A decade ago, many predicted that amplifiers with switching or class-D1 output stages would come to dominate high-end audio. In a post&#150;Peak Oil world in which the price of energy would always continue to rise, a class-D amplifier's very high efficiency in converting AC from the wall outlet into speaker-driving power would be a killer benefit. Although a conventional push-pull class-B amplifier has a theoretical efficiency of 78.5%, which would seem usefully high, this efficiency is obtained only at the onset of clipping; the need for the output devices to carry a standing bias current reduces that efficiency considerably, typically to around 50%. Class-A amplifiers are even less efficient, with a maximum of 25%; <I>ie</I>, three times as much power is dissipated by the amplifier as waste heat as is used to drive the loudspeaker (see "Sam's Space" in this issue).

A decade ago, many predicted that amplifiers with switching or class-D1 output stages would come to dominate high-end audio. In a post&#150;Peak Oil world in which the price of energy would always continue to rise, a class-D amplifier's very high efficiency in converting AC from the wall outlet into speaker-driving power would be a killer benefit. Although a conventional push-pull class-B amplifier has a theoretical efficiency of 78.5%, which would seem usefully high, this efficiency is obtained only at the onset of clipping; the need for the output devices to carry a standing bias current reduces that efficiency considerably, typically to around 50%. Class-A amplifiers are even less efficient, with a maximum of 25%; <I>ie</I>, three times as much power is dissipated by the amplifier as waste heat as is used to drive the loudspeaker (see "Sam's Space" in this issue).

A decade ago, many predicted that amplifiers with switching or class-D1 output stages would come to dominate high-end audio. In a post&#150;Peak Oil world in which the price of energy would always continue to rise, a class-D amplifier's very high efficiency in converting AC from the wall outlet into speaker-driving power would be a killer benefit. Although a conventional push-pull class-B amplifier has a theoretical efficiency of 78.5%, which would seem usefully high, this efficiency is obtained only at the onset of clipping; the need for the output devices to carry a standing bias current reduces that efficiency considerably, typically to around 50%. Class-A amplifiers are even less efficient, with a maximum of 25%; <I>ie</I>, three times as much power is dissipated by the amplifier as waste heat as is used to drive the loudspeaker (see "Sam's Space" in this issue).

A decade ago, many predicted that amplifiers with switching or class-D1 output stages would come to dominate high-end audio. In a post&#150;Peak Oil world in which the price of energy would always continue to rise, a class-D amplifier's very high efficiency in converting AC from the wall outlet into speaker-driving power would be a killer benefit. Although a conventional push-pull class-B amplifier has a theoretical efficiency of 78.5%, which would seem usefully high, this efficiency is obtained only at the onset of clipping; the need for the output devices to carry a standing bias current reduces that efficiency considerably, typically to around 50%. Class-A amplifiers are even less efficient, with a maximum of 25%; <I>ie</I>, three times as much power is dissipated by the amplifier as waste heat as is used to drive the loudspeaker (see "Sam's Space" in this issue).

A decade ago, many predicted that amplifiers with switching or class-D output stages would come to dominate high-end audio. In a post–Peak Oil world in which the price of energy would always continue to rise, a class-D amplifier's very high efficiency in converting AC from the wall outlet into speaker-driving power would be a killer benefit. Although a conventional push-pull class-B amplifier has a theoretical efficiency of 78.5%, which would seem usefully high, this efficiency is obtained only at the onset of clipping; the need for the output devices to carry a standing bias current reduces that efficiency considerably, typically to around 50%. Class-A amplifiers are even less efficient, with a maximum of 25%; ie, three times as much power is dissipated by the amplifier as waste heat as is used to drive the loudspeaker (see "Sam's Space" in this issue).

<B>Neil Young: <I>Official Release Series, Discs 1&#150;4</I></B><BR>
Reprise 519173-1(4 LPs, Limited Edition Vinyl Boxed Set). 2009. Neil Young, David Briggs, Elliot Mazer, Jack Nitzsche, Henry Lewy, prods.; John Nowland, reissue eng. AAA.

I may have had 4000 LPs and a perfectly wonderful <A HREF="http://www.stereophile.com/turntables/1103linn">Linn LP12</A> turntable, but I could go for weeks on end without listening to a single LP. But I still thought of myself as one of the vinyl faithful, even as I rationalized my digital-centric listening tendencies. I loved analog <I>in theory</I>&#151;I just couldn't bring myself to listen to it all that much.

Corrina sent me a link to this video for "70 Million" by Hold Your Horses, a band I know nothing about. It must have been so much fun to make this.