This would cause an effect called cathode stripping. The main reason coming from standby switch supporters is to protect the cold tubes against the sudden onset of the high voltage. Everything is designed to withstand even the worst case scenarios. Besides that, I would NEVER try to save a few bucks by using under-specified components. Today, high voltage capacitors are readily available at much more reasonably costs. What’s interesting though, when the new re-issues of these ‘vintage’ amps were released, like the VOX AC30 Custom Classic series, they added a standby switch!? ‘Vintage’ image marketing? I don’t know. Perhaps most notably the revered VOX AC30. Standby switch and all. Now we have two of the biggest selling names in the industry using standby switches and they became forever linked to tube amps. Brands like VOX and Gibson however didn’t use them. It’s a know fact that Marshall blatantly copied the early Fender amps. But, you were stuck with under-specified components nonetheless. In other words, the capacitors will never see the higher switch-on voltage and they will live a happier and longer life. By allowing the tubes to warm-up before applying the B+, their conduction will be (near) instantaneous with the resulting voltage sag down to the working voltage. One way of reducing the costs of an amp was to use capacitors with a voltage rating safely above the amps working voltage (warm tubes), but very close to, or even below the ‘cold switch-on’ voltage. Mind you, high voltage capacitors were very expensive at the time.
Especially with capacitors, who also have a physical limit to what this rating can be. Electrical components have a maximum voltage rating and exceeding it can have disastrous consequences. When tubes warm up and start to conduct, the high voltage (B+ from now on) will sag a given amount. Because of this low current demand, the voltages inside the amp are at their highest. When tubes are cold at the time the amp is switched on, they don’t conduct any current.
Handy, if you’re going for a break while keeping the tubes nice and hot. The main reason given for the switch at the time was a muting function of sorts by cutting off the high voltage supply to the tubes.
I believe it was the Tweed Deluxe to be the first and of course, every Fender tube amp after that. Note, the first Fender Tweed didn’t have one either. Why do amps even have them, how and why do people (still) use them and why can we do without just fine?įender was the first to provide a standby switch on their tube amps. There are a LOT of persistent myths surrounding the standby switch. Where’s the standby switch on a deBont tube amps? Well, there isn’t one, because they’re not really necessary. Think of an Ampeg SVT or Fender Bassman for example. Looking at tube amps from the past 60 years or so, either for guitar or bass, you’ll see a standby switch most of the time.