Universal Line Voltage Input, Protection Circuits

UNIVERSAL LINE VOLTAGE INPUT

Voltage selection is provided in two bands: 100-140 volts and 200-265 volts, (both 50-60 Hz) via two quick-connect termi- nals located on the EMI filter board, accessed by removing the top cover. The current-mode control system automatically corrects for the bulk of power line variation with each band. This allows most of the PWM action to be reserved for pro- gramming and regulation of output voltages. A flyback topology provides the numerous housekeeping low voltages required by various circuits.

PROTECTION CIRCUITS

Fan control circuit - Each amplifier channel has a fan control circuit that measures the temperature of the heatsink, and adjusts the fan speed accordingly. This thermally-tracking fan speed circuit keeps fan noise to a minimum when power demands are low. Typically the fans will be turning slowly even at idle conditions - although abnormally low room temper- atures may allow the fans to turn off completely. The fan control circuit also has a turn-on blast feature that runs the fans at full speed for a few seconds every time the amplifier is turned on. This serves the dual function of cleaning out the air tun- nel, and providing a simple means to check the fans for proper operation. If you suspect that the fans are not operating cor- rectly, try turning the amplifier off, then listening or feeling for the turn-on blast when the amplifier is turned back on.

Thermal Standby - If excessive heatsink temperature is detected, the individual amplifier channel will go into thermal stand- by mode. The amplifier will be turned off, and the THERMAL LED illuminates until heatsink temperatures return to normal. At that time the amplifier automatically turns back on, and continues operating normally.

NOMAD protection - The amplifier output MOSFETs are protected from excessive power dissipation by NOMAD protec- tion circuitry. NOMAD (Non-Multiplying Advance Decision) limits the power when it measures signal voltage and current conditions that will exceed the pre-determined power limit of the MOSFETs. This instantaneous power calculation is per- formed on each output MOSFET, causing the amplifier to automatically limit power when needed. In this way, a speaker load with an impedance “dip” over a particular frequency range will only activate the NOMAD protection when sufficient audio is present at that same frequency range, but continue operating normally otherwise.

Short protection - The NOMAD protection circuit also protects against shorts, and will instantly limit the output power if speaker wires are shorted together. Normal operation will continue immediately after the short is removed.

Power Supply Current Limiting protection- The switching power supply will protect itself from excessive power dissipation by continuously monitoring currents in the switching MOSFETs. The Current Limiting circuit measures the currents in the switching MOSFETs and will instantly limit them to a safe level.

Soft turn-on/fastturn-off- Speaker loads are protected from turn-on/turn-off transients by a circuit that monitors the power supply, and controls the amplifier when power on/off events are detected. At turn-on, this circuit waits for power supply voltages to settle, then sends a turn-on ramp signal to slowly turn the amplifier on. At turn-off, this circuit acts quickly to turn off the amplifier before power supply capacitors discharge, and voltages collapse into the output signal - causing speaker “pops”.

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GX2800, GX2800CE specifications

The Hafler GX2800CE and GX2800 are high-performance power amplifiers designed for audiophiles and professional sound reinforcement applications. Renowned for their reliability and audio fidelity, these models represent a seamless combination of innovative technologies and robust engineering that ensures impeccable sound quality.

One of the standout features of the Hafler GX2800 series is their high current output capability. This allows the amplifiers to drive a wide variety of loudspeakers, including those with demanding impedance requirements. With a power output of 280 watts per channel at 4 ohms, these amplifiers deliver sufficient power for large venues while maintaining clarity and dynamic range. The ability to handle low impedance loads without compromising performance is a hallmark of the Hafler brand.

The GX2800CE and GX2800 are equipped with Hafler's proprietary feedback technology, reducing distortion and enhancing overall sound quality. This technology ensures that the amplifiers perform well across the audio spectrum, allowing for rich, detailed sound reproduction. The low total harmonic distortion (THD) figures also contribute to a cleaner audio signal, ensuring that the listener experiences music as it was intended.

Another notable characteristic of the GX2800 series is its built-in protection circuitry. This includes short-circuit protection, thermal overload protection, and output DC protection, which work together to safeguard the amplifier and connected speakers during operation. The durable design of the chassis provides further reliability, suitable for both studio environments and live sound applications.

The amplifiers feature balanced XLR and unbalanced RCA inputs, providing versatility for various audio setups. Additionally, the rear panel includes binding post speaker outputs for secure connections to loudspeakers.

For those seeking a powerful and reliable amplifier that does not compromise on audio quality, the Hafler GX2800CE and GX2800 are exceptional choices. With their array of features designed to enhance performance and user experience, these amplifiers stand out in the competitive audio equipment market, making them ideal for both home and professional uses. Whether you are mixing in the studio or providing sound for a live performance, the Hafler GX2800CE and GX2800 will deliver exceptional results, making them a worthy investment for any audio enthusiast.