Owner Manual for RCF ST 12-SMA II and ST 15-SMA II Active Stage Monitors

Quick Guide

This manual provides essential information for the safe and correct operation of the RCF ST 12-SMA II and ST 15-SMA II active stage monitors. Always ensure the volume is at the minimum level before powering on the system. The mixer should be powered on before the speakers to avoid damaging the equipment or producing loud pops. Always turn off the speakers immediately after use.

Product Description

The ST Series is a line of active loudspeakers designed for professional monitoring. They feature high-output transducers, digital amplification, and FIR filtering technology for transparent sound and minimal latency. The cabinets are constructed from Baltic birch plywood with a rugged design suitable for stage use.

Rear Panel Controls

• Jack/Female XLR Inputs: Balanced inputs for microphones or line-level audio sources.
• Limiter LED: Blinks red when the soft clipping circuit is active. Occasional blinking is normal; frequent or continuous blinking indicates the signal level is too high.
• Signal LED: Lights green when a signal is present.
• Power Status LED: Lights green when the speaker is powered on.
• Male XLR Signal Output: Provides a loop-through for daisy-chaining speakers.
• Volume Control: Adjusts the amplifier volume.
• Flat/Boost Switch: Selects equalization. Boost is recommended for music applications on a floor stand; Flat is recommended for monitoring applications.
• Input Sensitivity Switch: Set to LINE for line-level sources (0 dB) or MIC for microphone sources.
• IEC AC Socket: Power cord connection.
• Fuse Carrier: Mains fuse housing.
• Power Main Switch: Turns the unit on and off.

Connections

The XLR connectors follow the AES standard:

• Pin 1: Ground (Shield)
• Pin 2: Hot (+)
• Pin 3: Cold (-)

Installation

The cabinet features a 35 mm socket on the bottom for mounting on a speaker stand. Warning: Never suspend the speakers by their handles. Handles are designed for transportation only, not for rigging.

Operation

The amplifiers use a microprocessor for DSP and amplifier control. Upon power-up, the system performs an initialization test where the Limiter, Signal, and Power Status LEDs remain off for approximately 2 seconds. Once initialized, the green Power Status LED will remain steadily on.

Troubleshooting

The microprocessor signals failures by flashing the red Limiter LED:

• Warning (1 or 2 flashes): Non-severe error, performance is not limited.
• Limitation (3 or 4 flashes): Error detected, performance is limited (sound level reduced by 3 dB). Contact service.
• Failure (5 to 8 flashes): Severe malfunction, speaker switches to mute.

If a failure occurs, check the power supply, ensure the amplifier is not overheated, and disconnect/reconnect the power. If the red Limiter LED persists, contact an authorized service center.

Technical Specifications

ST 12-SMA II: Frequency response 45-20 kHz, Max SPL 130 dB, 600W RMS / 1200W Peak power.

ST 15-SMA II: Frequency response 45-20 kHz, Max SPL 131 dB, 600W RMS / 1200W Peak power.