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The standby switch on my tube guitar amplifier is popping!

“My new amp makes a pop noise when I use the standby. My old amp never did this. This amp must have a problem.”

This is a common complaint we hear. However, the pop that you hear from the standby switch on your tube guitar amplifier is actually normal.  The reason it happens is because when your amp is turned on and running, there is a constant supply of voltage running through your amp. When you throw the standby switch from On to Standby, you are disconnecting the high voltage half of the power supply. This is releasing a lot of energy! When connecting or disconnecting high voltage, there is always the possibility the surge of the voltages will produce a pop noise. Depending on how the standby switch is designed will determine how much pop noise is created. The real problem is misuse of the switch.

Ever since standby switches have appeared on guitar amps, the common misconception is that they are for “standby” during breaks or some kind of mute switch. This usage of the standby switch as a Mute is actually not proper. Standby switches were designed to protect the capacitors (not the tubes)  in the power supply of your amp during tube warm-up only. Guitar amps use higher voltages to get more watts which can be tough on the capacitors in the circuit.

When powering up your amp, you would have the standby switch set to “Standby”  in order to allow the tubes to warm up before sending full voltage to the capacitors of the power supply.  The tubes take a few seconds to reach operating temperature. Until the tubes can operate, the voltage can rise higher on the capacitors which is hard on them. Once the tubes are warm, they pull down the power supply voltage to normal operating levels at which the capacitors will work better.  When powering down, it is not necessary to put your amp in standby. Simply turn off the main power switch.

This will cause no damage to your amp, according to our in-house amp technician. In fact, according to tube engineering theory, the tubes are actually stressed more when left in standby running hot with no high voltage on them. There is a condition called “cathode poisoning” that reduces the life of the tube. So, in actuality, the long time misconception that using the standby switch will make your tubes last longer is untrue.  If anything, it will reduce the life a little bit. Don’t get worried though. This is just to prove a point. Cathode poisoning take a long time to happen and likely not to cause any noticeable performance problem unless you left the amp on in standby for a week or more.

To recap, standby switches were never designed to be used as a break or Mute switch. If you want to take a short break, it is actually better to just leave your amp on. If you want to make sure your amp makes no sound, just turn the volume down. Some amps do have a “Mute” switch which is designed to mute the audio without making a pop.

We hope this clears up the mystery of standby switches. Just remember it is not a mute switch. Pops are normal.

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