RStAudio XOno 2019

this project / page is under construction


Current status of the project (2019/09/16) :
  – XOno circuit diagram created
  – XOno PCB design created
  – Controller circuit diagram created
  – 2 XOno circuit board supplied (prototyping)


Table of Contents



Since 2008 I provide printed circuit boards for a Pass Labs XOno replica and over the years unexpectedly many have been built. Unfortunately the gold dust – the outstanding 2SK170 JFETs from Toshiba – are running out. The supplier I always recommended can’t offer any more. So it becomes difficult to impossible to build an original XOno.

At the end of 2018 I decided to build a MC-prepreamplifier based on the XOno topology with the 2SK2145 JFET’s from Toshiba as a plug-in card for my DPV1 phono preamplifier. It should serve as a test setup for a new XOno to be designed. I put this plug-in card into operation at the beginning of 2019 with great success and thus nothing stood in the way of a redesign of the XOno.

The design should still be as close as possible to the original XOno design, but with a few useful improvements from the design of the XP-15 and my own experience of many years. I have written the following points into my personal specifications:

  • Optionally assembled with 2SK170 / LSK170 or 2SK2145.
  • Reference voltage source instead of the simple LED for the current sources of the RIAA amplifier.
  • Modern design of the inverter (XP-15).
  • Optionally assembled with DIP switches or relays.
  • Optional AC or DC coupling at the outputs of the RIAA stage and the inverter.
  • DC power supply input with CLC filter.
  • Discrete power supply regulation with a modified Jung regulator.
  • Extension Board with additional Equalization Characteristics (Columbia, Decca, EMI & Teldec)
  • Microcontroller PCB for the relay operation.
  • Use of mainly through-hole components.