Home Theater Receiver Power Ratings.

I am a big fan of Onkyo

Looking At Home Theater Receiver Specs.

It's no surprise that  the first specification that  people look at  (whether a novice or seasoned enthusiast) when buying a home theater receiver is its power output ratings.  And why not?, it's among the most important attributes of an home theater receiver not only because the receiver supplies the muscle to drive your speakers to acoustic levels that are satisfying but also because it lets the buyer know (at least it should) the actual amount of power in watts per channel that the amplifier will drive to each speaker in a home theater surround sound system. This way you know if you are getting the right gear for the space you are probably trying t flood with beautiful music or wicked explosions!  You home theater receiver is the nerve center of  performance of your equipment. There's so much confusing techno-babble in the manuals so I thought I would gather some info and make it a little more user friendly so that your shopping experience is a little more enjoyable.

The first thing that needs mentioned here is that there are no solidly enforced guidelines that receiver and amplifier manufacturers are compelled to adhere to as far as how they advertise their products power output ratings. The FTC passed a rule in 1974 as to how power ratings are to be advertised but they also acknowledge that there are at least seven different ways to calculate power output ratings and each method will give different results.  So the FTC basically left it up to the manufacturer as to how they will advertise their products power ratings. So if the following tidbits of info are not available for the home theater receiver you are interested in....buyer beware!

Home Theater Receiver Power Output Considerations:

1.) Watts per channel: This is the amount of power that an amplifier will push to each speaker on each channel. A channel is each speaker outlet.  For example, you have a left front speaker and a right front speaker.. correct?...each of these is a channel.  A 7.1  channel surround sound system will have 7 speakers and a subwoofer (the  .1 in the 7.1)

If you happen to find a product advertising an "all channels driven" power rating in watts per channel, or total power output of the power supply, then you can do a little quick math to figure out the usable power output per channel in your system by dividing the total power output by 3.   If the total power output isn't given as a single number, then take the per-channel power output with all channels driven and multiply it by the total number of channels (e.g. 100 watts per channel x 5 = 500 watts).  TThis hen divide 500 by 3 gives you 166.6 watts per channel. Your usable power  will be around 166 watts per channel.

2.)  Total Harmonic Distortion (THD): This factor of your power output is actually a pretty complicated subject.   Lesser THD allows the parts of a amplifier, speaker,  or microphone or other equipment to produce a more accurate reproduction by cutting down harmonics added by electronics and other audio media. The important thing for you to know as an interested consumer is that a THD rating of less than 0.1% is considered to be high fidelity and is not audible to the human ear. This means that if there is any distortion in the sound quality it will be so minimal that your ears won't catch it.

3. ) Speaker Impedence: Your only real-world concern with speaker impedance is if  you bought low ohm rated speakers like 4 ohms and have a low powered receiver.  The lower the ohm rating on the speaker the more power it takes to drive the speaker.  To make a long story short, your receiver is going to have to work overtime to power your speakers and will probably  trip the receiver's protection circuit and shut down.

4.)  Frequency and Bandwidth:   The frequency response is a measurement of the range that an amplifier can reproduce from the lowest pitched sounds to the highest pitched sounds .  Bandwidth response is a better measurement  for comparing home theater receivers.  It is the frequency response that the amplifier can provide at the rated RMS power output.  Most of us humans can hear in a frequency range  from about 20hz to 20kHz, so this is the range that you usually see on the manufacturers power specs.

Remember to look for this info on the spec cards or owners manual of the piece of equipment you are considering for purchase. If you don't see any of  this stuff you really have no idea what you're getting and it might not be much!  Now that you are a  little smarter than you were when you first arrived at this page you'll have a better idea of what you're looking at when doing some serious shopping for your next, or even your first home theater receiver.