AB amp efficiency difference @ 1ohm & 4ohm
09-28-2008, 09:59 AM
#1
AB amp efficiency difference @ 1ohm & 4ohm
Does efficiency change from 4 ohm to 1 ohm. My current AB amp is 900rms @ 1 ohm. Another amp similar is 900rms at 4 ohm. Can anyone shed some light on this for me?
tx
tx
09-28-2008, 10:42 AM
#2
it all depends on how the amp is designed...you can't really compare but in the end on a 900wrms amp it doesn't matter as long as its class D its going to be efficient enough that it won't tax your electrical very much
09-28-2008, 01:18 PM
#3
Efficiency ALWAYS changes with impedance changes. The harder the amp works, as with lower impedance, the less efficient it is. e.g. I have Arc Audio KS(class g/h), and the manual says something like:
850wrms @ 4 ohms = 75% eff @ 80 amps
1000wrms @ 2 ohms = 68% eff @ 105 amps
1000wrms @ 1 ohm = 53% eff @ 135 amps
Same goes for any other class amp. So, 900 wrms at 4 ohms will use up less amps to produce this amount of power, if they are both AB. But chances are, the Class D amp will be more efficient even at 1 ohm, then Class AB at 4 ohms.
850wrms @ 4 ohms = 75% eff @ 80 amps
1000wrms @ 2 ohms = 68% eff @ 105 amps
1000wrms @ 1 ohm = 53% eff @ 135 amps
Same goes for any other class amp. So, 900 wrms at 4 ohms will use up less amps to produce this amount of power, if they are both AB. But chances are, the Class D amp will be more efficient even at 1 ohm, then Class AB at 4 ohms.
Last edited by Sasha; 09-28-2008 at 01:21 PM.
09-28-2008, 03:53 PM
#4
Great to know - I recently added an AB amp from D (i think PDX's are D - if not G) and I'm getting some dimming that wasn't apparent previously.
Next amp is AB but 900@ ohms!
Cheers Sasha thanks for the response! I appreciate it!
Next amp is AB but 900@ ohms!
Cheers Sasha thanks for the response! I appreciate it!
Efficiency ALWAYS changes with impedance changes. The harder the amp works, as with lower impedance, the less efficient it is. e.g. I have Arc Audio KS(class g/h), and the manual says something like:
850wrms @ 4 ohms = 75% eff @ 80 amps
1000wrms @ 2 ohms = 68% eff @ 105 amps
1000wrms @ 1 ohm = 53% eff @ 135 amps
Same goes for any other class amp. So, 900 wrms at 4 ohms will use up less amps to produce this amount of power, if they are both AB. But chances are, the Class D amp will be more efficient even at 1 ohm, then Class AB at 4 ohms.
850wrms @ 4 ohms = 75% eff @ 80 amps
1000wrms @ 2 ohms = 68% eff @ 105 amps
1000wrms @ 1 ohm = 53% eff @ 135 amps
Same goes for any other class amp. So, 900 wrms at 4 ohms will use up less amps to produce this amount of power, if they are both AB. But chances are, the Class D amp will be more efficient even at 1 ohm, then Class AB at 4 ohms.
09-28-2008, 04:17 PM
#6
sure if you have one amp designed for 1 ohm if you run it at 4ohms it will be more efficient. If you have one amp designed for 1 ohm and then another designed for 4 ohms you can't say which will be more efficient without testing because either one could be
09-28-2008, 04:21 PM
#7
exactly what he said ^^^ it all depends on what the amp is designed to do.
sure efficiency goes down when load gets lower, but it is only true if we are talking about one and the same amp. this isnt always true if you compare 2 or more different amps that are designed to perform at different loads.
09-28-2008, 06:13 PM
#9
Not precisely true. At lower impedance amps work harder, therefore losing efficiency to heat. Common physics. Yuli, we talked about this already last year. So long, that we are comparing apples to apples, as in same class amps. D will always be more afficient than AB due to amp design.
Last edited by Sasha; 09-28-2008 at 06:16 PM.
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