Drawmer SL22 Speaker and Headphone Limiter
The development of the SL22 was undertaken in conjunction with a multinational media company needing to conform to Noise At Work Legislation and protect the hearing of the DJ’s in their radio studios. During testing they had become very disillusioned by the current products on offer, finding that they were either so crude that they didn’t really work, or, at best, the attenuation could be heard and was intrusive. Many types were tried resulting in the conclusion that the SP2120 was the most transparent product on the market but required a few adaptations to fully suit their requirements – the SL22 is the result of this development.
Whether you need to protect your speakers, your hearing or your license the Drawmer SL22 Sound Level Limiter is the perfect tool for the job. By eliminating the possibility of ’unauthorised’ excessive sound pressure levels it offers strict level control and tremendous peace of mind to users in three distinct areas:
1) Safegaurd your hearing
- Conform to Noise at Work Legislation and help prevent hearing damage by controlling user’s exposure to high audio levels via speakers or headphones whilst at work.
2) Confirm to regulations
- By calibrating and controlling venue noise levels and in a secure manner you conform to Local Authority Noise Regulations
3) Protect your speaker and ears
- Prevents the damage to amplifiers, speaker drivers and ears by catching unwanted signals such as ‘bangs’ and ‘pops’ through speaker or headphone output.
Features:
- Limited speaker and headphone outputs.
- No sound quality loss even during protection processing
- Large LED level indication for ’at a glance’ monitoring of signals and warnings
- Time delay relays on outputs for clean power up/down
- Tamper-proof plate limits access to settings.
- Fast, simple installation.
- Once installed and calibrated completely eliminates the possibility of ’unauthorised’ volume levels
- A security label is supplied to further secure the calibration settings and show evidence of tampering.
- Tamper-Proof bracket (available separately) to lock-in the XLR’s and conform to Local Authority regulations.
- Reduces ’call-out’ costs of sound system service/repair engineers, sound system ’down time’ and the consequential loss of venue income, as well as the reputation of the venue.
- External control of Dim and Mute for connection to Fire Alarms or remote operation
- Trigger output when in PROTECT mode
- Logging inputs for both ALERT and PROTECT statuses.
The SL22 front panel features an integral security plate to ensure that adjustments to maximum volume levels are implemented by authorised personnel only. Once removed two front panel pre-sets are exposed and available for adjustment by the installer. The first calibrates the protect indication to the incoming audio and dictates the point at which ’protection’ processing commences. The second sets the absolute volume level to which the sound system is allowed to perform. If the SL22 receives increased signal levels, the transparent ’protection’ circuitry is activated which maintains the specified system volume level without degradation in sound quality. With the security plate replaced a security label can be placed across (supplied) to provide further security and show evidence of tampering with the settings. In addition, on the right side of the panel three LED indicators complement the simple setup with simple and ‘at a glance’ monitoring.
To the rear the difference between the SL22 and the SP2120 is just as apparent. In its development we liaised with and were approached by local authority commissioners, installation specialists and venue owners who all advised and recommended attributes to suit their own specific requirements, the result being the addition many more versatile features that so many other sound level limiters lack. As well as the standard input and output XLRs (that can be securely locked using the optional tamper-proof bracket) the SL22 also features a limited headphone output, that works in the same manner as the XLRs.
We also introduced the ability to control certain functions externally (Dim and Mute) via a fire alarm or operator, along with connections to allow data logging of the SL22’ Alert and Protect modes and a trigger out to provide visual indication via a light on a wall, for example.
Specifications
INPUT
Input Impedance: 20k Ohms
OUTPUT
Output Impedance: 100R
Headphone Output Impedance: 110R
Gain Range @ Output: -30dBu to +44dBu
Recommended Output Level: 0dBu
Crosstalk: 90dB at 10k Hz
Noise: -93.5dB (Unity gain / 22Hz-22kHz)
Power Requirements: 115Volt or 230Volt at 50-60Hz, 9VA
Fuse: (Conforms to IEC127-2.) 230V=T63mA, 115V=T125mA.
Dimensions: 482mm(W) x 44mm (H) x 190mm(D)
Weight: 2.2kg