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6th or 8th order subwoofer?

post #1 of 13
4/2/12 at 11:35am
Thread Starter 
So about 5 years ago while I was working at a Storage facility, I came across a DIY Sub with an NHT1259 in a 3 chamber box, with 3 ports outside, and 2 internal. My Pro sound knowledge led me to believe this is a 6th or 8th order bandpass. When i ran a plethora of audio through I found to be quite flat as a sub, doesn't really favor any one frequency. Aren't 6th/8th order boxes supposed to favor like one narrow band at high SPL's? Overall this box kicks, and all my audio engineer buddies borrow it from time to time sayings its one of the flatest subs they've heard Either way this box baffles me and was hoping for some insight.. Yes I'm new here....
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post #2 of 13
4/2/12 at 4:57pm
I believe in these designs efficiency can be traded for bandwidth, which is apparently what they did.
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post #3 of 13
4/2/12 at 5:13pm
The ones I built 25 years ago had a very narrow response with extreme output and acoustic lpf and hpf. I hated the sound. Course that was along time ago.
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post #4 of 13
4/2/12 at 5:50pm
Triple chamber bandpass?

http://www.audiokarma.org/forums/sho...amber+bandpass
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post #5 of 13
4/2/12 at 7:39pm
Quote:
Originally Posted by mobeer4don View Post

Triple chamber bandpass?

http://www.audiokarma.org/forums/sho...amber+bandpass

The JBL design is a very close relative to manifold boxes, and differs substantially from the OPs design, though exactly what it is I can't say from the pictures alone.
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post #6 of 13
4/2/12 at 10:42pm
Hey, that's a Bose box.
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post #7 of 13
4/3/12 at 3:29am
It could be an acoustic bi chamber (ABC) box. In an ABC box the front and the rear of the sub woofer are ported a different frequency's, one high one low.
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post #8 of 13
4/3/12 at 3:37am
In the day that 1259 was the cats meow. I think AR used it too.....
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post #9 of 13
4/3/12 at 5:04am
Quote:
Originally Posted by datranz View Post

Hey, that's a Bose box.

That's what I was thinking of. If memory serves the Bose AM are 8th order boxes with one to two drivers (The ones that *aren't* t-lines that is); it gives them a fairly narrow passband that is relatively flat and achieves (relatively) good output. They don't "favor" much either - figure from 40-200hz or 50-200hz they're good, and everything else is garbage. Most clones get something wrong in the math or construction.

Interesting to see it done in a bigger box with bigger (better?) drivers.
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post #10 of 13
4/3/12 at 5:19am
Back In my car audio days, I made quite a few of the Orion double reflex boxes. Actually, I may have made them all... The plans were In an Orion newsletter called "Automotive Audio". I recall the Orion rep telling me they needed to stop making plans available for the double reflex boxes because of a patent infringement on Bose. Your box looks very similar, I bet It rocks.
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post #11 of 13
4/3/12 at 6:21am
I remember those news letters! I had an Orion xtreme single reflex news letter. I still have a mtx rt2 book.
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post #12 of 13
4/9/12 at 10:12am
Thread Starter 
Thanks Everybody! I apreciate all the info, Walbert you may be right, as anything about 250-300hz up sounds a little boomy and muddy. When I cross it over around 200Hz or even 150Hz this thing will shake the entire house with only 150 Watts from a Carver Cube M400A. I'm Building a new house currently and have been thinking of ditching this guy (or putting it in the man cave) and building an IB in the floor. I was thinking about building a cheap IB for now and upgrading the drivers later. Could any of you guys reccomend the best bang for the buck on a few 15"'s or 18"s? My lady hates the space the sub takes up and I know I'll get more clearer bass from an IB. Thanks
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post #13 of 13
4/9/12 at 9:24pm
It's hard to tell from those pics because they are confusing.

It might be an 8th order bandpass. In that case, both chambers containing the driver output vent into the other chamber, which itself has a port as well. A 6th order differs in that it doesn't have that third chamber. In an 8th order, all output comes goes through a single port in the third chamber.

Looks like it could possibly defy definition.
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