Speech Reinforcement: Power

By: Owen T. Heisler
Updated: 2021-11-11
Published: 2016-08-05

This article is part of a series; see Speech Reinforcement.

It is helpful to have a reliable power source in case of a power outage.

Uninterruptible power supplies

In my experience, the most common kind of “power outage” is caused by an electrical breaker being tripped, where only the sound equipment is affected. In this case, it is really nice to have a battery backup even if it only powers the system for a short time (it is generally not difficult to get a half hour or more of run-time from a 1U rack-mount UPS).

When looking for an uninterruptible power supply (UPS), consider the following:

  • Does the UPS have an on-battery alarm and if so, can it be disabled? Similarly, does it have a separate low-battery alarm?

  • Will the UPS be used to switch the power on and off for the entire system? If so, does it have a switch suitable for this? And will the battery charge while the system is switched off? Otherwise the battery may not be fully charged when it is needed.

  • Can the UPS be installed in a rack? Having equipment that can be mounted in a rack is important for any system that will be moved on and off of the location.

  • What is the UPS topology? I recommend the line-interactive type, which in general provide cleaner power, especially during the transition to battery-backed power. Line-interactive UPSes do not tolerate overload conditions so should be size appropriately to the load.

  • Ideally, to reduce battery sulfation, the UPS should be charged regularly.

Suggested UPS

I suggest the CyberPower OR700LCDRM1U UPS, or a similar model appropriate to the load.

  • The battery will charge even when the unit is off. This allows you to use power button on the front of the unit to turn the entire system on/off without concern about whether the battery will be fully charged.

  • The on-battery alarm can be silenced by holding the select button for 3 seconds. This does not disable the following alarms: low-battery (seems to be activated when only 5 minutes of battery time is remaining), overload, UPS-fault, and replace-battery.

  • It is a line-interactive topology UPS providing automatic voltage regulation (accepts input voltage 90-140 VAC). If it is overloaded (even on AC power), it will power off with a long beep.

  • You can read input/output voltages, estimated run-time, load capacity, and battery capacity from the display (and via USB and serial ports).

  • 700 VA / 400 W

  • Note that the stock batteries do not seem to last very long (as little as 18 months plugged in with minimal outages). When the batteries fail, it can cause odd behavior such as the display showing garbage until the device is power-cycled. So if the device seems to have failed, be sure to check the batteries.

  • Replacement batteries: CyberPower RB0690X2. This is actually a combination of 2 batteries. Each battery is 6V/9AH with F2 style terminals measuring 3.4 W × 9.5 H × 15.1 cm (1.34 W × 3.74 H × 5.94 L in.). Batteryspec.com offers a 2 year warranty (if the UPS is kept plugged in) on their compatible TBC113+ (APC RBC18+ compatible) kit with two TR9-6A batteries.

  • Manual (PDF)

  • Datasheet (PDF)

  • Product page

The following models are similar:


  • 2021-11-11: Updated details about CyberPower RB0690X2 replacement batteries.

  • 2021-06-30: Added note about failing stock batteries on the CyberPower power supplies.