CR blown speaker

Well, there’s a problem

We met with Campbell River rec staff at the RFABC trade show this past spring. They were keen to talk to the sound system supplier because, as they mentioned, there were some audio problems in their arena.

We meet a lot of customers this way. Sometimes a quick conversation with facilities staff reveals the problem is straightforward (the fitness instructor can’t grasp the ‘system on’ steps) or age-related (the sound system was installed in the last century), or something else (as was the case this time).

So we contacted the arena staff and heard about their A/V system woes: out of eight channels of amplification, only one channel was working, and the others were dead. We instructed the staff to try replacing the fuses, which resulted in the amps emitting a loud BANG!, indicating a significant failure within the amplifiers. Which was puzzling, as the seven-year-old amps should not have self-destructed in such a short period of time.

We packed up our service truck, set off across the Salish Sea for Campbell River, and investigated the amp failure problem, and overall sound quality issues.

CR rack old

This is the wrong way to install an audio rack (don’t worry, we fixed this)

CR rack new

A sound rack installed the way it should be

It didn’t take long to find the source of the problems:

  • The amplifiers put out a total of 4000 watts, yet the system was plugged into a single 15 amp outlet rated at 1800 watts. The amplifiers could never achieve full power, and as a result, they would redline (‘clip’) prematurely, causing instability within the amplifiers and lead to failure.
  • Both subwoofers in the arena exhibited glue bond failure of the speaker cones, causing a buzzy bass.
  • The digital signal processor (DSP) was a modular system, and one output module driving the amplifiers was putting out a high level of ultrasonic frequencies, causing amplifier channels to clip.
  • One input module of the DSP had a high level of noise coming out of it, resulting in a very noisy sound system, even at low volume levels.
  • The speakers in the arena had been installed incorrectly, causing incorrect sound dispersion, which resulted in dead spots both in the bleachers and on the ice surface
  • Incorrect mounting hardware was used to hang the speakers, creating a potentially unsafe installation should the speaker cabinets ever be hit by a lacrosse ball or hockey puck.


Making it work

We started the upgrade of the sound system by mounting the 10 mid-high speakers correctly, and with proper aircraft cable and double crimps, ensuring that the speakers would never fall. An ice level and bleacher area sound check verified the speakers were aimed correctly as the sound coverage was far improved.

We pulled out both four-channel amplifiers and replaced them with larger, more powerful two-channel QSC amplifiers. We had the local electricians install two more 15 amp AC circuits, providing enough clean power to the amplifier rack. We bypassed the defective input module to the DSP unit, and replaced both output modules to ensure long-term reliability. The rack wiring was cleaned up, and proper crimps were used on all wiring for a solid connection to the DSP unit and the amplifiers.

Finally, the entire system was equalized and calibrated via a real time analyzer, and internal volume levels were set properly to prevent the overdriving of the speakers. The improvement to the sound system quality was significant, and coverage was even throughout the arena.

The ice will be going in the coming days and we can rest easy knowing the users will be able to hear the calls, announcements and music.