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Citation : 5) Power attenuators damage amplifiers. There is some truth to this myth. But, attenuators can be safely and successfully used – and every guitarist should know how and when they can be safely used. Here are the facts:

- A properly designed power attenuator does not apply any more stress to the amplifier than does a speaker cab – in fact a good attenuator will usually apply slightly less stress than a cab alone. However...
- ...when using an attenuator, guitarists typically drive their amplifier much harder than they ever would when driving a cabinet directly. Driving the amp this hard will significantly reduce tube life regardless of whether the amp is driving an attenuator or a cab. As a consequence, it seems like the "attenuator wore out the tubes." In reality, the guitarist was just enjoying much more overdrive than he ever would have without the attenuator and is paying the piper.
- Some amplifiers are simply not built to be driven hard. When the guitarist uses an attenuator and then runs the amp harder than he would have into a cabinet, very bad things happen and then the guitarist says, "that attenuator ruined my amp." No, driving the amp at "10" ruined it – the attenuator is only incidental in that you never cranked the amp to 10 because it was just too danged loud! This problem is particularly common with low-power combos. I have a little 15-watt class A Ampeg Jet J-12T. It's a great sounding little amp that I never cranked higher than about about "4." One day I decided to see if it would do "metal." Using a guitar with hot humbuckers I cranked the little Ampeg to "10" and played for about 2 minutes before the volume just became too painful (I was not using an attenuator, this was directly into the built-in 12" speaker). When I turned the amp back down to reasonable levels I could hear a crackling sound. In two minutes or so I'd blown both of the screen resistors and ruined the tubes. The tech at my local guitar shop called Ampeg (the amp was still under warranty). They told him, "fix it but tell the guy not to turn the amp up to 10 anymore."
- Attenuators can be used safely if you follow these rules:
Make sure that the attenuator contains some inductance. This will help maintain natural tone and causes the impedance to increase with frequency.
The attenuator should either have approximately the same inductance as a speaker or should be of slightly higher resistance than a speaker. It is better to reflect a slightly higher than normal impedance through the output transformer than too low of an impedance.
Have a reputable tech "cool off" your amp. Explain to the tech that you are going to be driving the amp very hard into an attenuator and you want it biased a bit cold to save the tubes. This will cost a bit in tone (chances are you won't notice this because you probably never drove the amp so hard anyway) but will make the tubes last a lot longer and reduce the chances of damage to other components such as the expensive output transformer. A knowledgeable tech can also tell you if the model of amp you are using is known for blowing transformers and what have you (many guitar amps have output transformers that are not rated anywhere near the amp's max output).