JBL SB-2, SB210 manual Adjusting Volume of 70V/100V System, Multiple Systems

Adjusting Volume of 70V/100V System

Adjust the tap setting to change the amount of power that gets to the entire sub/sat system.

Multiple Systems

Multiple sub-sat systems can be utilized on a single 70V/100V distributed speaker line. Each can cover a different area with full-range sound. Systems can be mixed on a 70V/100V line as long as all the systems utilized the MTC-210T-SAT module. See Figure 2.

Subwoofer Distance Consideration

Even though it’s not easy for the human ear to tell where the sound from a subwoofer is coming from (non-localizable), that doesn’t mean that a single subwoofer can always cover an entire space.

The sound level from a subwoofer is louder nearby to the subwoofer and quieter farther away from it. As rooms get larger the level variation gets more uneven because the distance from the subwoofer gets longer. It may be necessary to add a second subwoofer on the other side of the room. Locating multiple subwoofers near the center of opposite walls within the room often works well, resulting in more even coverage of the entire room.

When greater subwoofer output is desired, an alternative is to locate the subwoofers near opposite corners of the room,

although the subwoofers can get excessively loud in those corners compared to the rest of the room.

For rooms where very even subwoofer coverage is desired, a distributed subwoofer system might be a better solution than using one of the passive subwoofer/satellite systems from this guide. If so, see the subwoofer chapter of the JBL guide entitled Designing

Better Sounding In-Ceiling Business Music Systems.

Affect of Room Size on Sound Level

The Max SPL figures listed for each system are based on a listening distance of approximately 20 feet.

For larger rooms where some listeners will be father than 20 feet from the speakers, the true sound level capability of the sub-sat system will be lower. For example, the Max SPL level at 40 feet

--twice the listening distance -- will be 6 dB lower than the listed figure.

In addition, as the room gets larger, there will be more level variation of the sound from both the satellite speakers and the subwoofer from place to place within the room. This can lead to unacceptably high variations in sound level, where the sound might be too loud in some areas and too soft in others.

In rooms where this is the case, it may be necessary to utilize more than one subwoofer/satellite system, or to use a more highly distributed system than a small subwoofer/satellite system is capable of doing.

ROOM 1 ROOM 2 ROOM 3

Low Impedance	Low Impedance	Low Impedance
Satellite Speakers	Satellite Speakers	Satellite Speakers

Set system volume with		Set system volume with	Set system volume with
70V/100V tap switch		70V/100V tap switch	70V/100V tap switch
	70V/100V Input	70V/100V Input
	to Subwoofer	to Subwoofer
From
70V/100V Amplifier	70V/100V Distributed Speaker Line

Figure 2

Multiple 70V/100V sub-sat systems on a single distributed speaker line.

70V/100V Input to Subwoofer

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