Port location

[SCS_Audio]

Yea I would try not to go down on the port area when increasing cone area by 150% or so.

Box rise is the actual load the amplifier sees. The subs were wired to 0.5 ohms, but you did not play them "free air" so the enclosure itself added some resistance to the total. If you have a volt meter and a clamp amp meter you can get the actual output of the amp to the subs in the enclosure. From those two numbers, you can also see what your actual impedance is compared to your 0.5 ohm subs.

Lowering your box rise will allow the amp to put out more power (it sees less impedance), but this is only a benefit if your subs can handle more power. It is not always a bad thing, just something else to keep an eye on.

[ALPINE408]

spl port driver side

music port on top

port should never be on pass side for loudness

That's what I also have heard. But what if I can't get enough port area on the driver's side?

If driver side port is to small just go top port won't be optimal but still gets load as shit

[206xtreme]

I see. So I have to go top port or built a normal wall, and not a box-wall as this I am having right now. What do you think of an SPL port area for two DD 9518's????

[206xtreme]

Yea I would try not to go down on the port area when increasing cone area by 150% or so.

Box rise is the actual load the amplifier sees. The subs were wired to 0.5 ohms, but you did not play them "free air" so the enclosure itself added some resistance to the total. If you have a volt meter and a clamp amp meter you can get the actual output of the amp to the subs in the enclosure. From those two numbers, you can also see what your actual impedance is compared to your 0.5 ohm subs.

Lowering your box rise will allow the amp to put out more power (it sees less impedance), but this is only a benefit if your subs can handle more power. It is not always a bad thing, just something else to keep an eye on.

Oh I see!!! We call box rise, as box's complex impedance!!! Problem is I don't know how to calculate it and "play" with it. For example I don't know how to lower it or get it higher. The only thing I know is that its related to the box's tunning frequency and nothing else. Is there a formula that I can calculate it?

I know how to measure my amplifiers output but I don't have a clamp amp meter in my tool box

[Torres]

don't even worry about rise if it's mostly a daily system

[206xtreme]

I'd like to know a formula that I can calculate it because I'll do it for dB drag competitions also!!! Is there any math formula?

[206xtreme]

Hey guyyyyyyyyys is there any way to minimize box rise???? How can we calculate it before the subwoofer box-wall built??? Only thing I know is that box rise depends on tunning frequency. What are the other dependencies???

[ALPINE408]

Hey guyyyyyyyyys is there any way to minimize box rise???? How can we calculate it before the subwoofer box-wall built??? Only thing I know is that box rise depends on tunning frequency. What are the other dependencies???

Box size has a lot to do with ohm rise for the most part bigger boxes have less rise than smaller ones number of subs is a factor to a lot of times the more subs the higher the rise

[SCS_Audio]

Hey guyyyyyyyyys is there any way to minimize box rise???? How can we calculate it before the subwoofer box-wall built??? Only thing I know is that box rise depends on tunning frequency. What are the other dependencies???

Box size has a lot to do with ohm rise for the most part bigger boxes have less rise than smaller ones number of subs is a factor to a lot of times the more subs the higher the rise

No equation. Rules of thumb but every install is different.

It's just something to keep an eye on and test rather than worry about. It might be possible to wire to a lower impedance for SPL if your box rise is too high and you are not getting the power you need.

I wish there was an equation!!! Or at least some hard facts!!

Only very experienced builders seem to have a handle on it. I am not one of them lol. I just keep measuring it, experimenting, and trying to learn.

[206xtreme]

Well, let me express something and then you tell me if I am wrong.

When do we have a possibility of getting impedance rise with only one parameter (let alone box size and number of subs for example). Probably when we have back pressure of the air that the subwoofer pushes. Right?

So how can we get rid of it? We simply don't add depth to our port. Right?

We make the math to get the desired tunning frequency without adding depth to our opening. I am talking only for competition purposes.

Is my thought right?