Which is better?

[Mike P]

Good afternoon. It's been almost 30 years since I messed with car audio and a lot has changed!

I have a general question regarding subwoofers and amps. I'm purchasing/installing two (2) 10 inch DVC subs in a down firing box in my son's 2017 Silverado Double Cab. The subs are rated for 400 watts RMS (200 per coil). The choice for subs comes in a 4 ohm and 2 ohm variety. It was recommended that I purchase the 4 ohm subs and then a 750 watt mono amp that is 750 watts RMS x1 at 1 ohm.

My question is whether it's better to buy the amp as described above and wire the speakers to handle the 1 ohm load, or just look for a two channel 4 ohm amp that delivers 400 watts per channel at 4 ohms? I thought I read somewhere that it's always better to match the ohms..... ie) 4 ohm sub with a 4 ohm amp output.

Any help is appreciated and I apologize if this is a repeated question. I searched prior to posting and could not find anything.

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[dragon.breath 10+ year member]

Four 4 ohm voice coils can be wired in parallel for a 1 ohm mono load.

 

[supernov4]

Either one will work just fine
Although getting a 4 channel will give you more versatility if you ever want to change things around

The 4 channel could typically also be bridged to make a 2 channel at higher wattage if you ever change subs or can be used for components etc

Example:
I am running an alpine r2 a150m mono block 1200w on a 2 ohm load
With a stereo integrity sql 15 dual 4

I may switch to a sundown salt 500.4

Which will give me
500 x 4 @ 4ohm
700 x 2 @ 2ohm
1400 x 2 @ 4 ohm bridged

the ohms and rms rating on amps are just a reference to be in the ball park to help match woofer rms to amplifier rated power
When a speaker is playing on music the ohm load changes dynamically with the music
ie it jumps around

 

[Deiimos]

I don’t know what subs they are, if we assume they are true 400w RMS each, I would get a class-D amplifier that does 800 to 1000w RMS at 1-ohm and set it properly. This makes it easy to wire a pair of subs with 4-ohm DVC coils in parallel, and not having to match multi-channel amp gains.

The amp just needs to handle the speakers combined final load (4-ohm or 1-ohm in this case, whichever you decide on), and put out the desired power at said load.

The main goal with the impedance is to not blow up an amplifier do to running too low impedance it isn’t designed for.

You can certainly run a bigger mono amp that can do the 800w at 4 ohm, or use 2 or 4 channels that can do 800w or whatever. You really wouldn't notice any difference at either load with the same exact amplifier power in each scenario. Also keep in mind multichannel amps are often still class AB, so they will run much hotter and be less efficient than a class D. Although, class D has become more common in the multichannel amps these days.