Bóng công suất Emission Lab 520B

EML520B is a premium tube. It has developed from the older 52B, with many technical improvements added. Two of the most important, the EML520B has extremely stabile bias, and it is also mechanically more rugged. All critical parts, like filaments, grids and Anodes are constructed of hard metal for higher reliability and reproducible quality. Note the relation between the tube base, and and the glass bulb. Then compare this with our 300B. This gives an idea of this tube’s remarkable size, which is the same as an 845 tube.

Sound Character and use of the EML 520B

1. Use as improved 300B tube

Though this is no drop-in replacement for 300B, it is possible to replace a 300B with this tube, provided some things which must be checked. Care needs to be taken to have the right bias, and also it needs to be sure the heater supply will still do 5V at the higher current of the 520B. (2.1 Ampere vs 1.3 Ampere of 300B). With some knowledge of electronics, these can be used as ultimate upgrades for 300B tubes.

One of the best things of the 520B is the lower Anode resistance (480 Ohms of 520B vs 700 Ohms of the 300B). This will lead to higher efficiency of the amplifier, and a more output signal, even at the SAME bias settings. Moreover the signal will be less distorted at higher volume, The lower Anode impedance will also give better control of the BASS speaker chassis, since the damping factor increases with 25% compared to standard 300B. This will not give so much louder bass, but more natural sounding bass. This can be done with existing 300B amplifiers, provided the technical checks, described in the previous text.