Evaluating Surround Sound Receivers

Evaluating Surround Sound Receivers

Surround sound receivers round out your home theater system. A good one will deliver the punch your movies require while a bad one can make those movies sound like they’re playing underwater, or worse. As with almost anything else, you can spend a couple hundred dollars and get a nice receiver, you can spend a few hundred dollars more and get a really nice one, or you can spend more than a thousand dollars and get a great one, with an expensive name brand.

Why is It Called a Receiver?

Surround sound receivers take the audio signals sent to them and separate these signals based upon where in the environment the sound comes from. Stereo amplifiers from years gone by — your dad’s “Hi-Fi stereo” — only had to deal with left and right audio channels. As this technology matured, a third channel — the bass — was added.

Today’s home theater receivers, however, not only have to decipher left and right, but in order to give a true movie theater experience, they have to separate sounds coming from the front and the rear on both sides, four individual and separate channels. They also have to separate the sounds coming from the front center of the viewed area in the scene. This makes five separate channels. The home theater receiver “receives” a signal in the audio program that helps it differentiate and separate the different channels.

Matched System or Component System?

Home theater audio systems can be purchased as either a complete system that either does or doesn’t include a DVD/Blu-Ray player, or it can be assembled from components from various manufacturers and/or product lines from single manufacturers. How you build your home theater audio system is up to you. I’m going to guide you in how to select the right one out of the crowd of available surround sound receivers.

If you go with a component system you need to make sure that the speakers can handle the power output of the receiver and that the receiver can properly drive the speakers. If you get a receiver capable of only putting out 50 W RMS, there’s no real reason to buy speakers that can handle 200 W RMS, especially if they have lower sensitivity ratings. The ideal setup is for the speakers to be able to handle a little more than the amplifier can produce.

Frequency Response is Paramount

Much of the effect of the audio program in a movie theater is the emotional response derived from the physical sensation of the sound. Movie theater equipment has equipment that delivers excellent response throughout and beyond the ranges of human hearing. This response is known as frequency response. The human ear can hear sounds in the approximate range of 20 Hertz (Hz-cycles per second) to 20 KHz. Anything within about 10 Hertz either way, especially down, can’t be heard, but can be felt. Sure, you need power to rumble the seats, but without frequency response rumbling your tummy, its effect is limited.

How Much Power Do You Need?

Power is a matter more of quantity than quality. How much you need is also determined by the efficiency of your speakers. If your speakers have a sensitivity of 90 dB or more, you will actually need less power to get the amount of sound you need or want. Also, if you live in a house, you’ll be able to use more power than if you are in an apartment or condo with neighbors crowded in tightly. I have speakers with a 98 dB sensitivity. They can handle up to 500 watts each when the need arises. However, in my duplex I only needed 200 watts, while in my apartment only I only needed 100 W of power. If I had the house my parents have, with lots of space and lots of space between neighbors, I’d probably go with the full 500 W.

You’ll also see peak and RMS power. As you can imagine, peak power is the maximum power the amplifier can produce, for brief bursts. RMS power is root mean square, or average power. So an amplifier that can produce, or a speaker that can consume, a peak of 500 W may only be able to dissipate 200 W RMS.

The final considerations when looking at surround sound receivers and power are signal to noise ratio (S/N) and total harmonic distortion (THD). S/N is just that, the amount of the actual audio signal versus the amount of noise produced by the amplifier. This is measured is decibels (dB) with a bigger number being better.

Even more important is total harmonic distortion, THD. This is a measurement of how much distortion is present in the amplified signal. Noise can make an audio program hard to hear, but distortion will not only make it hard to listen to, but it can also destroy speakers and amplifiers. Thus, the less THD the better.

Comparing Two Surround Sound Receivers

Let’s compare the Sony STR-DH550 and the Marantz NR1403 receivers. They are both five-channel amplifiers. The Sony produces 90 W RMS, while the Marantz only produces 50 W RMS. They both have a 20-20k frequency response and low THD (.09% for the Sony and .08% for the Marantz.) It sounds like the Sony is the better amplifier, so why is it more than $150 cheaper? Because the Marantz names comes with a certain amount of prestige and they just build better amps. Enough to justify that much price difference? I don’t think so.

Choosing Your Ideal Surround Sound Receiver

First, decide whether you are building a whole new system or upgrading a current system and whether you’re going to build it from component separates or as a unit. Then set your budget, as this will limit your price range. Next, decide on a power range that you need/want. Once you have the power range, you can select five or six contenders within your price range. From there, check frequency response, S/N ratio, and THD. Next, if possible, go listen to them and make your choice based upon every piece of information you can.

Connecting Components to Achieve the Highest Quality Audio Possible

You want the best possible signal transfer you can get at all stages of the process. Ideally you will connect your Blu-Ray/DVD player to the receiver using an optical cable This type of connection uses fiber optics and lasers to transfer data, thus delivering the cleanest possible signal for the amplifier and surround processor to work with. If you can’t connect using optical, make sure the regular RCA-type connectors are gold-plated and connect firmly.

Place Your Speakers for Optimal Signal Propagation

Signal what? Signal propagation is how the sound waves produced by a loudspeaker look and where they go. Higher frequencies, like those above a normal speaking voice, are very directional, while lower frequencies aren’t. You can immediately tell what direction the squealing tires are coming from, but the low frequency boom of the explosion seems to wash over you. For the best environmental experience possible from a movie, you need to get the front and rear speakers as far from you and the TV as possible.

Ideally your viewing area is an almost perfect square and you can place the speakers in the exact corners and aim them directly at your couch or chairs which are situated in almost the exact center of the room. However, most of our rooms are far from ideal for the best surround sound experience. Getting your speakers as far away from you and your TV as you can is the best start you can make.

Configure Your Surround Receiver for the Best Experience

Now it’s time to adjust the settings on your amplifier to help you achieve the best listening experience possible. Sound travels at a set speed and this is why you want your viewing area to be the same distance from the front speakers as from the rear speakers. This isn’t always possible, so manufacturers allow us to change a setting on the rear, surround channel called delay. More delay means the signal to the surround channel is delayed by a certain amount of time. This is done to make up for the differences in distance between the viewing area and the front and rear channels.

With some systems, delay is adjusted either on the receiver front panel or on the remote. On some you will need to access the settings menu items for it. If your receiver has video out capability, this will make viewing the menu options and adjustments easier. Increase the delay until you want to turn your head to follow on object on screen that moves from one front side through the center and off screen to the back on the opposite side. Some newer systems do this automatically for you.

Photo Credit: William Hook