crazykev81

the 4" port tube is 20 1/4" in length.. and the i ported the back of the box (apparently i was supposed to put the port within 45 degrees of the sub?) anyways, say if i was to put an elbow inside the box pointing down... would this trick the box into thinking the tube is ported through the top? or is this just not going to work? if i port the top of the box, the tube won't fit under the rear deck...

will the elbow thing make the situation any better?
Thanks!

Ex-Maxx

Have you already cut the hole for the port? You could always use a slot port instead which would make it easier to bend around the inside of the box.

crazykev81

yeah i tried it out... it's not too bad, was just wondering how much of a difference it would be if i put the hole on the correct side of the box. the hole is about 4" (1 port diameter) from the top of the box, on the back side. right in the middle between the two sides. i went ahead and built the box, tuned it to 30Hz with a "ghetto port".. there's about 14" of port tube outside the box.. unusual yes, but it is a 1.6 cu/ft box ported to 30Hz~

anyways, another Q.. would i notice a huge difference if i went with a PVC tube rather than the cardboard tube? i had to use the inside of a carpet roll from work. tried out a few and i found one that i could fit the flange into. if i put a flange on the part of the tube taht is inside the box, would that be for the better also? sorry for all the questions.. just learning as i go kinda thing! thank you all

zarx

port material doesn't make too much difference. Its the diameter and length that decide how it will sound. I personally think you should do whatever you can to try to get the port to the front of the box. The whole point of a ported box is to reinforce the pressure wave made from the front of the speaker with the wave made from the rear of it. The port is there to allow the wave some distance to travel so that they are in phase when they meet (the rear wave is 90 degrees out of phase). If you shoot the port out the back, then it is almost guaranteed that the two sound waves will be out of phase (except for specific frequencies). You would be best off to try to move the port so it fires forwards IMHO

veeman

iTrader: (3)

If it sounds good and gives you lots of bass then it's probably not going to make a big difference if you move the port. I've found that it is much more important where you place the box in a specific vehicle to get maximum output and SQ.

crazykev81

yeah notes around the tuning frequency are fine but higher ones do sound a bit out of phase. i dont have the best sub for SQ by any means... but i guess it probably would make a pretty big difference if i had the port on the same face as the cone of the sub.

i asked this before i think but i forget what the answer was... i have a Cavalier coupe with the fold-down seats, i keep the cone firing toward the rear of the car. i dont want to face the cone frontwards because they tell me it wouldnt sound right and if i went up through the rear deck i'd have to seal off the trunk. so for now, if i was to put the port sticking out the front of the box (cone side) toward the trunk... would i lose alot of SPL or SQ having the port firing away from the cabin toward the back of the car? or would the air still flow ok, etc?

hopefully next spring i will have a slot-ported box made but for now modding this box will have to do

zarx

typically you are better off having the sub and the port firing to the rear of the vehicle. This largely has to due with the sound wave phase again. A sub note (40-120 hz) has a wavelength of about 10-20 feet at room temp (http://www.mcsquared.com/wavelength.htm). If the sub faced to the front, and the distance from the back of your back seat to the back of your car was maybe 5 feet, then the rear travelling sound wave will reflect and end up travelling 10 feet until it is right were it started. If the wavelength is 20 feet it is now perfectly out of phase. By facing the sub to the trunk there is now only maybe 2 feet to the back of the car and the wavelength has to be 8 feet before cancellation occurs (this is over 150 hz)

crazykev81

that would be a good reason why some notes are louder outside the car than inside... it's probably way out of phase and certain notes don't intensify until they travel outside the car lol.. almost like my buddy's regular cab pickup... the bass is twice as loud 10ft away from the truck than it is inside.. yeah i need to fix my box, see how it sounds with the cone and the port facing the rear