what size amp do i need to run 2 10" subs in my car?

Answer 1

Look at what the rms wattage for the two subs. You can ignore max wattage, rms is the important one.

For 2 channel amp (not going to bridge), find an amp whose rms wattage matches up with the subs rms wattage. Again, ignore max watts.

For bridged, find an amp where the bridged rms wattage will equal what each sub can handle for rms wattage.


btw, rms pretty much stands for continuous watts, which is why it is more important than max.

Answer 2

When matching amps to speakers, a good rule of thumb is to get an amp with a wattage 20% over the power rating of the speakers. I know this sounds like an odd thing to do, but there is a good reason to do this.

I'm going to try and keeep this simple, so here goes.

An amp outputs an AC current to the speakers. At full power, the speakers will try to draw their maximum wattage from the amp. If the amp can't provide that level of output, it will start to clip. Clipping happens when a stessed amp clips the tops and bottoms off the wave form of its AC output. This effectively means that DC is going into the speakers. DC current and speakers don't mix well, as the direct current causes the electomagnetic coils inside them to heat up and burn out.

If you have a 1000watt amp driving 800watt speakers, the amp is unlikely to clip as it won't be stressed by the speaker.

Here's another example. If you think of a speaker as being like a light bulb. A 100watt bulb will want to draw 100watts. Speakers are the same, a 100watt speaker will want to draw 100watts. If it is connected to an 80watts amp, the speaker will still want to draw 100watts. In attempting to give that extra 20watts, the amp will clip which affects the sound quality and potentially damage the speaker. Hence you need an amp with head room.

Hope that's not too compicated.

Regards A.

Also, PMPO and RMS. PMPO is the maximum power handling capability of a device before it burns out. RMS is the Root Mean^2 of this. When looking for equipment, make sure you do as the others here have said. Use just the RMS for power ratings.

Answer 3

Yup, the RMS thing is pretty important...

Here is info on sub wiring methods and other tips http://spkrbox1.spaces.live.com

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In response to below:

As long as the gain is set correctly to match the RMS Volts from the head unit, you can get away with a smaller amp. The only issue would be the output would'nt be as much.

Also, the "light bulb - speaker" comparison is a little off.

For instance, if a 100 watt sub is connected to an 80 watt amp, the speaker will still only consume 80 watts, not 100 watts. This is because of the resistance loaded onto the amp. If the amp is designed to provide 80 watts @ 4 ohm then a 100 watt 4 ohm speaker will still only use 80 watts with the gain set correctly.

You can't get something from nothing or in this case, more watts from a source with a set resistance no matter the power handling.

More on this here http://www.bcae1.com/2ltlpwr.htm

See my site for sub wiring methods, enclosure types and construction and other tips http://spkrbox1.spaceas.live.com

Answer 4

whats the rms of the subs, what kind of subs, how are they hooked up haha i have a jl A1400 amp for my 2 10 w3 so maybe this will help the subs are about 600 rms

Answer 5

a 700w should do it