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 the audio power amplifiers shown in these web pages, featuring low noise, good RIAA frequency response curve, low distortion and good high frequency transients behavior due to passive equalization in the 1 to 20 KHz range.
Circuit Diagram:
Parts:
- R1 = 47K
- R2 = 100R
- R2 = 6.8K
- R4 = 68K
- R5 = 2.7K-1/2W
- R6 = 2.7K-1/2W
- R7 = 2.2K
- R8 = 39K
- C1 = 100uF-25V
- C2 = 100uF-25V
- C3 = 100uF-25V
- C4 = 47nF-63V
- C5 = 47nF-63V
- D1 = BZX79C18
- D2 = BZX79C18
- Q1 = BC337
- Q2 = BC327
- J1 = RCA Jack
- IC1 = LM833, Opamp
- 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 channe