PLACEMENT OF LARGE MONITOR SPEAKERS
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The closer a speaker is to the walls, ceiling or floor the more bass it
produces.
A speaker in the middle of a room radiates low frequencies in in all directions (into ' full space' ).
If the speaker is placed against a wall the low frequency energy is concentrated into half the space, which boosts the lows by 3 db.
Putting a speaker in a corner maximises bass output into 1/4 the space. Highs aren't much affected by speaker placement because they radiate mainly out front.
One way to prevent rear wall reflections is to flush mount the monitors in the wall. They should be isolated by foam rubber, fiberglass or rubber shock mounts. If flush mounting is impractical, wall reflections can be weakened by placing the speakers at least 3ft from the rear wall and 4ft from the side walls.
(LEDE) Live End Dead End arrangement is where the front half of the control room around the speakers is made very sound absorbent (dead) by applying muslin covered fiberglass or acoustic foam to the walls and ceiling. The wall behind the engineer is hard and reflective to provide ambience and increase loudness. This surface is broken up to diffuse the sound. Reflection Phase Gratings are often used for this purpose.
LEDE rooms are not always absorbent in the front and reflective in the rear. The speakers can be flush mounted in a hard wall array that is angled to eliminate early reflections. The idea is to create a reflection free zone at the mixing position. Many control rooms can be improved by putting thick material on the walls behind and to the sides of the speakers or by pulling the speakers out from the wall at least 2ft.
Some of the claimed benefits of an LEDE control room are :
- Mixes are easier and faster to do because you hear more of the sound from the studio and less from the control room.
- The overall sound is clearer.
- Stereo image and depth is improved greatly.
- Frequency responce is flatter.
- Boom and ringing is reduced and transient responce is sharpened.
In any control room the speakers are mounted at ear height or slightly higher. For best stereo imaging align the speaker drivers vertically and mount the speakers symmetrically with respect to the side walls. Place the two speakers as far apart as you're sitting from them (about 8ft) ; aim them towards you and sit exactly between them.
Wire the speakers in the same polarity to obtain a sharp centre image. For both channels,connect the amp positive terminal (+ or red) to the speaker positve (+ or red).
Polarity adjustment is also called speaker phasing. To determine whether a speaker is wired in correct absolute polarity :
1. Produce a kick drum sound (standard polarity microphone or drum machine)
2. The speaker cone should go out the instant the drum is struck.
Reverse the leads of both speakers if the opposite occurs.
To adjust the stereo balance,play a mono signal and assign it to channels 1 and 2 at the console. Adjust the faders so that the signal reads the same on VU meters. Then while sitting exactly between the speakers the sound image should be localised midway between the monitors. If necessary center the image by adjusting the left or right volume control on the power amp.
Listening level during mixdown should be maintained at about 85 db SPL.
The Fletcher Munson effect says that you hear less bass in a program that is played quietly. If you mix while monitoring at say 100 db SPL, the same program sounds weak in the bass when heard at a lower listening level. Therefore programs meant to be heard at 85db should be mixed and monitored at that level.
Play a musical program at 0 VU and adjust the level to obtain an average reading of 85 db on the sound level meter. Mark monitor setting.
To avoid losing power from heating the speaker cables put the power amps close to the speakers and use short cables with thick conducters. The low resistance of these cables allows maximum damping of the speaker by the power amp. Use following -
Less than 25ft cable length - No.16 gauge.
25 - 50ft - No.14
50 - 100ft - No.12