10" TC OEM with 104sq in of port

[mobeious 10+ year member]

also how can u tell how much the sub is moving if u dont have real time T/S hooked up

 

[Rashaddd 5,000+ posts]

Sure, the sub is moving less, but the coil will be getting just as hot (if not hotter).

What's the typical way to increase mechanical power handling? Smaller box, no? Meaning worse efficiency? Same heat, if not more?

This way you not only have a bigger radiating surface, but also increased efficiency.

Bigger box = more excursion, less mech power handling, more efficient. Bigger port = less excursion, more mechanical power handling, more efficient. So you end up with the same mechanical power handling roughly (at tuning), and a significant increase in efficiency, at least shown by a significant increase in amount of air being moved in the port.

 

[Rashaddd 5,000+ posts]

also how can u tell how much the sub is moving if u dont have real time T/S hooked up

guessing...I never claimed anything was actual exact numbers or anything in terms of excursion...just based on what it looks like. Irrelevant really unless I was trying to quantify this information, which I'm not right now, just conceptualizing.

excursion is biased on the tunning of the port and Fs of the actual box and i dont know if i would say box size affects powering handing as it does to control the sub below/above tunning i guess u could say u could have more power to a sub below tunning in a box that is smaller then recomened from the back pressure on the cone do to the small area the sub is compressing

a smaller port also = more mech power handling below tuning, as below and above tuning the box acts more like it's sealed if the port is smaller, and more like its got a big hole in it if the port is larger.

If you're tuning to 35hz and hoping to be able to pic up the 25hz notes nicely, in no way should you have a huge port.

 

[mobeious 10+ year member]

port size has nothing to do with excursion if the box is designed correctly

 

[mobeious 10+ year member]

guessing...I never claimed anything was actual exact numbers or anything in terms of excursion...just based on what it looks like. Irrelevant really unless I was trying to quantify this information, which I'm not right now, just conceptualizing.

understood

 

[Rashaddd 5,000+ posts]

port size has nothing to do with excursion if the box is designed correctly

Smaller port = less air actually moving through it, and more being wasted as friction at the ends of the port where it's trying to funnel into it. I'm giving this sub about double the power I was @ tuning when it had half the port area, and excursion is about the same, actually a little less now iirc. Granted it should be a little less based on the 6hz raise in tuning, but I'm still giving it double the power...

 

[tommyk90 5,000+ posts]

Power handling is ~the same actually...except for below tuning where it steeply rolls off (like I said)
Above tuning yes it is decreased somewhat, but because of the fact that higher frequencies have less excursion anyway, its really just increasing power/excursion efficiency at those frequencies without any chance of bottoming out or reaching mechanical limits.

Eitherway this is up for discussion, and that is why I even shared it.

Edit: and once more...perhaps you know better, but I know the majority of the people here including audioholic would have guessed that this would bottom out with its thermal rating going to it, and/or port velocity would have been extremely low...its really the exact opposite.

Power handling will be the same as a normal box, that's what I said. Thus what was the point? To show how a port works? Of course it's going to act the same, you are playing the enclosure at its tuning.

This enclosure would be completely impractical anyways, so doing this as an experiment really holds no credible value.

No, the sub won't bottom out at or near tuning, why would anyone think otherwise? You are playing the enclosure at its tuning, thus reducing excursion. There's no reason for the sub to bottom out.

 

[bball09124 10+ year member]

What's the typical way to increase mechanical power handling? Smaller box, no? Meaning worse efficiency? Same heat, if not more?
This way you not only have a bigger radiating surface, but also increased efficiency.

Bigger box = more excursion, less mech power handling, more efficient. Bigger port = less excursion, more mechanical power handling, more efficient. So you end up with the same mechanical power handling roughly (at tuning), and a significant increase in efficiency, at least shown by a significant increase in amount of air being moved in the port.

So why aren't SPL boxes large in volume? You can't really make the generalization that a bigger box is always more efficient.

 

[Rashaddd 5,000+ posts]

Power handling will be the same as a normal box, that's what I said. Thus what was the point? To show how a port works? Of course it's going to act the same, you are playing the enclosure at its tuning.
This enclosure would be completely impractical anyways, so doing this as an experiment really holds no credible value.

No, the sub won't bottom out at or near tuning, why would anyone think otherwise? You are playing the enclosure at its tuning, thus reducing excursion. There's no reason for the sub to bottom out.

There's alot more net air movement than if this was the equivalent box with a standard amount of port area.

ALOT more total air movement.

 

[mobeious 10+ year member]

tommy do u understand this dude? i figure if i have 100sq or 20sq of port i can bottom a sub out if i want so i dont see how it controls the excursion of th sub

 

[sundownz Pro Seller]

One draw-back is that a HUGE port has less band-width -- it is really loud at tuning but doesn't do as much around tuning as a smaller port.

I use a big port for SPL - not quite that big, though. But my box has 96 in^2 for a 15" driver.

I lose 4 dB with an equivalent 12" driver in the same box.

I missed the other thread... what exactly was the debate ?

 

[tommyk90 5,000+ posts]

Smaller port = less air actually moving through it, and more being wasted as friction at the ends of the port where it's trying to funnel into it. I'm giving this sub about double the power I was @ tuning when it had half the port area, and excursion is about the same, actually a little less now iirc. Granted it should be a little less based on the 6hz raise in tuning, but I'm still giving it double the power...

Because you are decreasing the enclosure pressure, thus less of an air-spring effect on the sub.

This is also why your port velocity is so high.

 

[Rashaddd 5,000+ posts]

So why aren't SPL boxes large in volume? You can't really make the generalization that a bigger box is always more efficient.

My guess would be, its easier to throw a ton of power at a sub to get it louder, than it is to increase box size and port area substantially. People don't often have unlimited room...

 

[tommyk90 5,000+ posts]

So why aren't SPL boxes large in volume? You can't really make the generalization that a bigger box is always more efficient.

Bigger boxes usually are more efficient, but tend to decrease power handling and drop tuning. Regardless of the port area/length, the enclosure itself will have a resonant frequency that can affect tuning.

 

[tommyk90 5,000+ posts]

There's alot more net air movement than if this was the equivalent box with a standard amount of port area.
ALOT more total air movement.

This doesn't mean it's a good idea.

Besides, it's totally impractical in every aspect, so why bother? Just trying to sound smart?

tommy do u understand this dude? i figure if i have 100sq or 20sq of port i can bottom a sub out if i want so i dont see how it controls the excursion of th sub

I'm not going to bother. This test is completely irrelevant to anything remotely close to car audio/SPL.