Help with sub specs and meaning?

[Wfs0801 10+ year member]

I'm looking at buying the below subs, I will have 2 in my trunk. I'm still confused on what exactly the 'dual 4ohm' means and what that means when I go searching for an amp that will power both of these subs at once.

http://www.ebay.com/itm/Rockford-Fosgate-T0D4-10-Dual-4-ohm-10-Power-Series-T2-Subwoofer-T0D410-/170936438006#vi-content

Could anyone offer some help/advice? As you can tell, I'm a total noob at car audio, but I'm trying to learn.

Also, with these subs and another amp powering the 4 interior speakers, will I need to add an extra battery or will a high output alternator do work fine?

Click to read more...

 

[oTurtlez 10+ year member]

The dual 4ohm refers to the subs voice coil(s). In this case, it's a dual voice coil setup, where each coil has 4 ohms resistance. The only thing you gotta look out for is when you're buying your amp, find what resistance you want to run at, 1 ohm, 2 ohms, 4 ohms, etc, and match the power of the subs (rated) combined, (1100w) to the rated power of the amp. With two D4 subs, you can run at a 1 ohm load and a 4ohm load. It'd be easier and cheaper to find an ~1100W RMS @ 1ohm amp.

As for the second question, an extra battery wouldn't hurt, but you should be fine with a H/O alt.

 

[Wfs0801 10+ year member]

I will most likely be getting a 2 channel amp, 1 channel for each sub. Will I still need to find an amp that matches the subs combined RMS? Or will a 550 Watt RMS 2 channel amp constantly put out 550 Watts to both channels separately?

 

[oTurtlez 10+ year member]

Well if you can find a dual channel that does ~600W @ 2ohms per channel, go for it, but you would honestly be better off going for a ~1100W mono and running the subs together to the same channel for a 1 ohm load. It'll be much cheaper that way.

 

[™Caveman 10+ year member]

That dual 4 ohm would pull 2 ohm parallel and 8 ohm in series... wheres the 1 ohm coming from? A dual 2 ohmer would be pulling a 1 ohm load parallel 4 ohm in series

 

[oTurtlez 10+ year member]

Wire the D4's together. Wire each sub in parallel with itself to drop the resistance from 4 to 2, then run the two subs in parallel again to drop from 2 to 1ohm.

 

[Wfs0801 10+ year member]

Ok I think I'm understanding now. So, if I run a mono amp to both subs, and at a 1 ohm load, the amp will split it's RMS Output in half to each sub? Meaning a 1100W RMS amp would send 550W RMS to each sub? Just want to avoid any confusion.

Obviously, I'm new to all this and I won't be doing the install myself. I'm just trying to figure out what I need equipment wise, and how I need to explain to the shop I would like it installed. So I just basically need to tell them I want the mono amp run to the subs at a 1 ohm load. And that's about it?

Quick question, what if my mono amp exceeds the RMS of the subs? Example, I buy a 1200W RMS amp for the 550W RMS subs. would that eventually damage the subs? I thought I heard something a while ago about the amp doesn't put out it's max RMS at all times, only if you listen to it at max volume. Is this true? Or is that referring to the Peak Power rating of the amp?

 

[™Caveman 10+ year member]

Oops my balls. Figured it was one sub.

 

[oTurtlez 10+ year member]

Peak power matters but most of the time it's just a gimmick to get newer people to buy things, e.g. Sony Xplod amps at walmart branded 1200w that actually only do 200w. It all depends how you wire to the amp. If you wire in parallel (posi to posi, neg to neg) it'll cut the impedance in half. Wire it in series, (posi to neg, posi to neg) and it'll double the impedance. When you wire multiple subs to a mono amp, it'll essentially divide the power among them evenly. You should be fine running 50w extra on each sub. Hell, some people run an extra 600w or so on some subs and they still ask for more. If the amp is CEA rated, it'll do its rated power. There's also box rise to take into effect, whereas, while playing audio, the impedance wont always be 1 ohm, therefore the power wouldn't always be that 1200w. If you ran a good 1.2k, it'd be the perfect match for those. What kind of money are you trying to spend?

Oops my balls. Figured it was one sub.

No worries haha.