Please help me understand this subwoofer design

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What kinda power into what load is your amp capable of? The TangBand W6-1139 is a 4ohm driver, 6.5" subwoofer, 11.5mm xmax. There is a design on Parts Express that uses 4 of them, you could half that if necessary or maybe even use 3 if thats all that will fit. http://www.parts-express.com/projectshowcase/indexn.cfm?project=Boogieman


Does your car have the mounting holes that the Bose box uses to hold it down? I suppose you could make a box with no bottom on it if it was tightly secured to the carpeted deck. This would give you a bit more volume or even use a thinner piece of ply for that panel as it will be held in place sandwiched between the box and deck.
Are you gonna try to incorporate midrange drivers into this box like the Bose has or go about the rear fill another way?
 
@navin: thanks for the links. This shallow sub looks interesting.

@901Fixer: Audison LRX amp can delivers 65W per channel on 4 ohm, 105W per channel on 2 ohm (continuous RMS). In bridge mode, it's 220W on 4 ohm.

@901Fixer: yes, my car has the mounting holes. Eventually I may add midrange drivers, it might be nice to have a tiny bit of rear fill.
 
Arno...

a Tangband based sub like the Boogieman would definitely work...but if you make an Isobaric , you can get away with a lot smaller enclosure...

regarding "rear fill", I've yet to go to a live performance of any musical event that asks the audience to sit with their backs to the stage...
If properly done rear fill is OK, but a good basic layout of door speakers, and dash and/or kick panel speakers can easily portray music in a very appealing manner.
 
Re: Arno...

@901Fixer: Audison LRX amp can delivers 65W per channel on 4 ohm, 105W per channel on 2 ohm (continuous RMS). In bridge mode, it's 220W on 4 ohm.

@901Fixer: yes, my car has the mounting holes. Eventually I may add midrange drivers, it might be nice to have a tiny bit of rear fill. [/B]

If you intend for this box to fullfill the same need as it did earlier (woofer + wide range) you might be better of using a woofer such as the Dayton, Fountek, Peerless linked below
http://www.parts-express.com/pe/showdetl.cfm?Partnumber=295-335

http://www.madisound.com/catalog/product_info.php?cPath=45_228_256&products_id=8492

http://www.madisound.com/catalog/product_info.php?cPath=45_228_256&products_id=8234

Otherwise as a subwoofer the Tangband 1139 will go lower
and produce more low bass levels

http://www.parts-express.com/pe/showdetl.cfm?Partnumber=264-832

Nanook said:
a Tangband based sub like the Boogieman would definitely work...but if you make an Isobaric , you can get away with a lot smaller enclosure...If properly done rear fill is OK, but a good basic layout of door speakers, and dash and/or kick panel speakers can easily portray music in a very appealing manner.
exactly something like this
http://www.stardi.com/diy-4th-order-isobaric-subwoofer-5-6/

as far as rear fill goes it is often just personal taste. if the HU of the car audio system has TA (time alignment) for all channels the rear fill can well be used for spatial effects.

BTW the audison amps are quite good esp the VRx series.
 
Do you have any pictures of where this thing goes in the car? I can't imagine the car being so small that there isn't somewhere available that can be fiberglassed and accomodate one of the uber-shallow mount style subwoofers or a couple of those tiny tangbands.

If you've got space in the engine compartment or anywhere else outside of the interior cabin, you could build a 4th order bandpass and run the vents into the cabin... I always wanted to do that with a Pontiac Fiero. :D
 
FWIW, when I looked at the photos the other day I saw a rather innovatively laid out, high tuned (small front chamber) 6th order BP once secured/sealed to a surface with a pair of high Fs 'full-range' drivers to presumably add some surround ambiance and after taking a 'fresh' look just now I still believe it is. IOW, other than the layout, just another typical B@$3 alignment.

GM

Looks to me like there's some pretty decent engineering here. For the life of me, I've never been able to understand all the hate for Bose. (Don't want to hijack the thread.) Basically their stuff is crazy overpriced, but I've never found the engineering to be all that bad. I think that if their stuff sold for 1/4 the price people wouldn't hate them as much. But if they sold their stuff for 1/4 the price they likely would have gone belly up thirty years ago. Heaven knows there have been tons of well-engineered speakers which went kaput because the manufacturers sold them for a price that was too low. (cough cough NHT)
 
Looks to me like there's some pretty decent engineering here. For the life of me, I've never been able to understand all the hate for Bose.

Didn't say it wasn't, just what was old is yet new again. They often take lapsed patents and make them their own, claiming it their breakthrough innovation.

I intensely dislike them for their bully type marketing, like trying to strong arm Consumers Union for having the audacity to publish an unflattering, yet accurate, frequency response of one of those lifestyle two way cube, BP sub systems and IIRC the private individual that posted his own similar one on-line.

Then there was the bogus marketing where what potential customers heard in the stores was being enhanced behind the scenes. Ditto the early door-to-door selling of the TL loaded radio/CD player. Me and a buddy got taken in on this scam. I didn't buy one, but recommended it based on the demo, but what he paid $800 for back in the mid '80s didn't perform nearly as well and he got no satisfaction from corporate AFAIK.

As for pricing, to charge less than the market will bear is a bad business plan, so can't fault them for that. After all, last time I noticed, they sell more consumer systems than most others combined, so they are apparently a bargain for those folks who aspire to own them, as unbelievable as that seems to folks like us.

GM
 
So, Arno, what have you done in the last 3 years?

Since my last post I have acquired a '96 Mazda Miata so I'm in the same "limited space" position you are when it comes to bass. I had considered building a vented enclosure for the package tray behind the seats using two TB W6-1139 but each would need ~.88cuft net volume plus a rather large displacement vent/port.

I gave in to technology and bought two Elemental Designs E3.8 8" subwoofers. They only need ~.35cuft each sealed. I may need only one since the Miata is so small and I'm not a basshead. I'm amazed at how small enclosures can be these days for sealed subwoofers.
 
Originally Posted by Brian Steele View Post
They might have been doing 126dB when given a 44 Hz signal, but are you sure that the output was 44 Hz and not a whole lot of distortion?
...no? it was 44hz.
If you measured with a dB meter, you are measuring the combination of harmonics and fundamental.
If you measured with an RTA, you will see what the harmonic content is in relationship to the fundamental. It is not at all unusual for the harmonics to exceed the fundamental when driven hard, and since the first harmonic is an octave, it sounds quite similar to the fundamental.
 
what exactly are you trying to argue? it WAS 44Hz at 126dB from two 4inch mids...

measurements were on a termlab SPL meter, they don't even register anything above 80Hz.
Oh.

Please show your "termlab RTA" results, the link you posted clearly shows a 46 Hz fundamental at 159 dB with a 92 Hz harmonic at 138 dB.

To state the obvious, Termlab registers above 80 Hz, though the SPL reading would be a combination of whatever is loudest and the lesser output below or above the fundamental frequency used.

A -21 dB first harmonic at a 159 dB level would be outstanding, only 8.91% distortion.

I'll not hold my breath waiting for your Termlab RTA reports of 126dB at 44Hz from two 4 inch mids.
Then again, you did not state the measurement distance or size of the room (car?), so anything is possible, especially in a closed small chamber.

Art
 

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in car.

folded horn.

126dB, 44Hz, no pics because this was years ago now.

and, what link I posted? :/
Sorry, I looked up Termlab, the picture was from their site, not a link from you. As you can see, the Termlab reads above 80 Hz, so the 126 dB could easily have been a combination of 44, 88 and 132 (and even higher harmonics) Hz, no way of knowing without an RTA picture what made up the 126 dB.
 
So, Arno, what have you done in the last 3 years?

Since my last post I have acquired a '96 Mazda Miata so I'm in the same "limited space" position you are when it comes to bass. I had considered building a vented enclosure for the package tray behind the seats using two TB W6-1139 but each would need ~.88cuft net volume plus a rather large displacement vent/port.

I gave in to technology and bought two Elemental Designs E3.8 8" subwoofers. They only need ~.35cuft each sealed. I may need only one since the Miata is so small and I'm not a basshead. I'm amazed at how small enclosures can be these days for sealed subwoofers.

There's a dude on Diyma that's running dual fifteens in infinite baffle in a Honda S2000.
Might be worth a look. Infinite baffle is a very attractive option in the car, due to space limitations.
 
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