12b4 Tube

Tube Stores

• vacuumtubesinc 12B4 / 12B4A 5.00
• thetubestore $7.95
• thetubecenter $4.00
• esrcvacuumtubes $4.00
• audiotubes $6.00

12B4 pre-amp recommendation

Audio Asylum - Tube DIY

Two Terminal Constant Current Source

K and K Audio

Low Voltage Power Supply

After cobbling together untold numbers of small power supplies for "auxiliary" functions in tube preamps and power amps, I decided to design something with a regulator that is better than the ubiquitous 7800 series three terminal regulator and try it in places where it powers something more than relay coils. In locations like low voltage negative supplies and as power for a USB to SPDIF digital audio converter I found this supply sonically superior to my previous slapdash efforts. This power supply uses the LT3080 regulator, which is adjustable by changing one resistor for output voltages between 1 and 24 volts DC in this implementation. A charging slope lowering resistor and Schottky rectifier diodes are provided to be kind to the power transformer and reduce both supply noise and radiated magnetic field noise. Along with plenty of output bypass capacitance, this compact package does a thorough job of supplying up to 4 watts of power at low voltages. Resistors are provided for 5, 6.3, 8, and 12VDC. You can obtain other 0.25w resistors for other voltages. The supply can accommodate both 115V and 230V mains voltage and has an on-board fuse holder for safety. With the standard supplied 8+8 volt secondary power transformer, the maximum possible DC current draws are approximately:

• 5VDC 870mA
• 6.3VDC 700mA
• 8VDC 550mA
• 12VDC 470mA

The PC board is 2.75" (7cm) x 3.3" (8.4cm) and the height is 1.6" (4cm).

$36