Just the Bassics: Amplifiers

5 03 2010

As this scene from Spinal Tap famously parodies, it’s surprising how many musicians don’t know anything about the basics of their amplification system (or even their instruments!). Don’t be one of these guys! It’s important to at least know the basics of how your equipment works.

What an Amp Does

Electric guitars and basses are usually passive (although some have an “active” mode as well, powered by a battery inside the instrument), which means that they don’t need to be plugged into the wall to work. Therefore, an amplifier’s job is to take the sounds of the guitar and make them audible through a speaker.

Most amps have three basic parts:

  • A pre-amp:  boosts the guitar’s electrical “signal” with enough power so that it can be driven to the power amp (gets the signal primed)
  • A power amp: takes the signal and gives it more power
  • A speaker: takes the electrical signal and tranfers it into vibrations that we can hear

The Two Main Types of Amplifiers

Understanding amplifiers can be as simple or as complex as you want it to be. To introduce you to them, I will talk a bit about guitar amps in general, and then get into the specifics of how bass amps are a bit different.

There are two main types of amplifiers: tube amps  and solid-state amps. (There are also a lot of “hybrids” out there these days, which utilize a mix of the two, but we’re keepin’ things simple.)

Here’s what the inside of a tube amp looks like:

And this is a solid-state amp:

So what’s the difference between these two types of amplifiers? In theory, both of these amps should sound similar: They have most of the same parts, and they do the same thing.

In actuality, however, there are some noticeable differences between them. Tube amps tend to have a warmer sound, but they are also more fragile and require more upkeep (they are also more expensive than solid-state amps). Solid-state amps are usually sturdier, but they tend to have less tone and not as many abilities when it comes to heavy distortion.

Differences Between Guitar Amps and Bass Amps

Bass amps, as you’ve probably guessed, have to be designed a bit differently in order to focus more on the lower sounds. Even though I don’t usually recommend Wikipedia, this article sums it all up: Bass Amplification

Some common questions about this:

1. Can I play a bass through a guitar amp?  Yes. Many bassists, including Robert Trujillo of Metallica, play using “guitar” amplifiers. You just have to be sure the amp isn’t making any grunting noises: That’s a sign that you’re pumping too much bass through it. If your amp starts making funky noises, especially grunting or rattling, turn down the volume or you might damage the electronics.

2. What about if I play guitar through a bass amp? You can do it, it’s not going to damage anything electronically. It’s also not going to sound very good, however: Bass amps are made to amplify the lower range of sound, so you will lose out on some of those sweet 12th fret solos you’re wailing away on. You can also amplify keyboard through a bass amp if you need to for a little while, but don’t go out and buy a bass amp to amplify anything but a bass.

In conclusion: Do your research about your equipment! It’s fun to learn about how stuff works, and you’ll be able to hold your own when all your fellow musicians are yakkin’ on about replacing their vacuum tubes.

Keep slappin’ dat bass!