Help me understand amplifier current draw and watts

[Based]

Keep in mind, unless you have stellar electrical, you wont stay at 14.4v.
At 1ohm and stock electrical, i bet that pioneer would drop down to about 12.8v

Less voltage= more amperage required. Also, the lower load an amp sees, it usually gets less efficient

actually I just took my DMM to my battery and for some reason my car charges at only 12.6! It's a brand new car and I've never had trouble starting it. I wonder why it charges so low?

 

[kr15 5,000+ posts]

It probably had one of those dumb voltage regulators the 90s integras were notorious for.

 

[Based]

Most of the amps I own do not have fuses.
You are putting too much thoughts on what the fuses are.

If you want some cheap power get the CAB 1600.1 or Skar RP2000 neither amp has on board fuses, not that it matters.

Yeah the next amp I'm getting is the CAB 1600. I just am trying to learn how to calculate how big of wire I need and how big of a fuse to put by the battery.

 

[staan]

Ok so I have a pioneer 1200 watt amp now. It does 1200rms @ 1 ohm. 1200w/14.4v = 83a. So why does it have 3 40a fuses? Is that because it's peak power is probably around 1800w? Right now I have it on 10 feet of 6 gauge wire with a 100a fuse. Nothing gets hot.
I'm trying to understand this before I buy a bigger amp so I know what size wire I need and what fuse.

efficiency. if the amp is inefficient it will take more amperage to reach the power output.

 

[Boomin_tahoe 5,000+ posts]

That's easy.... use 1/0 and for the amp too.

 

[n2audio 5,000+ posts]

how do I get RMS from peak? A quick Google search says you can just multiply your peak by .7 and get RMS.
I just did a test. A hifonics 1200 has 2 70a fuses. 140*14.4 = 2016. 2016*.85 = 1713. 1713 peak * 0.7 = 1199 rms.

A BOSS 1100 amp has 1 30a fuse. 30*14.4 = 432. 432*.85 = 367. 367 peak * 0.7 = 257rms.

Maybe I'm wrong idk.

It happens to work, but it's just a coincidence. .707 (more accurately sqrt(2)/2) is what is used to calculate the rms voltage of a sine wave. For example -- ac power in your home. We call it 120v, but that is the rms voltage. The peak is actually about 170v, but multiplied by sqrt(2)/2 gives you 120v.

It really has nothing to do with amp power because amplifier ratings are typically ambiguous, and in a lot of cases complete lies. On top of that, "rms power" is a misnomer anyway. RMS is a way to quantify voltage, not power. The power we refer to with an amp is actually just "continuous average power".

How do I calculate what it "should" do at more than 1 ohm?

The gm-d9601? It's a quality amp. Its ratings are trustworthy. Being rated for 1200 at 1 and 800 at 2 and 500 at 4 figure on ~1000 at 1.5, 650 @ 3 etc.

Ok so I have a pioneer 1200 watt amp now. It does 1200rms @ 1 ohm. 1200w/14.4v = 83a. So why does it have 3 40a fuses? Is that because it's peak power is probably around 1800w? Right now I have it on 10 feet of 6 gauge wire with a 100a fuse. Nothing gets hot.
I'm trying to understand this before I buy a bigger amp so I know what size wire I need and what fuse.

As was said before -- efficiency. If an amp is ~85% efficient and does 1200w -- 1200/.85 = ~1400w required from the elect system to produce that 1200w which would put you at about 100A.

efficiency. if the amp is inefficient it will take more amperage to reach the power output.

That.

I think for you to start to understand all this stuff better you need to recognize that the performance of an audio amplifier is not at all a "rigid" situation. It is very fluid. Everything has an effect on how an amp plays and the actual power it produces. Primarily, the type of music you listen to and how loud you listen.

The only way a 1200w amp will produce 1200w for any significant period of time is if you're driving around blasting ~50hz test tones a full volume. If you're listening to music -- even loud music you will rarely see 600w coming from the amp, and on average (averaging the time where there's very little or no bass at all) that amp's probably not doing more than 300-400w at HIGH volume with instantaneous bursts to ~1000+

actually I just took my DMM to my battery and for some reason my car charges at only 12.6! It's a brand new car and I've never had trouble starting it. I wonder why it charges so low?

That's unfortunate. Try it while revving the engine a little. I bet it comes up. I had an alt once that didn't energize until it hit like 1500 rpms. It would sit at ~12.5 at idle, but once I tapped the throttle it would kick up to 14.3-14.5.