Sunday, August 31, 2014
Phonon Preamplifier Circuits Wiring diagram
In recent years, following CDs introduction, vinyl recordings are almost disappeared. Nevertheless, a phonon preamplifier is still useful for listening old vinyl discs from a well preserved collection. This simple but efficient schema devised for cheap moving-magnet cartridges, can be used in connection with the audio power amplifiers shown in these webpages, featuring low noise, good RIAA frequency response curve, low distortion and good high frequency transients behavior due to passive equalization in the 1 to 20KHz range. Transistors and associated components provide ±18V supply to the op-amp, improving headroom and maximum output voltage.
Phono Preamplifier Circuits Diagram
- R2, R3, R4, R7, R8, C4 & C5 should be low tolerance types.
- Schematic shows left channel and power supply.
- For stereo operation R1, R2, R3, R4, R7, R8; J1; C1, C4 & C5 must be doubled.
- Numbers in parentheses show IC1 right channel pin connections.
Technical data:
Sensitivity @ 1KHz: 2.5mV RMS input for 200mV RMS outputMax. input voltage @ 1KHz:120mV RMS
Max. input voltage @ 10KHz:141mV RMS
Max. input voltage @ 20KHz:127mV RMS
Frequency response @ 1V RMS output: 100Hz to 20KHz ±0.5dB; -0.75dB @ 30Hz
Total harmonic distortion @ 1KHz and 6V RMS output: 0.006%
Total harmonic distortion @10KHz and 1V RMS output: 0.02%
Parts:
R1_________47K1/4W Resistor
R2________100R1/4W Resistor
R3__________6K81/4W ResistorR4_________68K1/4W Resistor
R5,R6_______2K71/4W ResistorR7__________2K21/4W ResistorR8_________39K1/4W Resistor
C1-C3_____100µF25V Electrolytic CapacitorsC4,C5______47nF63V Polyester Capacitors 5% toleranceD1,D2__BZX79C1818V 500mW Zener DiodesIC1_______LM833Low noise Dual Op-ampQ1________BC33745V 800mA NPN TransistorQ2________BC32745V 800mA PNP TransistorJ1__________RCAaudio input socket
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