Twin Sundown SA6.5 SW D2 32Hz Ported 0.6ft3 in Ford Escape Box Build

imsickofweed

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I just bought 2 of these subs from the yard sale, hopefully I can get them going without too much trouble, if not I guess Ill buy some more.

Here are my box requirements:

1. Built behind the front passenger seat and allow for enough legroom and recline for a 6’3” guy (me) to lay down and sleep on a road trip.

2. Short enough to allow the rear seats to fold down even with the top of the box to carry cargo.

3. Only as long as 1 persons seat width from the door allowing 2 adults to sit with the standard legroom behind driver and center console. Right side seat will mainly be used for one of my sons car seat.

4. Box volume will be 0.3ft3 per sub totalling 0.6ft3, port are is 4in2 per sub total of 8in2 (port will be 1”x8”x28-29”)

5. 1/2” 7 ply Baltic Birch screwed and glued with a layer of fiberglass inside for strength. I would not have enough volume using 5/8” or 3/4”.

6. Subs will be downfiring so my boys can climb all over the box and kick it constantly while we drive.

Specs for the subs (woofersetc.com):

Power Handling: 200 Watts RMS

1.5" Coil with 1" winding length

Thick 10mm Extended Top Plate

Hyper-Extended Pole piece with integrated cooling channels

Full height magnet ID shorting ring for reduced inductive distortion

Fully stitched surround

Flat tied-on high-current tinsel leads

T/S Parameters D2:

Fms: 48.9 Hz

Res: 45.5 Ohm

Re: 4 Ohm

Qms: 4.82

Qes: 0.50

Qts: 0.46

Rms: 4.8 kg/s

Cms: 0.14 mm/N

Mms: 74.8 gr

Nref: 0.09 %

Bl: 13.5 N/A

SPL: 81.6 dB

VAS: 4.1 L

Rp: 31 Ohm

Lp: 24.7 mH

Cp: 829.8 uF

Le: 1.69 mH

Enclosure Specifications:

0.25cuft - 0.35cuft ported (NET) per woofer (0.3cuft recommended)

Port area: 4sqin per woofer

Mounting Depth: 3.79"

Current System:

Alpine PDX-V9 4x100w 1x500w (dyno sheet says 4x118w 1x525w @14.4v)

Focal PS165V2 component set 75w to mids 35w to tweeters @13.7v

Ill start the subs off at 400w @2ohm for the pair and move it up to 450w @2ohm to see where I like it.

Progress:

I spent a lot of time marking up the ends with some cardboard, Ive eliminated a lot of the rounded curves for ease of construction and calculation of volume. My calculations for available space after port is 0.67ft3 without bracing.

Questions:

1. Ive heard these can handle more than 200wrms anyone have any experience with the limits of these little guys?

2. I cant find the volume of the sub, the x6.5s are 0.05ft3 so Im estimating 0.04ft3 for the SA6.5

3. If 1/2” 7ply Baltic birch strong enough for this box without fiberglass? With fiberglass?

Ill try and get some pictures up soon so you can see my odd space. Any help or advice is greatly appreciated, thanks in advance.

 
You should list the max width, length, and height of the enclosure you are building and let shredder2 help you design the box. He’s very good at it and does it for free but does take donations as he suffered a pretty bad stroke that left him unable to work.

 
Last 6.5" sa box i looked at doing was 40hzish... really couldn't go much lower with the tune and get a decent response IMO.

I'm sorry, I was mistaken about the driver. It was an X-6.5 enclosure that I looked at... with a 55hz fs

CAtziG.jpg


Those underseat boxes are not easy... lol

 
You should list the max width, length, and height of the enclosure you are building and let shredder2 help you design the box. He’s very good at it and does it for free but does take donations as he suffered a pretty bad stroke that left him unable to work.
Its not that easy, its not a square shape, and its not under the seat; its between the rear bench and front passenger seat. Ill get some pictures or a video up to explain a little better. On each end I have an area 8.25-10.75” width x 2” deep, an area 10.75-12.25” width x 3” deep, and 12.25” width x 1.25” deep, total length is 20” (interior measurements not counting port). Total volume is 0.756ft3 using true 1/2” material. I bought 1/2” birch, but stumbled on some possibly 5/8” birch that measures at 1/2” thick.

The tuning was suggested to me by the manufacturer in the specs. They say 4in2 port tuned at 32Hz, is that not correct? Its the same recommendation they use for the sundown x6.5s. Should I be tuning the port at Fs of 48Hz?

 
I saw the manufacturer recommendations and tried to model em according to what they said... to me the response curve looked strange... idk... once tuning was raised it began to look better... that's ported btw... maybe I did something wrong but a 40ish tune is what looked ok to me. The 32hz ported was kinda off imo... idk... just sayin.

That's the X-6.5 ... idk bout the sa series.

 
I saw the manufacturer recommendations and tried to model em according to what they said... to me the response curve looked strange... idk... once tuning was raised it began to look better... that's ported btw... maybe I did something wrong but a 40ish tune is what looked ok to me. The 32hz ported was kinda off imo... idk... just sayin.That's the X-6.5 ... idk bout the sa series.
Sundown doesnt gave the SA specs on their website, but amazon, woofersetc and others share the specs I posted with the 4in2 port per sub and tuned to 32Hz. Maybe Ill call sundown and hopefully get a straight answer.

 
This is what I'm referring to... green is a 32hz tune, yellow a 40hz tune and pink a 44hz tune all in the same .3ft3 airspace. That's the X-6.5 but it's another higher Fs driver... I suppose they would sound ok with a 38-39hz tune but I really don't know. Looks like a TON of output loss to me with the lower tune... just sayin'...


WxwgTb.jpg


 
Theres got to be a reason why sundown recommends tunings at 32Hz, perhaps theres some variable that we are missing? I like the way the 32Hz curve looks because its more of a flat response as opposed to the big peaks. Sundown says not to use a sealed on these because of the suspension, perhaps thats what makes this a better sub than what the model shows? This is my first ported box build, so I really appreciate the help, I just thought I had it all figured out following the manufacturers recommendations.

 
Theres got to be a reason why sundown recommends tunings at 32Hz, perhaps theres some variable that we are missing? I like the way the 32Hz curve looks because its more of a flat response as opposed to the big peaks. Sundown says not to use a sealed on these because of the suspension, perhaps thats what makes this a better sub than what the model shows? This is my first ported box build, so I really appreciate the help, I just thought I had it all figured out following the manufacturers recommendations.
I'm not sure myself... I'm wondering whether a T-line or bandpass would be a better option if you got the space (which you do not)... but I learned that a lower tune that looks to be losing output coupled with small cone area is a recipe for meh. I suppose if SQ is your goal but I like some output as well... IDK

 
I cant read the T/S on those sheets theyre too blurry on my iphone, can anyone please post them? I can see the frequency curves that peak and high 30s and low 50s, is that why you think 40Hz is the better tune? FYI Im using the D2 version (DVCS in parallel, subs in series) so the amp will see 2ohms, I noticed your graph has 4ohms.

Heres a little video showing my progress and space available.

 
On my handy dandy port length calculator I can tune to 38Hz with around 19”, which makes the port with 1 board instead of turning the corner on the door side to get 32Hz with 28” port.

 
I cant read the T/S on those sheets theyre too blurry on my iphone, can anyone please post them? I can see the frequency curves that peak and high 30s and low 50s, is that why you think 40Hz is the better tune? FYI Im using the D2 version (DVCS in parallel, subs in series) so the amp will see 2ohms, I noticed your graph has 4ohms.
Heres a little video showing my progress and space available.


Use 2 fingers to zoom in on that sheet.

The parameters fo the 32 hz tuning is the same on the x6.5

 
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