Specifications

Due to the dynamic nature of the product design, the information contained in this document is subject to change without notice. Viking Electronics, and its affiliates and/or
subsidiaries assume no responsibility for errors and omissions contained in this information. Revisions of this document or new editions of it may be issued to incorporate
such changes.
DOD# 489
ZF302270 Rev A
Printed in the U.S.A.
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Since there are multiple uses and inputs to the PA-30, priorities need to be established to prevent contentions. If two inputs are acti-
vated at the same time, the one with the highest priority will take effect. Examples: Paging is higher priority then Loud Ringing, so
Paging would interrupt loud ringing tones. Background Music input is always the lowest priority, and thus can be interrupted by any
other input. Two different DIP Switch programmable Priority selections are available as listed below.
G. Priorities
Normal Priority (DIP Switch 2 OFF)
1. Aux In
2. Paging
3. Ringing
4. Background Music
Alternative Priority (DIP Switch 2 ON)
1. Paging
2. Aux In
3. Ringing
4. Background Music
The PA-30 contains two separate high current amplifiers, each of which can drive up to fifteen 8-ohm speakers. This means the
PA-30 is capable of driving a total of thirty 8-ohm speakers. For best results, connect ½ of the speakers across screw terminals
1 & 2 (the first amplifier), and connect the other ½ of the speakers across screw terminals 3 & 4 (the second amplifier), to bal-
ance out the power handling.
H. Speakers
1. Typical 8-Ohm Speakers
An important part of installing any paging system is to understand how amplifier power is lost, and then know how to take meas-
ure to reduce this loss if needed. For example, if eight 8-ohm speakers are all connected together, their combined parallel imped-
ance would be 1 ohm (8 ohms divided by 8 speakers equals 1 ohm). If these eight speakers are wired 125 feet away from the
PA-30 using #16 gauge wire, ½ of the paging power would be lost in the long run. This is because a 125 foot full loop of #16
wire contains 1 ohm of total resistance, so half the power would be lost in the wire, and ½ the power would be produced across
the speakers. For reference, ½ power is a 3dB loss.
There may be enough amplifier “headroom” for this to be acceptable in most applications, but in applications in which this much
power loss is not acceptable, some measures can be taken to get some additional power to the distant speakers as listed below:
1. Use heavier gauge wire. Every 3 gauge sizes heavier represents ½ the resistance.
2. Double-up on the existing gauge wire.
3. Have more wire runs and fewer speakers in parallel for each run. Each speaker wired on its own “homerun” would
maximize this approach.
4. Install the PA-30 closer to where the speakers are installed to minimize the wire run lengths.
5. Use 70 volt speakers as described below.
2. Managing Power Losses
Paging systems often utilize 70 volt speakers as a way to distribute audio with a minimal amount of power loss in the wire run.
Typically, 70 volt speakers have an integral step down transformer that converts the high 70 volt signal down to a lower voltage,
but higher current signal the speaker needs. The benefits of running a high voltage paging system are identical to the benefits
of running high voltage power lines. That is, the higher the voltage is, the lower the current becomes. This is good because, as
with lower current, there is less loss of power in the long wire runs due to resistance in the wire.
Since the PA-30 has two amplifiers that are running in differential mode, the output across them together will have double the
voltage swing. This Bridge Tied Load (BTL) strapping of the two amplifiers enables the use of 70 volt speakers when wired
across screw terminals 1 and 4. If increased volume levels are needed, use a higher power tap on the 70 volt speaker. Even
though the PA-30 is able to drive either 70 volt or 8 ohm speakers, it is not recommended to mix 70 volt speakers and 8 ohm
speakers on the same PA-30, because the 8 ohms speakers will play louder at any given volume setting.
3. 70-Volt Speakers
If the installation requires very loud paging, one or two 8 ohm speakers can be BTL strapped across the PA-30’s two amplifiers,
(like 70 volt speakers as described above). Connecting one or two 8 ohm speakers across screw terminals 1 and 4 of the PA-
30 will provide 6dB more speaker volume than normal. If more than two 8 ohm speakers are needed, wiring them as described
in section “1.” above will provide best results.
4. Very Loud Paging
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