Can I get a quick, simple explanation for subwoofer design? Please! - AVS Forum
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post #1 of 9 Old 05-13-2012, 02:19 PM - Thread Starter
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So I've spent a little while trying to figure out what a subwoofer motor is and how it affects performance--all I can get on the web is equations and variables. I like math, but I need a verbal explanation before I apply the math. Here is my question: What is the difference, physically, between the Dayton HO and HF subwoofers? What is a motor? Is this the difference? I know the HF requires a bigger box, but goes lower. I assume (dangerous, I know) that this has to do with the suspension stiffness, i.e. the HO is stiffer because it is built for smaller boxes and ostensibly higher pressures. Because of this stiffness it is not as efficient and therefore does not reproduce the lower frequencies as loud. This is total amateur hour, I know. Please help a newbie out!
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post #2 of 9 Old 05-13-2012, 02:58 PM
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the motor is (mostly) the combination of the voice coil, the magnet and the steel. when current is applied, those are the parts that make the cone move.

iirc, the ho has more windings on the voice coil, which allows it to take more power, but increases inductance, which increases several forms of distortion. how much difference you will be able to hear is up to you.

the hf has a softer suspension, which is better for detail. the ho has a tighter suspension which is better for pounding on the driver, particularly in ported applications with no high pass filter.

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post #3 of 9 Old 05-13-2012, 03:02 PM - Thread Starter
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I thought the HO was meant for smaller, sealed boxes? Also, does any of this have to do with the Q?
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post #4 of 9 Old 05-13-2012, 03:19 PM
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you can do that too.

the ho will have lower sensitivity by about 5 db down near 20 hz, so will require about 3.5 times the power to hit the spl at 20hz.

it also rolls off earlier.

that is fine if you are in a car where "cabin gain" or whatever you want to call it kicks in. this gives you lots of free low end "boost", technically ~9db per octave in real rooms.

in a medium home room, it kicks in around 25hz or so.

in a car, it kicks in much higher, 70hz+.
LL

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post #5 of 9 Old 05-13-2012, 04:40 PM - Thread Starter
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Why does it roll off earlier?
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post #6 of 9 Old 05-14-2012, 09:09 PM - Thread Starter
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Quote:
Originally Posted by JohnnyWash1 View Post

Why does it roll off earlier?

Anybody?
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post #7 of 9 Old 05-14-2012, 09:20 PM
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if you really want to know, have a look at thiele and small's work.

their papers are available online. the answer is so far over your head (and mine) at this point, that most folks would say, just accept that it works like that.

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post #8 of 9 Old 05-16-2012, 12:21 AM - Thread Starter
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Quote:
Originally Posted by LTD02 View Post

if you really want to know, have a look at thiele and small's work.

their papers are available online. the answer is so far over your head (and mine) at this point, that most folks would say, just accept that it works like that.

Thank you!
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post #9 of 9 Old 05-16-2012, 04:35 AM
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Quote:
Originally Posted by LTD02 View Post

if you really want to know, have a look at thiele and small's work.

their papers are available online. the answer is so far over your head (and mine) at this point, that most folks would say, just accept that it works like that.

Luckily there are modelling programs (originally hand calculations) that will tell how the drivers perform in a given box and don't require us to learn or comprehend the math and physics that make it all work. You can get a feel for it taking one of the models and plugging in the T-S parameters for a given driver and changing the box (volume, sealed/ported, tuning frequency, etc) or picking a box design and plugging in different woofers.

Or you can take the easy way out and ask for recommendations for "$300, sealed, 1.5 ft^3 max, F3 about 24 Hz, HT use" or whatever your desires and constraints are.
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