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Old 10th July 2009, 12:12 PM   #1
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Question explain to a dummy

hello everyone.
i searched the forum for a simple explanations about speakers parameters.
couldn't find one(unless it's buried in a prehistoric thread )....
i understand some of them but in every speaker specifications
i meet those 3 or 2 letters combos (Qms,Vas,Le etc...)followed by a value that makes me feel like i don't understand anything

can someone please shed some light about these parameters?
and please make the explanation idiot proof cause this stuff is
really new to me

here is an example of these parameters that make you feel
like you should ask a pro:

Nominal Impedance 6 ohm
DC Resistance (Re) 4.2 ohm
Voice Coil Inductance (Le) 1.2 mH
Effective Piston Area (Sd) 508 cm2
Voice Coil Diameter 75.55 mm
Voice Coil Height 28 mm
Air Gap Height 6 mm
Linear Coil Travel (p-p) 22 mm
Maximum excursion (p-p) 0.87 T
Magnet Weight 2.03 kg
Net Weight 5.85 kg
Free Air Resonance 19 Hz
Sensitivity (2.83V/1m) 91 dB
Mechanical Q-factor (Qms) 7.8
Electrical Q-factor (Qes) 0.42
Total Q-factor (Qts) 0.40
Moving Mass incl. air (Md) 98 g
Force Factor (BL) 10.8 Tm
Equivalent Volume (Vas) 238 l
Compliance (Cms) 650 um/N
Mechanical Loss (Rm) 1.5 kg/s
Rated Power Handling 200 Watt
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Old 10th July 2009, 01:04 PM   #2
Mooly is offline Mooly  United Kingdom
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I think what you are looking for is an explanation of Thiel-Small parameters,
http://en.wikipedia.org/wiki/Thiele/Small

It's a hugely complicated subject
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Old 10th July 2009, 01:08 PM   #3
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I consider myself somewhat new to all of this even though I've been building and buying audio for many years. I hope there is a link to a good explanation of the various terms or at least a list of all of the acronyms. If you can get one of the various simulation programs for building enclosures I think that would help explain how different values effect things and how control the design parameters.

I'm no genius but usually pick up on new concepts rather quickly, not so much with Hi-Fi though. It has taken awhile to read thru and digest and ponder on to sorta get a grasp on what gets discussed here. After you get a grasp on all of the factual hard numbers data then you have to factor in personal preferrence and design compromise etc. This part can get heated.

Enjoy yourself and take the time to absorb all of the information on this wonderful site.
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Old 10th July 2009, 01:29 PM   #4
Dansk is offline Dansk  Denmark
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Default Thiele/Small/Elliott...

Alternatively, this could be a possibility. Very short and precise definitions, but also some further explanation:
sound.westhost.com/tsp.htm
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Old 10th July 2009, 01:35 PM   #5
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Quote:
Originally posted by Mooly
I think what you are looking for is an explanation of Thiel-Small parameters,
http://en.wikipedia.org/wiki/Thiele/Small

It's a hugely complicated subject
thanks. but this is surely not a dummy explanation
i was looking for a more simplified explanation.

901Fixer
i tried to play a bit with bassbox pro and winISD
but i couldn't make much of it.

if what you guys are trying to tell me is that there is no simple explanation
bring in the scuba gear im going in!
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Old 10th July 2009, 01:51 PM   #6
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Scuba gear required. I'm sure there is a general way to explain the basics but I haven't found it laid out that way anywhere and I have yet to experiment with any of the design programs but hope to eventually.
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Old 10th July 2009, 02:01 PM   #7
infinia is offline infinia  United States
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I think the simplest way of explaining the Theile-Small parameters (T-S,TSP) is that they provide an electrical model to a speaker drivers mechanical properties. This electrical model basically helps understanding the low frequency resonance effect of a drivers properties interaction in a closed box or a tuned resonator box (bass reflex).
The first place to start is to fully grasp the idea of resonance learned in basic physics. Also basic electric circuits, same physics course? Then look at the Small's AES papers which can be found on the net. He has a glossary of the terms as an appendix.
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Old 10th July 2009, 03:35 PM   #8
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Quote:
Alternatively, this could be a possibility. Very short and precise definitions, but also some further explanation: sound.westhost.com/tsp.htm
thanks! this one looks much more informative and
straight forward then the wiki page.


Quote:
basic physics
you actually mean: my worst nightmare
but i guess there is no running away.
i'm starting to get the picture...
no simple explanation.
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Old 10th July 2009, 03:51 PM   #9
MaVo is offline MaVo  Germany
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One doesnt really have to know the theory behind those parameters to use them. And using them is easy, since you usually just put them into a program and see what comes out
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Old 10th July 2009, 04:28 PM   #10
badman is offline badman  United States
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Quote:
Originally posted by Thebrain

thanks! this one looks much more informative and
straight forward then the wiki page.



you actually mean: my worst nightmare
but i guess there is no running away.
i'm starting to get the picture...
no simple explanation.
Perhaps, in that case, your nickname is ill-deserved?


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