Here is a nice little stereo phono preamp using a pair of JAN 6418 subminiature tubes. This design uses very few components and adds a nice bit of extra oomph and tube tone sparkle to your input signal. I have tested on turntables and cassette decks with great results.
Using an IC7660s as a charge pump to bump the 9-volt power up to 18 volts adds an extra bit of sparkle to the sound. The IC7660s can be omitted as this design can be run at 9 volts. The 6418s are rated for up to 30 volts and tend to sound better and better the more voltage you run to them.
If you are getting signal noise, try a ground loop isolator. This design doesn’t like dirty power.
Need some JAN 6418 tubes? We got’em!
Raytheon JAN 6418 pentode vacuum tube – 5 Pack
NOS JAN 6418 Vacuum Tubes
These Joint Army Navy 6418 sub-mini, 5 lead vacuum tubes are perfect for building battery powered boosts, condenser mics, preamplifiers, and even RIAA compliant headphone and phono preamps. This same tube is used in many DIY and commercial products including the Oatley K272 kit and the Audio-Technica AT3060 condenser mic.