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Originally posted by AustinKP+Jul 2 2004, 06:09 PM--><div class='quotetop'>QUOTE(AustinKP @ Jul 2 2004, 06:09 PM)</div><div class='quotemain'>Well, I think I understood the first sentence somewhat, but then you totally lost me. [/b]
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Translation:
<!--QuoteBegin-sandt38@Jul 2 2004, 05:00 PM
If you use greater power to push it to full excursion in a smaller sealed box you lose somew transient responce,[/quote]
The smaller you make an enclosure, the more difficult it is to compress the quantity of air contained within the enclosure... the air in the box behaves more and more like a stiffer and stiffer spring, rather than a cushion, if you will.
So, you'll
need more power to fight against the stiff spring, just to bring the sub to the same excursion (read: output) levels as it would have had in a bigger box, on less power.
Also, the damping of the sub will be worse in a small box compared to a large box...
Damping is like a shock absorber on your car.
Shocks with poor damping abilities will let your car bounce and oscillate after hitting a bump, like worn out shocks.
Shocks with great damping abilities will firmly control the car, keeping the car's ride level, firm, and distance off the ground consistant as you drive, rather than fluctating with the car bouncing up and down.
Likewise, a sub's cone motion - and therefore the sound it produces - will more closely mimick the signal it is fed - the music you are playing - in a larger enclosure, with good damping, compared to the smaller enclosure.
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risk boomieness and will suffer some power compression.
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Another trade-off of a small sealed box is low-frequency extension.
In a larger enclosure, your sub can play lower frequencies than in a smaller enclosure.
This is at least partly because a sub needs to reach ever-increasing excursion levels as the frequencies decrease to produce the same output levels... and those are harder for the sub to reach in a small enclosure.
Power compression occurs when a voice coil heats up... that simply means it becomes less efficient... it'll take more power to effect the same change in excursion level... and therefore heat up more... a vicious cycle.
A cool voice coil is an efficient voice coil. Well, relatively speaking anyway.
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However, if you use a big box and low power you may suffer motor strength as well. It is really a tradeoff, and is why the general rule of thumb of a .707 QTC enclosure is followed. It is simply damped enough to limit coloration and frequency boosts, as well as allow the driver to reach potential.
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The Qtc is a number that simply corresponds to the shape of the final response curve... and also accounts for these other things, like transient response, impulse response, cone motion overhang...
As you go bigger, Qtc gets smaller. 0.707 is considered the "ideal" middle-ground.
Higher than 0.707, and you risk getting boomy, losing low-frequency response, efficiency, etc.
Lower than 0.707, and you are potentially "overdamped", maybe even
too efficient, relative to the amp power that you want to feed it.
Note, the latter (lower than 0.707) aren't really
bad things...
That help?
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