Standard cab truck port help

[tezin87 0]

Ok guys here's the deal...... I've built two boxes so far this summer and have had problems with both of them. I need to know the best spot to put the port in a regular cab truck, preferably a Ford Ranger.

First Box:

This one got pretty loud but there was a ton of port noise. It is 1.1@33hz with a 3'' aeroport up-firing. The reason I ditched it was the port noise and I didn't like how it fit behind the seats....too deep at the top.

New box:

1.1@33 again with a 3'' aeroport. Now it fires into the corner about 4'' away from the side panel. The output dropped rediculously and also the bass is just so flat sounding....it sounds horrible.

What should I do? I'd appreciate help from all you standard cab truck owners.

[ramos 2]

Have you tried down firing? I had pretty good success down firing in my old comp s-10.

[tezin87 0]

Haven't tried downfiring yet....I don't really have the room for 11'' for bottom depth.

[ramos 2]

Just the port, not the sub. Sub still firing forward. But put the enclosure on some 2-3" spacers sitting off the floor. And put the port opening on the bottom of the enclosure

[tezin87 0]

Just the port, not the sub. Sub still firing forward. But put the enclosure on some 2-3" spacers sitting off the floor. And put the port opening on the bottom of the enclosure

Thats a great idea The only problem is on the back wall there is a lip that sticks out so I would have to build around it. Might as well give it a try though. I'll probably just modify this box first to see if it works, then I'll build a new one.

[tezin87 0]

Do you think a 3'' aero is too small for 1.1ft^3 and that's why I was getting port noise?

[95Honda 486]

Minimum port area has nothing to do with box size, at all. It all depends on the displacement of the driver. If you heard vent noise (chuffing) the vent was too small. A 3" Areo should be able to handle a lot of flow though....

Just model your sub and port and see what the vent velocity is. The higher this is, the more likely you are to hear port noise and run into compression problems. You'll notice that if you change box volume, the vent velocity stays almost the same as long as the response stays flat.

Edited July 11, 2008 by 95Honda

[tezin87 0]

Thanks 95HONDA. What do you think of a 1.5ft^ft3 after all displacements with a front firing port that is 10.5 x 1.5 tuned to 33hz? Man, I need the name of a program that I can use to design boxes so I can show you what I mean.

[shizzzon 461]

i was doin some graphin for ya and it seems at 1.1 cubes net-

using a 3" circular port(not aero just regular circular port like pvc), tuned to 33hz, you would only be able to use up to about 850w of amplifier rated power before port noise would be a nuisance.

I believe you use a rated power of 1000w correct?

IF this is true, 3.25" diameter would the lowest i would recommend. 3.5" diameter would be nice as in recommended but would require about 18.25" of port depth displacement if the internal port is not flanged. If it is it's only gonna save like 0.5" length theoretically.

a full 4.0" diameter would put you VERY nice but that's not completely necessary and may not be "doable" for your space.

Increasing the internal volume but maintaining the same tuning frequency will cause turbulence to increase a lot so if you plan on increasing your box size, it best to use that extra potential space for a larger port.

[95Honda 486]

There is a good answer for you.

I think alot of guys download WINISD on here, it is shareware and free. You can also use BOXPLOT, it is free also, it is not as detailed as WINISD, put it will still give you vent velocity.

Shizzzon also made a good point about power relationship to vent velocity. Since power is going to determain you driver displacement, it also determains your vent requirements. Even if you had a driver like say a XXX 18, you could get away with a single 4" port as long as you never used more than a few hundred watts, do you see the relationship? (THIS IS AN EXAMPLE)

You may just be running into port compression noise at full power, which should already be pretty loud and hard to pick up at that point, I would just be 100% sure the noise is from the port size, not something like sharp edges, wierd stuff in the box, leaky joints, etc...

[tezin87 0]

Thanks for all the great help guys. I appreciate you two sharing your knowledge with a beginner box builder. And you know better than I that it's very hard to get loud and sound decent in a standard cab pickup 95HONDA. I'm going to download WINISD and BOXPLOT and see what I can come up with. I may have to sell the BL for a treo of 8's or something and pick up another 3'' aero (two should be good enough for three 8s right)? Or I could do what I've wanted all along (a treo of 10s sealed) but I'm pretty low on funds right now.