I need advice for a ported box for 4 sundown sa8 v.3's in a 2014 F150 SCREW

[Trash King]

Hey guys, I am going to run 4 sa8 v.3's off a Massive Audio n4 (2000 watts rms) with 0 gauge wiring in my f150, I lifted the rear seats 2.5 inches so I have the room for enough air space and for the subs to actually fit. I had the same set up with the v.2's in my tahoe, and was happy with it, but wanted it to be tuned lower (it was tuned to 35hz). So my first question is, can I tune the box to 32hz even tho the specs for the subs call for 35? I was told by a stereo shop that it can cause the subs to "act funny" (his words), and the subs won't perform as well. I listen to a lot of rap, but also metal… FFDP, Korn, In this moment…so I want that low end, but also want to feel the double bass pretty hard. So My second question is, is 32hz a good frequency to shoot for?? Also, what is the best placement for the port?? On the face with the subs? Sides?? I should mention that the subs will either be down or rear firing, and I'm thinking about doing an external port. Rear firing is my preference if i can make it work with the height of the seats (they angle down toward the rear of the cab). My final question (for now) is, what style port should I use??

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[Boomin_tahoe 5,000+ posts]

Don't go back to that shop again. They have no idea what they're talking about.

Calling @CSCStang for some true help.

 

[CSCStang]

Hey guys, I am going to run 4 sa8 v.3's off a Massive Audio n4 (2000 watts rms) with 0 gauge wiring in my f150, I lifted the rear seats 2.5 inches so I have the room for enough air space and for the subs to actually fit. I had the same set up with the v.2's in my tahoe, and was happy with it, but wanted it to be tuned lower (it was tuned to 35hz). So my first question is, can I tune the box to 32hz even tho the specs for the subs call for 35? I was told by a stereo shop that it can cause the subs to "act funny" (his words), and the subs won't perform as well. I listen to a lot of rap, but also metal… FFDP, Korn, In this moment…so I want that low end, but also want to feel the double bass pretty hard. So My second question is, is 32hz a good frequency to shoot for?? Also, what is the best placement for the port?? On the face with the subs? Sides?? I should mention that the subs will either be down or rear firing, and I'm thinking about doing an external port. Rear firing is my preference if i can make it work with the height of the seats (they angle down toward the rear of the cab). My final question (for now) is, what style port should I use??

What year F150? They are so tight under there even with a lift. Gonna be tough to do rear fire and I don't recommend it...phasing issues. Best port placement is side firing off the side walls.

Unless you listen to decaf, rebassed music...you need to tune at 36-37 actually. 32 won't pick up that double kick much at all.

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[CSCStang]

As far as port...go with aero...more efficient and less displacement.

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[kr15 5,000+ posts]

In my experience, SA 8s do a pretty good job below tuning. I had 3 in 2.25 at 34, and it had no problem playing to upper 20s at all. 32hz would be more of a rap tune. Id tune em that low, but I listen to 95% rap.

Subs forward, port side

 

[Trash King]

Cscstang, thanks for your reply, it is a 2014 SCREW FX4. You're right, it is still very tight under there even with the lift. I would have to build the box further forward to make it work, so I will probably end up downfiring them. The main reason I want rear firing is that one of the stereo shops in town has a 13' Silverado with 4 8s that is rear firing at 32hz and it sounds incredible, it hits much lower than mine did in my Tahoe. The seats are higher lay flat in the chevy, mine are angled down in. The rear.( This was a different shop than the one that said I shouldn't tune my box to 32).

 

[Trash King]

Agreed, I just wanted to make sure there was no truth to that.

 

[trumpet 5,000+ posts]

In my experience, SA 8s do a pretty good job below tuning. I had 3 in 2.25 at 34, and it had no problem playing to upper 20s at all.

This should be the case as a port will retain control over the output down to 1/2 octave below the port tuning frequency. 0.75 x 34 = 25.5 Hz. That means a 29 Hz sine wave should be coming from the port while the cones are hardly moving.

 

[inteva6184]

Have you checked to make sure they will work down firing I suspect they wont. Remember the surround sticks down pretty far and with .62 inches of excursion you will need your baffle at least 2.5 inches off the floor honestly probably more considering how the box sinks into the carpet and deadening a bit. I just installed 2 of those subs in mine and after breaking them in absolutely love them. I took cscstangs advice and did them front firing with a aero port close to the door tuned to 35hz. My box only has two and wont work for you but here is what I did I still need to finish it maybe a cup holder I am not sure.

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[Trash King]

Thats true, it might not work, at this stage I am still playing around with ideas. How do you like it firing to the front? It's been my experience that the low end loses intensity when faced forward. I've played around with some of my smaller systems when i was really young, moving the box around, facing front, facing rear, and up ect. and has always been louder and lower when facing the rear. Thats why I'm trying to go back or down firing. But it is very possible that I only have enough height to face them forward.

 

[Trash King]

Hey cscstang, can you expand on what you mean by phasing issues??

 

[inteva6184]

Thats true, it might not work, at this stage I am still playing around with ideas. How do you like it firing to the front? It's been my experience that the low end loses intensity when faced forward. I've played around with some of my smaller systems when i was really young, moving the box around, facing front, facing rear, and up ect. and has always been louder and lower when facing the rear. Thats why I'm trying to go back or down firing. But it is very possible that I only have enough height to face them forward.

I did a 10 up firing and down firing. It sounded much much better down firing. I run the sa8 v3 front firing and they play very low and loud. I dont think you have another option for under the seat I think that massive little 8 will only fit under the seat facing forward. Here is a picture of mine with no seat lift. Its hard to imagine with an extra 2.5 it will fit rear firing. How did you go about lifting your seat 2.5 inches?

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[Trash King]

I bought a 2.5" seat lift kit from LMI welding online, it was very simple to install and looks good. I'm working on loading up some pics (I keep getting error codes so bear with me), so you can get a frame of reference, but it actually made a lot more space down there in comparison to factory height.

 

[CSCStang]

Hey cscstang, can you expand on what you mean by phasing issues??

Meaning the low end will extend and be louder but the rolloff would be quite steep because of the sub placement. But hey if you're looking for the lowwz I suspect that would be quite nice. With the lift do you have roughly 3 net cubes after all displacements?

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[CSCStang]

Rough mock up with 54w 16d 9.5 front and 6.75 rear height you're looking at only 2.96 gross cubes with 3/4" material.

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