Table of Contents

What Is a Submix System and Why It Matters

A submix system is an audio routing architecture where individual instruments or vocal sections are grouped into dedicated sub-mixes before being sent to the main mix bus. Rather than feeding every single microphone channel directly into the master output, you route related sources — say, all violins, all brass, all backing vocals — to a submix bus or a secondary mixer. That submix is then sent as a single stereo or mono channel to the front-of-house console.

This approach dramatically reduces channel count overhead, simplifies gain staging, and gives the sound engineer granular control over each section without needing to adjust dozens of individual faders simultaneously. For large bands, orchestras, or any ensemble exceeding 20 performers, a submix system is not a luxury — it is a necessity for achieving clarity, balance, and efficient workflow.

Why Large Ensembles Require a Submix Strategy

Orchestras and big bands typically involve 30 to 100 or more sound sources. Managing that many inputs directly on a single console becomes unwieldy, especially during live performances where quick adjustments are critical. A submix system offers several decisive advantages.

Reduced Console Channel Count

Even high-end digital mixers have a finite number of input channels. By grouping instruments into submixes, you free up channels for essential sources such as lead vocals, solo instruments, and effects returns. This also keeps your mixing surface manageable, reducing the cognitive load on the engineer during a show.

Section-Level Balance

With submixes, you can balance an entire string section with a single fader move rather than adjusting eight individual microphones. This makes it far easier to respond to changes in dynamics or to accommodate different pieces in a setlist that place varying demands on specific sections.

Cleaner Monitor Feeds

Submixes are invaluable for monitor mixing. You can send a dedicated submix of just the rhythm section to the drummer's wedge or in-ear system, while sending the horn section submix to the brass players. This eliminates bleed from unrelated sources and helps each performer hear exactly what they need.

Simplified Effects Processing

Applying reverb, compression, or EQ to an entire section via its submix bus is far more efficient than inserting the same effect on every individual channel. It also ensures a cohesive sound across the group, which is especially important for orchestral strings and vocal ensembles.

Essential Equipment for a Submix System

Before you begin routing, you need the right hardware. The specific gear list will depend on ensemble size and venue, but these components form the backbone of any professional submix setup.

Primary Mixing Console

This is your main front-of-house or monitor desk. It should have enough aux sends, group buses, or matrix outputs to handle your submix return channels. Most digital consoles in the $2,000–$10,000 range offer 8–16 subgroup buses, which is sufficient for most large ensembles. Popular options include the Yamaha CL5, Allen & Heath SQ-7, and Behringer Wing.

Submix Consoles or Stage Boxes

For very large orchestras, you may deploy one or more secondary mixers on stage to pre-mix sections before sending them to the main console. Alternatively, a digital stage box with multiple output routings can serve a similar function. These units allow you to set levels and apply basic EQ before the signal ever reaches the front-of-house position.

Microphones and Direct Boxes

Select microphones appropriate for each section. For strings, small-diaphragm condenser mics such as the Shure SM81 or Audio-Technica AT2021 are common. Brass sections often benefit from dynamic microphones like the Sennheiser e906. For acoustic pianos and woodwinds, high-SPL condensers with a flat frequency response are ideal. Direct boxes are essential for any electric instruments — keyboards, bass guitars, or DI-ready acoustic guitars — to maintain signal integrity over long cable runs.

Cabling and Patching Infrastructure

Use high-quality XLR cables for microphone signals and TRS cables for line-level submix sends. A properly labeled patchbay can save hours during setup and troubleshooting. Color-coding cables by section (for example, blue for strings, red for brass, green for percussion) speeds up both assembly and teardown.

Monitoring System

You will need both on-stage monitors for performers and nearfield monitors or high-quality headphones for the engineer to check submix levels before they reach the main mix. Active PA speakers such as the JBL PRX series or QSC K series work well for stage monitoring when paired with a separate monitor console or aux sends.

For further reading on selecting microphones for orchestral recording, consult Sound On Sound's guide to miking orchestras.

Step-by-Step Guide to Setting Up Your Submix System

The following steps assume you have your equipment assembled and powered on. Work through them systematically to ensure a clean, noise-free signal path.

1. Map Your Instrument Groups

Begin by dividing the ensemble into logical sections. For orchestras, typical groups are:

  • Strings: Violins, violas, cellos, double basses
  • Woodwinds: Flutes, oboes, clarinets, bassoons
  • Brass: Trumpets, French horns, trombones, tubas
  • Percussion: Timpani, snare drum, cymbals, auxiliary percussion
  • Keyboards/Harp: Piano, celesta, harp
  • Vocals: Soloists, choir sections if present

For a big band, groups might be: saxophones, trumpets, trombones, rhythm section (piano, bass, drums, guitar), and vocals. Write this map down and label everything before you touch a cable.

2. Place Microphones and Connect Sources

Position microphones according to standard techniques for each instrument family. For orchestral strings, a spaced pair of small-diaphragm condensers above the section often works better than spot miking every stand. For brass and percussion, close miking is more common to control bleed and increase isolation.

Run all microphone cables to your stage box or submix console. Ensure phantom power is enabled only for microphones that require it — typically condenser mics — and disabled for dynamic mics and ribbon mics to prevent damage.

3. Configure Submix Buses on Your Primary Console

On your main mixing desk, assign each instrument group to a dedicated subgroup bus. For example, route all string channels to Subgroup 1, all brass to Subgroup 2, woodwinds to Subgroup 3, percussion to Subgroup 4, and so on. Most digital consoles allow you to name these buses — take the time to do so. Clear naming prevents confusion during performance when you need to make split-second adjustments.

Set the subgroup faders to unity gain initially. Each subgroup output will become a single fader controlling its entire section. You can now adjust the overall mix by moving these subgroup faders, while finer adjustments are made on the individual channel faders within each group.

4. Set Aux Sends for Monitors

If you are using monitor mixes, configure aux sends to serve different performer needs. For instance:

  • Aux 1: Drum monitor mix (kick, snare, bass, click track)
  • Aux 2: Brass monitor mix (brass submix plus lead vocals)
  • Aux 3: String monitor mix (strings submix plus conductor reference)

Use the aux send levels on each channel to build these monitor mixes independently from the front-of-house mix. Many digital consoles let you set aux sends as pre-fader or post-fader — for monitors, pre-fader is standard so that performer levels stay constant even if you change the main mix.

5. Balance Each Submix

With all sources connected and buses assigned, solo each subgroup and listen critically on your monitoring system. Adjust individual channel gains and EQs within the group to achieve a cohesive blend. Pay special attention to phase alignment — if multiple microphones are picking up the same source, you may need to use polarity inversion or delay alignment to avoid comb filtering.

A good practice is to listen to each submix in isolation first, then bring in the other subgroups one by one. This makes it easier to identify conflicts in frequency range or dynamics before the full ensemble plays together.

6. Combine Submixes into the Main Mix

Once each submix sounds balanced on its own, bring all subgroup faders up to create the full mix. Now your primary mixing task is adjusting just 6–8 faders rather than 40–50. Use the subgroup faders to make broad dynamic changes — for example, pushing the brass section during a fortissimo passage or pulling back the string section during a delicate solo line.

For more detailed information on live sound mixing techniques, refer to ProSoundWeb's guide to subgroup mixing.

7. Create a System Check Routine

Before the performance, run through a systematic check:

  • Verify that every microphone is producing signal and not muted
  • Check polarity alignment on all spot mics in relation to overhead or ambient mics
  • Confirm that all aux sends are routed to the correct monitor destinations
  • Test subgroup muting and solo functions
  • Walk the stage to listen for feedback or excessive bleed

Best Practices for Managing Submixes During a Live Performance

Even the best-planned submix system requires active management during a show. These practices will help you maintain control under pressure.

Use Subgroup Compression Sparingly

Applying compression to an entire submix can be useful for gluing a section together, but avoid over-compressing. Strings and woodwinds often require a light touch (2:1 ratio with 2–3 dB of gain reduction) to preserve natural dynamics. Brass and percussion can handle more aggressive settings (4:1 ratio with 5–6 dB of reduction) if needed to control peaks.

Label Physical Faders Clearly

If you are working with an analog console or a digital desk in fader-bank mode, use colored tape or console scribble strips to label each subgroup fader. This prevents fumbling during moments of high activity, such as a sudden instrument change between pieces.

Assign a Second Engineer for Large Ensembles

For orchestras exceeding 50 performers, consider having a dedicated monitor engineer or an assistant front-of-house engineer. The primary engineer handles the main mix and overall balance while the assistant manages individual submix adjustments and troubleshooting. This division of labor significantly reduces stress and error rates.

Document Your Submix Configuration

Save your console scene or show file with all subgroup assignments, EQ settings, and aux send levels. If you are touring or working in a venue with repeat engagements, having a documented baseline speeds up subsequent setups. Include a printed patch list and a stage plot for reference.

Troubleshooting Common Submix Issues

Even experienced engineers encounter problems. Here are the most frequent issues and how to solve them.

Phase Cancellation Between Submixes

When multiple microphones pick up the same source — common in orchestral settings where ambient mics capture spill from nearby sections — you may experience a thin, hollow sound. Use a phase correlation meter on your console to identify problematic channels. Adjust microphone placement or engage polarity inversion on individual channels until correlation reads consistently above +0.5.

Submix Bus Overload

If your subgroup bus is clipping even though individual channels are at reasonable levels, reduce the channel faders feeding that bus or lower the bus trim. Digital mixers often have a bus trim parameter — a -6 dB reduction on the bus itself can prevent distortion while preserving headroom.

Feedback in Monitor Submixes

Monitor feedback occurs when sound from stage speakers re-enters open microphones. To mitigate this, apply high-pass filtering (around 80–100 Hz) on all vocal and string channels, and use narrow notch filters on feedback frequencies. If feedback persists, reduce gain before feedback by lowering the monitor send level rather than cutting EQ drastically, as heavy EQ can make the mix sound unnatural.

Latency Issues in Digital Submix Chains

Digital consoles and stage boxes introduce some latency. In most modern systems (such as Dante or AVB networks), this latency is under 1 millisecond and not audible. However, if you are combining analog and digital gear, or using long AES50 runs, latency may accumulate. Keep all digital devices on the same clock source and use sample-rate converters where necessary. For more on managing digital audio latency, see Audio-Technica's explanation of digital audio latency.

Advanced Techniques for Orchestral Submixing

Once the fundamentals are solid, you can refine your submix approach with these professional techniques.

Stereo Submixing for Section Width

Rather than sending each section as a mono submix, route them as stereo pairs. For strings, pan first violins slightly left and second violins slightly right within their own submix. This preserves the natural stereo spread of an orchestra and gives the audience a more immersive experience. Many digital consoles allow you to set up stereo subgroups easily.

Dynamic Subgroup DCA Control

Combine subgroup buses with DCA (digitally-controlled amplifier) groups for even finer control. For example, assign all subgroup faders to a single DCA master called "Orchestra." During a quiet passage, you can pull down the entire orchestra by 2–3 dB with one finger, while keeping the relative balance between sections intact. This technique is widely used by Broadway sound designers and touring orchestral engineers.

Matrix Mixing for Broadcast or Recording Feeds

If you are also sending audio to a live stream, broadcast truck, or recording rig, use matrix outputs to create separate mixes from your submix buses. The matrix can blend subgroup signals in any proportion — for instance, a "Strings + Woodwinds" mix for a camera position near the brass section, or a "Full Orchestra minus Percussion" mix for a spoken-word segment. This avoids the need for a completely separate console.

Integrating Submixes with Modern Digital Ecosystems

Modern digital mixing platforms allow remote control, recall, and networking capabilities that make submix systems far more flexible than in the analog era. For instance, using a protocol like Dante, you can route submix buses from a stage box directly to multiple destinations — front-of-house, monitors, recording, and streaming — over a single Ethernet cable. This reduces cable weight and setup time significantly for touring orchestras.

Software such as Audinate's Dante Controller lets you reconfigure signal routing from a laptop, making it easy to change submix assignments between sets without repatching physical cables. Similarly, Yamaha's QL/CL series consoles support "Dante Submixing," where input channels from a remote stage box are first submixed on the stage box itself before being sent to the console, conserving network bandwidth and console processing power.

Final Thoughts on Submix Implementation

Setting up a submix system for large bands or orchestras is a systematic process that rewards careful planning. By grouping instruments into logical sections, deploying the right microphones and cabling, and leveraging the subgroup and aux capabilities of modern consoles, you can achieve a level of control and clarity that would be impossible with a simple channel-by-channel approach.

Start with the fundamentals outlined in this guide, then gradually incorporate advanced techniques such as stereo submixing, DCA control, and matrix routing as your confidence grows. Every orchestra and big band is different — experiment with group assignments and monitor mixes during rehearsals, and always maintain clear communication with performers. With a well-designed submix system, you will deliver mixes that are both powerful and transparent, allowing the music to speak for itself.

For additional insights into live sound reinforcement for classical ensembles, the Oregon Symphony's primer on sound reinforcement offers a practical perspective from working professionals.