SL22

Transparent Sound Level Limiting
Maintains safe and consistent audio levels without compromising sound quality or interrupting the listening experience.

Speaker Protection
Prevents damage from excessive signal levels, transients, bangs, and pops, helping extend the life of speakers and amplifiers.

Headphone Protection
Includes a dedicated limited headphone output to help protect the hearing of DJs, engineers, students, and other regular headphone users.

Noise Regulation Compliance
Helps venues and workplaces meet Noise at Work and local authority sound level requirements through accurate system calibration.

Tamper-Proof Security
Lockable calibration controls and tamper-evident security labels prevent unauthorised changes to system settings.

Maximum Volume Control
Sets an absolute ceiling for system output, ensuring the audio cannot exceed the calibrated level.

Protection Threshold Control
Separately adjusts the point at which limiting begins, allowing protection to be tailored to the installation.

Visual Status Monitoring
Large LED indicators provide instant confirmation of signal presence, warning status, and active protection.

Remote Dim and Mute Control
Supports external control for fire alarms, emergency systems, operator override, or scheduled volume reduction.

External Status Outputs
Provides alert, protect, and trigger outputs for remote warning indicators, monitoring systems, or data logging.

Time-Delay Output Relays
Ensures clean power-up and power-down operation while helping prevent unwanted switching noises.

Flexible Installation
Designed for straightforward integration into clubs, theatres, schools, studios, public venues, and installed sound systems.

Optional Tamper-Proof XLR Locking
Supports an optional locking bracket that secures rear-panel connections against unauthorised access.

Professional Connectivity
Features balanced XLR inputs and outputs together with dedicated external control and monitoring connections.

Designed and Hand-Built in the UK
Engineered and manufactured by Drawmer for reliable professional audio installations.

General Specifications
Device Type: Sound level limiter
Channels: Stereo
Rack Size: 1U, 19-inch rackmount
Application: Speaker protection, headphone protection, venue noise compliance
Limited Headphone Output: Yes
Security Plate: Lockable with tamper-evident label
Optional XLR Locking Bracket: Yes

Audio Specifications
Input Impedance: 20 kΩ or greater
Output Impedance: 100 Ω
Headphone Output Impedance: 110 Ω
Gain Range @ Output: -30 dBu to +44 dBu
Recommended Output Level: 0 dBu
Crosstalk: -90 dB @ 10 kHz
Noise: -93.5 dB, unity gain, 22 Hz–22 kHz

Controls
Threshold: Adjustable
Maximum Volume: Adjustable
Signal Indicator: LED
Alert Indicator: LED
Protect Indicator: LED

Protection Features
Speaker Output Limiting: Yes
Headphone Output Limiting: Yes
Transparent Limiting: Yes
Tamper-Evident Security Label: Yes
Time-Delay Output Relays: Yes

External Control
External Dim Input: 20 dB attenuation
External Mute Input: 70 dB attenuation
Fire Alarm Interface: Yes
Trigger Output: 5 V, Protect status
Alert Logging Output: Isolated solid-state relay
Protect Logging Output: Isolated solid-state relay

Connections
Audio Inputs: Balanced XLR, stereo
Audio Outputs: Balanced XLR, stereo
Headphone Output: 1/4-inch stereo jack
External Control Ports: Screw terminal blocks
External Indicator Ports: Screw terminal blocks

Power
Power Requirements: 115 V or 230 V AC, 50–60 Hz
Power Consumption: 9 VA
Fuse Rating (230 V): T63 mA
Fuse Rating (115 V): T125 mA
Fuse Type: 20 mm × 5 mm, IEC 127-2, Class 3 Time Delay

Physical Specifications
Width: 482 mm
Height: 44 mm
Depth: 190 mm
Weight: 2.2 kg