Amplifiers

Configurations

"Too many people buy an amplifier that they don’t know how to adjust properly, thinking that it’s too complicated or that they simply wouldn’t be capable. Many also think that once the unit is hooked-up, hearing the sound passing from the front to the rear speakers, that the factory settings are sufficient… big mistake! If, effectively, the installation works, and if, over time, one gets used to the sound which emanates, the absence of correct configuration will mean that its possibilities will not at all be optimised as they should be. It is nevertheless true to say that the manufacturers’ instructions are often of such clarity that one has a headache studying them for any more than five minutes! What follows is an attempt to explain, in simple terms, what the basic adjustments are on your amplifier, and how to use them wisely.

Adjusting a central speaker in en Small/Normal, Wide or even Phantom -

Explanation: The three front speakers, right, centre channel and left, are supposed to split the sound from three identical portions of the screen of your TV or video projector. The central speaker is thus responsible or reproducing everything that happens in the centre, i.e. 70% of the film, and this, with the same register of bass, mid-range and treble as the right and left. You should thus, in theory, have a central speaker which is just as large and powerful as the two main ones. As it is often difficult, or even impossible to place a speaker as large as the two side ones on top of the television, sales representatives generally recommend a specific, so-called "centre channel" speaker, of the same brand as those on the right and left for reasons of sound coherence, but smaller and more aesthetic. The ability of this speaker to reproduce low frequencies is thus reduced, and if you don’t tell anything to your amplifier, it will send the speaker the same amount of bass, mid-range and treble as the left and right speakers. Being less powerful than the latter two, this risks seriously damaging your central speaker.

Conclusion: It should be underlined that 90% of so-called centre channel speakers are not designed to reproduce bass frequencies. You should thus configure your amplifier in "Small" mode. In this case, the amplifier will only send mid-range and high frequencies which will prevent your speaker from exploding. In the case that you are lucky enough to be able to place a veritable hi-fi speaker in the middle, it will be able to reproduce the sound spectrum as well as the other two, so you should set the amplifier to "Normal". If you do not have a central speaker, set your amplifier to "Phantom". In this case, the "ProLogic" faculty of your amplifier to extract the central channel from the right and left channels is suppressed and you obtain a simple Dolby Surround amplifier.

Particular cases: Certain Dolby Surround amplifiers, in particular those with a Dolby Digital decoder, also propose this adjustment on the right, left and rear speakers. The principle is exactly the same: "Large" for full range speakers, able to reproduce the full sound spectrum from low to high frequencies, and "Small" for those speakers that aren’t really able to dig down into the deep notes. Please note that for obvious reasons it’s not possible to choose "Phantom" mode for the right and left speakers, but the mode "None" corresponds for the rear speakers.

Hints: Even if you have, for example, five full-frequency speakers, try configuring all of them in "Small" in this case, the bass box will be responsible for reproducing all the low frequencies. This is not a bad thing in some cases, because the less work the amplifier has to do in supplying low frequencies, the better it works! All it has to do is to amplify the speakers in mid-range and high frequencies, which is much easier to do. For this, you’ll have to have a sufficiently powerful bass box, but it’s interesting in any case to give this a try. This also presents another advantage, this time for the speakers: in the case of two-way speakers, the woofer is responsible for reproducing bass as well as part of the mid-range. This speaker cone vibrates terribly during the reproduction of low frequencies, at the risk of reproducing a lower quality "lower-mid" frequency than if the speaker was only delivering the latter. You will thus obtain a much clearer mid-range. In a word, there are no taboos when it comes to testing your equipment and seeing for yourself what sort of results you can obtain."

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