Hafler Comprehensive Guide to Circuit Operation for P1500 Stereo Amplifier

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CIRCUIT OPERATION

trans•nova Implementation:

+18V

Positive Input

 

 

 

 

Positive Buffer, DC

 

 

 

 

 

Offset Integrator

 

Buffer

 

 

 

 

 

 

 

 

 

U2A, R11, C21,

 

U1A

 

 

 

 

C22

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Current Mirror

Q104, Q105

CMRR

Adjust

R8

Positive Output

Positive DriverQ4, Q115

Cascode

Q9, Q10

Drive

Signal

Local

Feedback

B+

Balanced Signal

Negative Input

Buffer

U1B

Level

Adjust

R24 A, B

 

 

 

 

+

Differential Amp

 

 

 

 

 

 

 

 

 

 

 

 

Q6, Q7

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Negative Buffer

 

 

 

 

 

 

 

 

U2B

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Current Source

 

 

 

 

Protection Switch,

 

 

Q103

 

 

 

 

Soft Start Delay

 

 

 

 

 

 

 

 

Q1, C29

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Feedback

Network

Bias

Adjust

R136

Negative Driver

Cascode

Q11, Q12Negative Output

Q5, Q116

Output

B–

–18V

The transistor Q1 is configured to operate as a switch which controls the current source, Q103, of the input differential amp, Q6 and Q7. When Q1 is off, the emitter voltage is low turning off Q103. Timing of the Soft Start function is controlled by the charging time of C29. Operation of Q1 is controlled by the THERMAL and SHORT protection circuits. U1A and U1B are buffer amps configured as unity gain followers which feed the resistive network comprised of R24A, R24B and R6 which attenuates the differential input at U2A and U2B. The output of U2A and U2B is taken to the inputs of the differential amp Q6 and Q7, U2A is also configured as a DC servo integrator to null the input offset currents. Transistor Q6 is the non-inverting input of the differential amp, taking the signal from U2A, the output is taken through the current mirror, Q105 and Q104 where the signal is inverted, then feeds the negative driver Q11 and Q12. Transistor Q7 is the inverting input of the differential amp, taking the signal from U2B. This output feeds the positive driver Q9 and Q10. The positive drivers Q9 and Q10, and the negative drivers Q11 and Q12 are cascoded stages which supply drive current and voltage to the output devices. Class AB bias current is controlled by R136. The network R1 and C1 form the short loop feedback for the output stage. Global feedback is supplied by the network R10 and C8.

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Contents Trans Declaration of Conformity R F O R M a N C E Specification S Power Cord Grounding Power SourcesPower Cord Protection CleaningCuadros DE Advertencias LEA LAS InstruccionesConserve EL Manual DEL Propietario Siga LAS InstruccionesConserver LE Guide DE Lutilisateur Suivre LE Mode EemploiLire LES Instructions Considérations DE Mise EN GardeInstsruktionen Lesen Erforderlicher ReparaturserviceService Betriebsanleitung AufbewahrenAvvertenze Leggete LE IstruzioniConservate IL Manuale Seguire LE IstruzioniOperation InstallationB L E O F C O N T E N T S Technical ReferenceT R O D U C T I O N Front Panel View Installation LocationInput From Source Input FromH E M a T I C D I a G R a M Removable Center Spread E R a T I O N Signal D L a Y O U T P3000U 120VAC, 60Hz Designator ValueParts List Modifications for P3000CE Parts List Modifications for P1500CEParts List Modifications for P1500U 120VAC, 60Hz C H N I C a L R E F E R E N C E Field Service ConsiderationsTheory and Operation of transnova Circuit Operation Transnova ImplementationOutput Short Protection Clipping Indicator CalibrationModule Replacement Wire Color Function Terminal/SizeHow to obtain service or technical support Length of WarrantyWhat is Covered Limit on Implied WarrantiesPage Hafler Division

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.