Box Questions for (3) SA x-8 v.4

[Ecohostile]

So I drunkenly purchased these because I’ve always thought 8’s are awesome, and of course I didn’t think about port size at all.

 

Gear:

3- SA x-8 v.4 D2’s

SIA 2500.1d

- 2500w @ 1ohm/2ohms

(1.3ohm load with 3subs and 2ohm with 2)

 

Car 2021 Mazda CX5 

 

First question:

would it be better to run 2 of these with 1cu ft of box space and 16sq in of port area each?

 

or

 

3 with .75 cu and 12sq in of port area each?

 

Second question:

what about sealed. I know it’s not recommended for the v.3’s but is it still the same?

 

third question:

I think I could save some space going with aero ports but I’m having a hell of a time figuring out the math.

 

I have a bunch more questions but I’ll start with that. I’ve been modeling up my trunk in sketch up so I’ll throw some visuals up later of what I have in mind.

 

also grabbing some cardboard from my job site so I can mock up some box ideas and test em out. 
 

Thanks!

 

Edited November 7, 2023 by Ecohostile
Dual 2 not 4

[Joe X]

Without sub specs you should call sundown and get the optimal box specs and go from there.

 

My only comment is that you might have space for 2 12s in that vehicle which would be far louder,  also 3 subs lead to impedance mismatch for most amps, you will need a constant power amp to get the most power form a non standard final impedance, some examples are the Taramps smart series and the rockford fosgate CP series.

[Ecohostile]

Did Some work on sketch-up and did a little math.

 

Came up with three wedges, All measure 19" (H) X 41" (W)

3/4 " Plywood and double baffle but no ports yet

 

The Smallest -

12.75" deep / 2.74cubes (2.35 with displacement)

Obviously I haven't factored in bracing or port either. Hoping to find out how much i need and adjust the design

 

 

Medium:

14.75" deep / 3.52 cubes (3.13 with displacement)

getting closer i think

 

Large:

15.75" deep / 3.97cu (3.58 after displacement)

 

what are your guy's thoughts?

[Ecohostile]

16 minutes ago, Joe X said:

Without sub specs you should call sundown and get the optimal box specs and go from there.

 

My only comment is that you might have space for 2 12s in that vehicle which would be far louder,  also 3 subs lead to impedance mismatch for most amps, you will need a constant power amp to get the most power form a non standard final impedance, some examples are the Taramps smart series and the rockford fosgate CP series.

the SIA 2500.1d is Sundowns version of the same tech that Taramps is using. Wiliston Audio has a video up on it.  Also I'm prety sure no amp ever see's exactly one or exactly 2 ohms. When you account for box rise and other variable the resistance is constantly fluctuating. So I see no reason why 1.3ohms would be bad for an amp thats rated down to 1ohm.

 

Also I realize I probably should have gotten different subs but these are the ones I got so I'm gonna use em!

[Ecohostile]

Decided to make one more "conventional" box before I call it a night.

 

41" L x 10" H x 22.85" D

 

NET 3 cu ft

 

36 sq in of port

 

tuned to 32Hz

 

port inlet 4.23" x 8.50 " x 24.22 Inches Long

 

 

This box just feel like it takes up so much more of my trunk, although I haven't accounted for port area on the other models

[Joe X]

Nice sketches, in my opinion:

 

1) use the last box style as it will be louder due to the subs being closer to the rear end of the vehicle, use double layer baffle and a lot of bracing as these are higher end 8s.

 

2) use a constant power amp of the power you intend to run including the Sundown SIA series or just get a more powerful amp so that you can still get your desired power at 1.3 ohm, power is cheap these days so that shouldn't be a problem.

 

3) call Sundown for box specs or wait for them to come out before building anything so that you don't have to rebuild a box.

 

Great work, hopefully you will build log and review those subs, should be interesting.

 

 

[mel80]

i also vote for last box design 

3x x8's should be p retty dang loud i ran 4x e8 v6's for a while on 2 x 1200w amps and they got loud if i had to guess id say a solid 145ish in my car i never did get that setup  metered before i went to 3x 12's in the trunk and then 5 12's in a flatwall int he same car 

 

my e8's were in a 4cft net box with 36inch of port area tunned to 32hz 

[mel80]

bassed on v3 specs im going to guess ur going to want 3cft net and about 46sqinch of port , though u have room to play with port area , less sqinch of port = less port lenght so u can use that to play with ur box design to get it to fit int he car nicely , i would stay within the 36-50sqinch's of port though andthing smaller then 36sqinch is likley to have port noise 

[Ecohostile]

51 minutes ago, mel80 said:

bassed on v3 specs im going to guess ur going to want 3cft net and about 46sqinch of port , though u have room to play with port area , less sqinch of port = less port lenght so u can use that to play with ur box design to get it to fit int he car nicely , i would stay within the 36-50sqinch's of port though andthing smaller then 36sqinch is likley to have port noise 

Ok cool, I’ll mess around a little bit with the design. If I can get the box slightly shorter to line up with the wheel wells I might do that.

[mel80]

something to this extent

 

Edited November 7, 2023 by mel80