The12volt gave me some clarification of efficiency a little bit ago. I used to think that just because a lower ohm load would allow the amp to produce more power that it also meant the amp was running more efficiently. He helped to clarify that this was not necessarily the case. Efficiency has more to do with factoring in the current draw and power lost to heat dissapation then just the impodence (ohm) level. So it actually looks like in some cases an amp may run more efficiently at a higher ohm level. Here's an excerpt from the12volt from that
thread I mentioned...
"My point is that efficiency of an amplifier and power output of an amplifier are not the same. Yes, an amplifier will produce more power at a lower resistance, however it doesn't mean that the amplifier is more efficient at a lower resistance. In some cases, current draw may be more than twice as much at 1/2 the resistance and the loss to heat may also be more than twice as much, making it less efficient while producing more power. Efficiency with an amplifier would relate more to the ratio of power output to current draw, and power output to power lost to heat."
And you would not necessarily be sacrificing "quality" if you went with a 4-channel amp. The main difference between most 2 and 4 channel amps is the power output. I haven't really seen that many 4-channel amps that can put out 150+ x 4 @ 4ohms. You can find some that would do that at 2ohms or at 4ohms mono, but usually not 4 channels @ 4ohms.
Since most component/coaxial speakers are 4ohms, your best solution for optimum SQ (if your headunit only has 1 set of RCA pre-outs) is finding a quality 4-channel amp that's rated at RMSx4@4ohms (in your case 60x4@4ohms). You would retain balance
and fade control, and would only have to worry about installing 1 amp. I said "quality" because a manufacturer of junk equipment will produce junk equipment regardless of if it's a 4-channel amp, 2-channel amp, mono amp, subs, etc... Junk is still junk, but in most cases it's more the manufacturer then a particular type of amp (ie 2-channel vs 4-channel).
If your headunit has 3 sets of RCA preouts (Front, Rear, and Sub) then you have some more options for optimum SQ (you can run multiple amps from 1 set of RCA pre-outs using RCA Y-adapters, but you end up losing either Balance or Fade control). You can either
a) Find two 4-channel amps rated at RMSx2@4ohms mono (in your case two 4-channel amps rated at 60x2@4ohms mono) and run the Front Left and Right speakers from 1 amp and the Rear Left and Right speakers from the other, or
b) Find two 2-channel amps rated at RMSx2@4ohms (in your case two 2-channel amps rated at 60x2@4ohms) and run the Front Left and Right speakers from 1 amp and the Rear Left and Right speakers from the other.
Either way (a or b) would also allow you to keep balance
and fade controls.
Obviously you will more than likely pay more for 2 amps then you would if you bought just one. It all comes down to
1) What you can afford
2) How patient you can be (i.e. it may take a little longer to find a quality 4-channel amp rated 60x4@4ohms at a decient price then it would finding 1 or 2 lower rated amps).
2) What you're willing to sacrifice (SQ, balance, fade, etc)
3) How much extra current draw your alternator can handle (because multiple amps will draw more power from the alternator than just 1 amp).
I'm getting ready to switch my system over to my Explorer, and will be installing 2 Kenwood KAC-649S 4-channel amps to push my components. Each amp is 80x2@4ohms mono, and retails for about $200-$250 a piece. They've actually come down in price since I bought mine a few years ago. But they are still running strong and work great for my mids and highs.
Hope that helped
Squirrel
"No more Cpt. Kirk chit chat"
If its too loud, then you're too old
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