D3A Phono Build - 0427

Connected Phono Board to PSU and hook'ed up to input and output RCAs Found that the on the input side, the "GND" silkscreen was reversed. Banged my head trying to find out why I wasn't getting sound only on one the left channel. Found that I had not connected B+ to the right channel. DOH !!! Ahh.. finally got sound out of both channels ! Amazing detail thru the Stax Lambda headphones using the iRIAA and iPhone. iPhone -> iRIAA -> D3A phono -> T-Amp -> Stax Lambda == Smiley Face


Next steps :

• Re-orient boards


• Run all joints thru a round of solder


• Install resistors on the secondary after parts get delivered


• Try mounting 15095A in the chassis for MC functionality (possibly MU metal shielding)


• Install switch for switching between MM/MC


• Install shielded hookup wire
  
• Heatsink solution for MOSFETs if they don't run cool even after installing the power resistors on and dropping B+ to 200 (current set to 220V)

D3A Phono Build - 0426

Tasks Completed :

• Bored hole for power switch on the face plate ; used 0.7" drill bit
• Completed wiring for power switch
• Completed extending secondary heater wiring
• Tested power on with switch - tested okay
• RCA female plugs are painful to tighten. Looking at Neutriks :





To Do :
• check ground wiring
• use hookup wire to hook RCAs
• solder terminal posts
• connect to main D3A phono board ; test B+, H+ voltages
• connect iRIAA and test

Randall Museum Tube Audio D.I.Y class

Finally the DIY'er in me in unleashed ! The Randall Museum in San Francisco is offering a Tube Audio D.I.Y class this winter session. This class provides the much needed hand-holding that I needed to start off a hobby project using vacuum tubes or thermionic valves (as the Europeans would say) for audio amplifiers.

The class is conducted by Edwin Yang, an avid SF Bay Area tube audio enthusiast and experience DIY'er. The project is to complete a simple line-stage pre-amplifier based on the EF86 pentode.

I intend to log the progress of this class until the completion of the line-stage pre-amp for about 6 weeks. So stay tuned....