L-Acoustics KS21i Owner's Manual
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L-Acoustics KS21i Owner's Manual

L-Acoustics KS21i Owner's Manual

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Summary of Contents for L-Acoustics KS21i

  • Page 1 KS21i owner's manual (EN)
  • Page 2 Document reference: KS21i owner's manual (EN) version 4.0 Distribution date: June 9, 2025 © 2025 L-Acoustics. All rights reserved. No part of this publication may be reproduced or transmitted in any form or by any means without the express written consent of the publisher.

  • Page 3: Table Of Contents

    Ai-FIXBRACKET............................20 Front screen................................21 Mechanical safety................................24 Loudspeaker configurations............................. 26 KS21i in standard configuration..........................26 KS21i in cardioid configuration..........................27 Inspection and preventive maintenance.......................... 28 How to do preventive maintenance........................28 Rigging part inspection............................29 Mechanical system overview..........................29 Adjustable fins check............................33 Acoustical check..............................34...
  • Page 4 Mounting an assembly with A15KS-Ui.......................45 Mounting an assembly on a ceiling with Ai-FIXBRACKET................51 Stacking................................. 55 Stacking KS21i............................55 Securing a screen..............................58 Connection to LA amplified controllers..........................60 Cabling schemes..............................60 Cabling...................................62 Corrective maintenance..............................66 KS21i..................................66 Specifications..................................71 KS21i..................................71 A15i-BUMP................................73 A15KS-Ui................................

  • Page 5: Safety

    Respect the Working Load Limit (WLL) of third party equipment. L-Acoustics is not responsible for any rigging equipment and accessories provided by third party manufacturers. Verify that the Working Load Limit (WLL) of the suspension points, chain hoists and all additional hardware rigging accessories is respected.
  • Page 6 This system is intended for use by trained personnel for professional applications. As part of a continuous evolution of techniques and standards, L-Acoustics reserves the right to change the specifications of its products and the content of its documents without prior notice.

  • Page 7: Introduction

    KS21i features one high excursion, direct-radiating 21'' transducer mounted in a bass-reflex tuned enclosure. KS21i couples with A15i and A10i to reinforce contour and extend bandwidth to 29 Hz and 31 Hz respectively. KS21i features L-Vents that substantially reduce turbulence and port noise at high levels while also increasing LF efficiency.

  • Page 8: Revision History

    APPENDIX C: Specifications for custom rigging systems (p.80). Jun. 2025 • Added A15KS-Ui rigging accessory, replacing discontinued A- U15i. • Added ferrule specifications for Cabling (p.62). • Updated mechanical safety for stacked KS21i. • Minor fixes and improvements. KS21i owner's manual (EN) version 4.0...

  • Page 9: System Components

    Refer to the LA2Xi / LA4X / LA7.16i / LA12X owner's manual for detailed instructions about the whole cabling scheme, including modulation cables and network. Rigging elements A15i-BUMP Flying frame for vertical deployment of A15i and KS21i A15KS-Ui U-bracket for A15i and KS21i CLAMP250...
  • Page 10 System components System component illustrations Cables 2 × 2.5 mm² cable custom 2-point speakON cable Rigging accessories A15i-BUMP A15KS-Ui CLAMP250 Rigging plates KS21i-LINK KS21i- KS21i-ULINK II FIXBRACKET ENDLINK Screens KS21i-SCREEN KS21i owner's manual (EN) version 4.0...
  • Page 11 System components Software applications Soundvision LA Network Manager KS21i owner's manual (EN) version 4.0...

  • Page 12: Electro-Acoustical Description

    Each set of terminal block connectors (+ and −) can be used interchangeably as IN or LINK connector. KS21i 1 × 4-point terminal block with push-in connection Internal pinout for L-Acoustics subwoofers Terminal block points IN + IN - Transducer connectors LF + LF - KS21i owner's manual (EN) version 4.0...

  • Page 13: Rigging System Description

    Rigging system description Rigging system description KS21i KS21i is compatible with four types of rigging plate kits: • standard rigging plates • S-shaped standard rigging plates (KS21i-LINK) (KS21i-SLINK) • end rigging plates • S-shaped end rigging plates (KS21i-ENDLINK) (KS21i-ENDSLINK) KS21i features 18 inserts on each side: •...
  • Page 14 Rigging system description Rigging screws Only use the rigging screws provided by L-Acoustics. Do not use the placeholder screws for rigging. Always put the placeholder screws back in place to avoid leaks. A DIN580-compatible M8 threaded insert is available to implement a secondary safety.

  • Page 15: Rigging Elements

    Rigging elements A15i-BUMP A15i-BUMP is a reversible rigging frame for flying vertical arrays of KS21i. A15i-BUMP is secured to the array with four M6x18 rigging screws and M6 nuts (provided). Multiple pickup points are available for site angle adjustments: 16 pickup points on each side, one front pickup point (F), and one rear pickup point (R).
  • Page 16 Rigging system description A15i-BUMP can be used as the main lifting accessory for flying vertical arrays of KS21i with one or two lifting points. KS21i owner's manual (EN) version 4.0...

  • Page 17: A15Ks-Ui

    A15KS-Ui A15KS-Ui is a U-bracket for mounting KS21i on a ceiling, a wall, or a truss. In combination with KS21i-ULINK II, A15KS-Ui can be used to mount or fly vertical arrays of two KS21i. KS21i owner's manual (EN) version 4.0...
  • Page 18 Rigging system description Do not use rigging plates other than KS21i-ULINK II between two KS21i mounted on A15KS-Ui. A15KS-Ui is secured to each side of the enclosure by two M8 screws: the central screw and the angulation screw. central screw angulation screw Position the central screw in the bottom insert to reduce space between the enclosure and the ceiling.
  • Page 19 Ø 15.2 mm / 0.6 in Ø 9 mm / 0.35 in Ø 11 mm / 0.43 in Fasteners for wall-mounting or ceiling-mounting Select screw length and anchors applicable to the wall or ceiling properties. KS21i owner's manual (EN) version 4.0...

  • Page 20: Ai-Fixbracket

    Rigging system description Ai-FIXBRACKET Ai-FIXBRACKET is a set of four fastening brackets for KS21i. The enclosure is secured to Ai-FIXBRACKET using the slotted hole. Secure Ai-FIXBRACKET at the bottom of an array to improve stability. Ai-FIXBRACKET can also be used to mount up to two KS21i under the ceiling.

  • Page 21: Front Screen

    Rigging system description Front screen The KS21i system features an acoustically transparent front screen suitable for every configuration. KS21i-SCREEN KS21i owner's manual (EN) version 4.0...
  • Page 22 The screws of the grill and the placeholder screws on the fins side can be removed through the rigging plates. The screens are equipped with tabs to hold the grill in place when securing the screen on the enclosure. KS21i owner's manual (EN) version 4.0...
  • Page 23 Rigging system description KS21i-SCREEN can be secured to the back of KS21i when used in cardioid configuration. The cable(s) can be passed through a cutout on the screen side. KS21i owner's manual (EN) version 4.0...

  • Page 24: Mechanical Safety

    Mechanical safety Mechanical safety Flown configurations The KS21i rigging system complies with 2006/42/EC: Machinery Directive. It has been designed following the guidelines of BGV-C1. 2006/42/EC: Machinery Directive specifies a safety factor of 4 against the rupture. The flown deployments described in this manual achieve a safety factor of 4 or more.

  • Page 25: Assessing Mechanical Safety

    Soundvision calculations are based on usual environmental conditions. A higher safety factor is recommended with factors such as extreme high or low temperatures, strong wind, prolonged exposition to salt water, etc. Always consult a rigging specialist to adopt safety practices adapted to such a situation. KS21i owner's manual (EN) version 4.0...

  • Page 26: Loudspeaker Configurations

    Loudspeaker configurations KS21i in standard configuration Deployed in a standard configuration, a KS21i system operates with an omnidirectional directivity pattern over the nominal bandwidth of the KS21i enclosure. The [KS21_60] and [KS21_100] factory presets provide the subwoofer system with an upper frequency limit at 60 Hz and 100 Hz respectively in order to optimize the acoustic coupling with a main full-range system.

  • Page 27: Ks21I In Cardioid Configuration

    Deployed in a cardioid configuration, a KS21i system produces a rear SPL rejection. The deployment consists of an array of four KS21i with one element turned towards the rear (reversed). Refer to the Cardioid Configuration technical bulletin for more information.

  • Page 28: Inspection And Preventive Maintenance

    Rigging part inspection (p.29) on each rigging part. Use the Mechanical system overview (p.29) to identify critical parts of the system. If any parts are damaged, contact your L-Acoustics representative for further instructions. Acoustics Perform the Enclosure check (p.34). Perform the Listening test (p.36) to detect any degradation in sound quality.

  • Page 29: Rigging Part Inspection

    • screens mounted on enclosures This inspection procedure covers only L-Acoustics products. To inspect other products that are part of the lifting chain, refer to the manufacturer's instructions. Prerequisite Perform the inspection in a well-lit environment.
  • Page 30 Inspection and preventive maintenance A15i Wide/Focus and KS21i array with A15i-BUMP and M-BARi shackle axis end is flush with the shackle rigging axes are secured with nuts and safety pins nuts are secured and tightened Rigging part inspection (p.29) Rigging part inspection (p.29)
  • Page 31 Inspection and preventive maintenance KS21i and A15i Wide/Focus ceiling-mounted with A15KS-Ui the supporting screws are tightened Rigging part inspection (p.29) Adjustable fins check (p.33) KS21i and A15i Wide/Focus ceiling-mounted with Ai-FIXBRACKET the supporting screws are tightened Rigging part inspection (p.29) Adjustable fins check (p.33)
  • Page 32 Inspection and preventive maintenance A15i Wide/Focus stacked on KS21i Adjustable fins check (p.33) Rigging part inspection (p.29) the fixing brackets are present and the plates are not bent tightened to the ground KS21i owner's manual (EN) version 4.0...

  • Page 33: Adjustable Fins Check

    5. When rigging and flying , check that the fins do not move because of gravity or wind pressure. What to do next Fins that do not pass the check must be replaced. Contact your L-Acoustics representative for repair instructions. KS21i owner's manual (EN) version 4.0...

  • Page 34: Acoustical Check

    6. Launch the ENCLOSURE CHECK. The amplified controller generates short sinusoidal signals simultaneously for each connected output. The amplified controller displays the results for each output. KS21i owner's manual (EN) version 4.0...
  • Page 35 Low variations from the typical reference value are acceptable: displayed percentage can be different from 0 and all transducers considered operational. These variations can be caused by the room temperature being different from the ideal 20 °C / 68 °F, and by component or cable tolerances. KS21i owner's manual (EN) version 4.0...

  • Page 36: Listening Test

    4. Carefully clean the speaker with a dry cloth. 5. Perform the reassembly procedure. Replace the speaker gasket and the screws. Apply the recommended torque. 6. Repeat the listening test. If the problem persists, replace the speaker. KS21i owner's manual (EN) version 4.0...
  • Page 37 One or more enclosure produces a high-pitched, leaking air sound. Possible cause • Placeholder screws are missing. Procedure Visually inspect the screws on each side of the enclosures. Secure placeholder screws in the empty inserts. KS21i owner's manual (EN) version 4.0...

  • Page 38: Rigging Procedures

    Securing rigging plates on an enclosure • Make sure that the inserts for the screens are accessible. Driving screws Do not fully tighten the screws unless otherwise instructed. Follow the indicated torque when tightening a screw. KS21i owner's manual (EN) version 4.0...
  • Page 39 Securing rigging plates between two enclosures • Always secure standard rigging plates with the linking section upwards. • After securing an enclosure to another enclosure, tighten all the screws on the supporting enclosure. 5 N.m KS21i owner's manual (EN) version 4.0...

  • Page 40: Tools

    Other manufacturers can be used. Name Reference Distributor set of 6-point 1/4" sockets RL.NANO1 / R.360NANO FACOM electric screwdriver with torque selector torque screwdriver (2 - 10 N.m) A.404 FACOM 10 mm wrench KS21i owner's manual (EN) version 4.0...

  • Page 41: Flying

    KS21i-LINK Rigging plates for KS21i Risk of falling objects Verify that no unattached items remain on the product or assembly. Secondary safety Use available holes on the rigging accessories to implement a secondary safety. KS21i owner's manual (EN) version 4.0...
  • Page 42 Procedure 1. Prepare the enclosures by removing the placeholder screws and securing rigging plates on both sides. KS21i 2. Secure A15i-BUMP on top of KS21i. Use the torque screwdriver and set the torque to 5 N.m. 5 N.m 3. Select the pick-up point and raise the array.
  • Page 43 Hold the enclosure at the bottom until the rigging plates are secured. Lift the rear of the new KS21i and secure it to the array by pre-tightening a rigging screw on both sides. b) Remove the rigging screws at the bottom front on both sides of the supporting KS21i.
  • Page 44 Rigging procedures e) Repeat the procedure until the KS21i array is completed. 5. Check that all the screws are secured and tightened and raise the array. Use the torque screwdriver and set the torque to 5 N.m. What to do next •...

  • Page 45: Wall-Mounting Or Ceiling-Mounting

    A15KS-Ui in horizontal position, with 1 enclosure 275 daN 65 daN Wall-mounted A15KS-Ui in horizontal position, with 2 enclosures 375 daN 75 daN A15KS-Ui in vertical position, with 1 enclosure 40 daN 30 daN Ceiling-mounted 150 daN — KS21i owner's manual (EN) version 4.0...
  • Page 46 781 mm / 30.7 in 120 mm / 4.7 in 2. Prepare a KS21i by removing the placeholder screws at the center of each side of the enclosure. 3. Using the screws provided with A15KS-Ui, drive a screw on both sides.
  • Page 47 Hold the enclosure at the bottom on each side. 5. Set the angle: For a single enclosure: a. Rotate the enclosure to align the second insert with the selected site angle. b. Drive a screw on both sides. KS21i owner's manual (EN) version 4.0...
  • Page 48 (p.77) for a list of possible site angles for each enclosure. Do not use rigging plates other than KS21i-ULINK II between two KS21i mounted on A15KS-Ui. a. Slide the KS21i-ULINK II rigging plates on A15KS-Ui, with the hooks facing front.
  • Page 49 Tighten all the screws. Use the torque screwdriver and set the torque to 7 N.m. 6. Prepare a new KS21i by removing the two placeholder screws at the center of each side of the enclosure. KS21i owner's manual (EN) version 4.0...
  • Page 50 7 N.m If the two enclosures are misaligned at the front, loosen the screws on the U-rigging plates and realign the two enclosures, then re-tighten the screws. What to do next Securing a screen (p.58) KS21i owner's manual (EN) version 4.0...

  • Page 51: Mounting An Assembly On A Ceiling With Ai-Fixbracket

    In a ceiling-mounted configuration, the array applies a force of 60 daN on the anchoring points. Assembly Procedure 1. Secure Ai-FIXBRACKET to the ceiling using M10 screws. Fasteners for ceiling-mounting Select screw length and anchors applicable to the ceiling properties. 828 mm / 32.6 in KS21i owner's manual (EN) version 4.0...
  • Page 52 Hold the enclosure at the bottom until the rigging plates are secured. 4. Lift the front of the enclosure and secure it to Ai-FIXBRACKET. 5. Tighten the screws on Ai-FIXBRACKET. Use the torque screwdriver and set the torque to 5 N.m. KS21i owner's manual (EN) version 4.0...
  • Page 53 7. Remove the bottom screws of the supporting enclosure. 8. Link the two enclosures at the rear by pre-tightening a rigging screw on both sides. This step requires three operators. Hold the enclosure at the bottom until the rigging plates are secured. KS21i owner's manual (EN) version 4.0...
  • Page 54 9. Link the two enclosures at the front by pre-tightening a rigging screw on both sides. 10. Check that all the screws are secured and tightened. Use the torque screwdriver and set the torque to 5 N.m. 5 N.m What to do next Securing a screen (p.58) KS21i owner's manual (EN) version 4.0...

  • Page 55: Stacking

    Always secure a stacked array to the ground using Ai-FIXBRACKET to ensure stability of the array. Ai-FIXBRACKET in stacked configuration In a stacked configuration, the array applies a force of 110 daN on the anchoring points. KS21i owner's manual (EN) version 4.0...
  • Page 56 Rigging procedures Assembly Procedure 1. Prepare a KS21i by removing the placeholder screws and securing rigging plates on both sides. 2. Secure Ai-FIXBRACKET to the ground using M10 screws. Select screw length and anchors applicable to ground properties. 828 mm / 32.6 in 3.
  • Page 57 Rigging procedures 4. Secure up to three additional KS21i on top of the first one. For the last KS21i, use KS21i-ENDLINK. Tighten all the screws on the previous enclosure after securing each new enclosure. Use the torque screwdriver and set the torque to 5 N.m.

  • Page 58: Securing A Screen

    2. Secure the screen using the provided rigging screws. Use the torque screwdriver and set the torque to 5 N.m. For configurations with A15KS-Ui, stick the provided washers to the screen before securing it on the enclosure. KS21i owner's manual (EN) version 4.0...
  • Page 59 Always use the self-sticking washers for securing screens when there are no rigging plates on the enclosure. If KS21i is reversed (cardioid configuration), connect the cables to the enclosure before securing KS21i- SCREEN. Pass the cables through the cutout on the screen side.

  • Page 60: Connection To La Amplified Controllers

    Power Budget values, otherwise the Fuse Protect algorithm may be triggered. For LA7.16(i), when powered by a 100 V power supply, reduce the number of enclosures in order not to exceed 75% of the power gauge. KS21i owner's manual (EN) version 4.0...
  • Page 61 Refer to the cabling schemes to connect the enclosures to different types of output configurations. One-channel speakON output custom cable 2.5 mm² cable 1+/1- Two-channel speakON output custom cable 2.5 mm² cable 1+/1- 2+/2- 2.5 mm² cable KS21i owner's manual (EN) version 4.0...

  • Page 62: Cabling

    This procedure describes how to connect the input cable to the enclosure. If the enclosure must be connected in parallel, remove the protective plug from the second cable gland and proceed identically for both cables. Procedure 1. On the connector sealing plate, remove the sealing nut from the cable gland. KS21i owner's manual (EN) version 4.0...
  • Page 63 Connection to LA amplified controllers 2. Insert the cable through the sealing nut and the cable gland. 3. Strip the wires of the cable. KS21i owner's manual (EN) version 4.0...
  • Page 64 4. Push the wires into the terminals. If necessary, use a small tool in the hole next to the terminal to unlock it. 5. Secure the connector sealing plate to the connector plate. 3 N.m KS21i owner's manual (EN) version 4.0...
  • Page 65 Connection to LA amplified controllers 6. Tighten the sealing nut. What to do next To remove the cables use the small tool to unlock the terminals and pull on the wires. KS21i owner's manual (EN) version 4.0...

  • Page 66: Corrective Maintenance

    • D/R - LF speaker (p.69) For advanced maintenance, contact your L-Acoustics representative. Exploded views In order to operate, follow the order outlined here. Each assembly refers to the corresponding Disassembly/ Reassembly (D/R) procedure and the necessary repair kit (KR).

  • Page 67: Disassembly And Reassembly Procedures

    For safety reasons, always use the new screws and spare parts provided in the KR. If no new screws are available, use blue threadlocker. If necessary, use a small screwdriver as a lever to remove the grill. 3 N.m KS21i owner's manual (EN) version 4.0...
  • Page 68 For safety reasons, always use the new screws and spare parts provided in the KR. If no new screws are available, use blue threadlocker. For reassembly, slide the fixing bars under the vent panel to attach them to the studs, then secure them with the screws. 5 N.m KS21i owner's manual (EN) version 4.0...
  • Page 69 For safety reasons, always use the new screws and spare parts provided in the KR. If no new screws are available, use blue threadlocker. Gradually tighten the screws following a star pattern. Tilt the speaker to remove it from the cabinet. Carefully disconnect the cables. 5 N.m KS21i owner's manual (EN) version 4.0...
  • Page 70 Corrective maintenance If the speaker gasket is damaged, remove and replace it. KS21i owner's manual (EN) version 4.0...

  • Page 71: Specifications

    Pantone 426 C pure white RAL 9010 custom RAL code on special order IP55 Peak level at 1 m under half space conditions using pink noise with crest factor 4 (preset specified in brackets). KS21i owner's manual (EN) version 4.0...
  • Page 72 Specifications KS21i dimensions 752 mm / 29.6 in 602 mm / 23.7 in KS21i owner's manual (EN) version 4.0...

  • Page 73: A15I-Bump

    Specifications A15i-BUMP specifications Description Flying frame for vertical deployment of A15i and KS21i Weight (net) 16 kg / 35 lb Material high grade steel with anti-corrosion coating A15i-BUMP dimensions 656 mm / 25.8 in 600 mm / 23.6 in 758 mm / 29.8 in...

  • Page 74: A15Ks-Ui

    A15KS-Ui dimensions 825 mm / 32.5 in 161 mm / 6.3 in Ø 15.2 mm / 0.6 in Ø 9 mm / 0.35 in Ø 11 mm / 0.43 in KS21i owner's manual (EN) version 4.0...

  • Page 75: Clamp250

    CLAMP250 dimensions 167 mm / 6.6 in 103 mm / 4.1 in Ai-FIXBRACKET specifications Description Fastening bracket for A15i, A10i and KS21i Weight (net) 0.45 kg / 1 lb Material high grade steel with anti-corrosion coating Ai-FIXBRACKET dimensions 35 mm / 1.4 in...

  • Page 76: Ks21I-Screen

    Specifications KS21i-SCREEN specifications Description Acoustically transparent front screen for KS21i Weight (net) 3.1 kg / 6.8 lb Materials steel with anti-corrosion coating acoustically neutral 3D fabric KS21i-SCREEN dimensions 771 mm / 30.4 in 110 mm / 4.3 in KS21i owner's manual (EN) version 4.0...

  • Page 77: Appendix A: Configurations With A15Ks-Ui

    0° (site) 0° — A+B (center 0° (site) -5° / +5° 10° screw) -90° (site) -20° / +20° 10° 0° / +20° (wall)* 0° (site) 10° -20° / +20° (pillar) 0° (site) 0° — KS21i owner's manual (EN) version 4.0...
  • Page 78 (-30° to 0° (azimuth) 10° +30°) A+B -20° / +20° (pillar) * The cables and connectors at the back of KS21i limit the range of possible site or azimuth angles when the assembly is wall-mounted. KS21i owner's manual (EN) version 4.0...

  • Page 79: Appendix B: Recommendation For Speaker Cables

    4 Ω load 2.7 Ω load ‒ ‒ Use the more detailed L-Acoustics calculation tool to evaluate cable length and gauge based on the type and number of loudspeakers connected. The calculation tool is available on our website: https://www.l-acoustics.com/installation- tools/...

  • Page 80: Appendix C: Specifications For Custom Rigging Systems

    Specifications for custom rigging Specifications for custom rigging Dimensions 752 + 3 mm / 29.6 + 0.12 in KS21i Center of gravity 291 mm / 11.5 in KS21i KS21i owner's manual (EN) version 4.0...
  • Page 81 Take into consideration the number of inserts used, weight and center of gravity of enclosure(s), and resulting action forces. Prevent screws from loosening (threadlocker, spring washer...). KS21i has 24 threaded M6 inserts and 4 threaded M8 inserts available for rigging. M6 standard inserts M6 shallow depth...
  • Page 82 L-Acoustics 13 rue Levacher Cintrat - 91460 Marcoussis - France +33 1 69 63 69 63 - info@l-acoustics.com www.l-acoustics.com...

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