I have a 12" sub, and I am able to get a second 12" for a great price. When should I look into getting a second battery to power them, or is the one battery enough for it to run well without cut outs? Any advice is appreciated!!

Okay, before everyone else jumps on you about this, umm...It would be in your best interest to post what kind of subs they are, down to the brand and model number, your amp that you will be running and it's model number, what kind of box that you will be putting them in (sealed or ported or bandpass) the resistance that the amp will be seeing, the gauge of wiring that you would be running to your amp, and the vehicle that you will be putting it into.

Until you can awnser most if not all of those questions, you won't get a response that will help you.

That being said, with the info that you've given, i'm sure that the awnser to your question is no.

Even without knowing that above information, I will say "No, you don't need a second battery yet."

Of greater importance is your electrical wiring:
From Battery - to the Chassis
From Alternator + to Battery +
From Alternator - to Chassis.

Upgrade those wires to 4, 2, or 0 awg first.

If you only have 2 12's, I really doubt you will need another battery unless each sub is getting a kilowatt each.

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Nostalgia just isn't what it used to be.

I think a better question for you to ask is:
"Can your amp handle a second sub?"
Stereo amps typically are 2 ohm stable stereo, 4 ohm stable bridged
Mono amps can range anywhere from 2 ohm stable to 1/4 ohm.
So what is the impedance of your sub(s)? Are the single or dual Voice coil?

Improper matching can cause excessive heat, amp failure, or even a BBQ in your car. Check all your specs before throwing an additional sub into your system.

Also, will the 12s be the same make? . . . please don't get mis-matched subs - too ghetto ugly, and they will perform very differently giving you sloppy sound . . . yada, yada yada.

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Nostalgia just isn't what it used to be.

I don't have very much knowledge when it comes to Car Audio, so I will tell you what I can for now. The Sub which I am looking to buy has it's own amp so I would have 2 subs and 2 amps, but they are different makes. I will probably be using a 0g wire to prevent future replacement if I decide to add add more later. I have so little knowledge that I probably will be getting them istalled, I just wanted to ask here so they don't try to rip me off. Or even if you think I should just stick with what I have. Here are links to the stuff i've got hopefully this will help!!

AMP:
http://rockfordfosgate.com/products/product_details.asp?cat_id=2&series_id=6&family_id =19&item_id=106475&locale=en_US&p_status=

SUB:
http://caraudiosecurity.com/shop/product/products_id/2629.html

DECK:
http://www.cardomain.com/item/JVCKDLHX550

BOX:
http://www.futureshop.ca/catalog/proddetail.asp?sku_id=0665000FS10061595&catid=1106 2&logon=&langid=EN

I've got a '98 Golf. Thanks for anything and everything.

lol that amp doesnt even match the 1 subs rms and how is it gonna do a second

lol. before you get a second sub, get a bigger amp and it will make your system louder, then upgrade the subs. a second sub and half the power will be at most, what 6 db's?

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He's says he has a second amp for the new sub. It won't push the sub for all it's worth but it should still work.

Baam, if your getting a shop to install your system, make sure they realize those amps are fairly underpowered for the subs, and let them know you don't want your settings set very aggressive. Most important is the amp gain, as that is a high output deck. Setting the gain too low, like <1 volt, will blow those subs in a hurry.

If you look to upgrading later, look for an amp that is ~1000-1200 watts RMS at either 1 or 4 ohms. I think someone on the board here has a 1500 watt @ 1 ohm amp. It's a bit much, but at least you'll have a nice clean signal, making the bass sound much better.

Good luck

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Clarion VRX76VD
Phoenix Gold Octane R 5.0 Comps
Phoenix Gold Octane R 6.5 Comps
2 12" Clarion PXW1252
Phoenix Gold RSD 300.4
Alpine PDX 1000.1
Mitsubishi 75amp Alternator (I swear i've heard it cry uncle)

So from what everyone is saying, I gather that I got ripped of and sold a wimpy amp which is powerful enought for my sub. What wattage of amp should I have for that sub to run at 100%, if I have a 12" I don't want it to sound like a 6". Damn you Best Buy!! It's all still in the boxes except for the deck, so maybe they take em' back. haha ya right. Also is putting in the 0g to start off a good idea, this way I won't need to upgauge it ever. Thanks again.

Ok, so here's what my buddy's got for sale.

Alpine V-Power Mono-Channel Amp
Model: MRP-M350
700Watts Max Power
http://www.bestwebbuys.com/electronics/Alpine_V-Power_MRP_M350_-_Amplifier-4274949.html?isrc=e-search

Alpine S Type 12" Sub
Model: SWS-1241 (I think its 600W max)
http://www.carstereomall.com/store/store.cgi?command=listitems&pos=0&type=search2&sea rch=alp-sws1241

Phoenix Gold Sub Box

What should I do? Stick with what I have? Use his amp, and my sub? Use everything? I need some advice? Please and Thanks!!