Not all amp-born distortion is created equal. In case you haven’t heard of the two before, the distortion that comes from your amplifier (instead of a pedal) can come from either preamp or power amp section. In simple terms, you can think of preamp distortion as the type of overdrive you get when the when the preamp becomes overloaded. Naturally, power amp distortion results from the overload of the power amp section. While they are very similar, they do have unique traits that the other doesn’t share. Below, we take a look at these differences.
If your amp has a master volume, and you turn the gain knob up but keep the master volume down, you are most likely hearing preamp distortion. This type of distortion usually features more gain than power amp distortion. It is also typically smoother and more compressed, along with more sustain at low volume levels. EQ controls usually reside in the preamp circuits, so preamp distortion usually features more gain and tone shaping tools.
Power Amp Distortion
If you keep the tone on the preamp section clean but turn the master volume up until the sound begins to hit distortion, you are beginning to hear power amp based distortion. In general, this type of distortion is said to sound richer, featuring more a more dynamic tone with a punchier feel and less compression. The downside to this type of distortion is that since it’s based on your master volume, you typically need very high volume levels in order to achieve it. Also, power amp sections don’t typically feature many tone-shaping abilities, so EQ options are very limited.
Other Things To Be Aware Of
In general, vintage amps sound best when they are driven into power amp distortion. It should also be noted that depending on the amp, preamp distortion may not even be possible. Today’s high gain amps are made to do more of the EQ and tone shaping work in the preamp and feature relatively clean power amps, although you can often turn the amp levels up to achieve pure power amp distortion (that features a clean preamp setting) or even a combination of power amp and preamp distortion.
If you feel like experimenting with power amp distortion, it is highly suggested you invest in a low-wattage tube amp (such as the VHT Special 6 Ultra) that can start hitting power amp distortion at relatively low volume levels. Hopefully, the info above has given you a good idea on what preamp and power amp distortion is along with a few of their notable differences.
Your Turn to Sound Off!
Which type of distortion do you prefer?