Receiver amplifier ratings are often overrated- how to read the fine print
Week of March 6, 2005
Q: Are today’s ratings for audio receivers the same today as they were back in the late seventies? I owned a Pioneer SX 980 receiver that in the day was rated at 80 watts per channel at 8 ohms. That thing weighed about sixty pounds and was a big piece of equipment. Today I own a Sony receiver which is rated at 100 watts X 5 at 8 ohms and is only a fraction of the size and weight. Is today’s equipment more efficient with power or have they changed the way the power is rated?
Timothy Brown
Peachtree City, GA
A: Anyone who has seen a tiny “600 watts system power” home theater in the box that and sells for only $199 has probably asked this question. The way the power is rated is the same, but manufacturers often play with the numbers to produce extremely optimistic power ratings.
That is why it is important to read the fine print when you buy a receiver or amplifier. You may see specifications such as “10% distortion” or “power measures at 1000kHz”. This means that the receiver can only produce the amount of advertised power at a distortion level that sounds terrible, or at a single sound frequency.
Better amplifiers and receivers are rated for a wide frequency range of 20hz-20khz at less than .2% distortion”. If you rated one of these “100 watt” receivers using these specifications, it could be as little as 20 watts per channel.
Some receivers have digital amplifiers, which are much smaller and lighter than the analog amplifiers typically found in receivers, but these still represent a very small percentage of the marketplace. If you see a small, inexpensive receiver with high power ratings, be sure to read the fine print.
Your modern digital receiver has some other noticeable difference from your older model that relateto its size and price. I receive questions about the subject often and will elaborate on them here.
Back in the 1970s and 1980s, a quality stereo (2-channel) receiver cost around the same as a surround receiver does today, despite inflation. As time as gone on, more and more features such as surround sound have been added, with additional amplifier channels to drive the additional speakers.
If you want to maintain a price point while adding features, the money has to come from somewhere. One area has been volume and tone controls, which used to be controlled with individual knobs. Now a digital processor with a single knob or a few buttons controls them. This is much less expensive to manufacture than multiple controls. Some view this as a beneficial change. Older analog receivers can have sonic problems when dust eventually works its way into the controls, and modern digital receivers are immune to this problem.
Another area money is saved is the AM/FM tuner, where quality has gone down as well. Many audiophiles have lamented that even in expensive modern receivers, the radio section cannot tune distant stations or does not sound as good as they would like.
