Each room possesses a natural tendency to soften some frequencies and to amplify others. These phenomena of “resonance” vary according to the geometrical characteristics of the room and the presence of various objects (each obstacle located near the listener can be a source of “reflections” harmful to the quality of stereo sound). Therefore, to obtain the best possible results you should try to stay as close as possible to the following configuration:
– Use a large room (the greater the dimensions are, the better low frequencies are restored).
– Use an absorbent coating on the walls and curtains on the windows.
– Try not to have both a reflecting floor and a reflecting ceiling (for instance, use a carpet or an absorbent ceiling coating).
– The wall located behind the speakers should be reflective to amplify the image.
– Lateral walls should be symmetrical, to avoid a distortion of the stereophonic image.
– Finally, the wall situated behind the listener should be absorbent to avoid a limitation of the resonant space.
Mechanical parts of the speakers will need a run in to reach their nominal characteristics. This will take between 20 and 100 hours depending on sound level. The change will mostly concern the bass and low midrange. After this period, you may have to readjust the positioning of your speakers.
PLACEMENT OF THE SPEAKERS
It is necessary to carefully plan the position of your speakers in your room. The stereophonic principle implies that the listener is situated atop an equilateral triangle whose basis is defined by the two speakers. To keep a high precision of the stereophonic image, you should put your speakers as far as possible from the lateral walls, especially if those are reflecting (windows, smooth walls, etc.). The minimal distance should be approximately 50 cm (20”).
The balance between bass, midrange and treble is strongly dependent on the distance separating the speakers from walls, especially for low frequencies (bass). Thus, a woofer located near the ground will see its acoustic level double. A similar effect will happen with lateral or rear walls. Consequently, you should, of course the limits between these configurations are not always easy to establish. You will be able to optimize the adjustment of your speakers after having carefully listened to your sound system. A sound lacking life is usually due to absorption of high frequencies. You will be able to increase their level by putting the strap on a higher position. If the sound is too incisive, it is probably caused by an excess of “reflections” from high frequencies, you will be able to decrease their level by putting the strap on a lower position.
Remarks concerning use with an audio video system:
Today, in movie theatres, the rooms are generally very absorbent and speakers are often located behind the screen. This creates an attenuation of high frequencies. To limit this effect today’s movies, have a specific soundtrack recorded with a high level of treble.
The conditions for a home theatre system are quite different and the sound on some video recordings can be felt as too aggressive in your room. You will be able to remedy to this by decreasing the treble level with an adjustment of the strap on the back plate of your front and central speakers.
To improve the quality of your Hi-fi system, it is necessary to use high quality cables. To insure a sufficient transmission of energy between the amplifier and the speakers, the section of the cable should be at least 2.5 mm² (1”²).
The spikes are used to improve the clarity of low frequencies. For the best possible result, you should use 3 spikes per speaker, 2 in front, 1 in the back. For a smaller speaker, you could use 4 spikes to ensure a better stability.
Regarding the kind of speakers, they are equipped with a specific terminal, some of them allow you to use mono or bi-wiring and mono or bi-amplification.
Mono wiring consists in linking your speaker to the amplifier with one set of cables while bi-wiring uses 2. To improve the quality of the link between the speaker and the amplifier this solution uses one set of cables for the boomer and another one for the tweeter and midrange.
Bi-amplification consists in using one amplifier to power the boomer and a second amplifier for the tweeter and midrange. This solution optimizes amplification and will improve the precision of the speakers.
Rear speakers require a specific setting. Their position will depend on their type:
– Direct speakers
The diffusion of sound is made on a 45° angle. This solution will give you a high precision, but placing can be a little difficult. If possible, this type of speaker should be installed behind the audience at a distance of at least 1m (3 ft). If the distance is short, try to limit the separation between speakers.
– Bipolar speakers
Diffusion is wide and homogeneous. This system brings high quality in tone and a great balance between direct and reflecting sound. Placement is not critical (back wall, ceiling, side walls) as long as the distance from the audience is at least 1m (3 ft).
– Di-polar speakers
This principle creates a «shadow» in the axis of the speaker. Direct sound is limited. This solution brings a large diffusion with sound reflected by the room, but loses in precision. Dipoles should be hanged on the side walls or ceiling. Listeners should be at the level of the «shadow» part of the speakers.
ADJUSTING THE SUBWOOFER
On active subwoofers, you have the following options for connections:
You must use the RCA subwoofer output of the amplifier and connect it to the red RCA input (marked “Low level” and “mono”). Set the cutoff frequency of the subwoofer to 100Hz. Adjust the main volume of the subwoofer about three quarters.
All other settings will then come from your AV amplifier.
You must connect each output (left and right) of the amplifier to both your main speakers and subwoofer. To do this you must use the input marked “High Level” on the subwoofer.
PLACEMENT OF THE SUBWOOFER
The installation of the subwoofer can have an influence on the sound quality. Put in the wrong place, the subwoofer can create a very high level of resonances in your room with spectacular differences of sound level from one place to another: the sound will be very high near the walls and in the corners but it will be very low in the middle of the room.
The location of the subwoofer must thus be selected carefully. The best solution will be to put it in front near the central speaker and not too close to a wall. In any case, avoid any corner of the room. This will increase the level of the resonances and will produce a muffled sound without any subtlety.