Bosch EVF-1122S/126 EVF-1122S/126-PIB Manuel D’Utilisation

Electro-Voice EVF/EVH User Manual

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The EVF-1121S and EVF-1151S low-frequency systems have integral passive low-pass filters that roll off 

frequencies above 100 Hz at the rate of 12 dB per octave. This means that these systems can be used 

to augment the low-frequency output of the EVF-1122/XX and EVF-1152/XX full-range systems without 

the use of an external digital signal processor (DSP) for crossover from the low-frequency to the full-range 

systems. As many as two full-range systems can be paralleled with an EVF low-frequency system on a 

single power-amplifier channel capable of driving a 2.1-ohm minimum impedance.

This simplified, cost-effective configuration is most appropriate for applications that require only moderate 

or moderately high acoustic output. This is because the full-range systems cannot have the full infrasonic 

protection provided by the high-pass filters specified in Table 3. However, useful overall cluster protection 

will be provided by employing the high-pass frequency recommended for the particular EVF low-frequen-

cy system used.

Note that the EVF-1181S, EVF-2121S, and EVF-2151D do not incorporate a low-pass filter.

In the biamp mode, the crossover and equalization must be achieved external to the loudspeaker. This 

is typically done with a digital signal processor (DSP) that has crossover and equalization filters that are 

adjusted by the manufacturer to provide the essentially flat frequency response mentioned above. The fac-

tory presets for the EVF and EVH loudspeakers have been determined for Electro-Voice processors and 

are available for download at www.electrovoice.com. Presets for other popular processors often can be 

provided by the Bosch Communications Systems/Electro-Voice technical support group; specific contact 

information can be found at www.electrovoice.com.

By providing a single loudspeaker system with uniform frequency response, the loudspeaker presets are a 

good starting point for equalizing a cluster of systems during setup and commissioning. Final equalization 

of a cluster should be accomplished with additional equalization made in front of the DSP device, not by 

modifying the preset crossover and equalization parameters in the low- and high-frequency outputs of the 

DSP. The later is likely to produce undesirable frequency-response and directivity changes in the cross-

over region.