Amps: Do you know what (amps) really means for instance? Everybody seems to think they know what it means, the expression having been around for so long. Unfortunately, few know the true definition. In audio, there's three types of power; peak power, RMS power, and last but not least, music power. So let's get to it!

In consumer electronics everything is measured by specs, but when shopping for audio equipment, it's also a good idea to go listen before buying. However, since in today's high technology systems, it's somewhat hard to buy a bad system (unless you go very cheap) so I wouldn't worry about it too much. The most common problem for bad output is connectivity (attaching your cables or wiring).

With this segment, we will be your guide in understanding all of the meaningless terms that tend to confuse consumers when it comes to buying a good to excellent home theater audio system.

CHOOSING AN AMP!

A good amp should be heavy (not on the scale) but heavy in deliverance. In other words, a high current amplifier is much better than one that isn't! It will generally give you a much crispier sound at a given power rating, and won't distort the sound until you reach a very high level.As an example, a 500 watt high current amp is better than a 500 watt regular current amplifier. I don't need to tell you that most all well known manufacturers make high end receivers or amps.

WHAT IS POWER RATING?

How does one compare peak, RMS, and music (all in watts)? Let's begin with RMS power, which means Root Mean Square, and is the most conservative rating. You'll understand as we explain further. The important thing is that the RMS ratng be indicated on the equipment, since it signifies a quality manufacturer. I remember many years ago many of my friends and I buying Marantz because the RMS (20 RMS per channel) was indicated and was, and still is, an excellent amp. (It can also be called 'continuous
average power').

When you're comparing, what you're looking for is an 8 ohm reading or load. Don't buy any less. If you see that a manufacturer only quotes, in his specs, peak power only without RMS, be weary. Furthermore, if you see words like 'music power', run away!

Peak power is double the RMS. Peak Music Power Output (PMPO) is a term used by smart salesmen when trying to sell you small wattage speakers that can be made to sound like 100 watt speakers. Stay away from these types of speakers.

Remember, as I learned in IT school, that volts X amps = watts. So how many watts RMS do you need per channel from your amp or receiver, all depends on your speakers.

YOU WANT SPEAKERS THAT SOUND LIKE THEY`RE SPEAKING TO YOU!

The sensitivity of speakers is rated in DeciBel Sound Pressure Level (dB SPL), at 1 metre (3.3 ft.) distance, and at 1 watt of power. In other words, the higher the number the louder the speaker. This is what dictates the power you need from your amplifier for a proper listening level and pleasure. In fact, everytime you double the wattage, you add 3 dB to the loudness of a speaker.

Example: If you have a speaker that's rated at 90 dB sensitivity, and you feed it 2 watts, it will be 92 dB loud. If you feed it 4 watts, then it will be 94 dB loud and so on at a listening distance of 3.3 ft. Factor in the loudness rop-off at a 10 foot distance (about - 10 dB) and you can see why just 1 watt is plenty loud. As a further example, a 250 watt home theater receiver will output about 101 dB, and a 500 watt receiver will output about 104 dB.

In general it's a good idea to get an amp that is a bit more powerful than the max rating of your speakers. Why? Because, not enough power can cause your speakers to blow! In other words, you should have more power in your amp than you really need. If your speakers have a max rating of 80 watts, your amp should be about 100 watt RMS per channel. But, don't use much bigger as you'll have the same effect of blowing your speakers.

Now, we have Hz (hertz). Hertz is the frequency response. It is the ability to replicate sounds at different frequencies. It is usually stated as a minimum and a maximum value in Hz and usually with the +/- dB rating.

Example: if you have a rated frequency of 50 - 20,000 Hz +/- 3 dB, this simply means that the speaker is 3 dB louder or quiter at different frequencies between 50 to 20,000 Hz. The +/- dB rating is important, since without it, it could be anything including being totally inaudible (no sound). You absolutely need that dB rating, and the smaller it is the better it is. So in general, a speaker that creates 50 Hz sound is going to be much more expensive than a speaker that creates 65 Hz sound, even though both speakers can attain 20,000 Hz.

You are now a pro in understanding the workings of audio, and no salesman will ever be able to fool you in your purchase of audio equipement. Armed with this information, you can generally buy online without any problems as long as you read the specs with the offer. All you need to do is remember that the output of your receiver or amp in RMS wattage has to be somewhat stronger than your speakers can take, but not that much stronger!