Hall Audio Upgrade

Auditorium sound system

Hall audio upgrade

Replacing the Console's analogue mixer and outboard equaliser with a single digital signal processor (DSP). What it is, how it works, and how to run it.

1 How it works

Follow the sound from the microphones through to the hall.

Signal-flow diagram of the hall audio system Microphones feed the DSP at the Console. The DSP sends a speech mix through the feedback suppressor and a separate singing mix that bypasses it; both are summed by the distribution amplifier and sent to the hall speakers. The DSP also feeds the hearing loop, foyer and recorder, and connects to Zoom over the Dante network. Microphones Console (Row 3) Audio Rack Hall & zones Row microphones ×10 each row → one channel Reading mic (boom) main + backup Singing mic (ceiling) Audix ADX40 · mainly Zoom DSP Symetrix Radius the new "brain" Feedback suppressor Distribution amp sums speech (A) + singing (B) Power amps primary + standby Relay changeover Hearing-loop amp Foyer amp Foyer / amenities Local recorder Main hall speakers speech + singing together Hearing loop Zoom (remote) 2 sends · 1 return A B Audio network (Dante)
speech / general audio singing (skips the suppressor) Zoom over the network
How sound flows from the microphones to the hall and to Zoom.
Detail Why singing gets its own path ›

The hall's feedback suppressor is a single-channel unit that works by listening for sustained tones (the early sign of a howl) and quietly notching them out. Sung notes are also sustained tones, so pushing singing through it would make it chase and dampen the very sound we want in the room.

So the DSP produces two hall feeds: Hall-Speech (rows + reading mic) through the suppressor, and Hall-Sing (singing only) bypassing it. The distribution amplifier sums them, with adjustable proportion. The singing mic is a cardioid pointing down at the congregation with the ceiling speakers behind it, and it's only lifted about 20% into the room, so feedback risk stays comfortable.

Detail How Zoom connects ›

Because all of the DSP's analogue inputs are used by microphones, Zoom rides the venue's audio network (Dante) instead — through small plug-and-play network adapters. This keeps every microphone input free and gives clean, reliable audio in and out of Zoom, with an analogue backup available if ever needed.

2 What's changing

The old setup and the new one, side by side.

Before and after comparison of the audio signal chain Before: microphones into an analogue mixer, then a separate graphic equaliser, feedback suppressor, distribution amp, power amps with an amp-to-amp backup, then the hall. After: microphones (plus a new singing mic) into a single DSP that also does the tone, so the separate equaliser is gone; then the same feedback suppressor, distribution amp, power amps with a proper relay changeover, then the hall. The control panel is replaced with a new panel and tablet, and Zoom moves onto the Dante network. Before — the system today Microphones rows + reading Analogue mixer 12-channel Graphic EQ separate unit Feedback suppressor Distribution amp Power amps amp-to-amp backup Hall speakers Old control panel partly working Zoom tapped off suppressor (jerry-rigged) After — the new system Microphones + singing mic DSP mixing + tone Graphic EQ now in the DSP Feedback suppressor Distribution amp Power amps + relay changeover Hall speakers New panel + tablet Zoom over Dante network
new improved removed (absorbed into the DSP)
Two boxes become one — the mixer and separate equaliser are replaced by a single DSP.

3 The system up close

For the technical crew — where things sit and how they connect.

Full signal wiring — current

Current system wiring Today: hand mics (rows 1–8), the boom mic (main/backup on a manual switch) and the ceiling boundary mic feed an analogue mixer at the Console. The mixer feeds a graphic equaliser, then the feedback suppressor, distribution amp and power amps, out to the hall. The amp backup is a risky amp-to-amp link and Zoom is jerry-rigged off the feedback suppressor. There is no singing mic — the boom is used for singing. Microphones Console (Row 3) Audio Rack Hall & zones Hand mics — rows 1–8 rows 9 & 10 not wired Boom mic (stand) main/backup — manual switch Ceiling boundary mic recordings only — not the mixer No singing mic — boom used for singing Analogue mixer AMIS strip + pots Old control panel partly working Graphic EQ Feedback suppressor (FBX / Plena) Distribution amp Power amps amp-to-amp backup (risky) Foyer speakers daisy-chained / overloaded Recorder (at Console) Hall speakers reading-taker tuned Hearing loop Zoom PC via jerry-rig jerry-rig
signal path ageing / risky
Current: mixer → EQ → suppressor → distribution → power amps → hall. Backup is a risky amp-to-amp link; Zoom is jerry-rigged off the suppressor.

Full signal wiring — new

New system wiring New: all mics (row channels, both booms, the new ceiling singing mic, and the boundary mic) feed the DSP. The DSP sends Hall-Speech through the feedback suppressor to the distribution amp input A, and Hall-Sing bypasses the suppressor to input B. The distribution amp drives the power amps through a relay changeover to the hall. The DSP also feeds foyer, toilets, a split local recorder, and the hearing-loop amp, and puts Zoom on the Dante network via AVIO adapters. A new control panel and tablet drive the DSP. Microphones Console (Row 3) Audio Rack Hall & zones Row channels 1–10 9 & 10 grouped → 1 input Boom — both live blend on tablet (no switch) Singing mic (ADX40) ceiling · phantom at rack Boundary mic recordings only — not the DSP DSP Radius NX12X8 12 in · 8 out · Dante Control panel + tablet 4 knobs · 4 buttons Feedback suppressor Plena — speech only Foyer amp Distribution amp A speech + B singing Power amps primary + standby Relay changeover SA-RRB Hearing-loop amp AVIO / Dante gear + phantom inject Foyer Toilets / amenities Local recorder (at Console) Hall speakers speech + singing Hearing loop Zoom PC 2 sends · 1 return A B
speech / general singing (bypasses suppressor) Dante
New: every mic into the DSP; speech via the suppressor (A), singing bypasses it (B), summed at the distribution amp, through the relay changeover to the hall. Zoom rides Dante; a new panel + tablet drive the DSP.

Where it all lives

Physical layout of the equipment The Console at Row 3 holds the DSP and control panel; the Audio Rack nearby holds the amps, distribution amp, feedback suppressor, hearing-loop amp, relay changeover and Dante gear; the Network Rack is separate. Three conduits (one power, two signal) link the Console and Audio Rack; Cat6 links to the Network Rack. Console — Row 3 DSP — Symetrix Radius Control Panel Local recorder row + boom looms land here Audio Rack Power amps (primary + standby) Relay changeover Distribution amp Feedback suppressor (Plena) Hearing-loop amp AVIO / Dante + phantom provisioned UniFi switch Network Rack UniFi UDM Pro 48-port switch (10G) 3 conduits 1 power · 2 signal 3 Cat6 · Console → Network Rack 2 Cat6
Where things physically sit, and the links between them.

DSP inputs & outputs 12 in · 8 out

DSP input and output allocation The DSP has 12 analogue inputs — rows 1 to 8, rows 9 and 10 grouped, boom main, boom backup and the singing mic — and 8 analogue outputs: Hall-Speech to the Plena, Hall-Sing to distribution amp B, hearing loop, foyer, toilets and amenities, local recorder, and two spare. Zoom and the recording feed ride Dante, not these analogue ports. DSP Radius NX12X8 1Row 1 2Row 2 3Row 3 4Row 4 5Row 5 6Row 6 7Row 7 8Row 8 9Rows 9 & 10 10Boom main 11Boom backup 12Singing mic Inputs 1Hall-Speech → Plena 2Hall-Sing → Dist amp B 3Hearing loop 4Foyer 5Toilets / amenities 6Local recorder (split) 7spare 8spare Outputs
DSP 7–8 = spare (2 free)
Back-row grouping is confirmed at commissioning. The ceiling boundary mic does not go through the DSP — it feeds recording gear directly. Zoom and the Dante recording feed use the network, not these analogue ports; the local recorder is a separate analogue split at the Console.

Zoom & the Dante network

Zoom and Dante audio network The DSP puts Zoom audio onto the Dante network, which runs on its own lane. Three AVIO adapters bridge to the Zoom PC with two sends out and one return in. A recording feed is taken off Dante, and a Focusrite provides an analogue backup path. DSP Dante A + B Audio network Dante · own VLAN 3× AVIO adapters Zoom PC own UPS Recording feed off Dante Focusrite backup analogue fallback 2 sends · 1 return
Dante (network) Zoom in / out analogue backup
Zoom rides the Dante network; an analogue Focusrite path is the fallback.

4 Key decisions

The choices behind the design. Open any one for the reasoning.

Singing takes its own path around the feedback suppressor ›

A feedback suppressor dampens sustained tones — and singing is a sustained tone. So the singing mic bypasses it on a separate feed, and the two are blended again at the distribution amplifier. Speech still gets full feedback protection where it's needed.

Zoom runs over the network, not a spare mixer input ›

All the DSP's microphone inputs are in use, so Zoom's audio travels over the venue's audio network using small plug-and-play adapters. It's no more expensive than the alternative, it's simpler to set up, and it fits how the venue already runs larger meetings.

The Console-to-Rack link stays as ordinary audio cable ›

The signals between the operator position and the equipment rack could have been sent over the network with an add-on converter, but that converter adds significant cost and only saves running cable we can easily run anyway. So the tried-and-tested audio cabling stays — the money is better spent elsewhere.

Only the amplifiers switch off; the processor stays always-on ›

The DSP and network are designed to stay powered all the time, so there's nothing to boot at the start of a meeting. The "Power" button now switches just the amplifiers — which is also the correct order for pro audio (amps on last, off first) and avoids any thumps through the speakers.

The audio network gets its own lane ›

Audio over a network is sensitive to timing. To protect it, the audio traffic runs on its own separate lane (VLAN) on the venue network, kept clear of video and general traffic so the sound stays rock-steady.

One processor, no cold spare — a considered, accepted risk ›

The new DSP is the single heart of the system. Rather than hold a duplicate on the shelf, we rely on it being new and highly reliable, plus the backups that already exist around it — a backup reading-mic path, a standby amplifier, a backup Zoom input, and battery power with a standby generator. If the feedback suppressor ever fails, its job simply moves into the DSP. This can be revisited for any especially high-stakes event.

5 Install & tasks

The cabling, the changeover weekend, and a live task list.

Cable runs

Cable runs Eight 1883A tie-lines (two in, six out) between Console and Audio Rack; three 6-core control cables to the relay box; three Cat6 from Console to Network Rack; two Cat6 trunk to the Audio Rack; one Cat6 UM spare for later; and a new always-on power circuit with dual GPO to the Console. Console Audio Rack 8 1883A tie-lines · 2 in / 6 out Console (Control Panel) Relay Box (Rack) 3 6-core control Console Network Rack 3 Cat6 · DSP control + Dante A / B Network Rack Audio Rack 2 Cat6 trunk Console Audio Rack 1 Cat6 · UM spare (later) Audio Rack Console new 2C+E circuit · always-on power + dual GPO Phantom power (48 V) is injected at the Audio Rack for both ceiling mics.
What runs where, with counts. Dashed = later / optional.
Detail The 2 in / 6 out breakdown ›

2 IN: singing mic (Audix ADX40) · ceiling boundary mic (re-run).
6 OUT: Hall-Speech (→ Plena) · Hall-Sing (→ Dist amp B) · Hearing loop · Foyer · Toilets/amenities · spare.

Changeover weekend Sat 18 – Sun 19 July 2026

Install-day sequence Pre-stage all cabling, then Friday land the DSP and terminate, Saturday cut over and prove it live, Sunday re-tune and label; the old mixer stays patchable for instant rollback until the new system is proven, then it's removed. Pre-stage Fri 17 Sat 18 Sun 19 After Pre-run all cabling (old system live) Land DSP terminate · phantom Cut over · test Sat service · tidy (PM) Re-tune · label walkthrough (maybe no service) Remove old mixer once proven Old mixer stays patchable — instant rollback
The old mixer stays as the live safety net until the new system is proven.

Task list

— / —

Saved to the shared team space — everyone with the link sees and edits the same list. Assign people, add or remove tasks and members.

Team
Add a task

6 Operating the system

The everyday cheat-sheet — four knobs, four buttons, and the tablet.

Four knobs (volume)

Stand micthe front reading mic
Hand micsmaster level over all the rows
Singing micbring up ~20% for singing only
Zoom-inhow loud remote (Zoom) talkers are in the hall

Four buttons

Powerbrings the amplifiers up (start of meeting)
Standbyswitches to the backup amplifier
Foyerfoyer speakers on / off
Cornersmutes the corner speakers (no sound into empty corners) — normally left on

The tablet

Keep it open during a meeting. Use it to mute a problem row, check where a signal is coming from, make small tone tweaks, and balance individual rows. It can do the things the knobs can't reach. Muting is row-level — you can't isolate a single mic (rows are grouped).

Common situations

Start-of-meeting, in short. Everything's already on — just press Power for the amps, set the knobs, leave Corners on, and turn Foyer on if you need it.

7 Still to confirm

Normal on-the-day checks — nothing that holds up the plan.