Amplifier Efficiency
04-03-2005, 07:45 PM
#1
Guest
Posts: n/a
I was reading a well-hijacked post over in the Install section about amp efficiencies, and thought I'd chime in properly...
Amplifier efficiency was correctly described as the amount of power that is sent to the amp that is provided to the speaker outputs.
Heatsinks and their efficiency only help control / prevent overheating. Inefficient amps need bigger heat sinks and many amps can be shut down because they overheat.
In terms of Class A/B, that theoretical maximum efficiency for an Class B circuit of 78 does not include the inefficiency of the amplifiers power supply, input stage and perhaps display or microcontroller - all those thigns add to the amps overall efficiency.
In terms of Rockford Products - here is what I have from my reviews:
Rockford Punch P2002 - 69%
Rockford Power T3002 - 67%
It does drop though as the supply voltage decreases and the load impedance decreases - most amps are most efficient at 4Ohms stereo.
In terms of Class D efficiency - I don't have any RF data that was done with my current (and trusted) test rig. But similarly priced products rank as such:
Arc Audio KAR900.1D - 81%
Polk Audio C500.1 - 74%
Elevation Audio DX1500 - 85%
Kaption D700.1 - 79%
Clarion DPX1200.1 - 88% (pre-production sample) Shh...
Them's the facts...
When things calm down in the summer, I'll grab a new Rockford Class D and take it for a spin on the bench...
Amplifier efficiency was correctly described as the amount of power that is sent to the amp that is provided to the speaker outputs.
Heatsinks and their efficiency only help control / prevent overheating. Inefficient amps need bigger heat sinks and many amps can be shut down because they overheat.
In terms of Class A/B, that theoretical maximum efficiency for an Class B circuit of 78 does not include the inefficiency of the amplifiers power supply, input stage and perhaps display or microcontroller - all those thigns add to the amps overall efficiency.
In terms of Rockford Products - here is what I have from my reviews:
Rockford Punch P2002 - 69%
Rockford Power T3002 - 67%
It does drop though as the supply voltage decreases and the load impedance decreases - most amps are most efficient at 4Ohms stereo.
In terms of Class D efficiency - I don't have any RF data that was done with my current (and trusted) test rig. But similarly priced products rank as such:
Arc Audio KAR900.1D - 81%
Polk Audio C500.1 - 74%
Elevation Audio DX1500 - 85%
Kaption D700.1 - 79%
Clarion DPX1200.1 - 88% (pre-production sample) Shh...
Them's the facts...
When things calm down in the summer, I'll grab a new Rockford Class D and take it for a spin on the bench...
04-04-2005, 05:54 AM
#3
1000 Watt CAFz'r
Join Date: Mar 2004
Posts: 1,093
that 83.86% effeciency was probably the BEST effeciency that they have gotten out of that amp! whcih means it was fed the "best" signal(from head unit), and optimum steady current (no voltage fluctuation) @ 12-14.4 volts, ... [img]graemlins/dunno.gif[/img]
Livin Loud
Livin Loud
04-04-2005, 07:51 AM
#4
Guest
Posts: n/a
But that number is more than believable... The bd output arrangement on those amps is quite impressive in terms of design and efficiency.
It doesn't matter what kind of signal you feed the amp, or how stable the current is though - measure input and output power at full crank and that's the answer.
Question for you guys - would you like to see full power efficiency numbers, or 1/3 power like Carsound does?
It doesn't matter what kind of signal you feed the amp, or how stable the current is though - measure input and output power at full crank and that's the answer.
Question for you guys - would you like to see full power efficiency numbers, or 1/3 power like Carsound does?
04-04-2005, 11:02 AM
#8
Yankee
Join Date: Oct 2003
Posts: 3,599
Amplifier efficiency can be measured different ways and a company will always be tempted to give a marketing spin (and does it represent current product)... Dave has a test that is consistant and repeatable. If everyone did exactly the same test in the same way then the manufacturer posted # would have value
04-04-2005, 01:37 PM
#9
Dave can you go into some detail on how your tests were preformed and how you calculated effeciency....
I swear Ive seen the calculations and once the PSU is taken into account %66 is maximum you can get out of a 12v powered AB class amp...
I swear Ive seen the calculations and once the PSU is taken into account %66 is maximum you can get out of a 12v powered AB class amp...
04-04-2005, 02:14 PM
#10
Haunz,
It is true that class A/B can be 66 to 69% efficient.....I think we can all trust what Dave MacKinnon has to say.
You keep relating to something you have seen that says A/B amps cannot be this efficient....What is your source for this info?
Here's something else for you to chew on......A typical class D amplifier achieves its approx. 80% efficiency at, or close to, full power output. At lower volumes they are typically not any more efficient than a class A/B amplifier.
The Rockford Class BD is a little different.....The Rockford amps are around 80% efficient at full output but also maintain their high efficiency at much lower output levels. Thats why they call it 'BD' instead of D. They re-worked the topology a bit. You get the efficiency when you will actually use it, not just in the DB Drag lane.
It is true that class A/B can be 66 to 69% efficient.....I think we can all trust what Dave MacKinnon has to say.
You keep relating to something you have seen that says A/B amps cannot be this efficient....What is your source for this info?
Here's something else for you to chew on......A typical class D amplifier achieves its approx. 80% efficiency at, or close to, full power output. At lower volumes they are typically not any more efficient than a class A/B amplifier.
The Rockford Class BD is a little different.....The Rockford amps are around 80% efficient at full output but also maintain their high efficiency at much lower output levels. Thats why they call it 'BD' instead of D. They re-worked the topology a bit. You get the efficiency when you will actually use it, not just in the DB Drag lane.
