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The plan is to have a 20" sonotube .......

This is another area of concern. Using a 20" sonotube will leave you with a very narrow end cap on the sub end. Have you considered that aspect? That's why most of us use a 24" sonotube. I know you have space constraints.

Using an 18 Hz tune as mentioned above with a 4th order high pass at 16 Hz and 1200 watts will have a port velocity of 23.5 m/s. 1200 watts is the actual power a NX6000 makes per channel into 4 ohms.
 

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Discussion Starter · #22 ·
This is another area of concern. Using a 20" sonotube will leave you with a very narrow end cap on the sub end. Have you considered that aspect? That's why most of us use a 24" sonotube. I know you have space constraints.

Using an 18 Hz tune as mentioned above with a 4th order high pass at 16 Hz and 1200 watts will have a port velocity of 23.5 m/s. 1200 watts is the actual power a NX6000 makes per channel into 4 ohms.
The plan with a 20" tube is to have slightly larger end caps to properly secure the driver. Once wrapped with thick felt it won't look awkward either. And wow, only 1200w, that's less then half the advertised wattage!?

23.5m/s is acceptable yeah? I may possibly hear a tiny bit of port noise in the 20hz and below range at reference volume but that's it?

A 24" tube is just not an option. It would be so close to the wall and my Left/Right speaker stands that it would look like garbage. I've custom built my own stands and entertainment unit, I take pride in the appearance of the setup. As much as the acoustics is import to me, I'm not going to completely sacrifice the esthetics for a disproportionately large enclosure for the set up.

If it is absolutely not possible to get my desired low tune with a box of limited size, I understand. I'm just hoping and believing there is a way, some sort of minor compromise or a trick or something. That's why I'm picking everyone's brains here and asking so many questions. I won't give up until I'm absolutely positive that a 4ish foot tall, 20" wide Sonosub cant hit 15-20hz with some serious oomph.

I appreciate all the input so far.
 

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UM18 is a decent driver but I like them better in sealed or larger enclosures. I like it, just not for vented unless it's a BIG girl. IMO 4cuft is small for sealed and twice that is small for vented. If you need it to be small there are better driver options and if you want the extra output of vented, and you want it tuned low, and you want it small, not only are there better driver options but you should consider passive radiator alignments, although they generally will not work with the PR up/down firing.

Chris
 

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If you need it to be small there are better driver options and if you want the extra output of vented, and you want it tuned low, and you want it small, not only are there better driver options ....

What other drivers do you recommend Chris, other than pro 21s?
 

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The plan ..

Yeah, they will make a little bit more than 1200 at certain frequencies, but that's a real world number. It's actually a good match for the UM18.

The port noise shouldn't be too bad. As long as you aren't boosting them excessively. What size room will they be in and do you normally run your subs hot?
 

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Discussion Starter · #26 ·
Yeah, they will make a little bit more than 1200 at certain frequencies, but that's a real world number. It's actually a good match for the UM18.

The port noise shouldn't be too bad. As long as you aren't boosting them excessively. What size room will they be in and do you normally run your subs hot?
Room is 12' x 16' with half of the back (6ft) open to the rest of the basement. 7 ft ceilings.

I don't boost my bass excessively. Although my wife and friends do, none of them appreciate subwoofers. Haha

I also wonder what other subs Chris recommends? That said, part of my problem is being in canada, and having a very limited selection of affordable audio gear. Most isn't sold here, or I have to pay an outregous amount on shipping.
 

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Since the Vas is 7.49 cuft to get the maximum efficiency (SPL output) rule of thumb based on the Thiel Small parameters a similar volume behind the driver is needed. Now the TS parameters are small signal models(1 watt) of the drivers. The WINISD is program that tracks the T/S model very well.

However a limitation on winisd is if you want to see port velocities and run the model in the non-linear range it isn't very accurate. I very good starting point though.

Since you have fabrication skill I would stay away from the sonotube since port mounting is a challenge and building a plywood box is easier to deal with for tuning purposes.
 

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Oh and one final note. The Fs on the driver is 19.5 Hz. If you run it below that point (17Hz) you will need a high pass filter to make sure you don't go above Xmax specification and damage the driver. Very easy to do.

I have a pair of SQL-15 from SI and will be doing a ported design for them.....Not sure though with shipping if my information will be of value to you.

I have been designing and building sub-woofers since 1971.....I usually use LEAP from LinearX for modeling subs. Test with a clio system
 

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Make friends in Maine or Washington, or whatever, and start an international mobile DJ business?

Or maybe just install them in your car audio system down south... :p
Yep. For $90 get this sucka shipped to a buddy near the border, screw 'em in and drive back. What? Those ol' things? Had 'em forever.

 
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