Comparisons   Scorecards   Buyers guides   Glossary   Retailers   Feedback Search magazine   Questions and answers Amplifier power and speaker rating - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -- - - - - - - Ohms ain't ohms Q. Can you shed some light on the rating of amplifiers and speakers when choosing an amplifier? A. In 150 words or less it's a hard ask, but here goes. The power output of amplifiers and receivers a routinely rated into a speaker impedance or resistance factor of 8 ohms (8 units of resistance). Most amplifiers and receivers can deliver power into a 8 ohm load reasonably well, but some have difficulty driving speakers that present them with lower impedance or resistance. Better quality amplifiers will be rated to work safely and effectively into a 4 ohm load (or half the resistance of a conventional 8 ohm rating) and really good amplifiers will be capable of safely driving speakers with 2 ohm impedance ratings. Choose amplifiers that are rated and guaranteed into low impedance loads. By choosing such products you have more freedom to choose speaker for your system and know they are not going to cause the amplifier stress or damage it. You will restrict your choice of speakers otherwise. Whew! Made it … by nine words. But you may also want to consider the following: When choosing an amplifier, straight power output should be the least important parameter on which you base your purchasing decision. Why? Because of the Bel. You see, the difference between 50 watts and 100 watts is 3dB (3 decibels, or 3/10ths of a Bel) and in terms of phonics that's about the lowest audible increase in sound level most of us can hear. So going for a 100 watt unit over a 50 watt unit just of power will not reap you many real rewards. In fact you're more likely you will get better performance and realize the additional outlay in enjoyment with an amplifier that pushes out its 50 watts RMS into an 8 ohm speaker resistance and maintains this power rating or improves on it into 4 and 2 ohms. Such an amplifier will sound louder because it's producing cleaner less affected sound. The Bel and the decibel define power differences as a ratio and are used to compare voltage, current, watts and sound pressure. It uses a logarithmic scale that corresponds to the logarithmic nature human of hearing. One dB (decibel) is a difference of 27 percent while a 3dB difference is a difference of two times or 100 percent - that's why a 100 watt amplifier is only 3dB more powerful than a 50 watt amplifier. From here on it gets a tad complicated. Ask a question or make a comment: YOUR COMMENTS YOUR NAME YOUR EMAIL YOUR COMMENT    YOUR INFORMATION WILL NOT BE DISCLOSED    Virtual Magazines reserves the right to publishing submitted comments.    Comment providors assign copyright license to Virtual Magazines.        HOME    BACK    NEWSLETTER    CLASSIFIEDS    FORUMS    LINKS    QUIZ    POLL  SOFA MAGAZINE  entertainment@home ISSN 1443-170X {ad-1} {ad-2}