Clipping Indicator, Calibration | Hafler P1500, P3000 guide

Clipping Indicator
Drive	Clipping	LED Driver	CLIP Indicator
Signal	Detector	U5C	CR3
	U5A

The CLIP indicator is driven by the buffer U5C which is controlled by the comparator U5A. The voltage divider R56 and R57 establishes the reference voltage for the Clipping detector at pin 7 of U5A. The reference voltage scales the output of U5A to indicate when the Drive Signal at pin 6 demands in excess of the available voltage or current of the output stage. The output of U5A is stretched by R55 and C30 to prevent the CLIP indicator CR3 from flickering. Hysteresis is applied to the LED driver U5C by R53 to stabilize the output during input transitions.

Signal Present Indicator
Amplifier	Signal	LED Driver	SIGNAL
	Detector		Indicator
Output		Q8
	U5D		CR4

The SIGNAL indicator is controlled by the comparator U5D and the transistor Q8. The amplifier output is connected to the input pin 9. The voltage divider R58 and R59 scales the output voltage to change the comparator output state at an equivalent input voltage of 30mV, with the level controls set for full gain. The output at pin 14 controls the transistor Q8 to shunt across and turn off the LED CR4.

CALIBRATION

WARNING: Only a competent technician should attempt the following procedure.

Bias:

The bias control establishes the quiescent Class AB output current of the amplifier. The bias should not need readjustment from the factory setting; however, if the amplifier is repaired and output devices have been changed, or if the two channels of the amplifier do not run at the same temperature, calibrating the bias is necessary. Disconnect the power to the amplifier before removing the cover. To adjust the bias, disconnect the input and speakers and remove the jumper JW7. Connect an amp meter across the exposed pins. Adjust R136 to get a current reading of 100 mA for the P1500, 200 mA for the P3000.

WARNING: Only a competent technician should attempt the following procedure.

Common Mode Rejection:

The input common mode null is adjusted by the trim pot R8. The CMRR should be greater than 75dB below rated output. If the CMRR requires adjustment, feed the amplifier input with a common mode signal and adjust R8. Disconnect the power to the amplifier before removing the cover. Use a sinewave generator set to 1 volt output at 1kHz. Connect the generator signal output to the tip and ring of a 1/4" plug and ground to the sleeve. Plug this into the amplifier input. Connect an AC voltmeter to the amplifier output binding posts. Adjust R8 to give the lowest voltage output from the

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P3000, P1500 specifications

The Hafler P1500 and P3000 are notable power amplifiers that have earned recognition for their performance and reliability in various audio applications. Both models are designed to deliver high-quality sound reproduction while offering users an array of advanced features that enhance their usability in professional and home audio setups.

The Hafler P1500 is a two-channel power amplifier that boasts a robust output of 150 watts per channel at 8 ohms, making it suitable for driving a variety of speakers with ease. One of its standout features is the intelligent cooling system, which ensures the amplifier operates at optimal temperatures, minimizing the risk of thermal overload. Furthermore, the P1500 is equipped with a high-quality toroidal transformer, which helps to reduce distortion while providing stable power, contributing to the amplifier's overall clarity and dynamic range.

In addition to its power capabilities, the P1500 includes features such as a variable speed fan and comprehensive protection circuitry to safeguard the amplifier from overcurrent and overheating. The user-friendly design includes both XLR and RCA inputs, allowing for versatile connectivity options with professional audio equipment and consumer audio devices alike. The rugged construction of the chassis is designed to withstand the rigors of touring and studio environments, ensuring durability and reliability.

On the other hand, the Hafler P3000 elevates the performance level with a powerful output of 300 watts per channel at 8 ohms. This amplifier is particularly favored in larger audio setups where significant power is required. It utilizes similar advanced technology as the P1500, including sophisticated thermal management systems and high-performance circuitry aimed at keeping distortion levels to a minimum.

The P3000 is recognized for its exceptional headroom and dynamic capability, making it an ideal choice for driving large speaker systems in professional settings such as recording studios and live events. The amplifier features balanced XLR connectors for professional applications, and its dual-level LED indicators provide real-time feedback on performance, giving users essential information on levels and operation status.

Both the Hafler P1500 and P3000 are exemplary models that blend innovative design with high-quality sound performance. Their reputation in the audio community stems from their ability to deliver powerful performance, reliability, and flexibility, catering to a multitude of audio environments from home theater systems to professional sound reinforcement setups. Their enduring popularity reflects Hafler’s commitment to engineering excellence, allowing audio enthusiasts to experience superior sound without compromise.