Sub power handling questions...

[ImBob 2]

Noob thinking out loud here. So in a ported enclosure, is the sub having to work "less" near port frequency? The sub moves less, but what does that mean from a power handling standpoint (if anything)? Is it easier for a sub to take power near the tuning frequency?

I believe I've read about "thermal" power handling. Does that mean there is another unit of measure for power handling? I could be way off, but from what I recall, it seems thermal is constant with no regard for enclosure, but another aspect of power handling does take enclosure into consideration. Hope I'm coming close to conveying what I'm trying to say here lol.

Also, I hear people talking about "efficient" enclosures, but wonder what all that refers too. I'm sure this is a nice, long discussion all in itself, but what are some basics? I've read double baffle, bracing, things like this keep vibration down which I guess translates into less energy wasted and more spl. I also read a bit about kerfing, letting the air flow smoothly makes sense. And I guess proper port area kinda follows the concept of getting the air to flow well. Are there more things I should look in to, or just KISS?

Sorry if this was a bit broad, but while my insomniac mind keeps me awake, I ask questions and try to learn shit lol. Thanks!

[SS Teacher 177]

Thermal power handling is related to the heat generated by the power it is receiving, the other type of power handling is called "mechanical" which suspension parts like the surround and spiders, along with the a bumped back plate- if you look at a ZCON you'll see an insane amount of motor structure behind the magnet- this is to prevent the pole the voice coil is wrapped around from hitting the back of the motor.

Ported boxes offer less mechanical resistance so they are more efficient, meaning it will be louder given the same amount of power.

I really like www.bcae1.com, it in no way delves into the depth that M5, Impious or Quentin Jarrell (or many others, sorry to leave you out) can, but it's a great start.

[Quentin Jarrell 671]

At system tuning the box acts like a sealed box. And directly above and below tuning the sub will show spikes in excursion.

Thermal power rating is a set rating. Normally it's a 100 kelvin increase of coil temperature. It's the temperature that the coil can withstand without falling apart. Typically the glue that holds it together is what fails and not the wire itself.

However, an enclosure will affect the rate at which the coil will heat up. The major contributor to coil heating is insufficient port area. A port that is too small will cause nonlinearies in the system that creates inductance in the coil which in turn creates inductance heating which increases coil temperature.

Extensive Klippel and Leap testing has been done on this by Pat Turnmire and Vance Dickason. Some of which can be seen in Vance's Cookbook.

[///M5 2,833]

Fundamentally there are only two ways to damage a sub playing music through them.

1) Thermal overload: exceed the heat dissipating capability of the coil assembly

2) Mechanical: send a signal to the sub that causes it to move too far causing mechanical damage

As for an efficient enclosure, amusingly I haven't heard that term being used like you imply; however, you can increase the output of a driver in a small section of the frequency range by tuning the enclosure to have more response there. Of course you lose elsewhere when you do this. Perhaps you were referring to EBP (Efficiency Bandwidth Product) which is a number that is calculated from sub parameters to help determine if it is better suited to a ported or sealed alignment.

[ImBob 2]

Thanks for the explanations guys. I'm gonna google some of this to read a little further. M5, I have seen the EBP term when using Winisd, but never knew what it meant. Does it look at QTS (total Q?)?

[///M5 2,833]

EBP = Fs / Qes