The 300B-mesh can replace a standard 300B in several cases, but not in all cases. So please read this data sheet carefully.
Do not simply plug & play a 300B-mesh instead of a 300B. Overheated anodes may result if you do not check the following conditions, and such a damage is not covered by the guarantee. The 300B mesh can replace a normal 300B tube, when you can meat following conditions:
- Bias and Plate dissipation must be reduced from 22 Watt to absolute maximum 28 Watt. (see below table)
- Filament current of minimum 1.4 Ampere can be supplied
- The larger length of the tube is no problem. (like with closed amplifiers)
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 Data sheet. The heat dissipation of the mesh wire is lower than for solid plate anodes. So the maximum plate dissipation of the 300B Mesh for continuous use must be limited to typical 22Watt, or absolutely maximum 28Watt. This is however a classical use condition in several Japanese products. Though 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.
Sound Character of the 300B-Mesh tube
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. A solid plate anode due to it's circular construction will have quite some ringing (bell like effect). A mesh anode will not have this effect. In most cases, 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. Chinese factories make a tube with punched plates, and for marketing call this "mesh". A punched plate from solid metal will also have this ringing effect, and can never have the superior resonance damping properties a wire mesh tube has.