19 Nov 2020

Old School OG PA with Page Pac and Redback

by Jason Allen

Page Pac Pty Ltd is one of the few remaining ‘old school’ PA, paging, and EWIS companies left in Melbourne. Their stock in trade is 100V line in public places, and lots of it. Current proprietor Alex Bernach bought the company from his mentor, the late Gordon Setterfield, when he retired in 2002. Trusty impedance meter in hand, Alex was recently called in for a quick fault-find in a high school and ended up replacing the whole system…

Balwyn High School is one of those vast, exceptional public high schools that parents move to the suburb to get their children into. Alex’s colleagues Dalton Electrical are the incumbent maintenance contractor and called Alex in when one of the existing PA amps ‘let the magic smoke out’.

“I was told that it had caught fire, or at least let some electrical smoke out,” laughs Alex. “It had then been replaced, but the system wasn’t really working across the whole speaker network.

“It had been deteriorating for a while, and certain zones didn’t work at all. Dalton called me to come and have a look. I was expecting to drop in for an hour, and ended up staying for four, auditing the system – I had no idea it would be so big!

“Balwyn High School has 2,500 students and 220 teachers! It’s bigger, and better resourced, than most of the private schools I’ve worked at.”

Balwyn High School – parents move to the suburb to enrol their children there

Alex’s impedance sleuthing located multiple faults across the speaker network that were causing the whole system to fault. The ancient power amps would let one page through and then power off because there was too much load caused by shorts.

The only practical solution was to locate and rectify the speaker cable faults, then replace everything in the PA racks.

Dalton Electrical called Alex in when one of the existing PA amps ‘let the magic smoke out’

“The 100V line network was run using the old multicore telephone cable,” relates Alex. “It’s easy to identify faults on that kind of network, and it was actually well designed.


“I measured about a 1300W load. It was split into three main areas, so I replaced the two old amps with three Redback A4395 500W mixer amps and shared the load across them.”

Redback A4395 500W mixer amp

The sources coming in are what you’d expect in a large school installation; paging, an evacuation controller, alert, and bell tones.

There’s also an integrated telephone paging input so anyone with an access code can pick up a phone, dial in, and do an emergency page through the school’s NEC telephone system.

A Redback A4510A yearly school timer can be programmed to play the school bell tone, and any mp3 file can be scheduled. The timer also has a relay out for triggering an external player.

Redback A4510A Yearly School Timer

The unit is programmed with school times two years out so the bell doesn’t sound during holidays, saving the neighbours the trouble of complaining to council!

Being an emergency system, the whole PA has back-up power supplied by two deep cycle batteries rated for 90 hours of operation. A Redback A4512 Backup Battery Charger keeps them ready for action.

Redback A4512 Backup Battery Charger

Redback is a go-to brand for Alex in these kinds of jobs.

“I use Redback because it has been designed for the Australian installer,” he says. “For example, on Redback’s six input mixer amps, each input is switchable between mic and line level.

“Other brands come with fixed configurations of two line and four mic, so they’re inflexible. There’s also a ducker in the Redbacks – when the paging mic inputs signal, the BGM fades under it, and when it stops, the music fades up again.

“I’ve used both these mixer amps and power amps in Coles Myer and Target stores. They’re just ‘end user proof’ and almost impossible to blow up.”

Reliability is also high up on Alex’s reasons for brand loyalty.

“We find with some other amps that, after a couple of years, they develop a bad earth hum and become a throwaway item. Redback gear comes with a 10-year warranty.

“If there was ever a problem, I’d drop them into Altronics’s base here in Melbourne, and they’d repair it. Not that it ever happens; once they’re in they don’t get touched.”

Shiny new rack

Tales From The Frontline
With servicing old-school public address becoming a lost craft, Alex shares some fault-finding pearlers from across his decades of experience.

“This is all the stuff they don’t teach in school. This knowledge has been passed down to me from my old boss and his engineers. It’s all learnt hands-on.”

“I did a service call for the ceiling speaker network at a Coles supermarket two years ago. The manager said ‘You’re the fifth person here. I hope you can fix it.’

I did a service call for the ceiling speaker network at a Coles supermarket two years ago – the manager said ‘You’re the fifth person here. I hope you can fix it.’

“An amp had blown up. The in-house service crew put in a new amp, and that promptly blew up too.

“I put my impedance meter on the line, found a low reading, searched the store and found a volume control that some bright spark had inserted in-line on the speaker cable run in the staff training room. It was shorting the whole network. Removed. Problem fixed.”

“Sometimes you get faults that you have to go back five times to find,” continues Alex. “You start asking yourself if it’s cheaper to just run a new cable network.

“The most difficult fault to find I’ll never forget; it was a rubber manufacturer in Moorabbin. Their paging system wasn’t working. I’d go there, see the fault on the line, and then it would disappear. I’d go away, and the next day it would come back.

“Several visits later, I was back and searching for the fault. When a certain machine was started up, it would vibrate the whole area. The speaker cable run was above it, and would rub against the metal of the roof when the machine was on.

“When the machine stopped, the fault would disappear. It was only by chance I found it. It was one of the worst jobs I ever had!”

Page Pac

Balwyn High School – The Gear

2 x Redback A4427 8 channel mixers

3 x Redback A4395 500w mixer amps

1 x Redback A4510A yearly school timer

1 x Redback A4565 Alert Evac System with remote
triggering and paging console

1x Redback A4564 Paging Console with Alert/Evac/Chime

1x Redback A4578 Remote Control Wallplate to suit

1 x Redback A4512 Backup Battery Charger

2 x Powerhouse SG4573 90Ah deep cycle batteries

CX Magazine – November 2020   

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