*) Increased "headroom", thus ensuring that the final, and only the final, clips on overdrive. Especially when gNFB is employed, multiple stages clipping at the same time makes for a real mess.
*) Lower distortion: the smaller the output swing relative to the maximum possible output swing, the lower the distortion.
(Although I've seen this done a lot more often with solid state designs.)
*) Lower distortion: the smaller the output swing relative to the maximum possible output swing, the lower the distortion.
(Although I've seen this done a lot more often with solid state designs.)
Depending on the tube the higher B+ may be needed to get the optimum load resistor without dropping to an excessively low idle current. BTW, I would consider 300V a pretty normal B+ not all that high really. Table radios often used lower B+ so that they could go direct wire PS without the added expense of transformer or doublers but this is to save money not to improve performance. Some tubes were made specifically for such low B+ but most general purpose tubes really do better with a bit more voltage.
He is reading the voltages backwards from output to input.
The highest voltage is at the output stage. RC filters are used to progressively better filtering as one progresses to the input stage which is most sensitive to power supply noise. Each RC filter stage drops the voltage relative to the previous stage.
The highest voltage is at the output stage. RC filters are used to progressively better filtering as one progresses to the input stage which is most sensitive to power supply noise. Each RC filter stage drops the voltage relative to the previous stage.
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