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Old 27th February 2013, 09:25 PM   #1
tigox is offline tigox  Portugal
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Question About sub boxes..

Hey, i've always seen big subwoofer boxes that give a hell load of bass...
but what i never in my life got is how do companies like samsung that make home theater subwoofers , like subs with 6.5 inch drivers and have a tiny box and with a port almost the size of my fist and still ratter my house???!!

Shouldn't smaller boxes give less bass?
And shouldn't big ports be long??
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Old 27th February 2013, 10:13 PM   #2
kouiky is offline kouiky  United States
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Often, its the same way Bose achieves an acceptable response from mere pedestrian grade components- generous electronic equalization and high excursion combined with low Fs and Qts, neither of which make the driver better sounding on their own. Bose and JVC used two different orders of bandpass alignment and Bose patented their quarterwave rear loading of the bass driver in the waveradio and later models of the acoustimass. For the most part, the eq plays a large role. I find it funny they patented a technology that they didn't invent, and had been used by others generations earlier.
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Old 27th February 2013, 10:19 PM   #3
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May be as much the resonance of your house. Also depends on what you mean by more or less bass. The music frequencies that people usually connect with bass are well within the range of a 6.5" driver. Especially, as noted, when EQ'd. Ever heard of "bass Boost?"
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Old 27th February 2013, 10:22 PM   #4
tigox is offline tigox  Portugal
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doesn't bass boost supposably make the subwoofer distord a bit ?

And also i don't understand very much about fs and qts etc.. combinations , can someone make me understand a little bit or does somebody have any wbe page on this subject?
Tnak you guys D
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Old 27th February 2013, 10:43 PM   #5
wg_ski is offline wg_ski  United States
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If you boost the hell out of a frequency that the "sub" has no problems reproducing and it will sound bassy. Give it 20 dB of boost at 90 Hz and filter everything below 50 (to keep it from falling apart) and you have the impression of "good bass". Until you hear a real system and then everything changes.
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Old 27th February 2013, 10:47 PM   #6
kouiky is offline kouiky  United States
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Better than webpage or whitepaper, I can explain the important basics right here. There is more to reproducing low frequencies than just a large driver in a large box. A woofer/driver has certain electrical and mechanical characteristics derived from its moving mass, magnet flux strength, coil impedance, suspension linearity and native compliance, diaphragmn displacement, inductance and several other characteristics. Years ago, two researchers set out and mapped how these interact with each other to form the basis we use today to model and make modern bass enclosures. The driver has a natural mechanical resonance frequency, a note at which it moves the easiest and requires the least input power to produce movement. This frequency also tends to be near the lowest frequency that the driver will realistically produce, although there are a few exceptions. The Qts is the relationship between mechanical and electrical characteristics and total compliance of the driver. A low Qts driver can, with the correct combination of other factors, produce prodigious bass in a small or sealed enclosure compared to a high Qts woofer, which will be more linear in a horn or transmissionline cabinet. A specialized 6.5" woofer can extend deeper than an 18" woofer if the T&S parameters are idealized for the application. There are other factors but that is the readers digest version.

EQ can attenuate very low frequencies to reduce driver diaphragmn movement while accenuating bass just above this region to allow for good extention without out of control distortion.

Last edited by kouiky; 27th February 2013 at 10:59 PM.
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Old 27th February 2013, 11:01 PM   #7
tigox is offline tigox  Portugal
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oh ok, but what i don't get is how can a subwoofer work in such a small space?
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Old 27th February 2013, 11:05 PM   #8
tigox is offline tigox  Portugal
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Quote:
Originally Posted by wg_ski View Post
If you boost the hell out of a frequency that the "sub" has no problems reproducing and it will sound bassy. Give it 20 dB of boost at 90 Hz and filter everything below 50 (to keep it from falling apart) and you have the impression of "good bass". Until you hear a real system and then everything changes.
yeah but when i tested the ps-cw0 subwoofer from the samsung ht-c550 home cinema system i did it comparing it side by side with my jbl gt5-1204br car subwoofer ( a beast by my begginer standarts), and also th samsung subwoofer gives a looot of bass in my living room without giving the freaking vibration my jbl sub does, how it that possible?
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Old 27th February 2013, 11:08 PM   #9
kouiky is offline kouiky  United States
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The driver may have a generous amount of excursion, ie cone travel, and that combined with its resonance frequency, Qts tuning and finally the box tuning, can produce a relatively large peak in a narrow bandwidth, making it more efficient in that bandwidth. The right woofer and the right box size & port can yield a 5 to 10 dB peak, making it very loud. Add some EQ just above this quasi resonance point to smooth it out and suddenly we have loud deep bass from a shoebox. It will not offer any real extension in the deepest regions but will give the impression of being larger than it is, for a while. A bigger woofer will have a greater moving mass and physical reactance will vibrate the surroundings far more than a 6.5" woofer below the passband.

Last edited by kouiky; 27th February 2013 at 11:12 PM.
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Old 27th February 2013, 11:18 PM   #10
tigox is offline tigox  Portugal
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Quote:
Originally Posted by kouiky View Post
The driver may have a generous amount of excursion, ie cone travel, and that combined with its resonance frequency, Qts tuning and finally the box tuning, can produce a relatively large peak in a narrow bandwidth, making it more efficient in that bandwidth. The right woofer and the right box size & port can yield a 5 to 10 dB peak, making it very loud. Add some EQ just above this quasi resonance point to smooth it out and suddenly we have loud deep bass from a shoebox. It will not offer any real extension in the deepest regions but will give the impression of being larger than it is, for a while. A bigger woofer will have a greater moving mass and physical reactance will vibrate the surroundings far more than a 6.5" woofer below the passband.

So, something like this?
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