Wiring the station into your PA

1How it fits together

The iPad is just another audio source to your PA — like a CD player or radio used to be. It plugs into the amplifier's line-level input and the amplifier does what it always does. No software is installed on the amplifier, nothing on the school network is changed, and the existing microphone and speakers are untouched.

Where the iPad lives: in the comms rack or wherever the amplifier is — not the staff room. Once installed it's controlled from staff iPhones, so nobody needs physical access to it day-to-day.

2Hardware checklist

3Connecting the iPad — by model

4The amplifier side

Connect to any line-level input: sockets labelled AUX, LINE IN, CD, TAPE or MUSIC are all correct. On a mixer-amp, use any spare channel with a line input.

• RCA inputs (red/white): use a 3.5 mm-to-RCA lead — the most common school scenario.
• 3.5 mm aux input: a plain 3.5 mm-to-3.5 mm lead.
• 6.35 mm (¼") or XLR line input: a 3.5 mm-to-6.35 mm lead, or a 3.5 mm-to-XLR pair. For long runs (over ~5 m) prefer a balanced path via a cheap DI box to keep noise out.

100V line systems

Most school PAs are 100V line: one amplifier driving many ceiling/horn speakers along a shared run. Nothing changes — the iPad feeds the amplifier's aux input at line level, and the amplifier's 100V side is untouched. You never connect the iPad anywhere near the speaker wiring.

Microphone priority / ducking

Many PA mixer-amps have mic priority (VOX), which automatically ducks music when someone uses the paging microphone. This works perfectly alongside the station: scheduled music ducks for the office mic exactly like any other source, and comes back when they finish.

5Setting the levels

Do this once at installation and then leave everything alone — the goal is that day-to-day nobody touches a volume control anywhere.

1. Set the iPad volume to about 80% — high enough for a clean, strong signal; below maximum to leave headroom. Check the side switch/Control Centre isn't muting it.
2. Turn the amplifier's channel gain for the iPad all the way down, then start a test bell in the app (Bells → Test active bell).
3. Bring the channel gain up until the bell sits at a good level in the yard — clearly audible everywhere, not distorting anywhere.
4. Play a music track and a test announcement (Settings → Announcer voice → Test voice over PA) and confirm both sound right at the same setting. Bells in the app are mastered to sit slightly above music level by design.
5. Walk the site — far corridors, the far end of the yard — and adjust the master once if needed.

6Hum & noise

If you hear a low mains hum through the speakers when the iPad is both charging and connected to the amp, that's a ground loop — common with any powered source, and fixed in one minute:

• Fit a ground-loop isolator (~$15) inline on the audio lead. Hum gone, permanently. This is standard practice, not a workaround.
• Alternatively, powering the iPad from a charger on the same power board as the amplifier often removes the loop on its own.

Hiss at idle usually means the amp channel gain is too high and the iPad volume too low — rebalance as in section 5.

7Wi-Fi and the iPhone Remote

• The station and staff iPhones must be on the same Wi-Fi network (same subnet/VLAN). On school networks with separate staff/guest VLANs, put the station on the staff VLAN.
• Discovery uses Bonjour (mDNS) on the local network — nothing leaves the site, no ports need opening to the internet, and no server is involved. If your network blocks mDNS between VLANs, keep station and phones on the same VLAN.
• The internet can go down without consequence: bells, imported music and saved announcements are all local. Only Apple Music streaming and App Store updates need the internet.
• Pairing is code-protected — see the manual, section 12. Phones reconnect automatically after the first pairing.

8Making it permanent

1. Power: leave the iPad plugged in permanently. iPadOS manages the battery; a station iPad lasts years like this.
2. Auto-Lock: the app keeps the screen awake by itself while open — no iPad settings needed.
3. Screen lock: set a PIN in Settings → Screen lock and tap Lock screen now — the station shows the clock and asks for the PIN before anyone reaches the controls.
4. Guided Access: iPad Settings → Accessibility → Guided Access, then triple-click the top button in the app to seal it open — the iPad becomes a single-purpose appliance.
5. Backup: export a .bellbackup file (Settings → Backup & Restore) and store it with your site documentation. A replacement iPad is restored in minutes.
6. After a power cut: the iPad powers back on when charge returns; open the app (or have it in Guided Access, which returns automatically) and everything resumes — the schedule lives on the device.

9Troubleshooting

10Commissioning checklist

Sign off the install when every box ticks:

• iPad on permanent power, charging confirmed (with adapter fitted, if used)
• Audio lead into a line/aux input — bell, music and voice announcement all tested through the real speakers
• Levels set as in section 5 and walked in the yard; no hum, no distortion
• School name set; weekly timetable entered and checked against the school's bell times document
• Term holidays marked in the Holidays tab
• At least one staff iPhone paired and tested: ring bell, live announcement, schedule edit
• Screen lock PIN set and locked; Guided Access on for unattended stations
• Backup exported and stored with site documentation
• Office staff shown the Remote: ring a bell, rainy-day bell, make an announcement