What's the use of amps, exactly?

Cafe Society
1

This has been bothering me for a long time, and I can’t quite get the straight dope, so why not ask it here?

Suppose one has an electric bass guitar. Amps (or at least combo amps) do a few different things: 1. They boost the signal coming from the instrument, 2. They project that signal through speakers designed to get desirable tones, 3. They can also send that signal through a cable (or microphone) to a venue’s PA/sound system, thus making it audible through the speakers that face towards the audience, and the monitor speakers that face the musicians.

Now, if one has an effects processor, or anything else with a preamp, such as a headphone amp, one can plug headphones into it and hear the tone of the instrument, albeit without the particular characteristics an amp might provide.

Thus, if one is playing in a space with a PA, why not skip the amp entirely and set up one’s gear thus: bass---->device w/preamp---->PA---->speakers and monitors? Or, if the sound of an amp is desired, or one lacks a preamp, why would a large amp be necessary, since the final volume will be determined by the mixing board?

I ask because I have no amp and no car. I recently tried out a very small Peavey Amp that I could carry easily, and I found it remarkably loud, even in the noisy shop environment. I have an acoustic bass for songwriting/quiet apartment practice sessions, but I assume the amp would be suitable for full-band practice if we don’t want to spring for a practice studio that includes amps, and it could also work for playing in venues that have no sound system.

TL, DR: Why are amps, or at least big amps, desired by so many people? If they will just be wired/mic’d to the PA, or can be bypassed with something that boosts the signal, what’s the point? Am I missing something?

2

You could do that, if your venue had a really damn good PA system. But most don’t, and you’ll get much better sound by bringing your own speakers with you, and the speakers you bring will need an amp somewhere or another.

3

Amplifiers, particularly guitar amplifiers, colour the sound significantly in a way that most players find desirable. The way to setup a guitar amp if you want to preserve your amp’s sound is to set it all up how you want it and then put a microphone in front of the speakers and send the mic’d sound to the PA system. You would generally not DI the sound from your guitar because you can get some nasty treble sounds in the mix that an amp would normally moderate. I believe this is not as important for the bass guitar as you are more likely to want the basic sound of the instrument with little colouration from an amplifier.

4

Also small combo bands use small amps because that’s what they use when playing together when not in front of a crowd. You can’t expect a band to write and practice their music with a whole live PA system at hand, suitable for a club or stadium, right? Each member has the equipment to a) craft their own tone so that b) they can hear themselves and each other’s crafted tone when playing and practicing their music.

Once they get to the venue, the only thing needed is to take exactly that tone they all crafted together and make it louder. Dumping all the equipment they used to make that sound and starting over with each venue PA and replicating that same tone on new equipment would be a crazy amount of experimentation they don’t have time for between showing up at a club to set up and actually playing live. So instead you often just mic a smaller and run it through a bigger amp to get that tone. Obviously there are exceptions - vocals often run straight to the PA with some sweetening added, etc.