First Box Design

[Island Bumpkin]

Hey all,

I'm planning out the system that I want to put in my 88 F250 this summer, and I wanted to bounce a couple ideas off some people with more knowledge than me.

My plan originally was to run a single Sundown SA-10, but after some research I decided to go with a single E10 since I'm shooting for sound quality and not SPL. I don't have an amp selected yet, so I'm open to suggestions!

Anyway, Sundown recommends 1 cf of volume on a ported box, have a port area of 16 sq inches, and to have it tuned to 32 Hz. I fiddled around with the slot port size calculator on the12volt.com for a while, until I came up with a 1x16 port that needed to be 38.8 inches long. From there, I turned to Solidworks and started building.

This is the result, designed to use 3/4 inch MDF and flush mount.

I read that when figuring the volume of the box, I needed to add mfg recommended volume+volume of air in the port+displacement of the sub. Using that, I needed a volume of roughly 1.5 cubic feet. This design gets me a volume of 1.55 cubes. Initially, my box volume was too large, so I increased the size of the largest chamfer to take up some extra space. Naturally, the chamfers won't actually be solid, but this is how Solidworks does chamfers.

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So, there you have it. Any tips or feedback is greatly appreciated!

Thanks
Jameson

[Island Bumpkin]

Anyone?

[Triticum Agricolam]

Ah, a couple things. With a 1" x 16" port you have an aspect ratio of 16:1. That is significantly less than ideal. You don't really want to go over 8:1 and the lower the better. I try to keep things under 5:1 if I can. The problem with high aspect ratio ports is they have a lot of surface area for the amount of port area they have, this increases air resistance and causes all kinds of unwanted issues.

When calculated net internal volume, you are trying to find the airspace that isn't being taken up by anything else. This is why you subtract out the space the sub takes up and the space the port takes up. You don't just calculate the air in the port, you need to calculate the space the port panels take up too.

[Island Bumpkin]

Ah, that's good to know.

When it comes to the port aspect ratio, I'm not totally sure how I would work something like that. Trying to keep a port area of 16 sq in while maintaining a 8:1 ratio and a manageable length is going to present a challenge..

Is there much difference in how the port type affects sound quality/SPL? Is one better than the other for each thing?

Thanks,

Jameson

[Triticum Agricolam]

Well the aspect ratio of the port shouldn't have any effect on the length. Giving your box size/shape I understand it may be difficult to lower the aspect ratio and still be able to fit the port into the box neatly. If you list your box dimensions I may be able to come up with something that might help.

What do you mean by "port type"? Properly sized all different ports should all perform pretty much the same.

[Island Bumpkin]

I wasn't sure if there was a difference in sound quality from a square, round, or slot port.

To get the aspect ratio lower and keep a 16" CSA, I can change the dimensions to a 1.5x32/3 (10.66). That means the aspect ratio is 1.5:10.66 which is smaller than a 1:8 ratio (1.5:12 scaled up). I realized that I was mistaken with the port length, in that it will not change as long as the area is the same.

Thanks

Jameson

[Triticum Agricolam]

If you can lower your aspect ratio to below 1:8 that would be good. High aspect ratio ports are just so inefficient.

[Island Bumpkin]

It is below a 1:8 ratio, so that's what I'm after?

[Joe X]

OP where are you planning to place this box?

[Island Bumpkin]

It will be behind the front bench in an extended cab truck. I was thinking centrally located since I have jump seats in the back instead of a bench