Volume pots... I go through them so quickly

[paulyc]

I also come from the camp that thinks the incorporation of a standby switch on a tube amp is unhealthy on the tubes. They exist only because users have been misinformed for such a long time and are afraid to buy an amp without a standby switch. It is not bad for tubes to apply high voltage when they aren’t warm. Because they aren’t warm, they only slowly draw current as they warm up. A typicall set of tubes lasts me 5 years of daily use and then some.

While on the standby switch subject. It was introduced to protect the filter caps. As we know the tubes do not conduct until the cathode is warmed up, and we know during this "warm up" time the PT is putting out higher voltage since it's not yet loaded. If the filter caps are not well over rated they will be over volted causing damage over time, and premature failure.

This is less of a concern in modern times because the cost of higher voltage caps are not as cost prohibitive, and size constrained as they were in the old days.

Now that being said, I've seen some modern amps that I'm pretty sure will have over voltage cap damage if you fail to use the standby switch.

The explanation I remember reading about the need for a standby switch was “cathode stripping” while the tubes were warming up.

 

[scottosan]

I also come from the camp that thinks the incorporation of a standby switch on a tube amp is unhealthy on the tubes. They exist only because users have been misinformed for such a long time and are afraid to buy an amp without a standby switch. It is not bad for tubes to apply high voltage when they aren’t warm. Because they aren’t warm, they only slowly draw current as they warm up. A typicall set of tubes lasts me 5 years of daily use and then some.

While on the standby switch subject. It was introduced to protect the filter caps. As we know the tubes do not conduct until the cathode is warmed up, and we know during this "warm up" time the PT is putting out higher voltage since it's not yet loaded. If the filter caps are not well over rated they will be over volted causing damage over time, and premature failure.

This is less of a concern in modern times because the cost of higher voltage caps are not as cost prohibitive, and size constrained as they were in the old days.

Now that being said, I've seen some modern amps that I'm pretty sure will have over voltage cap damage if you fail to use the standby switch.

have you measured this. I’d expect the amperage to be low but not real big jump in voltage. An amp with caps not specd to hand an unloaded B+ is a bad designed amp

 

[scottosan]

I also come from the camp that thinks the incorporation of a standby switch on a tube amp is unhealthy on the tubes. They exist only because users have been misinformed for such a long time and are afraid to buy an amp without a standby switch. It is not bad for tubes to apply high voltage when they aren’t warm. Because they aren’t warm, they only slowly draw current as they warm up. A typicall set of tubes lasts me 5 years of daily use and then some.

While on the standby switch subject. It was introduced to protect the filter caps. As we know the tubes do not conduct until the cathode is warmed up, and we know during this "warm up" time the PT is putting out higher voltage since it's not yet loaded. If the filter caps are not well over rated they will be over volted causing damage over time, and premature failure.

This is less of a concern in modern times because the cost of higher voltage caps are not as cost prohibitive, and size constrained as they were in the old days.

Now that being said, I've seen some modern amps that I'm pretty sure will have over voltage cap damage if you fail to use the standby switch.

The explanation I remember reading about the need for a standby switch was “cathode stripping” while the tubes were warming up.

Thats the byproduct of having the heaters warm and no B+ applied. Standby switches were original designed for muting the amp, not for tube longevity

 

[CornNutz]

I also come from the camp that thinks the incorporation of a standby switch on a tube amp is unhealthy on the tubes. They exist only because users have been misinformed for such a long time and are afraid to buy an amp without a standby switch. It is not bad for tubes to apply high voltage when they aren’t warm. Because they aren’t warm, they only slowly draw current as they warm up. A typicall set of tubes lasts me 5 years of daily use and then some.

While on the standby switch subject. It was introduced to protect the filter caps. As we know the tubes do not conduct until the cathode is warmed up, and we know during this "warm up" time the PT is putting out higher voltage since it's not yet loaded. If the filter caps are not well over rated they will be over volted causing damage over time, and premature failure.

This is less of a concern in modern times because the cost of higher voltage caps are not as cost prohibitive, and size constrained as they were in the old days.

Now that being said, I've seen some modern amps that I'm pretty sure will have over voltage cap damage if you fail to use the standby switch.

have you measured this. I’d expect the amperage to be low but not real big jump in voltage. An amp with caps not specd to hand an unloaded B+ is a bad designed amp

Yes on a typical 100w Marshall type of circuit you'll be in the 530 to 540 vdc range before the tubes warm up. Now not to start anything with manufactures, but look at a recent BE100, the single non-series screen cap is rated 500vdc. You flip the power and standby on at the same time, and you'll be over 500vdc for 10 to 15 seconds. Do this for months, and you'll be killing that cap.