L-Acoustics KS28 User manual

KS28
user manual (EN)

Document reference: KS28 user manual (EN) version 3.0
Distribution date: March 7, 2017
© 2017 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.

Contents
Safety................................................................................................................................................................ 4
Instructions................................................................................................................................................4
Symbols................................................................................................................................................... 4
Welcome........................................................................................................................................................... 5
System components.............................................................................................................................................6
Loudspeaker cables...................................................................................................................................7
Loudspeaker congurations..................................................................................................................................8
KS28 in standard conguration..................................................................................................................8
KS28 in cardioid conguration.................................................................................................................. 9
Loudspeaker connection.................................................................................................................................... 10
Connectors............................................................................................................................................. 10
Connection to LA12X.............................................................................................................................. 11
Preset description..............................................................................................................................................13
Recommendation for speaker cables...................................................................................................................14
Maintenance.................................................................................................................................................... 15
Disassembly and Reassembly procedures.................................................................................................. 15
D/R - Grill....................................................................................................................................16
D/R - LF loudspeaker.....................................................................................................................19
Acoustical check..................................................................................................................................... 20
Enclosure check........................................................................................................................... 20
Listening test................................................................................................................................. 22
KS28 specications...........................................................................................................................................23
3

Safety
Safety
Instructions
Inspect the product before operation.
If any sign of defect or damage is detected, immediately withdraw the product from use for maintenance.
Never incorporate equipment or accessories not approved by L-Acoustics.
Read all the related PRODUCT INFORMATION documents shipped with the products before
exploiting the system.
Do not store the product on an unstable cart, stand, tripod, bracket, or table.
Beware of sound levels.
Do not stay within close proximity of loudspeakers in operation.
Loudspeaker systems are capable of producing very high sound pressure levels (SPL) which can instantaneously
lead to permanent hearing damage to performers, production crew and audience members. Hearing damage
can also occur at moderate level with prolonged exposure to sound.
Check the applicable laws and regulations relating to maximum sound levels and exposure times.
This system is intended for professional use.
Read the RIGGING MANUAL before installing the system.
Use the rigging accessories described in the rigging manual and follow the associated procedures.
Read the maintenance section of this document before servicing the product.
Do not expose the product to extreme conditions.
Do not expose the product to rain or sea spray.
Do not expose the product to moisture (mist, steam, humidity, condensation…) or excessive heat (direct sun,
radiator…) for a long period of time.
Contact L-Acoustics for advanced maintenance.
Any unauthorized maintenance operation will void the product warranty.
Symbols
The following symbols are used in this document:
This symbol indicates a potential risk of harm to an individual or damage to the product.
It can also notify the user about instructions that must be strictly followed to ensure safe installation or operation of
the product.
This symbol noties the user about instructions that must be strictly followed to ensure proper installation or
operation of the product.
This symbol noties the user about complementary information or optional instructions.
KS28 user manual (EN) version 3.0 4

Welcome
Welcome
Thank you for purchasing the L-Acoustics KS28.
This document contains essential information on using the system properly.
As part of a continuous evolution of techniques and standards, L-Acoustics reserves the right to
change the specications of its products and the content of its document without prior notice. Please
check www.l-acoustics.com on a regular basis to download the latest document and software updates.
KS28 reference subwoofer
The KS28 is a reference subwoofer designed to extend the frequency response of large format systems. The KS28
features two high excursion, 18’’ direct radiating transducers mounted in a bass-reex tuned enclosure. The optimized L-
Vents laminar vented port reduce turbulence and port noise at high levels while also increasing LF efciency.
The KS28 operates from 25 Hz. The excursion capability of the transducer, combined with L-Vents contributes to deliver a
high SPL, with low distortion. The KS28 can offer standard or cardioid directivity, by combining physical deployment and
the suitable preset.
The KS28 is the rst L-Acoustics enclosure to fully utilize the LA12X amplied controller power. The LA12X ensures
advanced crossover functions, linearization and L-Drive protection of the transducers. Its onboard library offers standard
and cardioid presets, each available with two low-pass lters to accommodate various coupling conditions and LF
contour requirements.
The KS28 cabinet is assembled with birch and beech plywood panels. The use of panels optimized for thickness and
combined with stiffeners gives the KS28 maximized internal volume, mechanical integrity and a low weight of 79 kg. It
feature six ergonomic handles for a solid grip and efcient handling. Bottom and side runners ensure safe stacking. A
two-point suspension system is ush-mounted into the cabinet.
The KS28 is the ideal companion to large format systems in stacked or own deployments. KS28 can signicantly boost
the LF extension and contour of line sources.
The KS28 can be stacked horizontally or vertically in standard or cardioid arrangements. With KS28-BUMP, KS28 can
be own in vertical arrays of standard or cardioid arrangements, up to 16 units.
5 KS28 user manual (EN) version 3.0

System components
System components
Loudspeaker enclosures
KS28 Flyable subwoofer 2 x 18''
Powering and driving system
LA12X Amplied controller with DSP, preset library and networking capabilities
LA-RAK II Touring rack containing three LA12X, LA-POWER II for power distribution and LA-PANEL II for
audio and network distribution
Refer to the LA12X user manual for operating instructions.
Loudspeaker cables
SP cables 4-point speakON loudspeaker cables (4mm² gauge)
SP cables come in four sizes: SP.7 (0.7m/2.3ft), SP5 (5m/16.4ft), SP10 (10 m/32.8ft) and
SP25 (25m/82ft)
SP-Y1 breakout cable for two passive enclosures (2.5mm² gauge) provided with a CC4FP adapter
4-point speakON to 2 × 2-point speakON
DO 8-point PA-COM loudspeaker cables (4mm² gauge)
DO cables come in three sizes: DO.7 (0.7m/2.3ft), DO10 (10m/32.8ft) and DO25
(25m/82ft)
DOSUB-LA8 breakout cable for four passive enclosures (4mm² gauge)
8-point PA-COM to 4 × 2-point speakON
DO3WFILL breakout cable for one 2-way active enclosure and two passive enclosures (4mm² gauge)
8-point PA-COM to 1 x 4-point speakON and 2 x 2-point speakON
Information about the connection of the enclosures to the LA ampliers is given in this
document.
Refer to the LA12X user manual for detailed instructions about the whole cabling scheme, including modulation
cables and network.
Rigging elements
Rigging elements or procedures are not presented in this document.
Refer to the KS28 rigging manual.
Software applications
Soundvision 3D acoustical and mechanical modeling software
LA Network Manager Software for remote control and monitoring of amplied controllers
Refer to the Soundvision help.
Refer to the LA Network Manager video tutorial.
KS28 user manual (EN) version 3.0 6

System components
Loudspeaker cables
0.7 m / 5 m / 10 m / 25 m
CH(1)
CH(2)
1 m
SP.7 / SP5 / SP10 / SP25 SP-Y1
0.7 m / 10 m / 25 m
SPK1
SPK2
SPK3
SPK4
5 m
DO.7 / DO10 / DO25 DOSUB-LA8
2W CH(A)
2W CH(B)
3.5 m
DOFILL-LA8
7 KS28 user manual (EN) version 3.0

Loudspeaker congurations
Loudspeaker congurations
KS28 in standard conguration
Deployed in a standard conguration, a KS28 system operates with an omnidirectional directivity pattern over the
nominal bandwidth of the KS28 enclosure.
The [KS28_60] and [KS28_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.
The KS28 subwoofers can only be driven by the LA12X amplied controller.
vertical
on-end
block
stacked
upright
horizontal
Preset [KS28_60] [KS28_100]
Low frequency limit (-10 dB) 25 Hz
Delay values
When combining a line source with subwoofers, delays may have to be added to the presets.
Refer to the Preset Guide to obtain the pre-alignment delay values.
Grouping subwoofers
Place the subwoofer enclosures side by side. If not possible, the maximum distance between two adjacent
acoustic centers must be 2.8m or 1.7m if the upper frequency limit of the subwoofer system is at 60Hz or
100Hz, respectively.
KS28 user manual (EN) version 3.0 8

Loudspeaker congurations
KS28 in cardioid conguration
Deployed in a cardioid conguration, a KS28 system produces a rear SPL rejection. The deployment consists of an array
of four KS28 with one reversed element, i.e. turned towards the rear. Refer to the Cardioid Congurations technical
bulletin for more information.
The [KS28_60_C] and [KS28_100_C] 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.
The KS28 subwoofers can only be driven by the LA12X amplied controller.
vertical
on-end
block
stacked
upright
Preset [KS28_60_C] [KS28_100_C]
Low frequency limit (-10 dB) 25 Hz
Delay values
When combining a line source with subwoofers, delays may have to be added to the presets.
Refer to the Preset Guide to obtain the pre-alignment delay values.
Grouping subwoofers
Place the subwoofer enclosures side by side. If not possible, the maximum distance between two adjacent
acoustic centers must be 2.8m or 1.7m if the upper frequency limit of the subwoofer system is at 60Hz or
100Hz, respectively.
9 KS28 user manual (EN) version 3.0

Loudspeaker connection
Loudspeaker connection
Connectors
KS28 is equipped with one 4-point speakON connector.
KS28
IN
1k = IN k
1 - = IN -
Znom. = 4 Ω
Readmanual and safety
instructionsbefore use
Madein France
EuropeanCommunity
SAFE USE:
16 KS28
FOROTHERCONFIGURATIONS,CHECKMECHANICAL
SAFETYWITHSOUNDVISIONSOFTWARE
USEONLYWITHL-ACOUSTICSAMPLIFIEDCONTROLLERS .
KS28
Weight:79 kg / 174 lb
Internal pinout for L-Acoustics subwoofers
speakON points 1 + 1 - 2 + 2 -
Transducer connectors LF + LF - Not linked Not linked
KS28 user manual (EN) version 3.0 10

Loudspeaker connection
Connection to LA12X
Maximum number of enclosures per LA12X
enclosure max enclosures in parallel max enclosures per controller
KS28 1 4
Impedance load
KS28
1 enclosure: 4 Ω
Connecting subwoofers
SP and SP-Y1 on speakON output
OUT1/OUT2 OUT3/OUT4
same as OUT1/OUT2
SP SP-Y1
CC4FP
CH(1) (OUT1)
CH(2) (OUT2)
DO and DOSUB-LA8 on CA-COM output
CA-COM
DO
DOSUB-LA8
SPK1 (OUT1)
SPK2 (OUT2)
SPK3 (OUT3)
SPK4 (OUT4)
11 KS28 user manual (EN) version 3.0

Loudspeaker connection
Connecting a 2-way active enclosure with subwoofers
DO and DO3WFILL on CA-COM output
CA-COM
DO
DO3WFILL
2WAY (OUT3/4)
SUB1 (OUT1)
SUB2 (OUT2)
SP
KS28 user manual (EN) version 3.0 12

Preset description
Preset description
[KS28_60] [KS28_100]
outputs channels routing gain delay polarity mute
OUT 1 SB IN A 0 dB 0 ms + ON
OUT 2 SB IN A 0 dB 0 ms + ON
OUT 3 SB IN A 0 dB 0 ms + ON
OUT 4 SB IN A 0 dB 0 ms + ON
[KS28_60_C] [KS28_100_C]
loudspeaker elements outputs channels routing gain delay polarity mute
SR OUT 1 SR ON
SB OUT 2 SB ON
SB OUT 3 SB ON
SB OUT 4 SB
IN A 0 dB 0 ms +
ON
13 KS28 user manual (EN) version 3.0

Recommendation for speaker cables
Recommendation for speaker cables
Follow the recommended maximum length for loudspeaker cables to ensure minimal SPL attenuation.
Cable quality and resistance
Only use high-quality fully insulated speaker cables made of stranded copper wire.
Use cables with a gauge offering low resistance per unit length and keep the cables as short as possible.
The table below provides the recommended maximum length for loudspeaker cables depending on the cable gauge and
on the impedance load connected to the amplier.
recommended maximum lengthcable gauge
8 Ω load 4 Ω load 2.7 Ω load
mm 2SWG AWG m ft m ft m ft
2.5 15 13 30 100 15 50 10 33
4 13 11 50 160 25 80 17 53
6 11 9 74 240 37 120 25 80
For your installation projects, you can use the more detailed L-ACOUSTICS calculation tool to evaluate cable length and
gauge based on the type and number of enclosures connected. The calculation tool is available on our website:
http://www.l-acoustics.com/installation-outils-de-calcul-137.html
KS28 user manual (EN) version 3.0 14

Maintenance
Maintenance
Disassembly and Reassembly procedures
In order to operate, follow the order outlined here.
GRILL
KR SECUGRL
LF LOUDSPEAKER
G03229
15 KS28 user manual (EN) version 3.0

Maintenance
D/R - Grill
Tools
— torque screwdriver
— 5 mm hex bit
— screwdriver extension
— 100226 provided in KR SECUGRL
Disassembly
1. Loosen the captive grill screw.
5 mm
2. Slide the grill to remove it.
If necessary, pull down the safety O-ring.
KS28 user manual (EN) version 3.0 16

Maintenance
Reassembly
1. Position the grill starting with the top.
2. With the 100226, stretch the O-ring and pull it above the captive screw.
17 KS28 user manual (EN) version 3.0

Maintenance
3. Secure the grill with the captive screw.
3 N.m
5 mm
KS28 user manual (EN) version 3.0 18

Maintenance
D/R - LF loudspeaker
Tools
— torque screwdriver
— 5 mm hex bit
Repair kits
G03229
KR speaker KS28
×1 ×8 ×4
17545 S100054 100689
18" speaker - 8 ohms M6x30 hex 18" speaker gasket
Pre-requisite
Grill disassembled. See Grill (p.16).
For safety reasons, always use the new screws and spare parts provided in the KR.
If no new screws are available, use blue threadlocker.
Exploded view
Gradually tighten the screws following a star pattern.
Check that the cable tie is intact.
5 N.m
x8
5 mm
19 KS28 user manual (EN) version 3.0

Maintenance
Acoustical check
Enclosure check
This feature is available on:
LA12X
ENCLOSURE CHECK measures impedance at the reference frequencies for the connected loudspeaker family. The
measured impedance is compared to the expected range allowing for fast detection of loudspeakers presenting circuit
continuity issues.
The results can be used for preliminary diagnosis but cannot replace a comprehensive quality control.
Pre-requisite
ENCLOSURE CHECK measurements can only be reliable if the following requirements are met:
Environment and temperature:
— Ambient temperature must be comprised between 0°C / 32°F and 40°C / 104°F. Ideal temperature is 20°C /
68°F.
— Enclosures must be at room temperature. If warm from a recent high level use or recently moved from a cold
environment, let the loudspeakers reach room temperature before starting.
Enclosures:
— Enclosures must be included in the embedded factory preset library.
— Enclosures must be in nominal operating conditions:
— Remove covers or dollies obstructing the loudspeakers or the vents.
— Check for obvious physical damage or air leak: visually inspect the grill, gasket, cabinet, and connector plate
for loose, missing or damaged parts.
Connection:
— Use only 10 m / 30 ft 4 mm² / AWG 11 speaker cables.
— Do not connect enclosures in parallel.
Amplied controllers:
— Load a preset corresponding to the connected loudspeaker's family. Presets from the user memories may be used on
condition they are made of presets supported in the embedded factory preset library.
Procedure
1. Power up the amplied controller.
2. Connect the loudspeaker enclosures to the amplied controller.
3. Load a preset from or built from the embedded library corresponding to the connected loudspeaker family.
4. On the amplied controller, use the encoder wheel to select MONITORING & INFO. Press the OK key or the
encoder wheel to validate.
5. Use the encoder wheel to select ENCLOSURE CHECK.
Beware of sound levels.
Although the sound pressure levels generated for the ENCLOSURE CHECK are moderate, do not stay within
close proximity of the loudspeakers and consider wearing ear protection.
6. Press the OK key or the encoder wheel to launch the ENCLOSURE CHECK.
The amplied controller generates short sinusoidal signals simultaneously for each connected output.
The amplied controller displays the results for each output.
7. Depending on the displayed results, follow the instructions in the table.
result interpretation instructions
OK measured impedance is within expected range enclosure is in working order electrically
KS28 user manual (EN) version 3.0 20