Receivers – Brains & Brawn behind Home Theater
Your speakers and your television do exactly what they’re told by the receiver – the brains and brawn behind home theater. The brains come from the ability to separate incoming audio and video digital signals from multiple sources and distribute them to the correct channel. The brawn comes from the ability to dramatically increase the playback volume of the sounds you hear (and feel) without changing the characteristics of the signal.
You could own the best speakers and HDTV in the business but without the smarts and the power of a receiver, you have nothing. You’re worse off than watching your old cathode-ray tube television and listening to those tiny speakers located at the base of the cabinet.
The home theater receiver is known by many different names, but they all refer back to the same thing. That’s as long as you’re talking about a receiver capable of at least 5.1 channels of digital processing and amplification for home theater.
- Home Theater Receiver
- Audio/Visual Receiver
- A/V Receiver
- Surround Sound Receiver
- Dolby Digital/DTS Receiver
Example of the front, back, and the remote control of a typical home theater receiver.
When choosing your home theater receiver, there are several specifications you’ll need to understand such as watts and decibels. But, don’t purchase your receiver based only on a watts-per-channel rating as that is only part of the story.
WHAT DOES A RECEIVER DO?
The receiver acts as a control station and processor for every single input and output signal of your home theater system. You don’t see or hear anything unless the digital signal was received in and then transferred out of your receiver. The receiver receives these digital and analog signals, processes them, and distributes them as separate audio and video channels. The home theater receiver can also has functions as an AM/FM tuner and docking station for iPods® (video and audio).
As a control station, the home theater receiver performs the duties of three pieces of hardware in one compact unit:
- Tuner – Receives all the standard AM/FM stations. Some units have the capability to broadcast XM or Sirius satellite radio (premium service), high-definition (HD) radio, and/or internet radio.
- Preamp – Separately controls the audio and video digital signals for distribution to the speakers and to your television.
- Amplifier - Distributes multi-channel (e.g., 5.1, 6.1, 7.1) digital audio surround sound signals and power to the speakers.
THE PARTS OF A RECEIVER
Since a home theater receiver is comprised of several different components with the most important being the receiver, we’ll explain the parts and the terminology so you’ll understand how your receiver works, what features you need, and where to place it in the room.
Watts Per Channel (WPC)
Watts equates to how much power is being driven to the speakers calculated in watts per channel (WPC). If you have a 700-watt, 7.1 channel receiver, the amplifier inside the receiver has to divvy up those 700 watts between each of the 7.1 channels (100 watts for each channel). What about the .1 channel? That is for the subwoofer which has its own preamp inside the speaker box so it doesn’t need or use any of the WPC. Those 100 WPC don’t sound as powerful as a 700-watt system but you’re getting those 100 watts some seven times over plus the boom sounds from the subwoofer.
Total Harmonic Distortion (THD)
Distortion specifications are expressed in percentages and are calculated at full WPC output. A receiver can have a specification sheet that brags about a high amount of WPC but if the THD is also high, you’ll be listening to distortion instead of music. Receivers with a high THD rating of 10% at full output would be completely unlistenable while a receiver with a very low TCD rating of 0.1% at full output would be music to your ears at all volume levels.
Decibels (dB)
A misconception among some listeners is that wattage equates to loudness in decibels. Does this mean a 150 WPC amplifier is twice as loud as a 75 WPC amplifier? Not exactly. In order for one amplifier to reproduce sounds twice as loud as another amplifier calculated in decibels, it would need 10 times more wattage output. This means to have an amplifier twice as loud as a 75 WPC amplifier, you’d need 750 watts of power output. The relationship between the volume knob and the wattage rating of your amplifier is logarithmic (computed as WPC x 10) rather than linear (direct comparison of 150 WPC is twice as powerful as 75 WPC).
Signal-to-Noise Ratio (S/N)
A second factor in determining what you’re going to hear is the S/N ratio. Also expressed in decibels, the S/N ratio is the amount of sound you hear in comparison to the amount of background noise you hear. The higher the S/N ratio dB rating, the better sounds you’ll hear without it being tainted with excessive background noise. An amplifier with a S/N ratio of 106dB is a much better buy than a amplifier with a S/N ratio of 45dB.
Dynamic Headroom
The amount of WPC your amplifier holds in reserve for extreme variances in dB is known as dynamic headroom. Especially when enjoying home theater, sounds can vary from total silence and whispers to an action climax that can knock on the pain threshold of your ear (130dB). For example, if two movie characters are having a conversation with each other in a room at approximately 60dB, and then a car crashes through the wall at 110dB, the power to drive that spike of 50dB has to come from somewhere. The need to draw on that extra power would be immediate, but brief and quickly peak; possibly lasting from one-fifth of a second to one second.
If the receiver’s amplifier has little or no dynamic headroom, distortion would be temporary but would be noticeable. If the specification sheet shows a dynamic headroom rating of 3dB, this would mean the receiver’s amplifier has the ability to double its power for brief periods. An average receiver will have a rating of 1.0dB to 2.0dB and might be expressed with the plus sign in front of the value (+1.5dB).
Continuous Power (RMS)
This is the rating to gauge if a receiver will run at a specified power continuously, not just for peak intervals. If your receiver can’t maintain full power at a specific volume for an extended period of time without melting its innards, then it has a weak RMS rating. To obtain a true RMS wattage result, the wattage of an amplifier is calculated three different ways. The true RMS wattage is obtained by adding the Root wattage, the Mean wattage, and the Square wattage (hence RMS) and then dividing the grand total by three.
Ohms
The rating of your speaker’s resistance to the flow of wattage from your amplifier is rated in ohms. And in turn, your receiver’s amplifier is rated in WPC at a specific ohm rating. The lower the ohms rating, the increased amount of wattage is needed to drive your speakers. Let’s say your speakers are rated at 4 ohms, then it would take more of your amplifier’s wattage to get your speakers playing music or the soundtrack from your favorite movie. And in contrast, the higher the ohm rating (8 ohms), the less amount of wattage from your receiver’s amplifier will be needed to get sounds screaming from your speakers.
Some amplifiers are rated at WPC at one specific ohm rating. But, others will have different ohm ratings depending on where the power is being distributed. For example, wattage provided for the front, center, and subwoofer might be rated at 6 ohms while the surround sound speakers will be rated at 3 ohms.
UPSCALING
Most home theater receivers have the capability of providing the upscaling or upconversion of both digital and analog signals to display on high-definition televisions (HDTV). Upscaling is a mathematical process which matches the pixel count of the output signal to the physical pixel count of your HDTV’s resolution set at 1280×720 (720p), 1920×1080 (1080i), or 1920×1080 (1080p). Although the images are upscaled, they are not true high-definition images even if the upscaled images were derived from a DVD. The images are simply better than the original source which results in better detail and color consistency.
SYSTEM ILLUMINATION
Ensure you system has an illumination dimmer feature that will change the brightness of your display from normal to dark or even very dark. After you’ve extinguished all the lights and you’re sitting in the room waiting for the movie to queue, nothing can be more irritating than the brightly lit screen on your receiver displaying its current status. This is even worse that watching ‘Set Clock’ flash hundreds of times on your VCR. When you dim the lights, dim your receiver.
LOCATION
A receiver can be located anywhere in your home theater Mecca but it must be within infrared range of your remote control. Considering everything is physically connected to the receiver by cables, you’ll probably want it within a few feet of your television to centralize your audio/visual control point.
FINAL THOUGHTS
Ensure your home system has the brains and the brawn to send thundering audio to your speakers and a rainbow of colors to you HDTV. A poor receiver will take away everything that defines home theater. Look at all the capabilities and the specifications sheet and don’t just focus on one feature – such as watts per channel. The receiver is your amplifier, your radio, your iPod® docking station, and your signal processor for HD audio and video. You won’t have to spend a lot of money to get something compatible with your speakers and your television. Check out our line of home theater receivers here.
Still have questions? – feel free to speak with an hhgregg associate. We offer the best-educated associates in the business who are smart enough to make it simple. Price and Advice Guaranteed!
