Tube rectification

2nd Phd.

I believe the issue is that all forms of SS rectification introduce some type of high-freq noise. A tube does not do this. After owning 10 or so tubed pres, some with tube rectification and some not, tube rectification became a must-have feature for me in a pre. About the only must-have, FWIW.

Many components with tube rectification also use SS rectification for select circuits such as filament supplies. Most tube components with SS rectification also fail to use the best fast- or zero-recovery SS rectifier bridges made of Schottky(or in high-voltage circuits, SiC Schottky) diodes. Given the wide range of design combinations and compromises, generalizations are of little value on this point.

If the rectifier circuit does not have a feature to slow the high voltage from coming up to full: The life of your tubes will be severely shortened. A tubed rectifier circuit allows the tubes to slowly warm up to full operating temps. Because there is no warm up of a rectifier tube when using a solid state device, it is critical that a standby switch be used that will allow the power tube filaments to warm up and generate an electron "cloud" around the cathode before high voltage is applied. This will prevent "cathode stripping" in the power tubes. It is a good idea to use a standby switch when using vacuum tube rectification, but it is critical when using solid state rectification. My Cary SLM-100's have SS rectification, and a standby switch. My BAT VK-D5 CD player's tubes always have a small voltage to the heaters, keeping them ready for use, in standby mode.