I’ve got the same sub and was planning on a 1 ft3 sealed box. But now I keep seeing infinite baffle come up and I’m slightly interested in trying that out. Wasn’t sure if this sub would work for that or not


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Personally, I would keep it running sealed.

 

The optimum ported box for the SQL12 is 1.25 to about 1.4 and tuned for 24-25 Hz but the problem is figuring out how to build such a small ported box tuned that low. You need around 20-25 sqin of port area at 1kW and that ends up being about 6 FEET long to hit 24 Hz so you have to do a labyrinth port and the total box size gets big due to the port volume. I've created a few designs in Sketchup but most people forget the ported box once they've heard the SQL in a proper sealed enclosure.

Mine started out as a Denovo 1 cuft knock down from Parts Express that had extra bracing added to get the net volume down to 0.7 cuft on Taramps Smart 3K and while it will handle that power I rarely turn it up full volume.

If you make your own box from 3/4" MDF it ends up only being 14"x14"x10" external dimensions to get a net internal volume of 0.62 cuft and there's literally no room left for bracing.

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The optimum ported box for the SQL12 is 1.25 to about 1.4 and tuned for 24-25 Hz but the problem is figuring out how to build such a small ported box tuned that low. You need around 20-25 sqin of port area at 1kW and that ends up being about 6 FEET long to hit 24 Hz so you have to do a labyrinth port and the total box size gets big due to the port volume. I've created a few designs in Sketchup but most people forget the ported box once they've heard the SQL in a proper sealed enclosure.

Mine started out as a Denovo 1 cuft knock down from Parts Express that had extra bracing added to get the net volume down to 0.7 cuft on Taramps Smart 3K and while it will handle that power I rarely turn it up full volume.

If you make your own box from 3/4" MDF it ends up only being 14"x14"x10" external dimensions to get a net internal volume of 0.62 cuft and there's literally no room left for bracing.

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Wow, that pretty much takes ported out of the equation. The temporary prefab has no bracing, but I've been assuming if I build a new sealed box, a driver this potent will require a beefier, braced construction. But it sounds like you're saying a box towards the smaller end of the range is preferable in-car? I suppose I could add bracing to the prefab, which would subtract some volume.

 

Thanks! Any opinions about the size of a sealed box? SI says .65 to 1.0 cubes.

 

Prefab box joints (edges) are the weak link - if you stay in the 0.6-0.7 range the extra Qtc means it will handle even more power and create more pressure. For this kind of pressure the edges really need to be dadoed and/or have additional material added in the corners and a double thick front baffle to be as inert as possible. But it all really depends on how hard you plan to run it as a daily. You can add bricks or 2x4s to your prefab box to test different volumes before you build a final.

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the 1 cu ft enclosure should be fine for that driver considering total volume after displacement of the driver. those drivers work best sealed, so i would run it sealed.
if IB is best for you, then get rid of the sql and buy a driver specifically designed for IB for better results.

 

Agreed - The SQL12 has a displacement of 0.15 so like[emoji121]said you should already be at 0.85 so it wouldn't take much to get down another couple of tenths. Also, your particular installation may benefit more from the slightly extended response from a bigger box without adding more power so the testing may show you that the box you have is fine.

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Great stuff, guys. Just the kind of input I was hoping for. For sure when I build the final box, it will be far better braced than the prefab. And good tip on placing wood/bricks to test different volumes. That would make me far more confident about building the correct sized box.

 

I just finished a box for a SQL12 - about 1.2 cuft sealed. Haven't installed, tuned and listened yet, though, so I guess this post is worthless! Lol

Approx OD
32 x 14.5 x 8

 

Haha, worthless post, but very impressive box!

 

Lol! Thanks!

I'll update with listening impressions, asap...

 

Since porting the SQL 12 and 15 are a nightmare, I'd be curious to see how they perform with a passive radiator. PSI offers high excursion PR's, and they seem to be a good trade off for people who don't have the real estate or aren't willing to give up the real estate a ported design would require.

Has anyone designed or built a PR'd SQL 12 or 15 yet?

 

I imagine it would get tough to fit PR's on such strong drivers. I think you might need a pair of 15's on the SQL12 if you plan to hammer it with power. Maybe 2 12's, but still.

 

Indeed - finding PR's that have the Sd and excursion to keep up is the 1st hurdle. The second hurdle is that the box for the 12 with 2 x15 PR's is difficult to build since it really only needs to be about 1.3 cuft net internal and that doesn't leave much in the way of options for cabinet construction. For me, given the cost and how small the sealed enclosure can be and how cheap Watts are I'd rather but another active driver than do PR's but I do love a good sealed sub.

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Fug - now I can't stop thinking about it... models to come shortly! LOL

 

Yeah, I like the sound, simplicity, and size of sealed subs, but despite PRs not looking like a viable option for my setup, I am curious about whether it's even possible.

Initially it was indicated that I'd be receiving the SQL tomorrow, but looks like it won't be arriving until Thursday. Feel like a kid being told Christmas got pushed back a week! Got an email from SI that the carbon fiber dust cap slows down the process, plus gas shortages and such are slowing things down. Cant' be helped, and glad they sent an update, but the wait is killing me! I have little doubt it will be worth the wait, though.

 

i have no need for it, but i am so tempted to snag a 12 with the carbon dustcap.

 

So the 15" High Excursion PSI Sub works mathematically for the tuning = 1.2 cuft box with 900g of added mass for an Fs of 8.3 Hz and neither the active nor the passive hit's mechanical limits with 3kW of power BUTT (you knew that was coming...) it's $265 for the PR (almost another active) AND it has a 14.8" bolt diameter and a 7" mounting depth (NOT accounting for movement of the added weights on the back) so it's nearly as deep as the SQL so you'd have to make a box with a minimum of about 16" of mounting depth in order to mount them back-to-back and even with tapered sides I don't see it being possible - maybe an hourglass enclosure? Anybody feeling froggy to make one of the tightest enclosures on planet earth?

Sub Box Pro Model

 

time to start a gofundme for @Holmz

 

Haha! Yes, that's the plan. Ordinarily I wouldn't mind the delay, but it has postponed a 2 week road trip around northern California I've been itching to go on. Worth it, I expect, though. I don't blame SI - these things happen.

 

I just snagged one of the SPL-15's with the carbon dust cap for my next install so I'm interested to see how this plays out. I don't have the space for a ported enclosure so I'll stick with the sealed dimensions that SI recommends...even with about 1800 watts going to it I'm sure it's gonna make some noise!

 

Interesting that they list the 12 from .65 to 1.0, but only list 2.0 for the 15.

 

I can not speak to the sound/output of a ported SQL12 but can tell you in a 1.07 CF sealed box with 1100 watts that they perform excellent. They have amazing extension below 20hz and have a very tight attack and decay in a sealed box. They stay very true to the music and are amazingly loud for any sub much less an SQ specific sub. I will be running a pair in my other vehicle with 850 on each sub in a 1.1 CF sealed box and expect great things. These numbers are before driver displacement.
On the car where one has 1100 watts it is in the trunk of a Jaguar and their trunks are VERY well isolated from the cabin yet the sub still sounded great. In the other build its a truck and they will be sitting under the rear seat in the cabin with me so I am sure they will be able to get much louder than I can handle. I am using the SIQ amps and they are impressively powerful!

 

Newb question, but what is the proper wiring to run a D2 SQL-12 at 1 Ohm?

 

Watts = V*I
V=IR so I=V/R

So we can then get to this:
W = V*V/R
(Using the algebra.)

Hence V is over 30V, and I (current/amperes) is also a bit over 30A

So now find the wire size needed for 30+ amperes, and the acceptable voltage drop.

 

R1 x R2 / R1 + R2 for parallel

R1 + R2 for series

Therefore, your D2 in parallel will present a 1 ohm load. To be clear, this is not an SI SQL specific method, it's Ohm's Law.

 

R1 x R2 / R1 + R2 for parallel

R1 + R2 for series

+ from amp to + on sub
Jumper from + to +

- from amp to - on sub
Jumper from - to -

That correct?

Using 12 gauge speaker wire, figure this should be sufficient.

 

Without any real break-in time, still playing with DSP setup, and in a lowly prefab box (1.0 sealed), this SQL-12 is kicking ass! Pretty much exactly what I was hoping for to replace the ID10 I was using - at least as good in terms of being articulate and tuneful, but with substantially more powerful deep bass. And not feeling tentative about getting high output like I was with the ID10, which replaced another ID10 I had killed. Considering that I'm definitely not extracting all of its potential yet, very excited to hear what it does at closer to max performance.

 

You guys may think I'm crazy, but I built an enclosure for a SQL-12 that's 2.25ft^3 tuned to 22Hz with 19 1/2 sq in of port area.

I slammed this together during an overnight thrash session on a guy's vehicle to get him to a competition. Was a complete rebuild of the install.

You can see the Term-Pro chart, the construction, and the end result.

The port is 13" tall and 1 1/2" wide with a flare at the baffle exit to reduce turbulence.

The 3rd image shows the JL Tun software. You can see that there's a 70Hz LR4 on channels 7/8 and there's no EQ applied to the sub.

Just below the Tun window you see the response (six mic average at the listening position) in SysTune. It's damn near flat. Like a 2dB deviation at 40-ish.

Port noise wasn't an issue.

This sub will play anything in this enclosure. The 8Hz note in Bass I Love you was moving the guy's entire liftgate when the sub was powered with a DD Audio M1d. We measured something like 400 Watts that the sub was seeing.

People have a hard time believing they're listening to a single 12 and they all comment on how clean/effortless the bass is.

 

@JI808 Is there any way you can send me the specs for the designs for this box? I tried building it on sperkerboxlite and got pretty close based on your info and measurements. I just want to make an Identical box.

 

My cheap prefab box is a placeholder until I build a fiberglass stealth enclosure to regain usable trunk space, so opposite direction of your box, but dang that's impressive.