The ARCS®II SYSTEM is an arrayable radial coherent system, generation II, designed for medium to large rental productions. It leverages Wavefront Sculpture Technology® in a constant curvature line source solution, offering remarkable power, bandwidth, and coherence, along with flexible and predictable coverage. The system aims to provide an incomparable listening experience characterized by clarity, precision, and impact.
Function Description:
The ARCS®II SYSTEM is a comprehensive loudspeaker system designed for sound reinforcement applications. It includes full-range loudspeaker elements, low-frequency extensions (subwoofers), amplified controllers, and associated software for modeling, control, and monitoring. The system can be deployed in various configurations, including standalone full-range setups or in combination with subwoofers for extended low-frequency response.
Important Technical Specifications:
ARCS®II Full-Range Element:
- Operating Frequency Range: 50 Hz to 20 kHz
- Type: 2-way active, constant curvature WST® line source
- Transducers: KI grade drivers
- Coverage Angle (Line Source): Proportional to the number of enclosures in the array (N x 22.5°)
- Asymmetrical Coverage Angle (Other Plane): 60° (20°/40°), with orientation determining upward or downward coverage.
- Amplification: Exclusively bi-amplified by L-ACOUSTICS® LA8 amplified controllers.
- Connectors: Two 4-point SpeakON® connectors wired in parallel (IN and LINK).
- Internal Pinout (SpeakON®):
- 1+: LF+
- 1-: LF-
- 2+: HF+
- 2-: HF-
- Impedance Load per LA8 Output Pair (1/2 or 3/4):
- 1 enclosure: 8 Ω
- 2 enclosures in parallel: 4 Ω
- 3 enclosures in parallel: 2.7 Ω
- Maximum Enclosures per LA8: 6 ARCS®II enclosures (3 per output channel pair).
SB28 Low-Frequency Extension (Subwoofer):
- Operating Frequency Range: Down to 25 Hz
- Amplification: Exclusively by L-ACOUSTICS® LA8 amplified controllers.
- Connectors: One 4-point SpeakON® connector.
- Internal Pinout (SpeakON®):
- 1+: LF+
- 1-: LF-
- 2+: Not used
- 2-: Not used
- Impedance Load: 4 Ω for 1 SB28.
- Maximum Subwoofers per LA8: 4 SB28 subwoofers (1 per output channel).
- Cardioid Configuration: Supported with specific cabling and preset ([SB28_60_C]).
LA8 Amplified Controller:
- Function: DSP library, networking capabilities, power distribution.
- Protection: L-DRIVE thermal and over-excursion protection circuit.
- Networking: Ethernet-based L-NET protocol, allowing connection of up to 253 LA8 units.
LA-RAK Touring Rack:
- Contents: Houses three LA8 amplified controllers.
- Function: Platform for power, audio signals, and network distribution.
Loudspeaker Cables:
- DO Cables (PA-COM®): DO.7 (0.7m/2.3ft), DO10 (10m/32.8ft), DO25 (25m/82ft). Used for connecting LA8 to breakout cables.
- DOFILL-LA8: Breakout cable for two 2-way active enclosures (PA-COM® < 2 x SpeakON®).
- DO3WFILL: Breakout cable for one 2-way active enclosure and two passive enclosures (PA-COM® < 3 x SpeakON®).
- DOSUB-LA8: Breakout cable for four passive enclosures (PA-COM® < 4 x SpeakON®).
- SP Cables (SpeakON®): SP.7 (0.7m/2.3ft), SP5 (5m/16.4ft), SP10 (10m/32.8ft), SP25 (25m/82ft). Used for direct connection to LA8 or for parallel connections.
- SP-YI: Breakout cable for two passive enclosures (SpeakON® < 2 x SpeakON®).
Recommended Maximum Cable Length (Copper Wire):
| Cross-section (mm²) |
SWG |
AWG |
8 Ω load (m/ft) |
4 Ω load (m/ft) |
2.7 Ω load (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 |
| 10 |
9 |
7 |
120 / 390 |
60 / 195 |
40 / 130 |
Usage Features:
Operating Modes:
- FULL-RANGE mode: ARCS®II operates within its nominal bandwidth (50 Hz - 20 kHz) as a standalone line source, without complementary subwoofers. Driven by LA8 with the
[ARCS II] preset.
- LOW-EXTENSION mode: ARCS®II bandwidth is extended down to 25 Hz by combining with SB28 subwoofers. ARCS®II uses the
[ARCS II] preset, and SB28 uses the [SB28_60] or [SB28_60_C] preset, optimized for acoustic coupling at 60 Hz.
Deployment:
- Horizontal or Vertical Line Source: The ARCS®II can be deployed either horizontally or vertically.
- Coverage: The coverage angle is proportional to the number of enclosures. Asymmetrical 60° (20°/40°) coverage on the other plane, with orientation determining upward or downward distribution.
- Applications: Front of house for medium throw, distributed systems, center clusters, sidefill monitoring, flown or stacked center fill, stereo front fill, offstage fill, or delay systems.
Cabling Options (ARCS®II to LA8):
- Option A (DOFILL-LA8): Connect a DO cable from LA8's PA-COM® to DOFILL-LA8, splitting signals into two channel pairs (CH(A) and CH(B)), each feeding one ARCS®II. Up to two additional enclosures can be connected in parallel to each of the first ones using SP cables.
- Option B (SP Cable): Connect one ARCS®II directly to one of the LA8's SpeakON® connectors using an SP cable.
- Option C (DO3WFILL): Connect a DO cable from LA8's PA-COM® to DO3WFILL, splitting signals into one channel pair for an ARCS®II and two single channels for two SB28 subwoofers. This option requires a dedicated custom preset.
Cabling Options (SB28 to LA8):
- Option A (DOSUB-LA8): Connect a DO cable from LA8's PA-COM® to DOSUB-LA8, splitting signals into four channels, each feeding one SB28.
- Option B (SP Cable + SP-YI): Connect an SP cable from LA8's SpeakON® to one SB28, then use an SP-YI cable (with CC4FP adaptor) to split the signal for a second SB28.
- Option C (DO3WFILL): As described above for ARCS®II, this option allows feeding two SB28s from the DO3WFILL.
Software Integration:
- SOUNDVISION: 3D acoustical and mechanical modeling software for system configuration.
- LA NETWORK MANAGER: Remote control and monitoring software for amplified controllers, featuring Array Morphing EQ for tonal balance adjustment.
Presets:
- [ARCS II]: Full-range preset for ARCS®II in standalone or low-extension modes.
- [SB28_60]: Standard subwoofer preset for SB28 in standard configuration.
- [SB28_60_C]: Cardioid subwoofer preset for SB28 in cardioid configuration.
Maintenance Features:
Safety Instructions:
- Always read the user manual, safety instructions, and DANGER/OBLIGATION warnings.
- Do not use unapproved equipment or accessories.
- Refer to product information documents and rigging manuals before installation.
- Be aware of high sound pressure levels (SPL) and wear earplugs to prevent hearing damage.
Cable Quality:
- Use only high-quality, fully insulated speaker cables made of stranded copper wire.
- Ensure cables have low resistance per unit length and keep them as short as possible.
Acoustic Incompatibility:
- L-ACOUSTICS® does not recommend mixing ARCS®II and ARCS® enclosures due to sonic differences between the two generations, as ARCS®II features new KI grade drivers and a dedicated tuning/preset.
Delay Settings:
- When combining line sources with subwoofers, delays may need to be added. Refer to the LA8 PRESET LIBRARY user manual for pre-alignment delay values.
PA-COM® Standard:
- Using cables other than specified for PA-COM® connections may lead to speaker damage or affect acoustic results. Refer to the LA8 PACOM CABLES technical bulletin.
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