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Claudio Hi-end Phono
April 1 st , 2012 - working in progress ......
This project born to create a
good and simple phono preamplifier for my friend Claudio to connect to the
digital preamplifier with dynamic room correction.
The original design by Walter G. Jung, presented on AES and on OPA606 datasheet, has been implemented with some little changes.
It use the TI Burr-Brown ultra-low noise, high-precision monolithic operational amplifiers OPA37 and OPA606.
Any resistor in the schematic has been replaced with a parallel for two or tree Vishay MRS25 1% metal resistors to match the right value and to reduce the parasitic inductance, all the RIAA capacitors are Vishay MKP1837 100V 0.1uF 1% (cod. MKP1837-410-011 - cod. RS166-6487).
To get a very low noise the power supply use a virtual battery operation, invendted by Technics, and a virtual ground configuration.
There is no electrolytic capacitors on the signal path and in the power supply after the regulator has been used 15uF 250V MKP Solen.
The output capacitors are 2.2uF 250V MKP Solen bypassed by a 0.22uF Audyn Cap. PLUS.
|values||2x||totale||err %||3x||totale||err %|
The virtual battery has been implemented
using the IRF620 mosfet but any other model can be used
For the virtual ground I have used a strong solution TLE2426CLP (TO92) followed by a BUF634T (TO220-5pin).