Subject says it all. I will be running a 0gauge power wire into a distribution block with a 4gauge power wire running to both the 500/1 and 300/4 with a 1 farad cap next to the 500/1. I will be using an inline fuse on the 0gauge power wire within 6" of the battery. What size fuse should I get?

 

Seeing as those amps will probably never draw more than 75 amps under the GREATEST load. I would run a 70 amp inline fuse upfront and at the split a 50 amp fuse to each indvidual line. I have a JL 250/1 and an Alpine MRV-F340 with a 65 amp fuse inline at the bat and at the split 2 40 amp fuses. No problems here

 

At max load that will pull ~116 amps.

You are going to want an ANL style fuse/ fuse holder at the battery. Fuse rating should be close to 116 amps.

You can also get away with 2 awg power wire if you want to save a few bucks and make it easier to install.

At the fuse block the 500w amp will pull a max of ~72 amps, I would go with an 80amp for that.
The 300 will max at ~43 amps, so you should get a fuse rated for about that.


MIAPlaya- Your system will pull a max of ~68 amps.

 

Not with the RIPS system. The max load you would see is if the amp was running at a straight 12V off the alternator. The max amperage at that point would be a total of 800W/12V = 67 amps. If you have lower voltage than that supplying the amp, I wouldn't worry about it. You battery will be dead in a week. These amps do not "double" the output with a different load either. The max ranges for the loads can be 1.5-8 Ohms for normal operation. Regardless of the load, the system compensates with the voltage not dipping below 12 volts.

As it stands, I have the 450/1 and a 500/1 and never see my voltage gauge in the instrument cluster go below 14V, which is what is supplied by the alternator. So with that thinking, you will most likely see a max of 57 amps. Either way, what miaplaya said is exactly what you should do. Anything else is overkill.

 

Overkill is 0 guage for 75 amps, don't you think?

 

JL rates the 300/4 with a 40 amp fuse and the 500/1 with a 50 amp fuse. Simply add both together to get 90 amps. I am positive they'll never draw that much power with the engine running, but they may if it is not (at 12 volts the RIPS system would have to draw more amperage to maintain output than at 14 volts).

 

Oh, as a belatedly remembered issue: I would seriously consider improving the factory chassis ground. It's pathetic, and if you're running that kind of power for a stereo, it would behoove you to have the ground more or less equal to that wire gauge. I bought a new negative battery terminal, like a foot of clear insulator 1/0, and two crimp on ring terminals for mine. It replaced the factory ground exactly. Well worth it, in my book, since a circuit is only as good as the weakest point.

 

With my 500/1, 300/2 and W7 if i have my car on but i'm not moving and im cranking my music the voltage guage will show the voltage drop all the way down to 12volts and sometimes a little under that. When i had 2 10w3v2's (like your stealth box) that never used to happen. i wonder why.

 

Agreed....with the RIPS system you will not see the traditional current draw of an amplifier of that power rating. JL amps draw ver little current. Besides it is always a good idea to fuse lower. Fusing at the maximum amperage load for the amp could cause damage to the unit if there is some sort of freak current spike. I would rather blow a $1.25 fuse than a $500 amplifier

 

I'm still not clear how the RIPS system allows the Amp to pull less current.

JL rates the 450/4 with a 60 amp fuse, which is a small amount bellow what I calculate the max to be ~65 amps.
This makes sense, the fuse is rated slightly lower to protect the amp.

Jl rates the 300/2 and 300/4 with a 40 amp fuse, I calculate the max to be ~43 amps.

According to MonkeyBoys calc method, the 450/4 would only be pulling 37.5 amps. This doesn't make sense to me. JL has this rated for a 60 amp fuse. 37.5 amps is like 40% less then that.

The 300w amp would calculate out to 25 amps using that method, why would they require a 40 amp fuse?

I don't think the function of the RIPS system is being understood properly.

 

You are not doubling the total watts in the current draw calculation because of different speaker impedance, you double the total watts because these numbers are RMS. Doubling compensates for peak output.

 

The difference between my system and yours is that your sub is phenomenally better than the two I have. I am sure your gain is up there since you are not dealing with too much (if any) distortion. I am sure that if I had my 500/1 cranked I might be seeing the same thing as you are. Does your voltage gauge increase when you start to move? It may be that your alternator is not keeping up with the demands of the vehicle.

 

I understand what you are saying in terms of a fluctuating impedence that can raise or lower the total amount of current sent to the speaker. For any normal amp, I would completely agree. In the perfect sense, the JL would never exceed 500 watts. I am sure that it does however, since nothing is ever ideal. The only way to really determine this would be to take a power reading at peak bass hits, but I am sure you nor I have the time or inclination to care about this.

What I do believe is that the amps themselves do not "double" for peak output however. I would almost say that the engineers gave it a nice 25% fudge factor for the voltage rails to compensate and maintain the wattage for the varying impedence on the sub(s). I believe that would be the maximum difference however. The premise for the amp design was that the peak power would never exceed 500 watts; however, you can have a lower wattage supplied to your subs based off of the bass hit itself (voltage signal levels and all). I have heard that some people (this was a while back and complete hearsay) found that the 500/1 may reach around 630ish watts at a peak value, but don't quote me on that. They took a power reading like I suggested above, off of a W7, but I honestly cannot remember where I read that information.

 

Heres a link to a bench test of the JL 500/1 max current draw was 26 amps.... http://www.carsound.com/reviews/amps/jl_5001.html

 

Heres one for the 300/4 as well..
http://www.carsound.com/reviews/amps/jl_3004.html

 

Good links..Interesting stuff, so does this mean you can actually run a more powerfull system with JL amps, and have it be less taxing on your cars electrical system?

 

Why does it drop so low? I have 3 Xtant 3.1s, 3 Xtant 1.1s and an Xbox. Mine doesn't drop below ~13.8. Just wondering cause I'm not running a cap and still got stock battery. I was thinking of upgrading battery.

150amp fuse for the 3 3.1s. Had a 120amp but fried it.

 

if I am reading those articles correctly yes. All due to the fact that the power supply system can switch to voltage rails that will better match the required output and still provide the same power.

 

I actually don't have the gain too far up - not anymore than i had it when i had the 10w3v2's at least.

and yes when i'm moving the voltage is back up at normal level.s

 

In that case, I am pretty sure your alternator is having a hell of time keeping up with all of the current draws from the car. That would be the weak spot in your system, if you play the stereo without running the car.