Why no UM-18 or UM-15?
Cuz with two subs only the ported will beat the um handily in 20 to 35hz.
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post #6 of 15 Old 08-31-2014, 01:30 PM
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I'm giving my Dayton 390 ho 1500 watts for a month now with no issues . No chuffing. When we were at jbrowns we gave it 2000(forgot to put limiter on) and bassthathz felt driver when it was driven hard and it was fine.
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post #7 of 15 Old 08-31-2014, 07:07 PM - Thread Starter
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Quote:
Originally Posted by BassThatHz View Post
Why no UM-18 or UM-15?
Every thing I read indicated they like a really large ported box. PE is recommending 8 cuft on the 18. I guess I could try modeling them and see what happens.
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post #8 of 15 Old 08-31-2014, 07:15 PM - Thread Starter
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Quote:
Originally Posted by chalugadp View Post
I'm giving my Dayton 390 ho 1500 watts for a month now with no issues . No chuffing. When we were at jbrowns we gave it 2000(forgot to put limiter on) and bassthathz felt driver when it was driven hard and it was fine.
I don't think I've got the amp to drive them that hard unfortunately. Unless I send the inuke back and move up. But I'd prefer to stick with the 3000 if possible.
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post #9 of 15 Old 08-31-2014, 07:21 PM
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I don't think I've got the amp to drive them that hard unfortunately. Unless I send the inuke back and move up. But I'd prefer to stick with the 3000 if possible.
Yeah I traded my 3000 for a 6000. Not hard to sell the 3000 on classifieds here. Or get another 3000.

Its a 4db gain for one and 6db with two subs. 6dbs is significant .
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post #10 of 15 Old 09-02-2014, 06:31 AM - Thread Starter
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I'm going to give this a shameless bump to see if anyone is willing to take a few minutes and at least confirm that my modeling seems to be accurate. If someone would be willing to do that, I'd really appreciate it! That would at least give me some confidence I'm doing the modeling correctly, and then I can take a look at a couple other scenarios (UM, infinity drivers).
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post #11 of 15 Old 09-02-2014, 10:49 AM
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I recently did pretty much the exact modeling you have posted here and came up with the same results. I think the si 15 will work just fine in a 3.75 cu ft box an should give you better across the board for the same input power.
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post #12 of 15 Old 09-02-2014, 11:09 AM
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I'm also thinking of a (4.4net) enclosure for the SI15"

...This is the difference that 2 different people modeled between SI15 & SI18" in (5 cuft net)



Here is the other graph of the same 2
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post #13 of 15 Old 09-02-2014, 11:44 AM
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One thing to remember is the dayton driver can handle more power. About 400 watts more.
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post #14 of 15 Old 09-02-2014, 12:52 PM - Thread Starter
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chaluga - I actually ended up canceling my inuke3000dsp order. I wanted to make sure I left my options open since the 3000 can't deliver that sort of power into two subs @ 4ohms. The x4000 on the crown thread is an interesting option, but I'd need to tack on a mini-dsp to the purchase price I think.
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post #15 of 15 Old 09-02-2014, 12:59 PM
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6000 is capable of running four subs. If your not going crazy with 8 subs you wont need to upgrade.
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