The PA-2 is a fully balanced, solid state, stereo preamplifier. It features a relay-controlled balanced attenuator with precise 1 dB steps, optical isolation between digital and analog functions, a plug-in module for two phono/aux preamplifiers, and a remote power supply (not shown).

Comments

• maurizio49
• 15 January 2023 at 05:08AM
• Wow! impressive work. Beautiful. Can I have more informations?

• BEG
• 5 March 2023 at 07:48AM
• Thank you, maurizio49. You are very kind. I’m not exactly sure what kind of information you are interested it. The unit is all my design except for the FPGA that controls the attenuators and display. The FPGA receives input from two 8-bit ADCs that digitize the Volume and Balance control settings. The amplifiers are designed around the best op amps that I could find at the time (AD745, AD797, OPA627, OPA2132). I think that the line amp is fairly unique, and I hope to publish an article on it in the near future. I will point you to it if/when that happens. I made the chassis from 0.125” thick aluminum sheet and 0.5” x 0.5” square solid aluminum rod. I cut the aluminum on my table saw with a carbide tipped aluminum cutting blade. The rods are drilled and tapped for the stainless steel (SS) machine screws. I used SS inserts for all screws that need to be removed for repair or update. If you have more questions, please let me know.