Not just a replacement, but an improvement!

This tube can replace a normal 300B tube, with following restrictions:

1) Continuous Plate dissipation is maximum 28 Watt
2) Filament current of 1.4 Ampere can be supplied
3) The larger physical size of the tube

The 300B mesh is a "long plate" version, and the plates are 25% longer as with normal 300B we build. The physical size of this tube, inside and outside is the same as the larger 520B tubes we make, so it is much larger than you may expect from a 300B. Check the dimensions at the end of this datasheet. The heat dissipation of the mesh wire is lower than the hard metal that we use for the solid plate tubes. So the maximum plate dissipation of the 300B Mesh for continuous use must be limited to 28 Watt. Peak dissipation is higher, but we do not specify this value. Actually 28Watt is a classical use condition in many Japanese products. However many other amplifiers exceed this number, so it is important to check with your amplifier manufacturer first, if you are not sure about the plate dissipation.

Why Mesh plates? When a tube is given mesh plates, something magic happens to the sound! We believe this is caused by the better damping properties of the mesh material.  When using mesh tubes, you will experience a more transparent sound stage, meaning a more realistic stereo reproduction of the original sound recording.  With mesh tubes you will enjoy the very best of what small triodes have to offer.  Note: mesh means woven metal wire. The Chinese make a tube with punched plates, and for marketing call this "mesh". A punched plate will not have the superior resonance damping properties a wire mesh tube has. 

• Gray Wire Mesh plates, mounted on a hard metal frame for best stability.
• Gold plated, Wolfram Grid
• Soft rubber suspended tube base
• Center tapped filament
• Slow Start filaments, for best lifetime
• Hard metal Construction (Note1)
• Two extra large getters
• Hand blown Glass bulb
• Anti-microphonic plate- and grid  suspension
• These tubes are shipped in a high quality dual box
• Tube printing with real gold (metal),  red color is glass burned into the glass 
• Machined, solid tube base pins for highest contact precision. YAMAMOTO tube sockets highly recommended. 
• Gold plated pins,  black ceramic socket.  (White bottom.)

• Note 1)  This tube has gold plated grids, and additional to this it has several other new features, that we do not to publish for competition reasons. The result of this is, if a tube like this gets accidental overheated, the risk on damage is greatly reduced, compared to classical tubes, and compared to tubes as we produced them before. As end-user you can recognize a tube of this series by the gold plated grid. The gold color of the grid is visible with the bare eye, when you look carefully. We do not say you can overheat this tube, but chances on damage are greatly reduced in case it would happen anyway by mistake.
• 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 has  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