Parallel, same wattage?

[QuikSilverRS91 10+ year member]

Alright, I ran a couple searches and I read through the basics on http://www.bcae1.com again to make sure I didn't miss something but I couldn't find this info.

I went into a shop today to buy my new system, and I bought 2 Alpine Type-R 10"s with 4 ohm + 4ohm dual voice coils. I also bought a Rockford Fosgate 3001 amp which runs 300 watts at 2 ohms (single channel). I'm normally pretty good with resistances and stuff like that but I just wanna hear the truth about this. The guy said if i connect + to + and - to - on each sub then run the subs in parallel it'll be a 2 ohm setup and since the subs are in parallel they will each receive 300 watts. I bought the stuff cause if this guy is wrong I know the owner and he will regret it.

Given all that info there, here is my actual question:

The amp runs one channel, 300 watts at 2 ohms. Given the setup he told me, will the amp push 300 watts to EACH sub or will it split it to 150? He seemed very persistant, saying that in parallel each sub receives the same wattage.

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[trungthiendo 10+ year member]

so you have 2 alpine type R?? and they are dual 4 ohms each...

if you wired them to paralell then it would be 2 type R at 2 ohms....and if you did both of them parallell then it be 1 ohm...or if u did series parallel then it would be 4 ohms still

the amp in question is 1 chan at 300 watts 2 ohms...you are gonna get a total of 300 watts not each...if it was 2 channel at 300 then you would get 300 each...

each sub will see 150 a piece

 

[Berry47 10+ year member]

give us all the info on the equipment and we'll tell you how to wire it //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[QuikSilverRS91 10+ year member]

Well... the problem is I bought this on the grounds that each sub would receive 300 watts with this amp. I'm gonna go down right now and buy some new subs cause the Type-R's are to deep (I have to have a shallow enclosure). I'll talk to him a little more and then when I come back I'll give you guys all the info. And yeah, trungthiendo, I was thinking the exact same thing. I'm leaving now, as soon as I get back I'll write all the info on the setup.

 

[QuikSilverRS91 10+ year member]

Alright here's the setup now:

2 Rockford Fosgate 10" Punch Stage 2 Subwoofers

-200 Watts RMS

-400 Watts Max

-SVC

1 Rockford Fosgate 3001 Amp

-Single Channel

-300 Watts RMS at 2 Ohms

The guy understood that the amp only pushes 300 watts as I explained to him but he again said that in parallel it will push 300 to each sub - kinda like current running through two resistors in series, both resistors will each receive the full current and it won't be split. I don't know how wattage works in that area so if anyone has any suggestions I'll take them! Thanks.

 

[pavengmike6 10+ year member]

These are your only 2 choices to wire a DVC 4 Ohm sub. UNLESS you are only going to use 1 VC on each sub.

http://www.rockfordfosgate.com/rftech/wiringwizard.asp?WoofQty=2+woofers&WoofImp=Dual+Voice+Coil+-+4+ohms+x+2&image.x=19&image.y=11

Seeing you are not going to be able to run the 2 Ohm load you will not be getting the full 300 watts. (unless you only use one VC)

I do not know how much I would trust anything this guys says seeing he cannot even figure out the Ohm load of a DVC speaker.

 

[helotaxi 5,000+ posts]

Watts is voltage times current or P=V*I

In a series circuit the current through each load is the same. There is only one path to complete the circuit so the current must flow along that path and through all the loads on that path. The voltage drop across each each load will be dependant on its resistance (or impedance in an AC circuit with a reactive load) and the total resistance of the circuit. The total voltage will be divided among the loads. For example (and I'll keep the math simple for all our sakes) you have 1 volt on a circuit consisting of two 0.5 ohm resistors wired in series. The total load is 1 ohm. The current through the circuit is 1 A (V=I*R). The voltage drop on each resistor is .5 V. The voltage drop times the current will give you power. Each resistor is making .5 watts of heat and the whole circuit is 1 W.

In a parallel circuit, the voltage drop is equal across all loads regardless of their different resistances. The current through each load is inversly proportional to the load. Think of the circuit as a whole bunck of little single load circuits for the purpose of calculating power on each load. Take our numbers from the previous example and wire the two resistors in parallel. The voltage drop is 1V across each resistor. The current through each resistor is 2A. Each resistor is seeing 2 W and the source is generating 4W of energy.

Assuming the subs are all of the same impedance, they will equally share the power produced by the amp at whatever load they are wired to. It doesn't matter how they are wired (barring some unusual series parallel combinations that yield odd total impedances). If the amp makes 300W @ 2 ohms and the speakers are wired to a load of 2 ohms, then they will share that 300W. It doesn't make that much power for each speaker, that is the total.

 

[QuikSilverRS91 10+ year member]

Yeah, that's exactly what I thought. I've been through physics and I've spent two years doing these calculations, I just wanted to clarify with other people. The sound is to my liking, but still the store owner will definitely hear about this. Thanks all.

 

[Rockman 10+ year member]

Go back and ask him how a 300 watt amp will deliver 600 watts. Because that is what he is saying. Better yet post the shops phone number and his name and I'll call him myself. Lol. Anyway the power divides according to ohms law. If you have 300 watts and 2 subs each sub gets 150 watts. No way around physics....