How are commercial subs so small?

AlexKunec

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Mar 9, 2002
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Went up town the other day to see how commercial subs perform. looked at mostly paradigm, mirage. The paradigm 15" was about 2.5cuft SEALED and clamed it had an f3 at 18hz!
There 12" vented was a tad bigger and went down to 21hz.
How do they achieve this depth which these boxes??
 

Mark gas

Second Unit
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Mar 23, 2002
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322
My 15 inch kicker L7 only needs a 1.5 cube box. It all depends on the driver. Also a smaller box = less shipping.
 

Cam S

Screenwriter
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Jan 11, 2002
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But can that Kicker go as low as it would in a bigger box, say 4cuft, doubt it.
 

Brian Bunge

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Sep 11, 2000
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Actually, the add a lot of equalization to get flat response in such a small box. Of course, even with an F3 of 18Hz, it doesn't mean that it'll do 120dB at 18Hz.

Brian
 

Shawn Solar

Supporting Actor
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May 12, 2001
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763
They also use circutry in the amps to boost the subs lowend response. To force it to go lower. A nice thing about designing a sub from a manufacturers perspective is they can design the sub and amp around the enclosure and can change parameters of the driver and amp to suit there needs. Where the DIY'er has to build the sub enclosure around the sub driver then find a amp to work with it.
 

Mark Tranchant

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May 9, 2002
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Where the DIY'er has to build the sub enclosure around the sub driver then find a amp to work with it.
Not so, if you're willing and able to build some electronics. Look at this page - you can put pretty much any driver into any box and use this circuit to set it up how you want, trading off efficiency and maximum SPL for frequency response.
There is a full explanation of how this works at this page, although the spreadsheet download link is broken. The same sheet can be had from the first link, though.
I plan to use this in a fairly compact (1.3cu ft) sealed driver with a 12" driver to get an f3 of 20Hz. My domestic situation does not permit high SPL, so the compromise is fine. The (fairly inexpensive car subwoofer) speaker will still be able to give of 83dB at 20Hz before burning out (225W rms), so I'm looking at about 80dB with the 100W rms amp I plan to use. I'd still get told off at that level...!
 

Rudy H

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Mar 2, 2002
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They also use circutry in the amps to boost the subs lowend response. To force it to go lower. A nice thing about designing a sub from a manufacturers perspective is they can design the sub and amp around the enclosure and can change parameters of the driver and amp to suit there needs. Where the DIY'er has to build the sub enclosure around the sub driver then find a amp to work with it.
Precisely, and they likely dont measure they're sub in
anechoic conditions either.
 

Michael R Price

Screenwriter
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Jul 22, 2001
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Many manufacturers such as Klipsch use actual measurments, but the procedures are so absurd it might as well be lying.

The small size is accomplished with a lot of equalization. DIYers can do this too with EQ or a Linkwitz transform. But remember the Iron Law - potential efficiency at any given frequency is directly related to box size.
 

Ron D Core

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Mar 31, 2002
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Its all one big advertising scheme to attract all those people who want more than the TV's speakers and don't want a big box in their room and don't care a whole lot about the sound other than how loud it booms. I don't care what anybody says, some tiny prefab, heavily equalized woofer will never be worth the money you pay. Spend 400 dollars on a nice big ass Tempest sonosub with 250W plate amp, and it will eat those wee little, rigged up pieces of crap for lunch. Way more efficient, increased output and near perfect frequency response.
 

Mike Strassburg

Second Unit
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Nov 4, 2001
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421
As stated before with a small enclosure you lose SPL, usually don't go as low, and also require a LOT of power...think Sunfire Jr @ 2400 watts. But not everyone desires a "killer" sub, and many have to settle for a small box that can be hidden.....or else sleep in the garage!
"No replacement for displacement"...that's why I built a 480L dual Tempest. With only 250 watts per speaker I get 110db @ 16Hz and 127db @ 31.5......ain't no little cube gonna do that

I even demoed the huge Mirage "coffe table" sub and it didn't go very low and distorted soooo easily. The Rel did have some punch in the upper frequencies, but again it didn't do anything down low.
As MANY have said you can really come out ahead when building a DIY sub, so get busy!
 

Shawn Solar

Supporting Actor
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May 12, 2001
Messages
763
The biggest problem I find is a lot of manufacturers don't use the proper size port. more times than not I've come across subs that just chuf and weeze on low bass. And its probably due to the fact that they can not fit the bigger port needed in such small enclosures.
 

Chris Tsutsui

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Feb 1, 2002
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You can look at the specs on the commercial subs, but that's different than comparing how they "sound" to a DIY subwoofer that cost half as much.
I'll bet a lot of ppl are pleased with the bang per buck a DIY sub can give and remember, it's not the size of the sub that matters, but the motion of the ocean (bass).

I've heard a commercial sub hitting a low note but the reason it was so loud was the addition of a fluttering port noise that probably added 6 decibels. yeesh
 

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