Professional audio · SERVICE · REV 2026-10-06
Line Array systems
A Line Array is a vertical row of cabinets opened by splay angles so it follows the seating section: tighter angles at the top for the far throw, wider angles at the bottom for the near rows. If the room is short, or the array is a few straight boxes, you are buying a Point Source in the shape of an array.
Definition
The justification is geometric. The throw is long, the seats rise, and energy should stay off the ceiling and off the heads in the front row. A long array approaches, over part of its range and frequency, a cylindrical spread slower than the point-source six-decibel law. A real array is finite: behaviour changes with distance and frequency, and a straight line with no splay concentrates rather than distributes. This page gives no SPL for a named cabinet.
Module count is the result of coverage and splay on the seating section, not of how the hang looks. Curvature is built in prediction and then checked by a transfer-function measurement in the hall. The Subwoofer is a separate system: low frequency does not fall out of counting boxes in the array. If RT60 and HVAC noise set STI, spending the budget on the array before the room is the decision backwards.
When is this service needed?
A long throw
The distance from the hang to the last seat exceeds what one cabinet covers with its pattern without overloading the front.
A tall seating section
A balcony and a stalls section in nearly the same vertical aim. Controlled vertical coverage is the reason for the array.
The room budget is already real
Isolation, RT60, and the noise floor are specified. The array is not purchased instead of them.
This is not the time
A short room, a conference one cabinet can cover, or a wish for the array shape on the ceiling. A Point Source is more honest.
Where it is used
Large theatres
A deep house and a balcony. The array follows the section and leaves the balcony shadow to a delayed fill if needed.
Arenas and stadiums
Long throw and audience on more than one level. Low frequency is still a separate Subwoofer question.
A controlled outdoor show
With no ceiling to return the energy, the array goes where it is aimed. Wind and a crowd are not a reason to skip measurement.
Where it should not be hung
A meeting room, a classroom, or a small cinema. A short straight count does not make an acoustic line.
Parts of the solution
Modules and splay
Each cabinet and the angle to the one below it. The angle comes from the section, not from a template on this page.
Frame and hang
The hang point is a load on a designed rigging system, not on an architectural beam because it is there. The safety factor comes from the standard and the engineer of record.
DSP
Delay, equalization, limiting, and array processing. The preset is a file stored with the splay, not a technician’s memory.
Subwoofer
A ground or flown array separate from the speech hang. The crossover and the processing are part of the design.
Measurement
A microphone and a transfer function in seats that represent the front, the depth, and the balcony, not only at the mix position.
Engineering considerations
A finite array
A fall slower than 6 dB per doubling is a behaviour of band and distance, not a law printed on every hang. This page predicts no level.
Curvature
A tight splay at the top lengthens the throw. A wider splay at the bottom opens the near coverage. A zero-angle line concentrates energy.
Module count
Add modules until the section is covered by the required pattern and the line is long enough for the frequency you need to control. A count chosen for looks is rejected.
The room first
A long RT60 and a hard rear wall keep the tail however pretty the prediction. STI is from IEC 60268-16 if speech is the criterion.
No invented SPL
A level target, if one exists, is in the brief and is measured. There is no sound-pressure figure for a named cabinet on this page.
Materials
Cabinet and driver
One series, so splay and prediction stay consistent. Mixing unmodelled shapes breaks the prediction.
Cable and the hang point
Mechanical load and current are two items. The frame comes from the rigging documents, not from scenery steel.
Room treatment
Absorber on the late path and a reflector where it helps. The array does not replace the treatment page.
Related systems
Point Source fills
Under the balcony, and at the front if the array’s opening is not enough. Delay them so the image does not pull.
Subwoofer
Placement, delay, and coupling, and sometimes cardioid under stated conditions. Not an extra output on the same hang with no study.
Stage rigging
The array is a point load on a rated grid. Building steel is not a rigging system.
Tuning and operation
A DSP file, who may change it on show night, and a measurement after the room fills if absorption changes.
Design sequence
- 01
Draw the seating section from the available hang point: the start of the audience, the end, and the balconies.
- 02
Ask whether one cabinet or a Point Source cluster covers the section. If yes, stop drawing an array.
- 03
If the array remains, build the splay on the section until the angles cover the seats and stay off the ceiling and the front row.
- 04
Count modules from that curvature and from the length needed for control, not from a reference photograph.
- 05
Add Subwoofer and delayed fills as systems, then a measurement plan, not an ear session at the mixer.
Delivery sequence
- 01
The frame is hung on the designed points after the load is reviewed with the rigging lead.
- 02
Splay angles are set as in the prediction file and locked. An approximate angle on site is a different array.
- 03
The DSP is loaded with the file that matches those angles. Another hall’s file is not borrowed.
- 04
Measurement microphones go in agreed seats before the audience arrives.
- 05
The crossover to the Subwoofer is checked on the measurement, not only on how the curve looked in the office.
Testing
Transfer function
Magnitude and phase in seats that represent the section. An RTA alone does not set a delay.
Coverage, not the bright spot
Front, depth, and under the balcony. One good seat does not pass the hang.
No invented cabinet figure
Compare with the brief’s target if there is one, or with even coverage. No model SPL is written from this page.
Commissioning
Handover of the file
Angles, heights, the DSP preset, and the measurement positions. Without the file there is no system to restore.
STI where required
If the criterion is speech, the method is IEC 60268-16. This page does not calculate the index.
A show-level run
Limiters are checked at operating level, not at a whisper. No named-cabinet level is stated here.
Maintenance
A changed angle
Any splay opened for maintenance goes back to the file or the prediction is rerun. One degree on a long array moves the section.
Replacing a module
From the same series. A different box in the column breaks the prediction even if it bolts to the frame.
Remeasure after seating changes
Plusher seats or new curtains change the room. The old file is no longer this hall’s tune.
Common mistakes
Count from appearance
Ten modules because the photograph had ten, in a hall one cabinet covers. The budget was spent on the shape.
An array instead of acoustics
RT60 and the noise floor keep STI poor. The equipment does not purchase the room.
A straight hang
Zero angles on a deep section concentrate energy at one distance and leave the rest. Curvature is the design.
Measuring at the mix position
A technician’s ear is not the last balcony seat and not the seat under it. Coverage is a grid of seats.
Short comparison
The comparison is a way to choose a path. It is not a product recommendation and it is not a code.
| Path | Fits when | Weakens when |
|---|---|---|
| Line Array | A long throw and a vertical section that needs aim changing with distance. | A short room, or too few modules to form a line. You pay for an array and hear a point source. |
| Point Source | The seats sit inside one pattern or a small cluster, and the budget is more useful in the room. | When the last seat is outside the pattern and raising the level burns the front row. |
| Many boxes with no splay | There is no design case. This is an installation error that resembles an array. | Always. Energy concentrates, and a prediction that assumed angles does not match the hang. |
Discussion ranges
Any number here is a preliminary discussion range from practice or a named reference. Replace it with the project criterion, laboratory data, and on-site measurement.
| Item | What is discussed | Limit of this page |
|---|---|---|
| 6 dB and 3 dB per doubling | A point source in the free field falls about 6 dB per doubling of distance. A very long line approaches 3 dB over part of its behaviour. | A real array is finite and depends on frequency and distance. The figure is not a coverage prediction and not a cabinet SPL. Do not copy it into a quotation. |
| Module count | The result of the section angle, the splay, and the length needed for vertical control. | No count on this page. A count taken from a reference photograph with no section is rejected. |
| Splay angles | Degrees between cabinets built on the section: tighter for the far seats and wider for the near seats in the usual shape. | No ready-made degree here. The angle comes from prediction for that section, then from measurement. Copying another hall’s angle misses the coverage. |
| An STI or level target | Written in the brief if speech or the programme requires it, and measured by the named method. | IEC 60268-16 for STI. No named-cabinet SPL on this page, and no index calculated in place of a measurement. |
What this page does not claim
No fire classification, absorption coefficient, sound pressure level, or legal capacity on this page may be copied into a quotation. Those values come from a product test report, a measurement, or the local code adopted for the project.
Questions designers and owners ask
Does every hall need a Line Array?
No. A short room, and seats inside one pattern, are often clearer and cheaper with a point source. The array is a tool for throw and vertical coverage.
Who decides the box count?
Prediction on this hall’s section, then measurement. Not a catalogue of photographs and not this page.
Do I hide the subwoofer inside the array count?
No. Low frequency is a system with its own position and delay. Counting speech boxes does not design it.
Why measure if the prediction is good?
The room, the real angle, and the gain differ. The transfer function in the seats is the tune. Prediction is a hypothesis.
Do you publish a level for a model?
No. There is no SPL for a named cabinet here. The target is in the brief and the measurement, and the data are in the manufacturer file under its conditions.
Technical sources
- The manufacturer file for the series in use
Directivity, mechanical load, and prediction data under their conditions. This page extracts neither an SPL nor a module count.
- IEC 60268-16
If speech acceptance is an STI. This page does not perform the method.
- The rigging standard and the engineer of record
Hang load and the safety factor. This page does not quote a factor as if it were code text.
Last editorial review: 2026-10-06. Review means the text was checked, not that a project was measured.
Turn the question into a brief
A study starts from room volume, use, and existing condition, not from a product name. Fill the brief and copy it.
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