PhonoFet - discrete preamplifier for MM cartridge
After the development of several phono preamplifiers based on operational amplifiers, I have decided to design and produce the preamplifier built with discrete components and to utilize experience achieved during design and operation of Dispre 2-JFET and PRE3 discrete link level preamplifiers. Thus I have designed a phono preamplifier named PhonoFet. It is based on JFET and MOSFET transistors.
This preamplifier has a complementary-differential input stage followed by the MOSFET output stage.
The power supply part was designed especially for this product. It utilizes modified ZT15VA power supply (separate board) and on-board constant current source followed by a parallel voltage stabilizer. This circuit solution results in an excellent S/N ratio and suppression of HF interferences. The preamp is placed in a standard 19" case, 1U high and 280 mm deep. It will be supplied as an assembled module and as a completed product.
Measurement of THD and S/N
Pavel Macura 12/2011