Buying an AV receiver

The centrepeice of your home theatre system

By Michael Jones

June 2003

In home entertainment there’s no item as potentially confusing as its centrepiece – the AV receiver. Here’s a quick guide that will answer your questions.

What’s an AV receiver?

It’s an amalgam of several parts in one box. In an AV receiver you’ll find a controller, which selects among the various source components (CD, DVD etc) and controls the volume; digital processing for decoding the sound to be sent to the various speakers, and amplifiers for powering five or seven speakers.

Do I need an AV receiver?

That’s an excellent question, but one not asked as often as it should be.

If your main interest is in music, and obtaining the best from your collection of CDs and LPs, with minimal interest in movies, then you’ll be better off with a stereo amplifier. You’ll get better sound for your music at the same price as an AV receiver, or be able to spend less on the amplifier.

But if movies are a big interest and you want them in all their surround sound glory, then an AV receiver is for you

Talking to both buyers and staff in stereo shops, it’s apparent that many people assume that they need an AV receiver, even if they rarely, if ever watch movies in the home. Look carefully at your current home entertainment options and what you’d like to incorporate with any new purchases.

How many watts?

Power requirements confuse many people, mainly because the power required depends on room size, speaker sensitivity (how much power is required to achieve a certain loudness level) and how well an amplifier can drive real world speakers, as opposed to an 8 ohm resistor used for power measurements.

Use inefficient speakers (less than 86dB sensitivity) in a large room and you’ll need lots and lots of watts. With speakers 3dB more sensitive (89dB) you’ll need half the power.

Power ratings can be ambiguous for a variety of reasons (see next section). One reason is that loudspeakers are harder to drive than measurement resistors. A good power supply is, of necessity, heavy, so a rule of thumb is that the heavier the amp, the bigger and usually better the power supply.

What’s in a watt?

Be careful when comparing the power output of AV receivers, as some manufacturers rate them in a way that makes their receivers look more powerful than they really are.

Many spec sheets have the amplifier power rated in a way that meets legal requirements in the USA (X watts into 8 ohms at Y level of distortion over the 20Hz–20kHz audio band).

But some manufacturers will use other rating systems, such as power at 1kHz into six ohms, which can make their amplifiers look 30% to 50% more powerful than their competitors.

What are all these surround modes?

The whole point of an AV receiver, besides being a control point, is to put sound all around you. But this can all get very confusing.

There’s Pro Logic and Pro Logic 2, Dolby Digital, DTS, Dolby Digital EX, DTS-ES (both Matrix and Discrete), DTS:Neo6, plus various hall, cathedral, five channel stereo and other sound modes. What’s a poor movie lover to do?

Simplify. Most movies on DVD come complete with a Dolby Digital or DTS soundtrack. Play the DVD and your AV receiver should automatically detect which of the two is needed, no intervention necessary.

Pro Logic 2 or DTS:Neo6 can be useful for sound from TV or video tape. Many TV programs, including USA series such as The West Wing and many UK dramas, are recorded in Dolby Surround. This format tags along with a Nicam TV broadcast or stereo tracks from VHS tape, allowing surround sound in your home.

Don’t worry too much about the other sound modes, as the main reason for them is marketing bragging rights. It might be fun one time to put Madonna into a cathedral, but if that’s how you keep your AV receiver set, then don’t invite me around for a listen!

How much difference is there when the price increases?

The more expensive the AV receiver, the more you get. More power, more (and better) connections, more features and – usually – better sound, at least within each brand.

Which one should I buy?

No cop-out intended, but that depends. It depends on the sound formats you want, the features you want, the speakers you intend using and the quality of sound you need. You will need to think these issues through, but reading our reviews will help.

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