The Home Theater Receiver

The Home Theater receiver, or Surround Sound Receiver, is the very heart of a home theater system and provides most, if not all, the inputs and outputs that you connect everything into. The receiver provides an easy and cost-effective way of centralizing your system.

A Home Theater Receiver Functions-Components
1. AM/FM tuner;XM or Sirius Satellite Radio, and/or Internet Radio.
2. A Preamp that controls which audio/video source is selected (DVD player, VCR, CD player, iPod, etc…), processes the incoming stereo/surround sound signals, and distributes audio to the speaker channels and subwoofer. Video signals are carried on through to the screen or TV.
3. A built-in Multi-channel amplifier (5.1, 6.1, or 7.1 channels) that sends the surround sound signals and power to the speakers

Power Ratings (WPC) – Watts Aren’t Everything
Receiver descriptions always list the Watts-Per-Channel rating. One receiver has 50 Watts-Per-Channel (WPC), another one has 75, and still another has 100 or more. The more watts, the better, right? Not Necessarily.
Most people think that more watts means more volume. An amplifier with 100 WPC is twice as loud as 50 WPC, right? Many receivers may push a good deal of watts, however, they have very high distortion levels.

Distortion (THD) – If It Doesn’t Sound Good -The Watts Do Not Matter
A receiver that has excessive noise or distortion at high volume levels will have a terrible sound quality. You are better off with a receiver of about 75 WPC with a low distortion level than a more powerful amplifier with high distortion levels. Usually receivers that do have higher distortion levels have lower volume levels.
A receiver that has a distortion rating of 8-10% at full output is very poor. A receiver that has a .01% distortion level at full output level would be excellent at ALL listening levels. Distortion specs are expressed by the term THD (Total Harmonic Distortion). There’s of course nothing wrong with higher WPCs providing that receiver has a lower distortion level.
· Definition of Distortion (THD)- Distortion specs are expressed by the term THD (Total Harmonic Distortion), which is measured in percentage terms, where the percentage represents the amount of distortion present in the audio signal at full output level.
Signal-To-Noise Ratio (S/N) – Separating The Sound From The Background Noise
Another factor is Signal-To-Noise Ratio (S/N), which is ratio of sound to background noise. The larger the ratio, the more the desirable sounds (music, voice, effects) are separated from acoustical effects and background noise. In amplifier specifications S/N ratios are expressed in decibels. A S/N ratio of 70db is much more desirable that a S/N ratio of 50db.

Decibels (db) – Sound Level Performance
Sound level is measured in Decibels (db). Our ears detect changes in volume in a non-linear fashion. A db is a scale of loudness. A difference of 1 db is the minimum perceptible change in volume, 3 db is a moderate change, and 6 db is doubling of volume.

How Stated Power Ratings Can Be Deceiving
In addition to the continuous power rating, another factor affecting real amplifier power output, especially with surround sound receivers, is whether the manufacturer is basing their wattage output specification on one or two channels driven or with ALL channels driven. In addition, was the measurement made using a 1KHz test tone, or with 20Hz to 20KHz test tones?
In other words, when you see an amplifier wattage rating of 100 watts-per-channel at 1 KHz with one or two channels driven, the real-world wattage output when all 5 or 7 channels are operating across all frequencies will be lower, possibly as much as 30 or 40% lower. Of course, not all channels actually require the same power at the same time as variations in audio signals affect the requirements for each channel at any given time. Wattage output, as stated in the manufacturer’s specifications, may not be available across all channels at the same time.

Continuous Power (RMS)
Another factor is the receiver’s ability to output its full power continuously. In other words, just because your receiver/amplifier may be listed as being able to output 100WPC, doesn’t mean it can do so for any significant length of time. Always make sure when checking for specifications, that the WPC output is measure in RMS terms. This means that the listed power output is SUSTAINED OUTPUT at a specific volume level.

HDMI Connectivity
HDMI is a connection available on many receivers. Unlike other connections, HDMI can pass both audio and video signals through a single cable. However, depending on how HDMI is incorporated, access to HDMI’s capabilities may be limited.
Many lower priced receivers incorporate pass-through HDMI switching. This allows the connection of HDMI cables into the receiver and provides an HDMI output connection to a TV. However, the receiver can’t access the video or audio portions of the HDMI signal for further processing.
Some receivers access both the audio and video portions of the HDMI signals for further processing.
The Bottom Line – Take All Factors Into Consideration
Do not base your buying decisions from a single specification, such as a Watts-Per-Channel rating. A single spec, taken out of context with other factors, does not give a completely accurate picture of the receiver’s true capabilities. There are other factors to take into consideration, such as, sound quality, ease of use, and flexible connectivity with other components. Never buy a receiver without giving a listen for yourself, or at least look up some reviews on it before purchasing.

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