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Discussion Starter · #1 ·
I have a DC Audio XL12. The recommendation for this subwoofer is 1.5 ft. There is no rec. for sealed, but that 's what I want; a sealed enclosure. Here are the specs of the subwoofer:

XL 12"
Mounting Depth 7"
Mounting Hole Diameter 11"
Motor Width 8.75"
Weight 54lbs
VC Diameter 3" Flat 8 layer
Displacement .19³ ft
Magnet Weight 50lbs
Power Handling RMS/Peak 1500/3000
Impedance (Ohm) d.7, d1, d1.4, d2
Sd 494.00 cm²
Fs 38.90Hz
Qms 6.51
Qes 0.31
Qts 0.29
Xmax 26mm
Sensitivity 90.73
Suggested Sealed N/A
Suggested Ported 1.5³ ft

I want it sealed because I'm not competing, so I need more than one note.
 

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Vented can have a flatter response than sealed, its all in how you tune the box. Sealed can roll off smoother but still rolls off, if you port to say 30Hz most aim for flat response to there its pretty good for a car. If I have time later I'll try to figure that sub, but what kind of response are you looking for and how much room do you have?
 

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Discussion Starter · #3 ·
Thanks, shoestring. As for exactly what I'm looking for, I don't have a specific number. That's because I'm new. Not new to car audio, but new to paying attention to technical things. (I'm getting older).

I'm basically looking for a well rounded system, not a one note wonder. Which is basically what these things are made for but it's what I have to work with. It's going to be a daily driver, but at this point I'm totally open to ideas. Here's what I'm working with:

DC Audio XL12 - HCCA 275g4
DC Audio L2 8's- HCCA 250g4
Orion 3100 SVF 3way crossover

I have more stuff, this is just for the rear. It's all going to be in an Audi B5 A4. I have a ton of space in the trunk. Somewhere around 17 cubic feet. My initial idea was to suspend the 8's from the rear deck, rear facing 12 in the trunk. I'm pretty set on this, however the design of these enclosures are still up for debate. Sealed, vented, ported? I'm not sure what's going to give me the best "well rounded" sound. Let me know if you need any more info.
 

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Before we go into a box design, we need to know how much power you are giving that sub. If you have very little, IB. If you have a good amount, ported. If you have more, then a sealed would work. Why? Sealed takes the most power to get it sounding right since it is fighting itself, witch in return is more work for it.
 

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When its sealed, I find something smothered and strangled.... let that sub breathe. Go ported. If the mix is a tight then it will sound tight on ported too. All subs in the music mixing industry that producers mix on if ever, - are ported. So its better to use a more similar reference to what the original mix of the track was mixed on.
 

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Discussion Starter · #6 ·
Nick650, the 8's are going to see 800 to 1000 rms, and the 12 will see 1200 to 1400 rms. These numbers are between 12.5 and 14.4 dc volts. The amplifiers I'm using are all class a/b unregulated. The 275 has been known to clamp out at over 2,000 watts. I won't be maxing out any of my amps, but for what I want, I have plenty of power.

Arsenal; I hear what you're saying. Good info, thank you.

Sorry if I'm not answering as fast as some of you may like. I've been in and out alot this weekend.
 

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When its sealed, I find something smothered and strangled.... let that sub breathe. Go ported. If the mix is a tight then it will sound tight on ported too. All subs in the music mixing industry that producers mix on if ever, - are ported. So its better to use a more similar reference to what the original mix of the track was mixed on.
:lol: Dont listen to stupid **** like this. A dc level 4 is not going to give you perfect sq sound but it will sound damn good in a ported box. Thats what it was designed for. So model a few up to get the response you want and unless you take cabin gain into account its not gonna be what you see on paper anyway. One things for sure though thats one loud ass sub with the right amount of power.
 

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Discussion Starter · #8 ·
Thanks Thomasluke. That lets me know I need to research more. And ya, ultimately, mockups and my ears are the final determination. I sometimes get impatient though and think there's going to be "that magic number" when it comes to this ****. But believe it or not, I've been doing this at least long enough to know better. Doesn't keep me from asking though!

The cabin gain you mentioned; that's when you think of your trunk as a bandpass right? That's going to be a crazy one to figure out because first I have to include the size of the 8's box, (whatever that's going to be). And part of that equation could also involve my vent (or port) being part of the pass through I would need to create through my seats because my trunk is fairly well sealed.

I ran a W7 with its matching 1000/1 and when I had the seats up, no prob. Seats down and I could hardly make it through more than one song.

Also, I left my sub program on my old computer. What are people using? Win isd, or something like that, and is that reliable. The term "reliable" being completely relative!
 

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That sub MUST be ported or it will sound like horse $hit. My program tells me this because of it's QES. This will determine what suits it best. With that note, DON'T GO SEALED or ELSE!

Note: You have plenty of power to make it sound good in ported FYI.
 

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If you go sealed with it, it would probably need a Linkwitz Transform circuit or else have really poor response. And LT circuits use a lot of extra power.
 

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Discussion Starter · #11 ·
Fair enough. I will open up the enclosure. I'll start looking around and try to get some ideas on how I'm going to pass it into my cabin.

Thanks for the responses folks!
 

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Get a hold of Pete at pwkdesigns.com

Best blueprints. Models the sub and your car type for the response you want.

If you don't like your subs to sound bloated, then tune lower. Like said before, you can model them on WinISD or Unibox for free. a gentle roll off will more closely match the cabin gain in your vehicle. It's why a lot of people love sealed. The upper bass frequencies are not masked by the bloated lower bass. Some people LOVE bloated lower bass. It always comes down to your preferences and what else you have in your car. It's only subs and EQ's are cheap!
 

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If you go 4cf box tuned to 30Hz you can get +/-1dB 29-70Hz, this model is for a pair.

You can go down to about 3.2cf up to 5cf, tune 25-30Hz in that range it can be pretty flat. You could go 2.8cf and 31Hz but it will not quite reach to 30Hz and then it rolls off a lot. Still only 2dB drop from ~100Hz so its pretty flat yet. It depends on your cabin gain and how much dB you want to lose you could go smaller. Its really really ugly sealed. At 1.5cf ported it can't get under 40Hz. At 3cf you can get just under 30Hz losing 3dB, tuned to 29hz. How low do you need? If you like tighter subs that put out more at 50 than 30 you can get away with smaller plus the cabin gain will help. 3cf at 29 is like that, vent is 4" by 10.37 but that might not (I am sure) be enough port volume for those. If you want it to thunder low then you should go larger.

Another guy on here built a cool box with a single 10 for a pass through. He put dual slot ports ending on each side of the sub, it just fit up to the pass through you see the sub and ports face each other. Said it worked well, but you can't do that with pair of 12s of course lol. They would not work well IB the roll off is huge, it would be a mother to EQ just like if sealed. You might just face the box to the pass and sort of seal the sides, and most of it will go through, if you really want to wang then flip the seats.

What I put above is more of an SQ tune, something I would listen to for music in a daily driver but I like my 30Hz and 25 if I can get it (because I like bottom and can get rid of bottom much easier w/EQ than I can get more, depending on what type music I have in). It will be much different than a SPL tuned. The 1.5cf they recommend (per driver) does work, if you port to 45Hz you get a wicked peak at 50Hz (1kw shows 125dB). But if you port at 29Hz it will go down to 30 but you lose dB (1Kw shows 120dB). You go larger on the box you can get some dB back and still get to 30. So it will not be as 'loud' tuned lower, but sound way nicer with music. The way it models its hard to curve the response, its a low Q driver, 0.3 qts. You kind of port it to go as low as you want and its flat to there, smaller box makes it lose more on the bottom end and larger makes it gain on the bottom.
 

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I didnt read everything said here. but if you want a small sealed box, then pick a sub that will work in that! I will never understand picking a sub, then the box. if you pick a sub, you have to pick an enclosure it will work in. some will allow sealed or ported, some wont.
 

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Discussion Starter · #16 · (Edited)
Minbari, I didn't really pick the sub. I picked a completely different sub. But because DC Audio dragged me through the mud for 5 or 6 months, this is what they gave me. I wasn't going to turn down a two stage upgrade. so my questions are based on what I originally intended for this system. But since they're not compatible, I'm not going to do that.
 

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ok, but you still have to use it as intended. if it wont work for sealed, then ported is what you are stuck with.
 

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Discussion Starter · #19 ·
Thanks for all your help guys. I've been doing super basic stuff for a long time. Now I'm trying to learn to do it "correctly". Big difference. I've had it loud a hundred times. This time I want to do it right.
 
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