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How to build Phono Preamplifier
October 16, 2010 - category: Audio preamplifierCircuit diagram
Parts:
- R1 47K 1/4W Resistor
- R2 100R 1/4W Resistor
- R3 6K8 1/4W Resistor
- R4 68K 1/4W Resistor
- R5,R6 2K7 1/4W Resistor
- R7 2K2 1/4W Resistor
- R8 39K 1/4W Resistor
- C1-C3 100uF 25V Electrolytic Capacitors
- C4,C5 47nF 63V Polyester Capacitors 5% tolerance
- D1,D2 BZX79C18 18V 500mW Zener Diodes
- IC1 LM833 Low noise Dual Op-amp
- Q1 BC337 45V 800mA NPN Transistor
- Q2 BC327 45V 800mA PNP Transistor
- J1 RCA audio input socket
Comments:
In recent years, following CD's introduction, vinyl recordings are almost disappeared. Nevertheless, a phono preamplifier is still useful for listening old vinyl discs from a well preserved collection. This simple but efficient circuit devised for cheap moving-magnet cartridges, can be used in connection with both audio power amplifiers shown in preceding pages, featuring low noise, good RIAA frequency response curve, low distortion and good high frequency transients behaviour 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.
Notes:
- 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 output
- Max. 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%
circuit from http://www.diy-electronic-projects.com/p17-Phono-Preamplifier
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