W skrócie: przełącznik standby nie ma racji bytu we wzmacniaczu. Niszczenie katody wskutek "zimnego rozruchu" to mit wzięty z lamp obrazowych. Z drugiej strony, pozostawianie lampy na standby powoduje zatrucie katody.Contrary to popular belief, the standby switch is not there to prolong valve life-span. The theory is that if the HT is applied while the cathodes are cold they will be 'stripped' by ions crashing into the unprotected cathode. However, this simply does not happen. It is an urban myth borrowed from transmitter and cathode-ray tube technology NOT ordinary 'receiving' valves. The only valve which might ever be at risk of failure is a rectifier valve, because it has to supply inrush current to the reservoir capacitor, and some guitar amps fail to use enough limiting resistance to protect against this (see more on rectifies).
On the other hand, leaving a cathode hot without any anode current flowing does lead to the very real effect of cathode poisoning, which reduces the gain (transconductance) of valves. Fortunately this phenomenon really only becomes significant if the valves are left on standby for hours on end.
If you're wondering why all those old amps use a standby switch, its because they were designed on the cheap. The power supply caps would usually be rated only for the working voltage, not the peak voltage which occurs before that valves start drawing current. Leo Fender, and the rest, relied on the musician to use the standby switch to stop those caps bursting. The rest is history. Nowadays no designer (who values his reputation) uses underrated capacitors, so the standby switch has become obsolete, but your average amp tech doesn't know this.
Note that even the RCA Transmitting Tubes Technical Manual No. 4, p65, states: “Voltage should not be applied to the plates or anodes of vacuum, mercury-vapor, or inert-gas rectifier tubes (except receiving types) until the filaments or cathodes have reached normal operating temperature.” [My italics]. In a properly designed amp, a standby switch is nothing more than an expensive mute switch.
Stare wzmacniacze miały ten przełącznik, bo kondensatory filtru zasilacza miały napięcie pracy "na styk" i włączenie napięcia anodowego zanim lampa jest w stanie pociągnąć prąd z zasilacza spowodowałoby przekroczenie dopuszczalnego napięcia kondensatorów.
Cytat z http://www.freewebs.com/valvewizard1/standby.html
Czy ktoś mógłby się do tego ustosunkować?
Przyznam, że jeśli nie musiałbym montować tego przełącznika byłbym więcej niż szczęśliwy.