When it comes to recording acoustic guitar,
both stereo and mono have their benefits.
Here’s a quick question: when it comes to recording an acoustic guitar, what’s the better choice – mono or stereo? That is to say, is it better to use one mic or two? Unless you have an acoustic electric and plan on hooking that sucker up to a DI box or straight into a console, you’re stuck using a mic and with it the choice between a stereo or mono recording. While neither choice is the ‘wrong’ one, there are a few things to keep in mind depending on what road you decide to take with your own acoustic recordings, some of which depend on your specific needs and situation.
The Case for Stereo
For the most part, most musicians like to record their acoustic guitar using only one mic precisely placed pointing at the 12th fret, but using two mics for stereo recording does have its advantages. First of all, you are able to record the entire instrument instead of just a small portion of the guitar. Different parts of the guitar have different tonal characteristics and the more of these that you capture in the recording, the truer to the instrument it will sound. If you were to record your acoustic guitar using a mic pointed more towards the neck of the instrument, you will get a lot of high end while recording closer to the bridge will give you a lot of that low end. Simply put, if you want to record the best possible range of high and low frequencies for your acoustic track, using stereo recording is your best bet, or otherwise you will end up with a fraction of the frequencies that are not nearly as wide in range.
A common problem with recording and mixing acoustic guitar track along with a mono vocal track is that although the entire mix might sound pretty solid, it can be a bit lifeless, that is to say, narrow and flat. Some people negate this by adding a plug in or two while mixing, such as reverb in order to thicken up the sound but the problem with this route is that it rarely sounds natural. That same fuller feel can be created by the sound separation created in stereo recording. Think of it kind of like adding simple surround sound to your mix. Basically, when using two mics, they will pick up sound from the same source at different times. Although this difference in time in very small and almost indistinguishable, our brains can pick it up and what is essentially two mono tracks can become combined to sound like one, full track with plenty a lot more depth than a normal mono recording. If you have ever tried to make a basket having only one eye open you can clearly understand how having two eyes giving you two images mixed together as one becomes undeniably important in creating depth perception and the same holds true with using two mics instead of one.
And finally, using stereo recording allows you to be able to record with the mics much closer to the guitar than if you were using only one mic (since the two have to pick up less in order to sound just as loud as one). The reason having your mics closer is a benefit is because the closer you are to your instrument, the less noise you will pick up – plain and simple. Unlike electrified instruments can adjust their volume through an amplifier, acoustic instruments use natural acoustics for their output level which is nowhere near as loud. Certain noise that we don’t even think about when recording off of a loud amp – such as AC in the background, kids playing outside, cars honking in the distance – cant simply be drowned out when working with a much quieter instrument like the acoustic guitar, and while having a sound proof work area is by far the best way to cancel out all noise, having the ability to record placing your mics a bit closer to the instrument can help when outside noise is out of your control. It might still pick some up, but not nearly at the same level as if you were using a single mic.
The Case for Mono
Alright, so now that we have laid out some of the benefits of stereo recording, is there ever a situation where mono recording would be a better bet? Yes actually, a few in fact. Taking a look back at the first reason why you would want to record using stereo recording, that is getting a truer recording sample of the instrument, that might not be such a good idea if your acoustic doesn’t sound particularly good. Stereo recording may be a great way to bring out the entire sound of your instrument, but if your guitar’s tone isn’t ready for primetime, having that entire sound won’t really do you any good.
Another reason why you might want to avoid using stereo recording is because you don’t want to deal with phasing issues. As mentioned above, mics recording sound from the same source might record them slightly off from each other, and while this does a lot to create a fuller sounding track (before stereo records were the norm producers would have two mono tracks slightly out of phase with each other to create a similar fuller effect), you may find yourself dealing with a comb filter effect. It pretty much sounds kind of like using a flange or a phase effect and although it probably sounds nice with an electric guitar, it might not be what you were looking for in your acoustic track. You can fix this issue by making sure the two mics are exactly the same distance from the sound source or fix it in the mixing stage using common phase fixing techniques (like the ones stated in our bass recording article) but that is much easier said than done. Or you can simply record using a single mic.
And finally, if the acoustic guitar you’re recording isn’t going to be the prominent instrument in your mix, there is really no point in recording using the stereo technique since much of the benefits added – along with all of the extra time it will take to make use of those benefits – will all be a waste since the other instruments will assuredly drown them out. Just like deciding between DI or mic to amp with bass recording or deciding what effects to use, your choices should reflect what works best for the entire song.