First Try at Designing a Ported Box

[Skooter 10+ year member]

I'm in the process of designing a box that is SQL oriented for 2 Sundown Audio E8V3's. I've never used anything other than sealed boxes, so I don't know the, "rules of the port." I'm very concerned with port noise, as some of my friends have built ports and have that had a horrid noise coming from the port. I know that the area of the port, as well as how smooth and rounded the edges are have an effect on this, but I'm not sure what the rule of thumb for port area is. I took a shot in the dark and thought that maybe a 3" diameter PVC pipe would do the trick, but correct me if I'm wrong.

Here's the design I worked up on my own. The subs will be mounted side by side, with the port between them (unless you guys tell me otherwise).

My amp, currently, is a Hifonics BXi 610 that I got on an excellent trade for a cheap Boss amp. It does 600RMS at 1 Ohm, which is what I plan to wire them to. This amp will be replaced when I have the money... but as of now, this is it.

I'm a big reggae and rock guy, but occasionally listen to a tad bit of rap and dubstep when I'm in one of those bass moods, which doesn't happen more than once a week. I spend 2-3 hours in my car a day, so music is very important to me to get me through the day.

I did some research, and the cabin of my car (SUV-Buick Rainier) has a resonant frequency of 38hz, if that means anything to you. It doesn't to me, since I'm no expert whatsoever.

Any help and incite is appreciated.

Thank you,

Skooter

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[Slo_Ride 5,000+ posts]

Two e8s would need about 1.2 cubic feet of space so you should probably go with two 3" ports.

 

[undone1 10+ year member]

I personally would do at least a 4'' port,and an aero at that...3'' will definitely be noisy...but if length becomes an issue,may have to switch to slot port style to fit within any size restrictions you may have..

 

[Skooter 10+ year member]

Two e8s would need about 1.2 cubic feet of space so you should probably go with two 3" ports.

Alright. Well, then that brings up a new question that my calculator I'm using is bringing up... Is the port length cumulative, or for each one of them?

 

[Skooter 10+ year member]

I personally would do at least a 4'' port,and an aero at that...3'' will definitely be noisy...but if length becomes an issue,may have to switch to slot port style to fit within any size restrictions you may have..

I may sound stupid by asking this, but what is an aero port?

 

[Skooter 10+ year member]

Also, as far as size restraints go, I still want to be able to fit bikes in the back, as I'm a huge BMX rider and my car is used regularly as a trip car for parks and street spots up to 6 hours away. I fit these, 6 bikes, into my car with a 12" Alpine Type-S in a 1.2 cubic foot sealed box without disrupting the subwoofer.

EDIT: I know the box was too big for that subwoofer. It was all I had though, unfortunately.

 

[Slo_Ride 5,000+ posts]

I may sound stupid by asking this, but what is an aero port?

aero port is a brand name, instead of a straight cylinder the ends are flared to reduce turbulence and decrease port noise.

That port length would be for each port. E8s will give mechanically before they give thermally so dont go to big with the box or port or they will unload and come apart.

 

[Skooter 10+ year member]

aero port is a brand name, instead of a straight cylinder the ends are flared to reduce turbulence and decrease port noise.
That port length would be for each port. E8s will give mechanically before they give thermally so dont go to big with the box or port or they will unload and come apart.

So you're saying smaller box... I'm down with saving space! As far as the aeroports go, can I bevel the edges of the port with a router to achieve a similar result?

I'll get on fixing my box calculations to what you guys are telling me. Thank you!

 

[Slo_Ride 5,000+ posts]

So you're saying smaller box... I'm down with saving space! As far as the aeroports go, can I bevel the edges of the port with a router to achieve a similar result?
I'll get on fixing my box calculations to what you guys are telling me. Thank you!

You can bevel the edges with a router but i really wouldnt waste the time. Its just not enough of a flare. the only way the flare pvc is to heat up the plastic until its pliable and then flare out the last couple inches of each end. What kind of amp do you plan on using?

 

[Skooter 10+ year member]

You can bevel the edges with a router but i really wouldnt waste the time. Its just not enough of a flare. the only way the flare pvc is to heat up the plastic until its pliable and then flare out the last couple inches of each end. What kind of amp do you plan on using?

Would you recommend going with a slotted port then? I wanted to stay away from trying slotted as I've never built a ported box before, but if it's the only way, I guess I'd have to learn.

Until I have the money for something better, I'm working with a Hifonics BXi 610 which SAYS it does 600 RMS at 1 ohm. I'm not complaining... I traded a cheap Boss amp that I bought for 20 bucks back when I did my first system.

 

[Slo_Ride 5,000+ posts]

The good things with e8s are that they sound great on little power with a small box. But the smaller the box the longer the port has to be. It doesnt matter if you use a round port or a slot port, whichever is easier for you. You can bend a round port just as you can a slot port. Just go to the hardware store and buy a 90 degree connector. I once built a box for four e8s with major mounting depth restrictions. The worst part was trying to come up with a port design that worked.

 

[Slo_Ride 5,000+ posts]

Would you recommend going with a slotted port then? I wanted to stay away from trying slotted as I've never built a ported box before, but if it's the only way, I guess I'd have to learn.
Until I have the money for something better, I'm working with a Hifonics BXi 610 which SAYS it does 600 RMS at 1 ohm. I'm not complaining... I traded a cheap Boss amp that I bought for 20 bucks back when I did my first system.

With that amp I would do 1- 1.2 cubes with two 3" ports.

 

[Skooter 10+ year member]

The good things with e8s are that they sound great on little power with a small box. But the smaller the box the longer the port has to be. It doesnt matter if you use a round port or a slot port, whichever is easier for you. You can bend a round port just as you can a slot port. Just go to the hardware store and buy a 90 degree connector. I once built a box for four e8s with major mounting depth restrictions. The worst part was trying to come up with a port design that worked.

I see, I see... Using 90 degree connectors seems much easier in that case, at least for me, but what kind of length and volume do 90 degree connectors take up? Obviously a huge portion of the tuning of the box. Seems difficult to fit 2 ports of length ~25" in my mind.

 

[Slo_Ride 5,000+ posts]

I see, I see... Using 90 degree connectors seems much easier in that case, at least for me, but what kind of length and volume do 90 degree connectors take up? Obviously a huge portion of the tuning of the box. Seems difficult to fit 2 ports of length ~25" in my mind.

see if a single 4" will help

 

[Skooter 10+ year member]

see if a single 4" will help

Yupp. Here's the calculation:

EDIT: But I see that there's a difference in the volume of the port by ~.05 ft^3. Will this make a difference?