Easy info -
select the right Amplifier
You need to know how to choose an Amplifier for your Home Cinema set up. Do you go for separates or as part of an all-in-one system?
Here is practical info on Home Cinema Amps, Digital Amps, power outputs, surround sound speaker outputs (5.1 channel systems and beyond) and connections.
Do I actually need to use one?
The simple answer is: Yes. Its job is to take encoded sound information from a CD or DVD deck and decode it. That means that
multi channel sound from Dolby Digital and from DTS sources can then be amplified and sent through your speakers.
How is it different from a receiver?
A receiver will also include a tuner to receive radio broadcasts. It's not strictly needed for a home cinema set up, but many people find it a handy option for its ease of use.
Should I get separate components?
Well, the all-in-one systems are very convenient. They're straightforward when it comes to installing and should, therefore, be fully compatible. However, actually selecting separate components will, inevitably, take more
time simply because you'll have to look at and listen to each of the different components together. Remember that properly matched separates almost invariably will cost you more. The big plus is that a good separates system will deliver noticeably superior sound quality.
How many channels should the amp have?
You'll need at least five channels. That's two for the front stereo speakers; one for the centre speaker and then, finally, two for the two rear speakers.
To achieve a full 5.1 channel system you're going to need
an "active" subwoofer (active as in having its own amplification).
If your desire extends further to, say, Dolby Digital EX or DTS-ES 6.i channel soundtracks, you'll then need an amplifier with six channels of amplification, or, alternatively, you will have to connect an additional power amp to a five-channel model. You can be even more adventurous and go more channels of power (7.1
channel) or whatever might be released in the future.
Power output - what kind should I get?
When you see power output figures they ought to be viewed as what manufacture's know could be achieved in optimal conditions (i.e. not very likely in everyday situations) - but in broad terms, the bigger wattage per channel, the greater the power through to the speakers and so the louder the volume you can experience. For instance, a 40W per channel system would be OK for a small setup. If, however, you've got a larger than average lounge room (or even a separate room housing your home cinema) you will most likely
want somewhat more than that. Good digital amplifiers give you a whole lot more decibels per watt. What that actually means is that lower ratings are not anything to be particularly concerned about.
Why is it that amplifiers have to be so large and heavy?
I'll explain it this way: the amplifier's power section acquires weight as it acquires power, therefore, when you have a six or even seven channel beast pushing out in excess of 100W per channel, you can suddenly find
yourself with a decidedly heavy load.
I wouldn't say that this always means the heavy amp is the one you ought to go for. Just remember that you should try to select one which fits your particular needs. It might well turn out that the right amp isn't simply the largest and weightiest around.
What should I get: an analogue or digital amp?
Well, it's fair to say that digital amplifiers are obviously smaller and lighter than the analogue ones. Digital are also more efficient. That's down to the fact that they don't waste as much of the power get, so they can make do with power ratings which are noticeably reduced per channel and yet deliver the same as analogue amps having more substantial specifications. This higher efficiency in turn means that digital amps give out less heat and, thus, be housed in smaller more stylish units.
What about selecting the amp to go with my DVD player/recorder?
I would say that the main point is to check that communication between your DVD player and your amplifier is good. You've got a problem if your DVD player has optical digital audio output but your amp has only got an electrical one. Just make sure that the connections do infact match. Also, if your DVD player has six channel outputs (or an iLink output) for DVD-Audio or SACD playback, you must take care to make sure your amp will accept signals via the proper corresponding inputs.
Why are there video inputs and outputs on amplifiers?
Just a matter of convenience for anybody who has more than one delivery source or platform. By routing video signals through the amp and into a TV you can effectively use the amp like a "switching box". You would use it to put selected video signals to your TV, depending, of course, on the item currently in use.
Some amplifiers convert up to component video, but why?
This is just an easy way to enhance the performance from your existing equipment. A television with component inputs means that you can have higher quality signals even though you don’t have a true component output from an older DVD deck.
Why is it that you can have an auto-acoustic calibration on an amplifier?
That’s a straightforward method for setting up a system set up for a room. It automatically adjusts to the speaker settings. You can, of course, do that yourself with most amps, but it just requires a little longer to do it.
Would I need any special item for DVD-Audio or SACD?
Definitely. You must have an amp (with matching inputs) and DVD deck with six channel or Firewire outputs. You’ll need some (expensive and hard to find) DVD-Audio or SACD discs.
How about connecting high definition TV?
In the UK HDTV is connected by HDMI sockets and component video. You’ll need one or other of these inputs and out puts in order to carry signals through the amp. However, if you don’t want to send signals through the amp, then you don’t need to be concerned with these.
Can amplifiers do anything else?
A good many amps have DSP (digital soundfield processing) options which can give a simulated sound environment in certain places. Whilst this facility adds more interest to some sources of music, it seems to me to be difficult to say that it adds anything useful to the sound for a home cinema setup.
A more useful thing incorporated in amps today is capability to process a standard stereo soundtrack and change it to (apparently) a 5.1 or 6.1 channel sound track. Essentially, this gives a startling improvement in the playback quality of older sound sources. Remember that
a good amplifier is an integral part of a surround sound set up.
An enhanced sound quality adds tremendously to the overall cinema like experience.
Info on Amplifier connections
S-video - This is a high quality connection used for video switching.
Composite video - This is a lower quality connection used for video switching.
Component video - Another high quality connection which is used for video switching.
RS232 - This connection is used both for updating software and for remote control (from a PC).
HDMI - This is a relatively new high quality digital connection used on compatible DVD decks and increasingly being used with HDTV (high definition TV).
Speaker terminals - These are utilised for connecting cables from an amplifier to the speakers (binding posts as can accept significantly higher quality cable than spring clips).
Digital electrical inputs - A lot of people say that digital electrical connections are clearly better than optical ones. The signal is carried through a coaxial cable.
Digital optical inputs - These are used where there is an undecoded multi-channel audio (from a DVD deck). The amplifier's in built Dolby Digital and DTS decoders in turn create the surround sound track.
Ethernet - You’ll see this on amplifiers which have home networking capability.
i.Link (aka Firewire) - This is used with undecoded DVD-Audio and Super Audio CD signals originating from a compatible deck. It is also used in part of the set up in home networking.
5.1 audio phono inputs - Where a DVD deck has also has an in built decoder (for Dolby Digital or DTS) and the amplifier doesn’t, you’ll have to have these connections. They’re also useful with DVD-Audio and SACD playback where there is no i.Link.
Stereo audio phonos - These are used to connect any additional hardware item (say: as a CD player or Video Recorder).
My best advice for selecting your speakers
*Be sure they are not going to be just too big for your room;
*Only choose speakers that are matched tonally;
*Use only binding post terminals. They are much more suitable than spring clips;
*The power handling should be around the same as your amplifier’s output;
*Always ask if you can get further speakers - just in case you later need to upgrade.
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