4-Channel 1RU Digital Main Station

HelixNet System Operation

  • HelixNet System Host
  • 6 HMS can link over LAN & WAN
  • Supports up to 64 endpoints on HelixNet system
  • 12 partyline channels; expandable to 24 channels via optional license

Main Station

  • Easy to use CCM™ browser configuration
  • Fast front panel control & configuration
  • Plug-and-go with auto discovery
  • Central upgrades from main station

User Station

  • Headset or hands-free support with speaker & mic
  • 4 Keysets assignable to channels
  • All Talk, Stage Announce, RMK & Program Audio level controls


  • 2 Powerlines for distribution of Ethernet to HelixNet user stations via XLR cables
  • 3 Expansion slots for HLI modules: Ethernet, fiber, 2-wire & 4-wire ports
  • Program Audio input
  • Stage Announce output
  • 4 Contact closure inputs & outputs

LQ Integration Options

  • LQ® linking for high density 2-wire, 4-wire and GPIO expansion
  • Station-IC™ and Agent-IC® as integrated via optional licenses
  • SIP/VoIP integrated via optionally licensed LQ
Item Part Number:

HMS-24-UG: 24-channel license

Optional Interface Modules and SFPs (Sold Separately):
HLI-2W2: 2-wire module
HLI-4W2: 4-wire module
HLI-ET2: Ethernet module
HLI-FBS: Fiber module
HLI-MMFO: Single-mode SFP
HLI-SMFO: Multi-mode SFP

The HelixNets HMS-4X main station is a combination of a system host and an intercom user station with XLR Powerline connections to user stations. HMS-4X hosts up to three HLI interface modules for external connectivity including Ethernet and Fiber.

The HelixNet IP networking guide provides specifications, best practices and guidance for the integration of HelixNet into an existing or new IP network.

Technical Specifications


HMS is required as the HelixNet Host. Link Group may include five additional HMS members, including up to three LQ devices for a maximum of six HMS/LQ in Link Group. HMS
link using HLI-ET2 or HLI-FBS modules over LAN/WAN connections. Link Group supports up to 64 endpoints (station/port).
Note: HMS does not link to Arcadia.


System provides 12 or 24 intercom channels assignable to any user station or port in the system. Four Channels can be assigned to station. Program Audio can be associated with any channel with independent endpoint level control.


99 Roles for naming and dynamic configuration of user station settings. Role can be applied to multiple user stations.


Host: HMS-4X
Activation: Generated to unique HMS-4X device System ID
Transferable: No, fixed to HMS-4X
Recovery: Yes, by Clear-Com Support or Service Center

Permanent Licenses

Part numbers: HMS-24-UG
Capability: 24 Channels
Validity: Perpetuity


XLR Powerline: (2) 3-pin XLR-M/F
Gooseneck Mic: 3-pin Tuchel
Headset: 4-pin XLR–M
Program Audio: 3-pin XLR–F
Stage Announce: 3-pin XLR–M
Hot Mic/IFB Interface: 1/4″ (6.35 mm) TRS Jack
GPIO: 25-pin D-type female (4 GPI, 4 GPO, 5V)
USB: Type A & Micro AB (factory service use)
Input Power Connector: IEC-C14

Microphone Pre-amplifier

Headset Mic Impedance: 200Ω (Dynamic)
Headset Mic Voltage: 1.7V (Electret selectable)
Limiter: +23dB

Route to 4-wire output at 0dBu:
Mic Gain: 60dB (Dynamic), 45dB (Electret)
Frequency Response: 200Hz – 10 kHz ±3dB
Distortion: <0.2% THD @ 1kHz
Noise: <-55dBu (Dynamic), <-65dBu (Electret)

Headphone Amplifier

Load Impedance: >32Ω
Output Level: +12dBu before clipping
Sidetone: -12dB (selectable)

Route from a 4-wire input at 0dBu:
Max Gain: 0dB
Frequency Response: 40Hz – 10kHz ±3dB
Distortion: <0.1% THD @ 1kHz
Noise: <-65dBu
Headphone Limiter: 0dB (selectable)

Loudspeaker Amplifier

Load Impedance:
Output Level: +18dBu before clipping
Route from a 4-wire input at 0dBu:
Max Gain: 18dB
Frequency Response: 200Hz – 10kHz ±3dB
Distortion: <0.1% THD @ 1kHz
Noise: <-50dBu

Program Audio Line Input

Maximum Level Before Clipping: +18dBu
Nominal Input Level: 0dBu (selectable)
Input Impedance: >= 10KΩ

Route to 4-wire output at 0dBu:
Frequency Response: 20Hz – 10kHz ±3dB
Distortion: <0.2% THD @ 1kHz
Noise: <-65dBu

Stage Announce Output

Maximum Level Before Clipping: +18dBu
Nominal Output Level: 0dBu (selectable)
Output Impedance: <= 100Ω

Route from a dynamic headset:
Frequency Response: 300Hz – 12kHz ±3dB
Distortion: <0.1% THD @ 1kHz
Noise: <-55dBu

Hot Mic Output

Maximum Level Before Clipping: +12dBu
Nominal Output Level: 0dBu (selectable)
Output Impedance: <= 100Ω

Route from a dynamic headset:
Frequency Response: 300Hz – 12kHz ±3dB
Distortion: <0.2% THD @ 1kHz
Noise: <-55dBu


Two independent network XLR Powerlines
Frequency Modulated Ethernet – OFDM
Output Voltage: ±29.5V DC
Output Current (Max): 1.5A per Powerline
Frequency: 100kHz-25MHz
Requires shielding integrity between Powerlines
Support up to 10 beltpacks each
Support up to 3-10 stations each

Use HelixNet Cable Calculator to validate load and cable distance.

Logic Power Output

To power Logic Inputs
Output Voltage: 5V, separate pin
Current (Max): 1mA

Logic Inputs -GPI

Assignable to talk, call, mic and headset keys
Input: 4
Style: Optically isolated
Detection Voltage (Min): 3V
Input Voltage (Max): 5V

Logic Outputs – GPO/Relay

Assignable to talk, call, SA keys and channel events
Outputs: 4
Style: Power Relay
Normalized: Open or Closed, separate pins
Switching Voltage (Max): 30V
Switching Current (Max): 2A


Input Frequency Range: 100 – 240V AC
Input Frequency Range: 50 – 60Hz
Power (Max): 250W
Input Power Connector: IEC-C14
Practical Power Range:
Power (Normal): 80-250W
BTU (Normal): 275-850BTU/hr
Dependent on hosted modules and powerline connected beltpacks


32º – +104ºF (0 – +40ºC)
90% relative humidity


1.75 x 19 x 13in (HxWxD)
(44 x 483 x 320mm)


5.83lbs (2.65kg)

Network Specifications (Firmware Version 4.2+)
Network Protocols

Ethernet IPv4–Unicast Audio and Control
mDNS–Multicast Device Discovery
Layer 3 routable with mDNS function limitations
TFTP-File Transport Protocol
NTP–Network Time Protocol
RTP–Audio Transport
WavPack–Audio Codec

Network Ports

Port 69 UDP–Firmware File Server
Port 80 TCP–Web Interface, System Management, Expansion
Port 123 UDP–Time Stamps for Service Logs
Port 655 TCP–Link Group Audio/Database
Port 6001 TCP–System Management
Port 6001 UDP–Audio Streams

Port 5353 UDP–mDNS, Names, Discovery, Linking, Expansion
Optional for device names and linking
Mandatory for HMS/HRM Expansion

Network Parameters

Link Group Endpoint Support: 64
Endpoints are user stations, active Interface ports, Program Audio inputs and LQ accounts.

Bandwidth: 300 kbps each audio input linking between HMS/LQ
Link Group audio sent dynamically between members
300-600 (max) kbps from each endpoint audio input to HMS
1200-2400 (max) kbps from HMS to each endpoint audio output

Network Jitter Tolerance: <= 128ms jitter buffer per audio stream receiver automatically adjusted to network performance

QoS Tags: DSCP=41, Assured Forwarding (AF)
Link-Local Default IP Address Range:

System Reserved IP Ranges: for endpoints for Link Group

Recommended Ethernet Switches

• Managed Ethernet Switch – Layer 3
• 100/1000 Base-T ports for endpoints
• 1000 Base IP Trunks between switches
• QoS Configuration
• Energy Efficient Ethernet bypass option
• IGMP Snooping bypass option

Please refer to the Clear-Com HelixNet Network Guide for additional switch settings and network characteristics

Associated Products

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