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Old 31st August 2003, 12:31 PM   #1
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Default Isobaric 6th order box

Hi all. Sometimes I plug some numbers into WinIsd just messing around, and I find some relatively ordinary drivers will really deliver the goods down to the low 20's when in a 6th order box. Trouble is, they sometimes need to be about 500+ litres! Has anyone had any experience with using a 2 driver (or more!) isobaric 6th order setup? A halving of the box volume in this size range would make a big difference.
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Old 31st August 2003, 03:11 PM   #2
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yepp we filled up a pick up truck box with a 6 chamber enclosure with clam shelled 15 inch drivers and a isolated blow in through to the cab.....owner said there wasint enough bass....so after all the sweat that went into it I turned up the gain on the amp and blew out his front windsheild and shook my head...he bragged how he saved money putting it in himself the prior week but the idiot was willing to spend 25 grand on a system for his truck
to top it all off before the project I brought him into my vehicle and played a few tracks and he was impressed......I was running one 12 in sub
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Old 31st August 2003, 03:17 PM   #3
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lets think about this.... twice as many speakers.... twice as much wood cos you need some stupidly HUGE box... why not just buy a driver more suited to a smaller enclosure?
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Old 31st August 2003, 08:37 PM   #4
VEC7OR is offline VEC7OR  Lithuania
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I've built my bandpass using single 8" driver, it's doing 30hz without any problem - I had to make bigger box to hide vents inside (I could have used smaller shorter ones but I dont want to hear them whistle), I was using 4" vents tuned to 30 and 70 hz, they were 89 and 23 cm long - IF I have gone isobaric AND used 3" or even 2" vents(lets assume we making this sub for a car) - Instead of being 93x43x30(ports are hidden inside) - we can get away with 15l and 7.5l boxes, using 2" ports their lenths would be 32 and 10 cm - 30l IS a small box(well the floor is shaking )
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Old 31st August 2003, 09:39 PM   #5
7V is offline 7V  United Kingdom
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Quote:
Originally posted by JOE DIRT®
... owner said there wasn't enough bass....so after all the sweat that went into it I turned up the gain on the amp and blew out his front windshield and shook my head...he bragged how he saved money putting it in himself the prior week but the idiot was willing to spend 25 grand on a system for his truck
Way to go, Joe!

SkinnyBoy, with an isobaric configuration you use two drivers but only need half the volume. You lose 3dB on the efficiency too.

Circlotron, if you can stand a 3dB drop and if you like the 6th order configuration, isobaric will do the job well. It is, as you have said, an ideal configuration where cabinets would otherwise be too big.
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Old 1st September 2003, 01:59 AM   #6
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yep but u have to buy 2 crap woofers instead of 1 ,

or 1 good one..

so its more risky.
what if they have rubbing VCs, or an annoying rattle,

or anything.i thinks more suited to a CERTAIN cheep-e ,

dont forget tuning below Fs on cheep woofers-cant be too healthy.

here in NZ there is simply overpriced cheepie subs,or ADIRE from OZ,thats about it,,

so my 2226h is my weapon/transducer of choice.

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Old 1st September 2003, 08:45 AM   #7
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how cheap is cheap? I am buying some cheap 8 inch subs.... $39.90 Australian each (thats if you buy 8 or more, and I have gathered a bunch of people who all want some) putting 2 in about a 65 litre box tuned to around 35Hz.... using a 4cm X 24.4cm slot port.. details and a picture are here.... and I will attach my WinISD project file.. only cos Circlotron is an Aussie too.. The bigger subs in the Venom range require a HUGE tuned box to get a flat response... the 8inch only requires 30litres..

http://www.advanceae.com.au/car/prod4.htm

If ya tune it even lower (below the fs, say 30Hz) you should be able to get 110dB at 30Hz from 2 of these in a 65litre enclosure.. hahahahaha!!

hmm... didn't we use to be able to attach those files un zipped?
Attached Files
File Type: zip 8inchvenom.zip (833 Bytes, 14 views)
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Old 1st September 2003, 10:00 AM   #8
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Electronics World carried a full project article by Jeff McAullay sometime back (October 1995 or something but can't be sure) which used a sixth order alignment with electronic correction; the sub was a micro-reflex box with 4 X 8" woofers. The response was -3db at 20Hz. The box dimensions were 1'x1'x2' - a footprint of one sqaure foot.

You can make this great sub with almost just about any good 8" woofers or sub-woofers, apart from the ones specified by the author. Having made this sub a number of times using different brands of speakers as well as various amps, I can vouch that it is one of the best subs that I have ever heard, Velodyne, B&W, Jamo et al included.

You can't go wrong with this sub!!

You can't go wrong with this sub!!
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Old 1st September 2003, 11:56 AM   #9
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Thumbs down SkinnyBoy - Ace audio consultant...

In a previous gem of advice to me you said...
http://www.diyaudio.com/forums/showt...298#post110298

and yet in contrast, here today you say...

Quote:
Originally posted by SkinnyBoy
lets think about this.... twice as many speakers.... twice as much wood cos you need some stupidly HUGE box... why not just buy a driver more suited to a smaller enclosure?
You have just attained a new standard of some sort. Q.E.D.
http://www.swif.uniba.it/lei/foldop/...+demonstrandum

/Circlotron - builds real stuff, not vapourware. Also has a long and detailed memory of postings...
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Old 1st September 2003, 12:02 PM   #10
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Quote:
Originally posted by Samuel Jayaraj
[B]Electronics World carried a full project article by Jeff McAullay sometime back (October 1995 or something but can't be sure) which used a sixth order alignment with electronic correction; the sub was a micro-reflex box with 4 X 8" woofers. The response was -3db at 20Hz. The box dimensions were 1'x1'x2' - a footprint of one sqaure foot.
Mmmm.... sounds good. How were the woofers mounted? Can you post a rough sketch. This is interesting.
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