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Old 11-29-2010, 02:41 PM   #1
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Default Someone teach me about subs!

Wish I had the knowledge, but I don't. I do know there are a lot of people out there who do though.

Here'* a starting point, and I think it might be a good reference for other people in the future. We can combine the knowledge here and put it in the tech docs section.

http://www.woofersetc.com/p9263/SA10...-Subwoofer.htm

What do these numbers mean?
  • FS : 31.6 Hz
  • Qts : 0.45
  • Qes : 0.49
  • Qms : 5.64
  • VAS : 21.9 L
  • Mms : 187.4 g
  • XMAX: 19mm one way


And for the following, what does "yields F3 of 50 Hz" mean? What is Qtc alignment?

VENTED :
  • 1.25 - 1.5 cubic feet tuned to 30 - 35 Hz
  • Yields F3 in the mid to high 20s

SEALED :
  • 0.55 cubes for 0.707 Qtc alignment
  • Yields F3 of 50 Hz
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Old 11-30-2010, 12:06 AM   #2
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Quote:
Originally Posted by xtremerevolution View Post
What do these numbers mean?
  • FS : 31.6 Hz
  • Qts : 0.45
  • Qes : 0.49
  • Qms : 5.64
  • VAS : 21.9 L
  • Mms : 187.4 g
  • XMAX: 19mm one way

And for the following, what does "yields F3 of 50 Hz" mean? What is Qtc alignment?
  • 1.25 - 1.5 cubic feet tuned to 30 - 35 Hz
  • Yields F3 in the mid to high 20s
  • 0.55 cubes for 0.707 Qtc alignment
  • Yields F3 of 50 Hz
Fs = Also called F0, measured in hertz (Hz). The frequency at which the combination of the moving mass and suspension compliance maximally reinforces cone motion. A more compliant suspension or a larger moving mass will cause a lower resonance frequency, and vice versa. Usually it is less efficient to produce output at frequencies below Fs, though motion below Fs can cause uncontrolled motion, mechanically endangering the driver. Woofers typically have an Fs in the range of 13–60 Hz.

Qts = Qts is a measure of the driver'* tendency to resonate at Fs, based on its overall characteristics.

Qes = A measure of the driver'* tendency to resonate at Fs, based on its electrical characteristics, like magnet strength, magnetic circuit characteristics, etc.

Qms = A measure of the driver'* tendency to resonate at Fs, based on its mechanical characteristics, like surround compliance, the compliance of the spider, weight of the cone, etc.

Vas = The volume of air that has the same compliance ("springiness") as the driver'* suspension. Because less air is more "springy" than more air, a large Vas represents a "loose" suspension

Mms = Measured in grams, this is the mass of the cone, coil and other moving parts of a driver, including the acoustic load imposed by the air in contact with the driver cone.

Xmax = Linear (one-way) travel of the cone. Xmax is used to determine the maximum linear SPL capability of the driver, and can be defined in a number of ways.

F3 = Is the frequency where the response (loudness) is down from the reference level by 3 dB.

Qtc alignment = value for the damping provided for a driver in a sealed enclosure. Denotes the enclosures ability to control the driver response at resonance. Qtc = 0.707 is the optimum value for sealed enclosures, providing flattest response and highest SPL for deep bass extension.

Let me know if you have any questions on any of the explanations, I can go further into detail if needed.
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Old 11-30-2010, 01:15 AM   #3
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Phew!.... And why I stay away from Audio help unless it is in my grasp. Which is mainly electrical. Nice thread X, we need more like this to bring GMF to the same level we are at in Mechanical. Audio has become an important part of Car Maintenance. And continues to grow.
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Old 11-30-2010, 02:30 AM   #4
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Subscribed!
very interesting thread!
i'd love to learn everything about audio
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Old 11-30-2010, 07:40 PM   #5
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In general T/* parameters aren't overly important unless you are designing an enclosure (and know what you're doing). In general, just use the recommended box values given by the manufacturer, mix it in with some advice from people who have used the subs and you'll be set.

Here'* a page I have bookmarked that explains T/* stuff.

http://www.soundsolutionsaudio.com/f...ers-explained/
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Old 11-30-2010, 09:29 PM   #6
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Quote:
Originally Posted by rmac694203 View Post
In general T/* parameters aren't overly important unless you are designing an enclosure (and know what you're doing). In general, just use the recommended box values given by the manufacturer, mix it in with some advice from people who have used the subs and you'll be set.

Here'* a page I have bookmarked that explains T/* stuff.

http://www.soundsolutionsaudio.com/f...ers-explained/
I thought that went without saying But I agree with everything you said, for the majority of people the recommended box sizes will suffice
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