Fidele Audio

Analogue from Vinyl to Speaker

Quad 303NA Full Upgrade

This full amplifier upgrade is based on the Net Audio 303 upgrade. Fidele worked with Net Audio on 303 upgrades by providing a build and test service for Net Audio when required. There is a link to Fidele from the Net Audio web site.

For this upgrade the amplifier and power supply modules are completely re-built with all new components. The power supply and output capacitors are replaced and increased in capacitance. The output configuration is changed to a 'push-pull' design and the output transistors replaced with high quality audio transistors.

This upgrade provides the following:

  • Replace Power Supply capacitors with 2 x 4700uF
  • Replace output capacitors with 2 x 10000uF
  • Add by-pass film capacitors to main output capacitors
  • Replace amp module electrolytic capacitors with Elna Cerafine
  • Replace input capacitor with 1uF film capacitor
  • Add Constant Current diode source for TR101 and Bias Circuit
  • Replace trimmer pots
  • Replace the output inductor with high current type
  • Reduce output current limiting
  • Replace all amp module transistors with modern audio transistors
  • Replace all amp module resistors
  • Convert the output to 'push-pull' drive
  • Replace output transistors with complementary MJ21194 and MJ21193
  • Replace the rectifier bridge module with a modern bridge diode
  • Completely rebuild the power supply module including small modification to increase temperature stability.
  • Replace the power supply output transistor with MJ15003
  • Full alignment and bench test

The cost for this upgrade is £265.00 including return tracked and insured shipping to the UK. Please inquire for shipping to other locations.

Please refer to our Payments and Shipping pages for additional information.











Quad 303



Upgrade List