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Old 28th September 2007, 10:57 PM   #1
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Default Problem with my TB and sonotube

Hello, I have four of the Tang Band 8 inch neo subs and am trying to figure out what to do with them. I thought I would play with one of them so I put it in a sonotube since they are easy, cheap, and people like the end result. My tube is 10" inside diameter and 4' tall. Port is 2.75" inside diameter and 7" long. (no chuffing from what I can hear) So after displacement I should have a cabinet about 2 cubic feet tuned to 29 hz. I figured thats a good frequency since the driver has an fs of 30 hz.

It basically sounds like a sub in a tube, boomy, not loud at all. I like boomy but this is way to high of a cycle. Is my box too big? I thought bigger was better since I have seen pics of peoples' subs that have 12 inch drivers that reach the ceiling. Could it be because I have no acoustic stuffing in it? I put the TB in a cerwin vega cabitnet .86 cubic feet tuned to 45 hz and it sounded great. Hmmmm any ideas. I would like to keep the box big if it means more output, but I want it to sound like a sub.

Thanks
Dan
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Old 29th September 2007, 04:20 AM   #2
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Greets!

I can see why it sounds a bit 'one note' and by the time you got through stuffing it the result would be pretty near the sealed response (blue trace):

GM
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Old 29th September 2007, 04:44 AM   #3
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Vent length reduced to 3" and tube stuffed with 1.0 lb/ft^3 polyfil from driver down ~38":
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Old 29th September 2007, 05:27 AM   #4
owdi is offline owdi  United States
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Did you model the sub? 2 cubic feet sounds like too large of a box for that driver. Maybe you can replace the port with another TB driver to create a sealed box.

Dan
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Old 29th September 2007, 05:56 AM   #5
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Ok I'll try it thanks. What program are you using? If I shorten the port to 3 inches then winisd gives me a huge peak at 40hz. Although it doesn't allow me to factor in the poly fill. Am I using winisd wrong because you got a pretty smooth response. Does it matter that if the port and driver are on opposite ends. It kinda has to be that way since its only a 10 tube (biggest home depot sold lol).

Thank you again for you advise I will try it.

Lets say I were to sell these drivers to fund an 18" subwoofer project so that I can get to the lower frequencies, what 18" driver would you recommend. (ported cabinet/sonotube, cabinet size 12ish ft^3 or less, will hit 16 cycles or lower, and I can run it off of a 1000 amp) 1/2 ht and 1/2 music. I have been looking at the mach 5 ixl 18.4 but don't know. These 8" drivers won't go that low but sound nice. I'm sure 4 will get plenty loud too. Hmm sorry I am rambling. Time for bed. Thanks again

Dan
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Old 29th September 2007, 02:34 PM   #6
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Greets!

You're welcome!

Typical box programs like WinISD assumes a 'perfect' cab with a uniform particle density air mass while MJK's MathCad worksheet (WS) takes into account any high aspect ratio cab's harmonic structure which damps the vent's output, effectively making it perform as if it were larger/longer and the polyfil continues the trend: http://www.quarter-wave.com/

My 'hands on' experience is mostly with prosound drivers, ergo the few 18" sub drivers I'm most familiar with are very expensive and their high Vas requires huge cabs when tuned to Fs or below, so do a forum search to see what folks are using. There's probably some autosound 18"ers that will work well in tapped horns, sub duty pipe horn (aka BIB), and/or Sonotube style TL or MLTL (what you currently have), so lots of DIY options nowadays.

Anyway, four 8" is only ~ = a single 15", so stepping up to an 18" is worthwhile for a low tuned sub system if you have the space available and no major SAF issues.

GM
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Old 29th September 2007, 11:29 PM   #7
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You might want to consider 15s instead of 18s as there are a lot more good inexpensive 15s out there than 18s and a proper 15 can give quite a bit of low bass output. If you really need more two good 15s might still cost less than an equivalent 18 if you could find one.

just a though.

mike
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Old 30th September 2007, 07:42 PM   #8
owdi is offline owdi  United States
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I'm all hot and bothered over the Dayton Reference subs, especially because I can't have one right now. If I had 12 cu ft to work with, I would buy 4x 12" Dayton Ref subs, and build two bipole subs of 6 cu. ft each, tuned to around 18hz each with a big slot vent.

Dan
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Old 30th September 2007, 08:05 PM   #9
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Well, if we're going to get into multiples, then as much as I like bipoles, for sub duty I'd build four separate subs to get more room tuning flexibility.
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Old 1st October 2007, 06:24 AM   #10
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I don't think I could get the wife to go for multiple subs right now, the place is not all that big. Thats why I thought I could go to 12 cubes but smaller is better. I want output and depth so I thought an 18 would be the way to go, but I could go for dual 15s. I need to stick to one cabinet.

Dan
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