SA-8 enclosure design

[jokers10 19]

Hey followers of Sundown. I am thinking I want to use the SA-8 in my car. I designed an enclosure and am now looking for feedback before I jump in the Sundown pool. Let me give you some background of the car it is going in and the sound I am looking for.

I own a 2003 VW Jetta GLI. It has the factory Monsoon sound system with an aftermarket Kenwood Double Din. The factory monsoon amp consists of an 8 channel amp running a component set in each door. The woofers are low in the door and the tweeters are in the A-pillars in the front, and by the door handle in the rear. It gets plenty loud, and is relatively clean. What it is missing however is some low range.

I want enough bass to support the factory speakers with room for future upgrades. I listen to a large range of music. My most played artists would be Regina Spektor, Death Cab for Cutie, Eminem, and Paul Simon.

I have decided to go with the SA-8 due to the size enclosure recommendations, and from the reviews I have read great output for the size of woofer. I want it to be light weight and somewhat low power because the factory charging systems tend to be finicky on the VWs. I am looking to bridge a Sundown 125.2 to power 1 SA-8 D2 woofer wires in series.

My enclosure dimensions are as follows. Exterior measurements are: 23" wide, 10.5" tall, and 11" deep. The port will be a slot port 1" tall, 9" wide, and 20.25" long. This leaves a woofer cavity of 19.75" x 9" x 7". This is a .72 Cubic Ft cavity and with a .1 cube speaker displacement leaves a .62 Cube enclosure. This would put the tuning of the port right at 35 Hz. There won't be any additional bracing considering how small this box will be. (Picture is below. Couldn't figure out how to recess the speaker, but that is what I am going for.)

My concern is 2 fold. Did I design an enclosure that meets the requirements of the SA-8? and will a 9"x1" port whistle in my trunk loud enough for it to be a problem? Any constructive feedback is welcomed.

Screen shot 2011-09-18 at 6.46.47 PM by jokers10, on Flickr

[jokers10 19]

Forgot to mention I run a MAC, so I don't have the capability to run WinISD on it.

[Micksh 16]

Your port area is a little small...plus the 9:1 ratio is a little more than it should be. Is it going to whistle? Probably a little, especially if you don't round the edges. Will you hear it in the trunk? My guess would be no. I have an SA-8 in a center console enclosure. My port is a 3" aeroport, again, slightly smaller than it probably should be, but I don't hear any noise and that is in the cabin with me. anyone else have any thoughts for jokers10?

[Julian 641]

Your port area is a little small...plus the 9:1 ratio is a little more than it should be. Is it going to whistle? Probably a little, especially if you don't round the edges. Will you hear it in the trunk? My guess would be no. I have an SA-8 in a center console enclosure. My port is a 3" aeroport, again, slightly smaller than it probably should be, but I don't hear any noise and that is in the cabin with me. anyone else have any thoughts for jokers10?

Agreed, you "probably" wouldn't hear it, I'd suggest at a minimum of 27.48 in^2 of port area.

[ricksi30 923]

Your port area is a little small...plus the 9:1 ratio is a little more than it should be. Is it going to whistle? Probably a little, especially if you don't round the edges. Will you hear it in the trunk? My guess would be no. I have an SA-8 in a center console enclosure. My port is a 3" aeroport, again, slightly smaller than it probably should be, but I don't hear any noise and that is in the cabin with me. anyone else have any thoughts for jokers10?

Agreed, you "probably" wouldn't hear it, I'd suggest at a minimum of 27.48 in^2 of port area.

For one Sa8?

Edited October 1, 2011 by ricksi30

[dbsupra 69]

The volume will work well. I'm running .63 with mine.

The port is puny tho. Whether or not you could hear the whistle doesn't make it a good design. The tuning is freq is ok.

How much room can you use?

[Micksh 16]

If you can get it to 9x2 the port velocity drops SIGNIFICANTLY...that would be pretty sufficient for that sub with that amount of power...

[skittlesRgood 3]

the port is fine. it comes out to what, 13 square inches per cube? you will not get a whistle. trunk builds do seem to benefit from a larger port but that one wont give you any problems.

[///M5 2,833]

Ports too small. When it is the right size the box will be too big. If you are running a single driver a 10" is usually a better choice.

[jokers10 19]

That is the balancing act I am having in my head. Larger port area means I have to increase the enclosure size to remain at the tune the speaker needs. Without a physical trial I don't think I can be certain of what will actually happen. I was able to borrow the wife's netbook to run WinISD, and the port velocity was just slightly higher than what was recommended.

I have room for a bigger sub, but am trying to stay small to keep the weight down and the room required to make a suitable box for it. Plus I am only looking to replace the sound that is missing from the door speakers. I am sure I will eventually replace it with something larger, but I think this is what I want for now.

But is anyone has any other experience with the SA-8 and can get that to me before I start building, it would be appreciated.

Thank you for your input so far.

Edited October 2, 2011 by jokers10

[Micksh 16]

Like I said, I have mine as a center console box with a smaller port than optimal, and it actually sounds great...all I can say is go as large a port area you can in the space allotted, and I think you will be happy. Luckily with a small box like that, the cost isn't so bad that if you decided to rebuild it that you would be breaking the bank. I say go for it and see what you think...

[///M5 2,833]

The exterior dimension of the box for my 8 was larger than my 12. The 12 was sealed. Small box and ported 8 doesn't usually work.

[Micksh 16]

The exterior dimension of the box for my 8 was larger than my 12. The 12 was sealed. Small box and ported 8 doesn't usually work.

I do agree with you there. My center console takes up quite a bit of space...for me the decision on an 8" had to do with width between the seats...in a trunk, I generally would go a 12" myself.