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Dialing It In: Optimizing The Sound Of Acoustic Guitar In The Live Mix

Common problems fall into three categories: volume, EQ, and OOMC, short for “Out Of My Control” – here are some straightforward approaches to deal with them.
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I was ready to chuck the mixer out the window. Why did the acoustic guitar sound so bad? I checked and re-checked my EQ settings, but it wasn’t until talking with the guitarist that I discovered the problem. That’s when I wanted to chuck the guitar out the window, rather than the mixer.

Common acoustic guitar mixing problems fall into three categories: volume, EQ, and OOMC, short for “Out Of My Control,” and it was the source of my difficulties. So before tackling common volume and EQ approaches at the console, let’s first take a look at OOMC issues.

The quality of an acoustic guitar mix is affected directly by the quality of sound coming from the instrument. When it comes to acoustic guitar, there are three contributing areas that we can’t directly manage: the strings, the onboard EQ, and the pickups. Being aware of these potential problem areas and knowing how to work through them is key.

Common Ground

Guitar strings sound worse with age. Aging guitar strings can even be deceiving; in the process of becoming brittle, they can still stay in tune — but it doesn’t mean they sound right. A gentle discussion with the guitarist can help motivate them to change strings, maybe not for the current gig, but at least for the next one.

Guitars equipped with onboard EQ, such as an Epiphone DR-500MCE with eSonic2 preamp, can also be potentially problematic. The onboard EQ is under the musician’s control, so if a guitar isn’t sounding right, it’s important to talk about it with the musician, trying to (at least) make sure the instrument is set to standard baseline settings. In addition, onboard EQ is battery driven, so a dying battery can have impact on the guitar’s sound.

And then there’s the case of the guitar I was ready to toss out the window. It had been modified with some after-market electronics — three dime-sized piezo microphones under the bridge. One of them had worked loose, so the lousy sound was the result of receiving strong signals from just two of the three internal mics. Imagine the sound of only the first four strings of the guitar.

Loud & Soft

Balanced volume is key to successful music mixes. There’s a simple method for checking volume, but let’s start with the two of the most common mistakes: too loud or too soft. I know, it’s obvious, but bear with me.

Mumford & Sons had a huge hit with “I Will Wait.” The instrumentation of the song includes acoustic guitar, banjo, and upright bass. Listening to the studio release, the blending of the instruments is readily apparent. The volume of each instrument is closely aligned with the others, with the tonal characteristics of the instruments separating them in the mix.

The acoustic guitar and the banjo both drive the song. Pushing the acoustic guitar noticeably out front, with a volume boost, would take away from the melodic sound of the two blended instruments. There’s a time for an instrument to lead a song and there’s a time for it to serve a different purpose. The mistake of mixing too loud comes from the assumption that leading a song means dominating the other instruments.

On the other hand, there’s the problem of making the acoustic guitar too soft in the mix. The problem usually originates in the changing of the room dynamics. During sound check, the band plays to an empty room, but the moment the seats are filled, the acoustic properties of the space change. Frequencies react differently.

Further, audience participation adds new sounds into the room. That acoustic guitar might have been in the right place during the sound check but gets lost in the new dynamic that occurs during the performance. Often, a relatively slight volume bump can be enough to bring the instrument back into the mix.

There’s a simple method for testing the volume of the acoustic guitar: while the band is performing, mute the acoustic guitar channel. Pay attention to the lack of the guitar in the mix, then un-mute the channel and listen to the mix. It will be noticeable if the volume is too soft or too loud. (I do this with my eyes closed, which seems to help in terms of focus.)

Solid Methods

Misuse of EQ is another common problem. The biggest mistake is believing the guitar should sound great all by itself. Several years ago, I penned an article titled “Why You Should Create a Bad Sounding Instrument.” While the idea might seem extreme, it’s actually not. Four instruments that sound great on their own will not necessarily meld in the mix when brought together. A solid method for initial EQ work is cutting offending frequencies and then listening to the new combined sound and making proper adjustments.

Another common EQ mistake is making the acoustic guitar sound too bright. This happens in two ways. First, making a bright-sounding guitar sound even brighter. A naturally bright-sounding guitar can be wonderful, but if it’s boosted too much in the higher frequencies, it can come off as unnatural and also conflict with things like drum cymbals.

Even more common is going against the guitar’s natural tone, and this should also be taken into account in relation to other instruments on stage. Acoustic guitars produce a variety of natural tones, depending on the wood used in their composition. Some offer warm tones, while others are bright.

Part of the mix process is bringing out the natural sound, and sometimes while also balancing in relation to any signal processors the guitarist uses. When acoustic guitar is too bright without any boosts in my mixes, I first look to the 3.5 kHz range to make some cuts.

One more common problem is an acoustic guitar mix that lacks presence. When facing this, start with boosts in the 1 kHz to 3.5 kHz range to add definition and then move down to the 600 Hz to 800 Hz range for additional meatiness (depth). It’s also a good idea to look for frequency areas for cutting so that other frequencies can shine through.

The Process

Most of these problems can be avoided by applying a 3-step process on the acoustic guitar channel. First, clean up the low end by engaging a high-pass filter. The presence of drums and bass means frequencies below 100 Hz can be cut. Experiment to find the best spot for your scenario.

Next, clean up the guitar sound by cutting offending frequencies. Sweep through the mid-range frequencies, using a narrow Q value and a 6 dB cut until you get a better sound. At this point, problems existing at the guitar level should be apparent.

Lastly, turn to cross-channel mixing. Set the instrument’s volume in the right relationship to the other instruments and mix across channels. If there are two instruments competing for the same dominant frequencies, decide which instrument should own them, gently boosting it while (also gently) trimming the other.

The good news is that most of the problems that can occur with an acoustic guitar mix are easily corrected. Although, I once had a guitarist who wouldn’t replace his old tinny-sounding strings for three gigs in a row. By the fourth gig, I walked in with a pair of wire cutters…

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