Not just an replacement, but an improvement!

This tube has the high performance plates of the 52B,  but the grids + filament of the normal 300B. This makes the 300B-XLS combining the power and stability of the 52B, with the characteristics of the 300B.   In one tube we have combined the very best of two classical products.

Though the 300B-XLS has original WE300B settings, it can be operated in two ways. 

1) You can replace any 300B with this tube.  Just plug it into any 300B amplifier, and the tube will set  itself exactly  to the original 300B working point.   This is a very strong tube,  and it will develop the output power with more ease.  Specially for amplifiers that let the 300B tubes work very hard,  the 300B-XLS is the right product  to choose.

2) Another   purpose of the 300B-XLS is to get more power,  than is possible with standard WE300B tubes.  This can only be done when you have the possibility to adjust the plate current of the amplifier (so called: adjustable bias).   If you increase the plate current of the tube ABOVE the standard WE300B specifications, something very special will happen.  The tube  will now move to a part of the curves where it has a lower plate resistance. This will result in a better damping factor of the bass and mid loudspeakers.  A better damping factor is like vitamines to the performance of your loudspeakers, and will result in a more natural sound reproduction.  The damping factor can also be verified by measurements.

The improvement  is the largest at mid and higher power levels.

All critical parts, like filaments, grids and plates are constructed of hard metal for the best reliability and reproducable quality. 

Features

• Hard metal filaments and Plates, Wolfram Grids (Note1)
• 8 circular cooling plates (4 single + 4 double plates)
• Wolfram Grids (Note1)
• Two extra large getters, flashing the complete tube bottem. 
• Hand blown ST Glass bulb
• Anti-microphonic plate- and grid  suspension
• These tubes are shipped in a high quality dual box
• Tube pinting with real gold (metal),  red color is burned into the glass 
• Machined, solid tube base pins for highest contact precision. Ideal for the YAMAMOTO tube sockets. 
• Gold plated pins,  black ceramic socket.  (White bottem)

• Note 1)  Hard-metal filaments prevent filament breakage with DHT Tubes.  This material has a higher melting point than the classical nickel wires. Hard metal plates have a more precise plate distance, and do not change shape when heated.  This ensures  reproducable tube parameters, and long term stability. Wolfram grids  allow the most precise grid wire distance, because wolfram is an extreme hard metal.   This ensures better uniformity and linearity at the low end of the tube curves.
• Note 2)  Individual Test data, such as:  Matching Data, Grid Current, Vacuum, Filament Current, etc,  are on the Certificate that comes with each individual Tube.  Each tube  is numbered, inside the bulb  with a metal Tag
• Note 3)  Plate Curves:  Made with the Sofia Digital Curve tracer.  Plate curves with courtesy of AMR

• Note 4)  Maxmimum specifications. These data are only to show the safety distance to the recommended operationg point.   You can operate the tube at the maximum for a short period of time.  Exceeding the maximum, will decrease the lifetime  very rapidly.  For long term reliability,  the tube should not  be operated  above  the "typical"  dissipation  (green table)