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.
Specifications:
- 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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