mechanical power handling

[Matador 10+ year member]

"the larger the sealed box is.. the less power the woofer can take before exceeding its mechanical limits (i.e coil bottoming out, suspension locking down rearward.. etc) this is not related to the thermal power handling of the coil (amount of power before damaging the coil)

a woofer relies on its suspension, as well as the 'cushion' of air inside the box to keep the cone within limits. the larger the box, and less resistance the volume of air has, and the more the woofer cone will travel with power..." By Loyd

He explained to me the disadvantage of having a large box (mechanical power handling i guesS). This is more specific to the ED K's i guess, he told me that if it's more than 1.0 cu feet sealed, this would happen.

i dont' get this completely tho (sorry loyd), but can someone explain this? i mean what would happen if the large is too big? i know it would take less power to move it, but wat disadvantages? thanks

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[Trixter 10+ year member]

I have to agree with Loyd. You need to find the happy medium between too large of a box and the power that you want to put into it. I talked with a ED tech about putting 3 12" K's (in place of my HE2's) in a 6cu' box. He said that it would work out fine, but then again I was only going to put 300w rms to each of them. If I wanted to go with more power then i would need a smaller box to provide the adequate back pressure to compensate for the power increase.

I by far am a the box master but I hope this helps...at least a little.

 

[Savant 10+ year member]

Basically, you can compress air.. when the cone moves in a sealed box there are a few things that affect it.. The amount of power tells the sub how far to try and go (audio volume level or dB is based on how tall the sound wave is, 'freq' is how bunched up or stretched out it is).. When the sub is going into the box, it has to compress air.. the less space there is, the more you compress air and the more resistence (and the harder it is for the cone to move).. As the box gets bigger, it becomes easier and easier to compress the air because you have a totally different ratio now.. you have a lot more air to compress which also means there is less resistence (within the limited movement of the cone anyway, at a certian point you would have the same resistence, but you would have to compress a much higher volume of air to do that.. Now, when the cone tries to go out of the box, there is a vaccume inside the box.. that pulls on the sub.. the harder it pulls as the sub goes out, the more power you need to get it to go out to the same place.. the smaller the box the 'tighter' the vaccume..

So.. now.. if a sub is rated for X watts (rms)... that means it will take that much power (normally in the recomended enclosure) and the cone won't max out in movement in either direction (toward the mag and the metal tube that moves the cone will smack into the back of the casing stuff, away from the mag and you stress the surround and spider and can rip/distort/damage them).. That statement (and the power rating) depends on having enough resistence from the enclosure.. So, as you increase the box size and lower the resistence to the cone, the amount of power the speaker can handle before reaching physical limits goes down..

for example.. if a speaker is 500 rms in a 1 cubic foot sealed box.. you can put 500 watts into it and it should be ok.. if you increase the box to, say 2 cubic feet, there is (work with me) 1/2 the resistence on the cone.. so it only takes 1/2 the power to reach physical max.. so you could only put 250 watts in it..more than that and you can start to damage the sub's physical components (spider, the tubethingy that moves the cone, etc)..

Now, the math on that is probably totally wrong, I'm sure there are formulas out there that will tell you almost exactly what differences exist from 1 to 2 cubes, and that can be used to find the safe wattage.. but I'm just trying to show the relationship...

Hope that helps clear things up..

 

[Matador 10+ year member]

yeah thanks guys it makes more sense now. thanks savant, i got what you are said.

hmmm, i 'll be putting ~400rms for each 10 EDK. recommended is 0.5cu feet. Do you guys think 0.8-0.9 cu feet before displacement with 400rms should be ok n shouldn't affect power handling much? jmac or steve

 

[80_Cutlass_mn 10+ year member]

Just to teach a lil terminology here. The little tube thingy that Savant was talkin about is called the voice coil former.

Just thought id let ya in on that

 

[Savant 10+ year member]

Originally posted by 80_Cutlass_mn Just to teach a lil terminology here. The little tube thingy that Savant was talkin about is called the voice coil former.

 

Just thought id let ya in on that

Thanks //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif

 

[80_Cutlass_mn 10+ year member]

Originally posted by Savant Thanks //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif

No Prob //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif