Jürgen Grau sent me new photos of his latest creation - this is a hybrid tube phono preamplifier. It is sold as a kit and should take about an hour to assemble.





  • Operational Amplifier NATIONAL LME49860 (only 2.7 nV noise, 0.00003 % distortions)
  • +/- 20 V supply voltage for the OP amp
  • 65 V anode voltage
  • No inductive switching voltage converter used
  • Tubes are driven with line level, therefore no influence of external interfering fields
  • Adjustable anode current on Line level
  • Fully passive tubes RIAA equalization
  • Different dual triodes can be fitted by soldering jumpers, e.g. 12AU7 / 6DJ8 / 5670
  • Output of the cathode follower is wired direct to the RCA jacks
  • Additional low impedance output with 2 x NE5534 on 1/8" TRS jack on front
  • With solder jumpers the RIAA equalization can be disabled and the amplification reduced for using as a true line amplifier
  • All "critical" parts -even the SMT's- are just pre-assembled and soldered
  • No SMT parts within the audio path
  • Polypropylene capacitors with 2.5% tolerance
  • Assembling the complete kit within 1 hour is not a problem
  • Extra external GND connection
  • 2 x 6N3P-E dual triodes included
  • On request: 2 x JJ E88CC / 6N23P
  • The enclosure is also included
  • DC input via 5.5 / 2.1 mm jack
  • 12VDC 1A input for stabilized power supply (not included)
  • On request: Ultra Low Noise 12 V / 3.5 A switching power supply; suitable to power some extra components, too






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