For an acoustic guitar in a live performance scenario, are you better off with an acoustic amp or a PA system? Which one is more effective and ideal for that situation?
As with many guitar-related questions, the answer is dependent on a few variables that need to be addressed before we can give a clear answer.
Especially with this particular question, because the question itself assumes a couple things that are not totally correct. Primarily, the question assumes that an acoustic guitar amp and a PA system do the same thing.
They do not.
Read more: Best acoustic guitars overall
The Difference Between an Acoustic Amp and PA System
While they can both be used to amplify an acoustic guitar's signal, they're designed to do different things, primarily the following:
- PA system: Mix and project (add volume to) a full group of microphones and instruments
- Acoustic guitar amp: Serve as a preamp and EQ for a single acoustic guitar
An acoustic amp is first and foremost a preamp, just like the preamp on some acoustic guitars, or the ones that come in pedal form. A PA system is not designed to model instrument's sound, but to project a finished product with more volume.
This means that even a signal running through an acoustic amplifier should still be going through a PA system. One does not exclude the other.
As a result, I'd recommend re-phrasing our question:
Do I need the preamp power of an acoustic amp before my signal gets to the PA system?
In other words, do you need the added control of an acoustic amplifier?
It'll give you a lot more control and tweaking power over your tone, but once that's done, you're likely still going to send the signal to a PA system where it will be projected in a live scenario. In fact, most acoustic amps have a balanced line out (XLR output) on the back of the preamp so you can easily send the signal off to a PA system.
You Only Need an Acoustic Amp for Modeling Tone
As a result, the role of an acoustic amp - assuming you have access to a PA system - gets reduced to that of tone modeling and sound quality.
It's not going to be large enough to project in a live environment, in which case you'll need to use the balanced output to send your acoustic signal from the amp to the PA system.
Once that happens, the PA system is handling power, while the acoustic amp is handling tone and basic sound shaping.
A PA System is Always the Final Stop
Make sure you view your PA system - or whatever PA system you have access to - as the final stop for your sound.
While a good mixing board or software does have the ability to shape tone and sound (some are extremely powerful in this regard), it's still better to send your PA system a finished product, if at all possible.
Use your amp to take care of as much EQ as you can, then send the PA system a pure and finely tuned sound that doesn't need anything other than more volume.
Does the XLR out skip the power amp?
In most cases, yes.
When you send a line level output from an amplifier, or a balanced XLR out, you're sending the signal out of your amp before it hits the power amp stage.
This means that your amplifier is functioning as only a preamp, leaving power to the mixer and PA system which will have final say over the volume and output.
- Acoustic guitar pickup/preamp: Tone control
- Acoustic guitar preamp: EQ control
- Mixing board/power amps: Amplification/volume control
The Most Ideal Scenario: An Acoustic Amp before a PA System
It's ideal to have an acoustic amp for modeling tone and sending a properly EQ'd signal to your PA system. I'd recommend using the acoustic amp, then sending a balanced line out signal to one of the channels on your PA system's mixer. From there, it will get further tweaked and sent through the PA system's power amps before it finally comes out the main speakers.
The alternative is to have a simple DI box between your acoustic guitar and the PA system, if you don't have an amplifier or preamp.
This allows you to send a balanced signal like you would get from a preamp output.
You can read more about that in this article on how to plug an acoustic guitar into a PA system directly.
In summary, we've seen that an acoustic amp and PA system serve two fairly different purposes.
Be careful not to equate the two or to view them as interchangeable. For using an acoustic guitar in a performance environment, a PA system is almost always going to be necessary, while an acoustic amp or more of an optional, but helpful add-on.
Try to pair your acoustic guitar with some kind of preamp, either from an acoustic amp or a floor pedal.
If you have additional questions that the article doesn't answer, feel free to drop them into the comments section below and I'll help out as much as possible.
See you there.