Amp/Sub Ohm's Confusion

mattwz · 07-01-2005, 10:59 PM

I'm planning on buying a pair of Alpine SWS-1242D subs, which according to the specs run at 4 ohms.
For the amp, I want to buy the Hifonics BX605. According to the specs, it runs at 600 x 1 RMS @ 1 ohm or 300 watts @ 2 ohms. Would this amp work with these subs? If not, what type of amp would I need to run the Alpine subs? I'm having a hard time figuring out how the different types of wiring and things affect the ohms.

Thank You

Matt

mattwz · 07-01-2005, 11:26 PM

Well I checked out this http://www.the12volt.com/caraudio/wo...igurations.asp on the12volt.com, and it came out to a 1 ohm load when wired in a parallel configuration. I just bought both the subs and amp, so I'm hoping this works out. Now all I need is a box :\

-Matt

Cheekz185 · 07-01-2005, 11:33 PM

Just make sure you wire them correctly. Those subs will be fine with the amp...

mattwz · 07-01-2005, 11:51 PM

Thanks, just wanted to make sure.

I have a question about building the sub enclosure. The specs say the recommended cubic feet for a sealed enclosure is 0.85 - 1.5. I'm guessing I have to double that because I'm putting 2 in the box. So 1.7 - 3.0? Is there any type of ratio of the dimensions I should go by when building the box? I was looking at the calculators on the12volt.com, and there are many different combinations. I guess the biggest factor is the height.

Thanks

Matt

Cheekz185 · 07-02-2005, 12:00 AM

To be quite honest with you, those specifiactions dont really do much. When you build the box just make sure the subs have room to breathe. THe box i built houses 2 12" Kicker l7's. THe box is 25"L X 13" H x 14" D. I had a box before that that was ported and it was 29" L x 15" H x 18" D. My old box, my subs HIT HARD!!! but now in the smaller box my its sounds much much tighter just not as much bass. GO with the specifications. But you mite end up with a big box. I would build something like this:

xdjxklusivex · 07-02-2005, 12:35 AM

why would u run it at 1 ohm? just do a 4d dvc setup and run each sub at 2 ohms on 2 channels? less stress and its better sound and cheekz185 is hella right build the box right and u will love it

jdaniels · 07-02-2005, 01:03 AM

Quote: Originally Posted by xdjxklusivex

why would u run it at 1 ohm? just do a 4d dvc setup and run each sub at 2 ohms on 2 channels? less stress and its better sound and cheekz185 is hella right build the box right and u will love it

What kind of advice is that? Less stress?! The amplifier is a Monoblock, it only has one channel and it is DESIGNED to work @ 1 ohm. Manufacturers specifications aren't the end all be all when building an enclosure, they are usually designed for an in between type of sound to please most and act controlled in most any enviroment (install). I like to make my enclosures large and vented, for a 12" sub I run 2.25-3.0 cu/ft with 20 - 40 sq/in of port. I like to tune lower as well, between 30 and 35hz. It all depends on the vehicle though.

If you decide to stick with sealed, go to the higher end of the manufacturers suggestions and go with a medium size sealed box. Small sealed enclosers tend to lack lower end, and become overly "punchy".

pancit175 · 07-02-2005, 03:15 AM

Quote: Originally Posted by mattwz

Thanks, just wanted to make sure.

I have a question about building the sub enclosure. The specs say the recommended cubic feet for a sealed enclosure is 0.85 - 1.5. I'm guessing I have to double that because I'm putting 2 in the box. So 1.7 - 3.0? Is there any type of ratio of the dimensions I should go by when building the box? I was looking at the calculators on the12volt.com, and there are many different combinations. I guess the biggest factor is the height.

Thanks

Matt

The specs are for each single sub only. I wouldnt recomend a sealed box double the recommended specs both sharing the same airspace together unless they were both separated from each other, otherwise they'd just fight each other for the air space. so each sub with the dimentions of each separate enclosure the recommended volume separate from each other is what i say.

jdaniels · 07-02-2005, 08:36 AM

Quote: Originally Posted by pancit175

The specs are for each single sub only. I wouldnt recomend a sealed box double the recommended specs both sharing the same airspace together unless they were both separated from each other, otherwise they'd just fight each other for the air space. so each sub with the dimentions of each separate enclosure the recommended volume separate from each other is what i say.

They cannot and will not fight each other for the air space. I can't remember the last time that I DIDN'T build a common chamber enclosure.

mattwz · 07-02-2005, 06:03 PM

Thanks for the replies. How would I separate the 2 chambers? I've never seen the inside of a sub box before, so I don't know how the two sides are separated.

Thanks
Matt

pancit175 · 07-02-2005, 08:58 PM

I've found that separte chambers make the subs alot more tighter with bass and more responsive. To separate the 2 chambers just place a wall in between the two. I only build common chambers if the box is ported or bandpass. Plus if the manufacturer wanted a box built around 2 of their speakers to share the airspace, then they would detail the specs for such a box.

mattwz · 07-02-2005, 11:48 PM

So the 2 chambers are completely sealed off from one another? I'm going to make a sealed box since it's easier to make. Plus I think I would like the bass tighter, and more accurate. All of the tutorials I've found on how to build a sub box show how to make a single sub enclosure. I haven't found any on building two sub enclosures. So I'm guessing you just have to put a sealed wall in-between the 2 chambers.

Thanks,
Matt

mattwz · 07-03-2005, 11:47 AM

Well I was playing around with the volume calculator, and came up with these dimensions. These aren't final, but I wanted somewhere to start. I'm obviously not good at drawing stuff up in paint, but do these dimensions look okay?

Thanks,
Matt

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