Pretty much all the " things " you have heard about tube amps are myths, with the exception of a few very important ones.
1. The tube amp does warm up per se and it just takes a moment for the cathode to get hot enough to boil off electrons. The tubes don't care if there is a signal or not. In fact, I would strive to make it not try and conduct a signal while the tubes heat up. If you ask the tubes to do something they are not ready to yet, that may be worse than not asking them to do anything at all.
2. The standby switch isn't needed at all and it doesn't matter if you use it or not. In fact, using the standby switch is more likely to cause pops and damage than anything else you do. More in a bit.
The only actual, 100% important thing that must have care taken in assuring is that the amplifier is plugged into a speaker while it is on and running. In standby, this doesn't matter. While in standby, the HT or high voltage that feeds the tubes is switched off. With no HT, there is no way for any of the tubes or the output transformer to conduct, so you cannot hurt the amp if nothing is disconnected if and only if the amp is in standby mode. However, it is paramount to the life of your amp that it is connected to a speaker at any time the amp is able to fully operate!
The whole MUST have the SAME ohm rating of speaker cab as the tap set on your amp is literally only 1/2 true. The ohms tap on a transformer is like a gear in a car's transmission. Now let's imagine that the speaker is actually the tire size of the car. If you put a giant tire on the car and don't change the gearing in the transmission, the car will be hesitant to move and you could burn out the transmission's clutch or even the engine. Conversely, if you put a teeny tiny tire on the car, the transmission and engine will be spinning like crazy to make the car move at an acceptable speed. Same sort of thing for an output transformer and a speaker load. The output tap is the gear and the speaker is the tire. It is generally ok at nominal volume levels to be one impedance tap off from the speaker load. I.E. An 8ohm speaker into the 16ohm or 4ohm tap. Things change when trying to run the amplifier full tilt. A 16ohm speaker is a large tire and a 4ohm speaker is a small tire. A small tire ( 4ohm ) on the gearing for a big tire ( 16ohm tap ) will cause the OT to overheat because the amps engine ( tubes ) will be trying to conduct all the power that they can through the transformer with no resistance. Now if you have a 16ohm speaker on the 4ohm tap, the speaker is presenting a very high resistance to movement ( due to electrical conversion ), which loads up the transmission and engine ( amp ) if you will. This causes electrons to build up on the plates of the tubes, and excess energy is stored in the OT. If enough of this energy gets stored, the build-up of electrons in the winding of the transformer can break through the wire's insulation and cause arcing, or the tubes plates will simply melt. This takes a fair amount of effort though, the build-up of electrons on the plates and in the transformer takes time to build up, and if you stop playing, this unloads things and the charge will dissipate. So going from a 4ohm tap into a 16ohm speaker will greatly reduce output, and could eventually cause the tubes and transformer to burn up, but it takes a fair amount of work for that to occur. BUT going from a 16ohm tap into a 4ohm speaker means the amp will be trying to produce all the power it can all the time unimpeded, this is a problem as it will eventually cause the OT to heat up and melt. Another way to look at it is the amount of potential conduction. The less impedance the OT see's, the more it will try and conduct, this causes more heat and may eventually burn up. Loading the OT up with a higher impedance reduces the amount of conduction, but causes a build-up of electrons that can eventually cause arcing or melting of the tubes plates. You can be off either way by one tap safely, for example, a 4ohm speaker into the 8ohm tap, or a 16ohm speaker into the 8ohm tap, or an 8phm speaker into either a 4 or 16ohm tap. So long as you are within one tap difference from your speaker load, you should have no problems at nominal levels. I do suggest though, that if you plan on diming the amp, that you use the same speaker load as the tap that you lug into.
The good old standby switch. It does serve a purpose, but it is more for servicing than for playing under normal use. It is nothing more than a mute switch. It just so happens that instead of shunting the input signal to ground, it cuts the HT voltage from the tubes. If there is no HT voltage on the tubes, they cannot conduct, but there is still 300v to as much as 600v waiting to instantly turn the tubes on when the switch is flipped. Depending on how your standby switch is wired, it can allow a pop as you suddenly snap the HT voltage into all the tubes. The idea that having the standby switch on when you turn the amp on allows all the HT voltage to sit on the plate of the tube which can cause arcing is not very true except in amps that have cathode follower stages. The tubes can't conduct if the cathode is not heated, so there is little to worry about with voltage on the plates. In a cathode follower stage, the HT is actually placed on the grid of that tube! This can allow arcing to occur but is generally of little fear with healthy tubes. As tubes get older and worn, they become gassy or have a breakdown of the cathode element, which can allow paths for arcing to occur, once it happens once, it becomes more and more prevalent. By that point in time, it is necessary to replace the tube anyway. If you have ANY amp with a tube rectifier, you truly have no need for a standby switch. A tube rectifier takes time to " warm-up " and it won't conduct until it is ready, which means that by then, the other tubes will also be ready. In a solid-state rectified amp, the HT voltage is pretty much instantly ready to go, but there is generally a bleed resistor that discharges the capacitors while not in use. So when you turn on a solid-state rectified amp, the capacitors eat up that initial shock of voltage as they charge up. The inline resistors for the different power nodes also slow the shock of that sudden inrush of current. So while leaving the standby switch on when you turn on a solid-state rectified amp will allow the HT to go to the tubes before they are able to conduct, it is a soft start at least. For all intents and purposes, the standby switch is nothing more than a mute switch.
The standby switch is also part of the cathode poisoning myth. Which is only partially true again. The idea is that if you leave the standby off, with the amp on for prolonged periods of time, the cathode will build a high resistance layer on the cathode limiting its ability to boil off electrons. A tube is like a light bulb, it has a life expectancy. The more the tube is on, the closer to death that tube will be. A NOS tube, even used, is only still good because it hasn't gone gassy and has so little use it still has some life left in it. So if you leave an amp on whether the standby switch is on or not, the tubes are then on, slowly but surely sucking the life out of them. you cannot expect a tube to last 1 million hours just because you NEVER had the standby switch off while the amp was on. A tube's life is counted in hours. The more it is on, the closer you are to its last hour. It is certainly not suggested to leave an amp on for prolonged periods of time with or without the standby on. This is one very good reason that a standby switch is destructive. You remembered to hit the standby switch, but not the power switch. Imagine if there was only just a power switch to turn off and no extra step required to " shut down " the amp... The standby switch doesn't help with anything other than muting the amp. A Boss TU3 does that too.
1. The tube amp does warm up per se and it just takes a moment for the cathode to get hot enough to boil off electrons. The tubes don't care if there is a signal or not. In fact, I would strive to make it not try and conduct a signal while the tubes heat up. If you ask the tubes to do something they are not ready to yet, that may be worse than not asking them to do anything at all.
2. The standby switch isn't needed at all and it doesn't matter if you use it or not. In fact, using the standby switch is more likely to cause pops and damage than anything else you do. More in a bit.
The only actual, 100% important thing that must have care taken in assuring is that the amplifier is plugged into a speaker while it is on and running. In standby, this doesn't matter. While in standby, the HT or high voltage that feeds the tubes is switched off. With no HT, there is no way for any of the tubes or the output transformer to conduct, so you cannot hurt the amp if nothing is disconnected if and only if the amp is in standby mode. However, it is paramount to the life of your amp that it is connected to a speaker at any time the amp is able to fully operate!
The whole MUST have the SAME ohm rating of speaker cab as the tap set on your amp is literally only 1/2 true. The ohms tap on a transformer is like a gear in a car's transmission. Now let's imagine that the speaker is actually the tire size of the car. If you put a giant tire on the car and don't change the gearing in the transmission, the car will be hesitant to move and you could burn out the transmission's clutch or even the engine. Conversely, if you put a teeny tiny tire on the car, the transmission and engine will be spinning like crazy to make the car move at an acceptable speed. Same sort of thing for an output transformer and a speaker load. The output tap is the gear and the speaker is the tire. It is generally ok at nominal volume levels to be one impedance tap off from the speaker load. I.E. An 8ohm speaker into the 16ohm or 4ohm tap. Things change when trying to run the amplifier full tilt. A 16ohm speaker is a large tire and a 4ohm speaker is a small tire. A small tire ( 4ohm ) on the gearing for a big tire ( 16ohm tap ) will cause the OT to overheat because the amps engine ( tubes ) will be trying to conduct all the power that they can through the transformer with no resistance. Now if you have a 16ohm speaker on the 4ohm tap, the speaker is presenting a very high resistance to movement ( due to electrical conversion ), which loads up the transmission and engine ( amp ) if you will. This causes electrons to build up on the plates of the tubes, and excess energy is stored in the OT. If enough of this energy gets stored, the build-up of electrons in the winding of the transformer can break through the wire's insulation and cause arcing, or the tubes plates will simply melt. This takes a fair amount of effort though, the build-up of electrons on the plates and in the transformer takes time to build up, and if you stop playing, this unloads things and the charge will dissipate. So going from a 4ohm tap into a 16ohm speaker will greatly reduce output, and could eventually cause the tubes and transformer to burn up, but it takes a fair amount of work for that to occur. BUT going from a 16ohm tap into a 4ohm speaker means the amp will be trying to produce all the power it can all the time unimpeded, this is a problem as it will eventually cause the OT to heat up and melt. Another way to look at it is the amount of potential conduction. The less impedance the OT see's, the more it will try and conduct, this causes more heat and may eventually burn up. Loading the OT up with a higher impedance reduces the amount of conduction, but causes a build-up of electrons that can eventually cause arcing or melting of the tubes plates. You can be off either way by one tap safely, for example, a 4ohm speaker into the 8ohm tap, or a 16ohm speaker into the 8ohm tap, or an 8phm speaker into either a 4 or 16ohm tap. So long as you are within one tap difference from your speaker load, you should have no problems at nominal levels. I do suggest though, that if you plan on diming the amp, that you use the same speaker load as the tap that you lug into.
The good old standby switch. It does serve a purpose, but it is more for servicing than for playing under normal use. It is nothing more than a mute switch. It just so happens that instead of shunting the input signal to ground, it cuts the HT voltage from the tubes. If there is no HT voltage on the tubes, they cannot conduct, but there is still 300v to as much as 600v waiting to instantly turn the tubes on when the switch is flipped. Depending on how your standby switch is wired, it can allow a pop as you suddenly snap the HT voltage into all the tubes. The idea that having the standby switch on when you turn the amp on allows all the HT voltage to sit on the plate of the tube which can cause arcing is not very true except in amps that have cathode follower stages. The tubes can't conduct if the cathode is not heated, so there is little to worry about with voltage on the plates. In a cathode follower stage, the HT is actually placed on the grid of that tube! This can allow arcing to occur but is generally of little fear with healthy tubes. As tubes get older and worn, they become gassy or have a breakdown of the cathode element, which can allow paths for arcing to occur, once it happens once, it becomes more and more prevalent. By that point in time, it is necessary to replace the tube anyway. If you have ANY amp with a tube rectifier, you truly have no need for a standby switch. A tube rectifier takes time to " warm-up " and it won't conduct until it is ready, which means that by then, the other tubes will also be ready. In a solid-state rectified amp, the HT voltage is pretty much instantly ready to go, but there is generally a bleed resistor that discharges the capacitors while not in use. So when you turn on a solid-state rectified amp, the capacitors eat up that initial shock of voltage as they charge up. The inline resistors for the different power nodes also slow the shock of that sudden inrush of current. So while leaving the standby switch on when you turn on a solid-state rectified amp will allow the HT to go to the tubes before they are able to conduct, it is a soft start at least. For all intents and purposes, the standby switch is nothing more than a mute switch.
The standby switch is also part of the cathode poisoning myth. Which is only partially true again. The idea is that if you leave the standby off, with the amp on for prolonged periods of time, the cathode will build a high resistance layer on the cathode limiting its ability to boil off electrons. A tube is like a light bulb, it has a life expectancy. The more the tube is on, the closer to death that tube will be. A NOS tube, even used, is only still good because it hasn't gone gassy and has so little use it still has some life left in it. So if you leave an amp on whether the standby switch is on or not, the tubes are then on, slowly but surely sucking the life out of them. you cannot expect a tube to last 1 million hours just because you NEVER had the standby switch off while the amp was on. A tube's life is counted in hours. The more it is on, the closer you are to its last hour. It is certainly not suggested to leave an amp on for prolonged periods of time with or without the standby on. This is one very good reason that a standby switch is destructive. You remembered to hit the standby switch, but not the power switch. Imagine if there was only just a power switch to turn off and no extra step required to " shut down " the amp... The standby switch doesn't help with anything other than muting the amp. A Boss TU3 does that too.
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