4ohm vs 1ohm current draw on same power.

[codester 48]

So I've wondered this and never seen any tested answers. If i had a 750 watt amp at 1ohms and another 2000watt amp at 1 ohm and 750 at 4 ohms and I want 750 for my subs given same model and same efficiency at same ohm which would draw more current? A bigger amp wired to 4 ohm or a small amp wired to 1 ohm. Example would be a crescendo bc2000 at 4 ohm vs a aq750 at 1 ohm. Anybody tested this and have any thoughts, experiences etc. Hope this is easy to understand as I tried to word it best I could

[shizzzon 461]

well, when you say same efficiency, then it would draw the same, but you are wrong.

Efficiency is NOT the same at 1ohm vs 4 ohm.

Efficiency levels on Class D amps at 4ohms is around 86-88%. 1ohm, around 78-82%

[codester 48]

well, when you say same efficiency, then it would draw the same, but you are wrong.

Efficiency is NOT the same at 1ohm vs 4 ohm.

Efficiency levels on Class D amps at 4ohms is around 86-88%. 1ohm, around 78-82%

Sorry that was where my wording wasn't clear! I meant if the amps were both the same efficiency at the same ohm load. According to efficiency the big amp wired to 4 ohms should require less current but has this been the case for people

[shizzzon 461]

Like i said, if same efficiency, then same current draw, same output. That's how it could be same efficiency.

lets take 800w.

800w @1ohm = 28.3v 28.3a

800w @4ohm = 56.6v 14.15a

Both at ~84% efficiency, then same current draw, same output, The End.

[Impious 1,476]

If the efficiency is identical, and the output power is identical, then the current draw would likewise be identical.

If one amp has a lower efficiency, then the amp with lower efficiency would draw more current.

It really is that simple. Ohms law has nothing to do with this, and is one thing that gets people confused. The impedance of the load only matters in so far as how it affects the efficiency of the amplifier(s). The only thing that matters in this conversation is amplifier efficiency (along with power output and power supply voltage, but since those are assumed to be constant between the two amplifiers we can ignore them for the moment). As shiz said, generally speaking as impedance of the load decreases so does amplifier efficiency. But that doesn't mean that amp A wired to 1ohm will necessarily be less efficient than amp B wired to 4ohm. It completely depends on the respective designs of the amplifiers.

[codester 48]

Thanks, that was my assumption just wanted to make sure! I'm looking for an amp for my 300zx and don't want to go too big on electrical so I figure I should stay for sure under 1000rms and wondered the best way to do it so will be getting a amp rated at around 750 at one ohm. Thanks for the help