FEATURE

HOW TO BUY....  HOME CINEMA SEPARATES

1. AV AMPS/DECODERS

The consumer electronics industry is getting much better at packaging home cinema equipment and there are some excellent ‘one-box’ systems around at the moment.  However, all of them involve some sort of compromise on performance or flexibility, or it may simply be that you’re not in the market for a new TV, satellite receiver or hi-fi system right now. If you’re going to do the job properly then you have to think about building a system around carefully selected components, and the logical place to start is an integrated AV amplifier and surround-sound decoder.

AV amps come in a variety of flavours, from modestly equipped budget models costing less than £250, to serious high-end designs, with THX and AC-3 capabilities. Bear that in mind if you have a reasonably-sized budget, i.e. more than £700 to spend.  DVD is coming and if you decide to upgrade in the near future a multi-channel amp will make life a lot easier, and it could save you a packet on further upgrades.  

Output power is one of the first things to consider, taking into account the speakers you’re going to use it with, but remember, more doesn’t necessarily mean better. Don’t just look at the ratings for right and left stereo channels, the centre and rear channels are equally important. They need to be on a near-equal footing with the front channels, or at least in the same ballpark, otherwise the system could lack impact and it might be difficult to achieve a balanced soundfield.

Most mid-range AV amplifiers come equipped with a set of digital sound processor (DSP) modes, that generate a range of pseudo surround effects, or simulate the acoustic properties of a variety of venues. They can be quite effective, especially with mono sources, lightly engineered stereo material and older audio recordings, but don’t get carried away. Once the novelty has worn off it’s unlikely you’ll use them very much.

The Dolby Pro Logic decoders in most AV amplifiers have similar facilities, but some are easier to set up and use than others. At the very least there should be some means of independently adjusting levels on the front, centre and rear channels. An input level adjustment is useful too, to compensate for the differences between soundtrack recording levels. They vary a lot, and it can be especially noticeable on action blockbuster movies, where there is a wide dynamic range, between quieter sounds, and loud explosions or special effects.

AV amplifiers have to be able to handle a number of source components, not just the obvious ones, like a VCR, satellite tuner and laserdisc player; you may also want to use it with a video games console, camcorder, audio components and heaven knows what else in the next five years, so check there’s sufficient input sockets. Aim to have at least one or two spares when all of your system components have been accounted for.

A growing number of AV amplifiers now come with built-in AM/FM receivers. If you’re not committed to a particular receiver  they’re definitely worth thinking about; at the very least it means one less box in the system.

BOX COPY 1.

SHOPPING TIPS

* Output power is a consideration, but it’s more important there’s not a big difference between the front, centre and rear channels, otherwise the system can be difficult to balance

* Lots of clever digital effects can be fun, but ask yourself, do you really need them, and how often will they be used?

* You can live without remote control on most pieces of audio and video equipment, but not a surround-sound system

* An AV amp needs input sockets, and plenty of them, otherwise you’ll be forever swapping cables

* Think ahead if you’re planning to splash out on an AV amp. You might not have AC-3 or MPEG Audio sources -- like DVD or laserdisc -- right now, but in a year’s time, who knows?

BOX COPY 2

BEST BUYS

Kenwood KR-V99OD, £1300, HE38. An accomplished and solidly-built AV amp, ready and waiting for AC-3/MPEG audio. There’s plenty of DSP effects to play around with and it has a very competent DPL decoder, that copes equally well all kinds of movie soundtracks, from moody atmospherics to floor shaking explosions

Philips FR-751, £300 HE41. If you’re on a tight budget or just dipping your toes in the water, then this unusually well specified AV amp/receiver is worth shortlisting. Power distribution is good and DPL resolution is sharp. A slightly thin bass and a shortage of input sockets knock off a couple of points though.

Sony TA-VA8ES, £700, HE40. Sony may have gone a little over the top with all the DSP effects, but they’ve got everything else about right, including a set of inputs for AC-3/MPEG audio. It’s a lump of a thing, but it packs a real punch and the DPL decoder is a treat.

2. AV DECODERS

If you’ve just spent a considerable amount of time, money and effort getting your component hi-fi system to sound just right, the last thing you want to do is replace a cherished amplifier to upgrade to home cinema operation. You don’t have to, stand-alone Dolby Pro-Logic decoders are designed to integrate with any type of hi-fi set-up, with a minimum of disruption, and without compromising performance. Indeed, a DPL decoder is the only logical route, if you’re pursuing the very best home cinema has to offer.

As far as the hi-fi system is concerned, a DPL decoder is simply another audio source component. Interconnections are generally quite straightforward. DPL decoders have one or more stereo line-level inputs, which connect to the audio output of the AV source components, (usually a NICAM VCR, satellite receiver or laserdisc player). Most dedicated decoders have four line-level outputs; two are for the front right and left stereo channels; these go to one of the hi-fi amplifier’s auxiliary inputs. The other two outputs are for the centre-front dialogue channel, and the rear-effects channel. They’re connected to a separate stereo, (or two mono) power amplifiers, driving the centre channel speaker and two rear-effects speakers.

Most other DPL decoders have their own built-in power amplifiers, to directly drive speakers for the centre, and more often than not, the effects channel as well. Power outputs vary widely, but it’s a good ideal to choose one that roughly matches the output from the main hi-fi amplifier; if necessary err on the side of caution. Several top-end decoders are THX certified and/or AC-3 ready, that’s clearly a consideration if the rest of your system makes the grade, or you plan to upgrade at some point.

A number of DPL decoders are equipped with digital signal processors (DSP) facilities. They’re used to create surround-sound and spatial effects from non-Dolby encoded stereo and mono material. The results can be quite interesting but they’re not a substitute for the real thing and shouldn’t divert attention away from surround-sound performance.

It’s important to have an adequate number of input sockets, to meet present and future needs. A minimum of two are required for most set-ups, to cater for a VCR and satellite receiver, though it may be possible to route AV inputs through either the VCR or satellite receiver, if they can be connected together using SCART to SCART AV cables.  In that case stereo audio from the active component is automatically passed through to the decoder input. Don’t worry too much about video inputs and outputs, they’re mostly a convenience feature, to assist with cabling, and in most cases video signals pass in and out of the unit without being affected in any way.

The majority of decoders are simple to operate; models with independently adjustable input and output levels are the most flexible, better able to integrate with a system, and help create the most dramatic and natural sounding effects. 

BOX COPY 1.

SHOPPING TIPS

* Performance and prices vary widely, try to match the decoder to the capabilities of your hi-fi. A top-end decoder would be largely wasted on a system based around a mediocre hi-fi and cheap VCR

* If you’re choosing a decoder with built-in amplification try to match the centre and rear channel outputs with that of your main stereo amplifier

* You will need at least two input channels, three or four will leave you some room for expansion

* A remote control facility is essential, unless you enjoy having to keep getting up to adjust levels

* THX and AC-3 facilities are clearly worth having, just make sure the rest of you system is up to it

BOX COPY 2

BEST BUYS

Angstrom 200, £3495, HE37. And worth every penny, providing you’ve got a hi-fi system to match! It’s in a class of its own. The processor effortless resolves all of the information contained on a soundtrack, but with a smoothness, subtlety and articulation that’s missing on lesser decoders. It leaves you in no doubt that you’re experiencing precisely what the director and sound engineers wanted you to hear.

Mission Cyrus AV Master, £650, HE37. A potent mid-range decoder, with on-board amplification for the centre dialogue channel. It’s uncommonly flexible, and can be programmed to function in a wide variety of configurations. Features include an auto set-up and various DSP modes. A worthy companion for other Mission components.

Sony SDP-E300, £230, HE37. This is the cheapest DPL decoder to earn the coveted HE stamp of approval; it’s well specified and very flexible, with a comprehensive set of input and output socketry. Rear channel amplification is a little lightweight but the processor is fast and accurate with good centre-channel resolution.

3. HOME CINEMA SPEAKERS

A mystique has grown up around home cinema loudspeakers in the past few years. It’s partly to do with the way some manufacturers have latched onto this rapidly growing market, and the slightly unusual way in which they are used. In most respects, however, AV speakers are no different to any other kind of hi-fi loudspeaker, either technically or operationally. There’s good ones, bad ones, and all the others in between.

That said there are a few specialist design features, unique to some types of AV speaker, which we’ll be looking at in more detail in a moment. The way in which AV speakers are deployed is also different to most other types of audio system. The aim is to surround the viewer with sound, consequently there are more of them.

In a typical Dolby Pro Logic set-up there will be five, sometimes six loudspeakers. Two are used for the right and left stereo channels. The third speaker is for the centre-front channel. Speakers four and five carry rear-channel surround effects. The sixth speaker is an optional sub-woofer, used to boost or supplement the bass output of the front stereo channels.

The right and left stereo speakers are usually placed a couple of feet either side of the TV screen, facing the viewer. They operate in precisely the same manner, handling the same kinds of frequencies and power levels, as normal hi-fi speakers and because they’re some distance from the screen, magnetic shielding is usually unnecessary.

The centre-channel speaker is the odd man out.  It has to work very hard and spends much of the time handling dialogue. It’s not a demanding job sonically, but it helps if it’s moderately directional as its job is to focus the viewers attention on the screen. Centre-channel speakers are normally placed quite close to the screen, so this is one instance where magnetic shielding may be required, to prevent colour staining on the picture tube. In fact there’s nothing new about magnetic shielding, ordinary TV speakers have been that way since day one. Shielding requires no magic, advanced technologies or a huge increase in manufacturing costs, usually just a second magnet, to minimise radiated fields.

It’s important to choose a centre speaker that compliments the main stereo speakers, both in terms of tonality and dynamic range, otherwise the dialogue component of the soundfield can appear artificial or disjointed.  

The aim with rear channel speakers is to create as diffuse a soundfield as possible, so the viewer can’t pinpoint where the sounds are coming from. Some weird and wacky designs have emerged, though conventional compact enclosures, carefully sited a couple of feet behind, and a foot or two above ear level, are normally quite satisfactory. The rear-channel has a limited bandwidth, that tails off rapidly above 7kHz, so they don’t need especially sophisticated drivers.

Movie soundtracks, unlike most other forms of audio recording, often contain large amounts of bass information, to create an effect, and emphasise what’s happening on the screen. To that end it’s sometimes desirable to have a separate bass loudspeaker or sub-woofer. Normally only one is needed as low frequency sounds are not as directional as higher frequencies, though a lot of home cinema aficionados and experts recommended the use of two subs, to spread bass sounds more evenly.

There are two types of sub-woofer. The simplest, (though not necessarily the cheapest) are ‘passive’ subs, They’re driven -- via a filter circuit -- from the right and left stereo channels, or from a dedicated sub-woofer output on the amplifier. Active sub-woofers have their own built-in amplification, which relieves some of the strain on the main amplifier, and simplifies speaker matching. It also enables much higher power outputs, than would normally be possible using just the main AV amplifier on its own.

AV loudspeakers have something else in common with most other types of hi-fi speakers, you get what you pay for. If you pay peanuts, you could end up with something that sounds like barrel load of monkeys... Centre speakers are a case in point, and it’s worth spending a little extra on one that’s designed to do that single, rigidly defined job. The B&W CC3, which sells for around £150, is a good example of that kind of specialisation. The combination of B&W’s ‘Prism’ enclosure helps stabilise the sound output by eliminating internal reflections; two high quality drive units and a single tweeter produce a crisp and finely articulated sound that is well suited to dialogue.

Rear channel speakers don’t have to be complicated and the bottom line is that almost any competent hi-fi speaker will do the job. Nevertheless, speaker manufacturers have risen to the challenge and various designs have appeared, that provide extra dispersion, to help spread the sound. One of the best and most successful has been the Canon SV-15. They use an acoustic ‘mirror’ to help distribute the sound outwards, and downwards, so they’re ideal for wall mounting. Recent price reductions, to around £100 a pair, makes them reasonable value too.

Active sub-woofers have become one of the most popular home cinema add-ons, and it’s not difficult to see why. Action blockbusters and sci-fi epics come alive with gut-rumbling effects, that most conventional hi-fi speakers simply cannot replicate. One of the best examples of what can be done -- for a relatively modest outlay -- is the REL -50, currently selling for around £375. It’s rated at 50 watts, a manageable amount of power, that’s controlled, without sounding brash or coloured.

Comparatively few stereo speakers manage to bridge the gap between hi-fi and home cinema. Polk Audio’s RT10 are one of the rare exceptions, and at £480 they’re relatively affordable. They’re superbly well qualified for Dolby Pro-Logic duties with impressive bass capabilities, but their transparency and fluency means they can handle almost any kind of material with equal conviction.

Shopping for AV speakers separately can be a little daunting but don’t be put off, and never buy anything without hearing it first. However, if you want to avoid the hassle of mixing and matching, check out the growing number of package systems now available. They’re a very convenient way of buying speakers, but don’t loose sight of the operational points we’ve outlined, and don’t expect any discounts for quantity, at least not on any packages worth having...

BOX COPY 1.

SYSTEM BEST BUYS

* B&W 600 SERIES, £900, HE34. Although not conceived as a package, this collection of specialist AV speakers hangs together really well. DPL and stereo performances are consistently good and the CC6 centre speaker delivers an unusually assertive bass

* DEFINITIVE TECHNOLOGY/MK SYSTEM, £2645, HE27. A highly successful marriage between Definitive Technology’s articulate BP8 column speakers, CLR centre speaker, BP1 compact bi-polars and M&K’s gutsy sub-woofer. A unique blend of power with precision and subtle clarity. A true jack of all trades, equally happy with stereo and Dolby sources

* MISSION AV1, £330, HE37. A real value for money package, based around Mission 73 speakers and a matching passive sub-woofer. Its strength lies in the system’s simplicity and clear, accurate and detailed mid-range delivery. It has its faults, but if you’re looking for a tidy and cost-effective starter package, look no further

---end---

Ó R. Maybury 1996 1111