TOA bs-1030 User Guide
TOA Electronics Speaker Guide
Amplifier Selection
31
5. Use the top half of the chart for level change with power input (see Figure 5-2 on page
22) to locate the point corresponding to the required level increase, or dBW. Next, read
the power level from the bottom half of the chart. Then, using the speaker’s specifications,
select the speaker’s smallest wattage tap that is greater than the power level indicated
on the chart. This is the minimum power you need for each speaker.
the power level from the bottom half of the chart. Then, using the speaker’s specifications,
select the speaker’s smallest wattage tap that is greater than the power level indicated
on the chart. This is the minimum power you need for each speaker.
6. After determining the power needed for each speaker, add them up to get the total
speaker Wattage.
To allow for variations in transformer characteristics, it is a good practice to select an amplifier
whose rated output is at least 120% of the speaker Wattage total. If the speakers are connected
directly (in a 4 or 8
whose rated output is at least 120% of the speaker Wattage total. If the speakers are connected
directly (in a 4 or 8
Ω
system), the amplifier size should be at least equal to the speaker Wattage
total.
Subwoofer Power Requirements
To get full value from subwoofers, we recommend supplying them with as much power as they
can safely handle. The maximum continuous pink noise power rating is a good indicator of the
minimum power to provide for a subwoofer. This amount can be doubled if the added power
falls within budget. The subwoofer’s maximum program (sometimes called peak) rating typically
indicates the maximum power you should provide. Due to the nature of low frequency program
material, there is much room for error in any general guidelines for subwoofers. The best method
to insure the amplifier and subwoofer are matched is to listen to them together, using the same
speaker location and program material that will be used in the final job.
can safely handle. The maximum continuous pink noise power rating is a good indicator of the
minimum power to provide for a subwoofer. This amount can be doubled if the added power
falls within budget. The subwoofer’s maximum program (sometimes called peak) rating typically
indicates the maximum power you should provide. Due to the nature of low frequency program
material, there is much room for error in any general guidelines for subwoofers. The best method
to insure the amplifier and subwoofer are matched is to listen to them together, using the same
speaker location and program material that will be used in the final job.
Examples
High-Quality Paging System
A workspace needs reliable and intelligible paging in all areas, for both standing and seated
listeners. The room is 30 x 40 ft with a 10 ft ceiling. TOA model F-121CM speakers are selected
for their wide dispersion.
listeners. The room is 30 x 40 ft with a 10 ft ceiling. TOA model F-121CM speakers are selected
for their wide dispersion.
From the F-121CM’s coverage and spacing table (page 37), we first refer to the row corre-
sponding to the ceiling height for standing listeners (4 ft above listener height; h - l = 4). The
spacing recommendations for this height range from 7–14 ft, depending on the desired unifor-
mity of coverage. Using a square pattern with minimum overlap, the spacing between speakers
is 10 ft, which works out to three rows of four speakers (12 speakers total).
sponding to the ceiling height for standing listeners (4 ft above listener height; h - l = 4). The
spacing recommendations for this height range from 7–14 ft, depending on the desired unifor-
mity of coverage. Using a square pattern with minimum overlap, the spacing between speakers
is 10 ft, which works out to three rows of four speakers (12 speakers total).
Since the workspace will have a minimal noise level, the target operating level is set slightly
above the base level (75 dB) for paging, at 78 dB, with 10 dB of headroom, for a L
above the base level (75 dB) for paging, at 78 dB, with 10 dB of headroom, for a L
req
of 88 dB.
The F-121CM has a rated sensitivity of 90 dB, 1 W @ 1 m. The typical seated listener will be
about 7–8 feet away from the nearest speaker. Using the attenuation with distance chart (see
Figure 5-1 on page 22), this provides 82 dB with 1 W at the listener.
about 7–8 feet away from the nearest speaker. Using the attenuation with distance chart (see
Figure 5-1 on page 22), this provides 82 dB with 1 W at the listener.