How box size and port area effect bandwidth

[DylanBunch]

Just wanna get some info on how different box sizes and port sizes changes playable bandwidth. Also how it affects efficiency

[zack_e89]

in for knowledge, but i would think that would depend on recommended box specs for the driver and how close/far you are from those along with the power received

[Nightshade]

I will give you some perspective on the subject. I am going to give an example as it is easier to make the associations that way.

Let's say we have a box that is 3 cubes and we start with 25sqin of port. At these specs lets say it takes the ports being 20" long to tune the box to 32hz. Now if you would like the box to play higher there are a couple of things you could do here. First, you could just keep the same port area and length and shrink the inside of the box. This will increase the peak frequency and will make the bandwidth narrower.

If you wanted a lower tune and decided that you were going to keep the specs you would increase the box volume. If you wanted to keep the box volume constant at 3 cubes, then you could adjust the port length to longer for lower tuning or shorter for higher tuning. Usually boxes that are tuned lower have a better bandwidth and play flatter across the board. You can also look at it like this if you want to keep the same box volume but increase the port area you will raise the frequency, and if you were to decrease the port area it lowers frequency.

There are also a combination of things that you can do to achieve different results. Let's say you are looking for more spl, with the same specs you could increase the port area and adjust the port length accordingly. Most of the time when you have a higher port to volume ratio spl is higher due to the raised tuning, since most people tune lower for listening. You could also increase the efficiency of your output by taking the box and making it larger and adjusting the amount of port area to keep the ratio the same as well as the port length the same. This works better for lower power as the larger box increased the throw of the woofer, allowing it to travel further off less power because in a smaller box due to the smaller airspace the cone does not have as much air to push the woofer to reach xmax.

There is a whole lot more but this is a general understanding. I could type for a couple of hours on how to do this or that from what I've learned over the years but hopefully others will also chime in to add on the topic.

[Kyblack76]

^^^

jesus, that makes some sense.

I am into this as well. Id like Brian to get in here... ill try and see if he will play.

That said,

My own on goings. My enclosure is incredibly flat. I hear people say, "i run at .5 daily" . Well, you rise like a monster. I am wired "here", and in time, i can find songs i can NOT play, "lows" or running there for 10 or so songs, i will thermal.

Running the IMsg, i see im not over one ohm (REACTIVE) for 98% of the playable band (22-50)

I also get loud on not much power. I can blow a 50 at 23hz, but only a 54 at 36. Im extremely flat it seems.

Running the IMsg it shows im tuned around 31, which i missed trying to tune to 34. That said.... id love to know how, why, what..... in it all.

I also understand, EVERYTHING comes into account.

[hoit]

wow...tuned in for knowledge!!

[alaskanzx5]

If I'm not mistaken tuning will never be correct. I mean sure you can make a box that is 3cuft tuned to 35hz on paper but as soundwaves bounce off bracing, the speaker, or if you glass or paint the inside air flow and density changes and in turn changes tuning all together. You can get close but never dead on.

[Kyblack76]

If I'm not mistaken tuning will never be correct. I mean sure you can make a box that is 3cuft tuned to 35hz on paper but as soundwaves bounce off bracing, the speaker, or if you glass or paint the inside air flow and density changes and in turn changes tuning all together. You can get close but never dead on.

Add a second person, open a door, or window..

Fart, fuck.. open a beer.

That said, you DO have to start somewhere.....

[alaskanzx5]

Hell tuning can change based on how far your sub is traveling. Moves in and out which in return does change box volume ever so slightly. Mounting a sub inverted adds volume even. Cones on subs go inward towards the motor so you gain a slight amount of volume right there while also decreasing the amount of displacement you have.

Band with isn't just determined by volume and port area either though. You also have to factor in the vehicle, power, and choice of subs.

Box building is tea and error not a dead on science or mathematical formula.

[Kyblack76]

Ill admit, i have some "what the fuck??" moments on my gear.

Running the IMsg, showing impedance,. metering,.. this and that..

I have my own "WTF ?" shit going on..... i do

(retards that think your tuned here, with this power there,.... Ill bet my bank account, your wrong on all)]

EDIT - LOL, ok,.. not ALL of you. I know some of you, are, beyond DEAD bang.. That said, that isnt my set up.....