ETI Sound Systems, INC Official Manual for ETI Sound Systems US Series Stereo Amplifiers

NOTE: Match the pin designations printed next to the output connectors on rear panel to ensure proper connections.

9.Circuit breaker

The circuit breaker protects the amplifier from faults at the AC supply and serves as protection when the amplifier fails.

If the circuit breaker trips, cutting AC power supply to your amplifier, it may indicate a serious malfunction or failure. Wait for the circuit breaker to cool before resetting it by simply pressing the reset knob. If the circuit breaker repeatedly trips, especially when there is no signal on the inputs or outputs, this indicates a failure of your amplifier. DISCONNECT the power cord from the amplifier immediately and contact an authorized B-52 Service Center.

There are rare instances when the circuit breaker acts on a constant heavy overload with a very low imped- ance load connected to amplifier, protecting your amplifier against such improper usage. In such cases you need to check and correct your load (loudspeak- ers) to provide for the proper load impedance, and/or reduce output signal.

10. AC input

IEC connector for the AC power cable. Connect the supplied heavy-gauge 3-pin IEC power cable.

NOTE: Never disconnect the EARTH pin from the AC connection. It will defeat safety measures used in your power amplifier and void the warranty.

PROTECTION

US-Series amplifiers feature comprehensive protection circuitry that protects both the loudspeakers and the electronics from malfunctioning. The protection is non- intrusive, sonically transparent and does not affect the sound unless there are extreme conditions that acti- vate the protection circuitry.

The PROTECT LEDs on the front panel illuminate when the protection is active during the power-up sequence, when thermal protection is activated, or when there is a malfunction. When the PROTECT LEDs are ON, the amplifier’s outputs are muted.

Initial power-up:The protection circuitry will activate for about two to three seconds from the time you turn ON the amplifier. The speaker outputs are muted during this period. If the amplifier is operating normally, the protection circuitry will deactivate and the amplifier will switch to operation mode.

NOTE: It is normal for the PROTECT LED to fade gradually after the amplifier is turned OFF.

Thermal Protection: Excessive heat-sink tem- peratures will engage the thermal protection circuitry to avoid damage to your amplifier. The speaker output will mute and the PROTECT LED will illuminate. Thermal protection only engages on the channel

which has the overheating heatsink, except the US- 1200 where both channels will be muted. The thermal protection will automatically restore to normal opera- tion mode automatically once the heatsink tempera- ture drops to a safe level.

NOTE: If the thermal protection constantly activates, check the impedance of your loud- speakers and the condition of the air filters on front of the amplifier. The loudspeakers impedance must not be lower than what is specified in this manual for 2-channel and BRIDGE operation. 8 Ohms and 4 Ohms speaker loads per channel (8 Ohms and 16 Ohms in BRIDGE mode) should not trigger the thermal protection circuitry if the air access is not blocked and the air filters are clean. 2 Ohms speaker loads per channel (4 Ohms in BRIDGE mode) can cause the thermal protection circuitry to activate occasionally. If this occurs, decrease the signal level and consider reconthe speakers connections to reduce the load on the amplifier (for example, do not connect too many speakers in parallel to the same channel).

NOTE: Make sure there is adequate air access