What to look for when shopping for electronics.
Think of the receiver as the heart of a home theater system. It is actually several components in one chassis. Receivers are the best choice for most home theater systems as they are easy to buy and represent very high value. The functions of a receiver are:
Receives AM and FM radio stations.
- Preamp/Switching Center
The preamp section of the receiver controls volume, bass, treble and other basic control functions. It also serves as a switching station for your whole home theater system, allowing you to switch audio and video sources. Make sure the receiver you are considering has enough audio and video inputs and outputs to handle all your current and future sources. Be especially aware of the number and type of digital inputs it provides. Are there enough for all your present and future digital sources such as DVD, DSS, Digital Cable. If you have a Laser Disc player, make sure the receiver has a digital RF input. If your TV has an HDMI input, make sure the receiver has HDMI inputs and outputs (HDMI cables provide better picture quality). If you want the option of adding an outboard surround decoder in the future (such as DTS or some as yet-to-be-invented processing), get a receiver with 6 pre-amp level inputs.
- Surround Processor
This part of the receiver "decodes" the surround sound information from the source and directs the 5 (or 6) channels of information to the proper speakers. The major types of surround processors are discussed above. All receivers sold today have Dolby Pro Logic built-in so that you can get surround effects from broadcast and cable TV and videotape. Many receivers also feature built-in Dolby Digital processing in addition to Pro Logic. Some receivers are "Dolby Digital Ready" which means that an outboard Digital decoder can be added at a later date (but you will spend more money in the long run). Even if you are not getting a digital source (like a DVD player) right now, it still makes sense to get a receiver with Dolby Digital built-in as it is the de facto surround standard of today and is likely to be with us for a long time.
- Power amplifiers
The power amplifiers are the part of the receiver that drive the speakers. The higher the power (watts) of the amplifier section, the louder and cleaner the speakers will play. Don't worry about small differences in power, in order to get an audible volume difference (a 3dB increase) you need to have double the power. So if you are considering a 50 watt per channel receiver, the next significant step-up power wise is 100 watts per channel.
But beware, not all watts are created equal. It is not uncommon to have two receivers or amps of equal rated power where one plays louder and sounds better than the other. Why? Some manufacturers measure only one channel operating at a time, rather than all channels driven simultaneously (as you would use it). Also standard amplifier tests cannot mimic the same electrical conditions, or load, of an actual loudspeaker. But most of all, specifications cannot measure the quality of sound.
So how do you tell which receiver has the better amplifier section?
Here are a few clues to look for:
- Look carefully at the power specifications. A thorough and meaningful power specs would look something like this: "100W/ch @ 8 ohms, with no more than 0.1% THD, from 20-20,000 Hz, all channels driven." In this spec you can tell that the power was measured in the way you will use it: at low Total Harmonic Distortion (anything under .5% is low enough), through the whole audible frequency range (20Hz - 20kHz) and with all the speakers playing. A lessor quality receiver might quote power like this: "100W/ch @8 ohms, at 1 kHz, one channel driven." That's a lot like quoting a car's acceleration as "0 - 60 MPH, downhill with a stiff breeze."
- Look for power ratings at lower than 8 ohm loads (Ohms are a measure of the electrical resistance of the speaker). Ideally the amp should be able to put out at least 50% more power into a 4 ohm load as an 8 ohm load. If there is no 4 ohm power rating quoted, chances are that the amp will not drive a 4 ohm speaker. Almost all speakers are less than 8 ohms for some part of the frequency range (impedance varies with frequency) and many fine speakers are 4 ohm speakers. Get a receiver that can safely drive a 4 ohm speaker.
- Beware of the super bargain. If you see a receiver that seems to offer a lot of power for a ridiculously low price it is probably too good to be true - literally.
If you are a real audiophile and want the absolute best performance, you will be better off getting all of the above components as separate pieces. This approach will give you the greatest amount of flexibility and audibly better performance than can be had from a receiver, but at greater cost and complexity.
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