DVC sub wiring; 1 sub sometimes, 2 other times

[Mass Car Audio 10+ year member]

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Mr. Squeak ... New related question, if you don't mind:

Right now I have one of the 10" Alpine SWS-1043D 4ohm DVC subs wired to the Alpine PDX-5. I've tried squeezing every different shaped box design I can dream up for the 2nd Alpine sub, but I simply don't have enough space for the recommended 1.0 cu-ft sealed box. So, I was thinking of switching the 2nd sub to this 2ohm SVC 8" JL 8W3V3-2 model; It's recommended sealed box size is just 0.3cu-ft, which I can do.

Is there any reason not to connect the 4ohm DVC Alpine and the 2ohm SVC JL sub, wired just like you explained before? I think they're both 2ohm loads, correct?

And ... Would it be absolute heresy to mix and match sub makes/ models/ sizes like this?? //content.invisioncic.com/y282845/emoticons/crazy.gif.c13912c32de98515d3142759a824dae7.gif

(The JL would be pretty much completely out of sight, so I don't care that they're different makes/ models)

Thanks for your knowledge!

Just isobaric load the 2 Alpine SWS-1043D. You only need to make the box 1.5 cubic foot for two of those subs. So insted of having a 2 cubic foot box for the 2 10's it will be 1.5 cubic foot with them in a isobaric load configuration. The premise behind the isobaric configuration is that such an arrangement

allows the box volume to be 1/2 that of a single woofer configuration. Just remember to switch the polarity on the sub that is out of the box.

 

[drpeeb 10+ year member]

Just isobaric load the 2 Alpine SWS-1043D. You only need to make the box 1.5 cubic foot for two of those subs. So insted of having a 2 cubic foot box for the 2 10's it will be 1.5 cubic foot with them in a isobaric load configuration. The premise behind the isobaric configuration is that such an arrangement allows the box volume to be 1/2 that of a single woofer configuration. Just remember to switch the polarity on the sub that is out of the box.

Never heard of it! Gotta go read. Looks like one sub is entirely sealed in; Overheating problems? What does this gain??

Now that I think about it, not gonna matter much anyway: The one Alpine I have in right now is in a 1.0 cu-ft sealed box, and that's pretty much as big as I can get it on the driver's side. I'm wanting to add the 2nd sub to the passenger's side ... if there's a reasonable way to do it, and if it's gonna gain me anything at all.

Tks for the idea, though, I'm going to look into it more now just to know ...

 

[Mass Car Audio 10+ year member]

Never heard of it! Gotta go read. Looks like one sub is entirely sealed in; Overheating problems? What does this gain??
Now that I think about it, not gonna matter much anyway: The one Alpine I have in right now is in a 1.0 cu-ft sealed box, and that's pretty much as big as I can get it on the driver's side. I'm wanting to add the 2nd sub to the passenger's side ... if there's a reasonable way to do it, and if it's gonna gain me anything at all.

Tks for the idea, though, I'm going to look into it more now just to know ...

You actually should gain more sound pressure per cubic inch of cone area in a isobaric load configuration but you also will loss some efficiency. A subwoofer out of the box will actually run cooler than the one in the box. The air in a sealed box will get warmer and stay warm by the heat of the subwoofers motor.

 

[squeak9798 5,000+ posts]

How is he going to gain SPL isobarically when the cone area and excursion limitations remain the same as a single subwoofer and he is not going to increase power to the subwoofers? His amplifier power will not increase when using the dual woofers, which means he'll effectively have the same output capabilities as a single 10" on 150w if he mounted them isobarically....so he'll already be down by approximately 3db in peak output by doing an isobaric install. Assuming the enclosure size remains the same (rather than altering it so Qtc stayed the same), the response curve created by the different Qtc will change....but SPL (output) will decrease over the entire audible bandwidth. Altering enclosure volume to maintain a consistent Qtc will give him a full 3db loss in output over the entire bandwidth.

And to answer the original question......in general no, don't mix and match subwoofer size/brands/models.

 

[Mass Car Audio 10+ year member]

How is he going to gain SPL isobarically when the cone area and excursion limitations remain the same as a single subwoofer and he is not going to increase power to the subwoofers? His amplifier power will not increase when using the dual woofers, which means he'll effectively have the same output capabilities as a single 10" on 150w if he mounted them isobarically....so he'll already be down by approximately 3db in peak output by doing an isobaric install. Assuming the enclosure size remains the same (rather than altering it so Qtc stayed the same), the response curve created by the different Qtc will change....but SPL (output) will decrease over the entire audible bandwidth. Altering enclosure volume to maintain a consistent Qtc will give him a full 3db loss in output over the entire bandwidth.

And to answer the original question......in general no, don't mix and match subwoofer size/brands/models.

I understand the therory, But I have noticed a big difference when isobaric loading 2 subwoofers but I always change the box volume so the qtc drops and I add more power.

 

[drpeeb 10+ year member]

How is he going to gain SPL isobarically when the cone area and excursion limitations remain the same as a single subwoofer and he is not going to increase power to the subwoofers? His amplifier power will not increase when using the dual woofers, which means he'll effectively have the same output capabilities as a single 10" on 150w if he mounted them isobarically....so he'll already be down by approximately 3db in peak output by doing an isobaric install. Assuming the enclosure size remains the same (rather than altering it so Qtc stayed the same), the response curve created by the different Qtc will change....but SPL (output) will decrease over the entire audible bandwidth. Altering enclosure volume to maintain a consistent Qtc will give him a full 3db loss in output over the entire bandwidth.

And to answer the original question......in general no, don't mix and match subwoofer size/brands/models.

Ok, tks again. So my reasonable choices seem to be 1) Use only the single sub as is (man I hate to admit defeat & give up!), or 2) Put the 2nd 10" sub in a box about half the volume of Alpine's recommended 1.0 cu-ft. Bad idea?

Now I could make a sealed box about 1.0 cu-ft, but man it would be crazy looking. I could post my various CAD designs, but you'd want to be prepared to see an MDF Medusa. Again though, it's gonna be under the rear seat, so the only bad part will be making it, getting the joints to line up pretty well, then screws, glue and caulking! Of course, if that's going to gain me nothing, I'd rather skip it and put the 2nd sub on eBay I guess. Thoughts?

 

[squeak9798 5,000+ posts]

I understand the therory, But I have noticed a big difference when isobaric loading 2 subwoofers but I always change the box volume so the qtc drops and I add more power.

Well, if you lowered Q and increased power it's possible that you did gain some output in the lower octave due to the change in frequency response (though the same could have been achieved with a single driver in the same alignment and less power).

 

[squeak9798 5,000+ posts]

Ok, tks again. So my reasonable choices seem to be 1) Use only the single sub as is (man I hate to admit defeat & give up!), or 2) Put the 2nd 10" sub in a box about half the volume of Alpine's recommended 1.0 cu-ft. Bad idea?
Now I could make a sealed box about 1.0 cu-ft, but man it would be crazy looking. I could post my various CAD designs, but you'd want to be prepared to see an MDF Medusa. Again though, it's gonna be under the rear seat, so the only bad part will be making it, getting the joints to line up pretty well, then screws, glue and caulking! Of course, if that's going to gain me nothing, I'd rather skip it and put the 2nd sub on eBay I guess. Thoughts?

You can always experiment with the enclosure volume of the sub you have now. Try adding some scrap wood of known volume (L x W x H) to the inside of the enclosure and listening to it again will allow you to tell if you'll still be satisfied with the performance of the subs in a smaller enclosure.

If you do decide to use them both, make sure both subs are in the same volume enclosure.