Sundown E8 box build advice

[IrishChamp 10+ year member]

I'm building a box for two sundown E8's to go behind my single cab truck seats.

I've used WinISD to get the necessary tuning specs but I still am a little confused about slot port correction factors. I've read to add half the height of the port to the length and I've read to add half the width to the length, with my port being 2x5.5x24.16" that would make a big difference in length.

I also used a slot port calculator @ carstereo.com and that gave me a length just over 2" inches shorter than WinISD.

I've attached a rough diagram of my box, could someone critique the dimensions of my box and slot port and hopefully give me a definitive answer on port length to tune a 1.2 ft^3 tuned to 30hz?

It would also be helpful to understand if port length is the length of the inserted piece of material parallel to the box wall or with correction factor accounted for some other length?

Lastly, in others experience is 30hz the best tuning point for E8's, thats what the website says but I've read several other threads where 32 to 34hz was used but never heard why it was used instead of Sundowns specifications?

thanks!

Click to read more...

 

[Goindef154 5,000+ posts]

I'm a little confused on your port measurements, what are they again?

 

[Nut Hair Trick 10+ year member]

In my opinion I would fire the port to passenger side with subs together underneath. Let me take a look at your box to see what options you have to port.

 

[atlninja82 10+ year member]

yea ive heard port to passenger is generally louder in a single cab.

 

[Nut Hair Trick 10+ year member]

With your box dimensions, you have total cubic feet of 1.195. I personally would tune it at 35 hz. With the top panel of the box being 7" that would give you 5.5" in width. To get to 35 hz, I would go with a port height of 3" for a port length of 24.25". So, port at the top of the box like your diagram, but fire twords passenger side, subs close together underneath that. Your port would be 5.5" x 3" for 24.25" in length for a tune of 35hz.

 

[Nut Hair Trick 10+ year member]

Here's a good site for with a port calculator if you want to play around with it a little bit.

http://www.carstereo.com/help2/Articles.cfm?id=31

edit: oops you said that you were already using that calculator, anyways, it's a good one.

I used the formulas on the bottom to come up with the port dimensions, you can change it however you'd like. With the port area in the diagram that you showed, I'm afraid that it would be too small and whistle like a MFr

 

[IrishChamp 10+ year member]

2 inches tall, 5.5 inches wide and 24 long is what I came up with originally

I'm a little confused on your port measurements, what are they again?

 

[IrishChamp 10+ year member]

thanks for your help. I will change the design to port on the passenger side with both subs next to each other right below the port on the passenger side.

why do you suggest 35hz vs 30? how will that effect the sound quality and output characteristics?

Sundown's website says that ported to 30hz in .6 cu^f each it will have a F3 of 25hz which means that it will have a noticeable drop off in output at 25hz correct?

My last sub was a single Polk SR124DVC being powered with 800 RMS watts in a 1.2 cu^f sealed box that played flat to 20hz from what the white paper said. now that was in a MUCH bigger car coming out of the trunk so I know this is a different game now but I really don't know what to expect from this setup and building a ported box.

thanks again.

EDIT: also wanted to clarify if box area should be 1.2 before or after subtracting port area, braces, woofers etc, not sure if the programs out there do that automatically.

With your box dimensions, you have total cubic feet of 1.195. I personally would tune it at 35 hz. With the top panel of the box being 7" that would give you 5.5" in width. To get to 35 hz, I would go with a port height of 3" for a port length of 24.25". So, port at the top of the box like your diagram, but fire twords passenger side, subs close together underneath that. Your port would be 5.5" x 3" for 24.25" in length for a tune of 35hz.