Energy Efficiency

The Extron XTRA™ Series of Class D amplifiers are the commercial AV industry’s first complete family of ENERGY STAR® qualified amplifiers. XTRA Series Class D amplifiers have higher energy efficiency than conventional Class AB amplifiers. This means they draw less power from the wall to produce the same audio output power. They also produce less waste heat for the same audio output power, since the additional power drawn from the wall by a Class AB amplifier must be dissipated as waste heat. Higher energy efficiency translates to lower power draw and lower waste heat dissipation for the same amount of audio output power.

Table 1 shows the impact of the higher energy efficiency in the XTRA Series versus comparable Class AB amplifiers from competitive manufacturers. With equal audio output power, the Class AB amplifiers draw much more input power than the XTRA Series. The additional power drawn is converted to waste heat. The XTRA Series amplifiers have much lower input power requirements, as well as much lower waste heat to be dissipated.

The audio output power used for testing is generally chosen as 1/8th of the maximum output power of the amplifier, using a 1 kHz sine wave and a resistive load. This is in accordance with international compliance testing standards, such as IEC60065 in Europe and UL 60065 in the US, as it represents the average power of moderately clipped full range music. In some cases, the maximum output power ratings of two compared amplifiers are not exactly equal, but both are adjusted for the same audio output power for comparison purposes. Input power is measured using a power meter on the AC mains.

Automatic Standby Mode

Greater efficiency for an amplifier in active mode is not the only factor that allows Extron XTRA Series amplifiers to save energy. One of the most important aspects of the Extron XTRA Series amplifier design is that it features an automatic standby mode, allowing the amplifier to put itself into a very low power “sleep” mode after a 25 minute period in which no signal is present at the input. This is a key criterion for achieving ENERGY STAR qualification under the ENERGY STAR AV Specification 2.0. However, Extron offered this for the XTRA Series long before the AV Specification 2.0 was conceived.

Conventional amplifiers do not offer a standby mode. When the amplifiers are not in use, they operate in an idle mode, consuming power and dissipating it as waste heat the entire time the system is powered on.

The significant contribution to bottom line savings when using the Extron XTRA Series Class D amplifiers with their automatic standby mode should not be overlooked. For 6,680 hours a year, conventional amplifiers are creating a significant idle load during a system’s non-operational downtime. This is often referred to as vampire power which adds significant costs to a facility’s operational budget.

Calculating Annual Operating Costs

For the purpose of comparison, we calculate input power draw assuming 40 hours per week of active operation at 1/8 maximum audio output power. For the remainder of the time, the XTRA amplifier will be in standby mode, while the conventional amplifier will be in idle mode. This gives 2,080 hours per year operating at 1/8 power, and 6,680 hours per year in standby or idle mode.

Table 2 lists the annual cost of operation for Extron XTRA Series versus conventional Class AB amplifiers assuming $0.10 per kilowatt-hour, per the latest available data from 2009 provided by the US Energy Information Administration.1

On a yearly basis, the XPA 1002 consumes a total of 53 kilowatt-hours, costing $5.26 to operate. The Class AB amplifier from Competitor A costs $29.26 yearly to operate, 456% more than the XPA 1002.

It can be easily concluded from this data that converting to the XTRA Series from Class AB amplification in a multi-amplifier application can have a profound effect on operational costs due to the improved efficiency. For example, if four of the XPA 2002-70V two-channel 70 volt amplifiers were employed in a single system, the cost would be $72.04 annually to operate them. They would consume only a total of 720 kilowatt-hours per year. Four Class AB amplifiers from Competitor B would cost $274.20, or 3.8 times more to operate per year, and would consume a staggering 2.7 Megawatt-hours of power per year. The savings to the operation’s bottom line would be $202.16 yearly.

XTRA Series Class D Amplifiers

Extron XTRA Series amplifiers deliver a combination of energy efficiency, low heat dissipation, and space efficiency that lowers ownership costs for facilities compared to installing conventional Class AB amplifiers. For more information, download the XTRA Series efficiency white paper at

1 US Energy Information Administration, (n.d.) “Electricity: Energy Explained, Your Guide to Understanding Energy.” Retrieved March 21, 2011 from