How to determine current draw for 5 channel amp?

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KlutzyLou

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My understanding is that I need to multiply the number of channels by the RMS watts per channel. The specs for the amp I'm looking at have different RMS numbers for different ohms. On the spec sheet there are also a couple numbers that are much higher which I believe pertain to the 5th channel which is for a sub? Do I use the advertised total wattage?

Amp:
 
It's a much more complicated answer than it seems...
Yes, it has 80A fuses, but fuses are a long way from actual current draw when in use -- besides, fuses take time to heat up and open. That's beside the point.

On the surface -- it can produce 900w rms at min impedance. Digging a little deeper -- being class D assume it's ~80% efficient. So to get 900w out, 1100w+ would have to go in.
Then assume you'll get ~13v from your alternator. Power/Voltage = current -- That's 86A.

Then there's the issue of what signal you're playing. That amp will only approach 86A on a constant basis if you're playing test tones at full volume.
Actual power output of the amp will vary drastically depending on music type and volume. Some music only requires 25-30% test tone power. There's NO music that will get you close to max current draw constantly. However, you will likely see momentary spikes that high at high volume.

With all that in mind -- At low to mid volume, I'd guess ~20-25A. Mid-high volume, 30-50A.

A while back I was having elect probs in my car. The auto elect specialist immediately assumed my system was the cause. They hooked up a professional quality meter on the power lead to my amps (1200w rms). I put in Bass Mekanik and blasted it. It was drawing 50-60A.
 
It's a much more complicated answer than it seems...
Yes, it has 80A fuses, but fuses are a long way from actual current draw when in use -- besides, fuses take time to heat up and open. That's beside the point.

On the surface -- it can produce 900w rms at min impedance. Digging a little deeper -- being class D assume it's ~80% efficient. So to get 900w out, 1100w+ would have to go in.
Then assume you'll get ~13v from your alternator. Power/Voltage = current -- That's 86A.

Then there's the issue of what signal you're playing. That amp will only approach 86A on a constant basis if you're playing test tones at full volume.
Actual power output of the amp will vary drastically depending on music type and volume. Some music only requires 25-30% test tone power. There's NO music that will get you close to max current draw constantly. However, you will likely see momentary spikes that high at high volume.

With all that in mind -- At low to mid volume, I'd guess ~20-25A. Mid-high volume, 30-50A.

A while back I was having elect probs in my car. The auto elect specialist immediately assumed my system was the cause. They hooked up a professional quality meter on the power lead to my amps (1200w rms). I put in Bass Mekanik and blasted it. It was drawing 50-60A.

I appreciate the in depth answer, that definitely gives me a better understanding of it all. One thing that I realized I totally forgot to mention is that the reason I need this number is to determine the gauge for my electrical supply wire. With safety in mind I assume I would want to go with that 86 amp rating.
 
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KlutzyLou

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