NOS tubes are vintage tubes which sound better than new production which mostly come from Russia, although these tubes have been improving over the past few years.
The Project website states that the Tube Box S2 phono stage uses ECC83 tubes which is the European designation for 12AX7 tubes. These are widely used in audio components.
The following website provides good info on the different manufacturers and a description of how the tubes sound. Lower down on the page are the tubes for sale. There are many versions of 12AX7’s which include different plate types and internal tooling.
http://www.audiotubes.com/12ax7.htm
The Project website states that the Tube Box S2 phono stage uses ECC83 tubes which is the European designation for 12AX7 tubes. These are widely used in audio components.
The following website provides good info on the different manufacturers and a description of how the tubes sound. Lower down on the page are the tubes for sale. There are many versions of 12AX7’s which include different plate types and internal tooling.
http://www.audiotubes.com/12ax7.htm