Amphion Impact 400 Посібник користувача - Сторінка 6

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Subwoofer positioning

All speakers - subwoofers included - require pro-

per positioning to provide maximum performance.

Improperly placed and adjusted speakers will de-

grade the sound quality, therefore reducing listening

pleasure. In many cases 'perfect' placement may not

be possible and finding the most suitable position for

your environment will probably require some expe-

rimentation. Please try different locations during the

setup process to find out what works best in your

listening room.

General guidelines for subwoofer placement

Place the subwoofer along the same wall as the

main speakers. Normally the best possible position

is somewhere between the main speakers. Do not

place the subwoofer in the centre point of the back

wall as this is the minimum point of the lowest

standing wave. This leads to a dip in the systems

frequency response in the middle of the bass area

and results in a reduction of these frequencies.

Usually the best place is found behind the centre

point of the wall and the other main speaker, slightly

away from the back wall. If there is no space bet-

ween the speakers, it is possible to locate the sub-

woofer outside the main speakers but this may lead

to a slight reduction in the stereo image and bass

possibly being localised to the subwoofer.

Finding the best location by listening

The best location for the subwoofer can be located

by listening and experimenting with different loca-

tions. Special low frequency information test records

- which may make this easier - are also available.

Listen to a recording containing low frequencies and

move the subwoofer around until you find a position

where the reproduction of various frequencies are

as balanced as possible. Having someone to help

move around the subwoofer will make it easier to

compare different locations. It is possible that there

are more than one places which generate an even

frequency response. Stereo imaging and interior

decorative issues will help to choose between those

places which have an even response.

impact 400

Reversed location search

In same cases it is easier to find the ideal location by

positioning the subwoofer in the listening place and

moving around the room at floor level. Locate the

places where the bass reproduction throughout the

all lower frequencies is most even. The stability of

stereo image and matters relating to room aesthe-

tics and interior decoration also often dictates the

placement of the subwoofer. Please note that when

using this method the subwoofer should be located

in a position around 1 meter from the floor.

Adjusting the subwoofer

The Subwoofer can be adjusted to match the main

speakers by the controls on the back panel. Depen-

ding on the size and sensitivity of the main speakers,

the subwoofer's crossover and level are adjusted

via LOW-PASS CROSSOVER and VOLUME controls. It is

also possible to reverse the phase of the sub by the

PHASE switch.

Various factors, such as main speakers, room acous-

tics and listening preferences affect the settings and

therefore a 'rule of thumb' exists. It's best to experi-

ment to find the best settings for your own listening

environment.

Crossover frequency (LOW-PASS CROSSOVER)

The first task is to find the correct crossover frequen-

cy. The acoustical properties of a room and standing

waves affect the bass response and also the requi-

red crossover settings. Therefore the best result can

be only achieved by listening. Using a test disc helps

evaluate the point in the crossover where bass res-

ponse starts to dip.

Finding the correct phase (PHASE)

The next step is to adjust the phase of the subwoo-

fer. The correct phasing depends on the position

of the subwoofer in relation to the main speakers.

The goal is to ensure that the main speakers and

subwoofer are in the same phase at the crossover

frequency. The correct setting will be achieved by

testing both settings, phase 0 and phase 180. Listen

to either a test signal or music based around the