ESLmanual Feb02 11/02/04 9:14 AM Page 6
Each loudspeaker should be connected to its appropriate amplifier output so that the two pairs of wires are connected in the same way, to ensure that the speakers operate in phase.
Switching On and Off
The on/off switch has a rocker action; press the bottom to switch the ESL on and the top to switch it off. A red LED next to the on/off switch indicates that the speaker is on.
Amplifier Requirements
The ESL loudspeaker should be used with an amplifier of output capability between 20V and 30V rms
Amplifiers with an output capability in excess of 35V rms (150W into 8 Ohms approx) may be used but with caution – see Loudspeaker Protection.
If the Quad 405/2 power amplifier is used, the amplifier voltage limiters should not be fitted.
Loudspeaker Protection
The ESL loudspeaker is fitted with a protection circuit, incorporating a special device called a multifuse, which prevents damage from excessive programme input signals.
Should the loudspeaker be severely overdriven, for any length of time, the circuit will operate and effectively reduce the drive to the loudspeaker, causing a reduction in the volume level with some loss of quality. If this occurs, then the volume control of the amplifier should be turned down. After a delay of a few seconds to allow the circuit to reset, the volume can be increased, but only to a point below which the protection circuit initially functioned, otherwise the circuit may operate again.
Persistently overdriving the loudspeaker will cause the multifuse to completely fail, necessitating its replacement by a qualified engineer.
The above conditions are unlikely to occur in normal use or with amplifiers with a power output rating of less then 100W. Steady state signals in excess of 10V rms should not be fed to the loudspeaker.
When the AC power to the loudspeaker is switched off or disconnected, the signal input protection circuit operates to prevent excessive signals being fed to the loudspeaker elements – though care should be taken to ensure that the loudspeakers are not driven for long periods (minutes) with no AC power applied.
Positioning the Loudspeakers
However good the loudspeaker, the final results will depend very largely on the acoustic characteristics of the listening room and the position of the loudspeakers in it. Do not be afraid to experiment with both position and orientation and make a point of trying some of the less obvious as well as the more obvious positions. The benefits obtained from the time spent doing this can be very rewarding. The subject of room acoustics is complex and beyond the scope of this manual. It is assumed that the loudspeakers will be used in a room with moderate reverberation, neither too bright nor over damped. Furnishings can alter the acoustic characteristics of the listening room, and here common sense is the best guide.
The loudspeakers have constant directivity over a wide angle in both horizontal and vertical planes, so the response does not vary with the height of the listener’s ears from the floor.
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