“Picture a car with [just] an on/off switch—no transmission and no accelerator,” says Eric Harper director of marketing and product development. “When it's on, it runs 50 mph. To get it to run at 20 mph, you have to apply the brake appropriately and constantly. Typical Class A/B amplifiers work much like this: shedding excess energy to reach the desired output volume.”

Sunfire's TDC achieves its energy savings by adding the equivalent of a gas pedal and transmission. “The power supply tracks the audio signal so we're only producing what we need,” Harper says.

Knoll Systems, meanwhile, aims to save electricity by identifying times when power isn't needed. “In a multichannel system, most amplifiers go into standby state that is virtually at regular idle, which is consuming quite a bit of power: 40 to 50 watts,” Hanson says. “Ours is, at most, 4 watts. So it's a tenth of what our competitors are consuming.”

NO FAN OF HEAT

In AV, heat can be bad for a variety of reasons. For example, when the goal is to reduce power usage, too much heat can mean the room needs air conditioning. If the room doesn't already have AC, then extending the ductwork is an additional upfront expense.

But there is also the matter of heat's effect on the audio products themselves, such as components that fail after baking in high temperatures day after day. Building fans into the product is an obvious solution, but fans present several tradeoffs, including:

Ambient noise, which isn't something you want to introduce more of to audio applications.

Their own power requirements, which add to the system's total usage.

The possibility that their moving parts will eventually fail in the field, meaning repair costs and aggravation for the owner.

Fans also add to the vendor's bill of materials (BoM), which affects the product's competitive position. For example, if the product is aimed at a highly competitive part of the market, the fans could increase BoM costs to the point that it has to be priced higher than many rival products, potentially making it less attractive for users with a tight budget. BoM costs also affect the vendor's profit margin.

Sunfire says its amps don't produce enough heat to warrant fans. “At a recent trade show, we displayed a competitive amplifier next to our amp,” Harper says. “Using an infrared temperature sensor, we invited attendees to point it at each amp, taking note of the ambient temperature. The Sunfire TDC–based product ran almost 30 degrees cooler at idle.”

Hot-running products also can have a ripple effect on neighboring gear. “The problem with most racked gear is that the heat usually goes out of one box and into another, causing it to fail,” Harper says. “Our amps and receivers do not have top vents—only side—so there's less ‘creepage' into adjacent components.”

MATERIAL DIFFERENCE

Raw materials present another opportunity for audio vendors to go green and save money. Take copper, for instance. Soaring demand and frequently limited supply have pushed its price to record highs this year. By reducing the amount of copper used in their products, audio vendors can save money. On the green side, they also can note that using less copper helps reduce—even if it's just a drop in the bucket—the amount that has to be mined, which is a process that can be environmentally unfriendly.

“When you move to a digital switching power supply, you can reduce copper by 6 pounds,” says NuVo's Rodarte.