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Saturday, 31 October 2015

Mixing Live Acoustic

A couple of weeks ago I mixed some live acts at a pub and I thought I’d go through the what I tried to do in terms of getting a great sound while trying some new things.The desk I was using was an Allen & Heath Qu24 digital desk, which I personally really enjoy working with. They’re a very intuitive, feature packed digital desk that you can pick up for just AU$3750 brand new. With built in compressors, fully parametric EQ and gates for each channel, plus 4 x inbuilt digital effects with heaps of features, I had quite a bit of technology to work with.

Doing My Research

First I decided to do some research, so I looked up some articles on how other engineers went about mixing live acoustic music. I didn’t find much on mixing live acoustic sounds, most articles cover mic’ing up guitars in the studio. These ones were the most interesting that I found, and I got a bit of info from them.

Acoustic Guitar EQ

Thinking Outside The Boxiness

One thing that always tends to get on my nerves is the sound of acoustic pickups. Acoustic guitars usually have piezo pickups which sit under the bridge and as a result to accentuate a very sharp, boxy and mid heavy sound that isn't that appealing. I thought I'd try some experiments to counteract this and get a nice, full guitar sound using some short, sharp and shaped reverb. I got this idea from my TC-Helicon Acoustic Play pedal, which has a Resonance effect that makes the acoustic guitar sound much nicer than a straight signal. It does this by adding an extremely short reverb that is then EQ'd to simulate the natural resonance of the body of an acoustic guitar. 

Resonance Verb Setting
So, when I got onto the desk, I went about setting up a similar effect. I went through the reverbs that are available on the Qu24, trying out only the ones that sounded like they would work (short plate, small room etc.) and ended up liking the patch called "Room Kickbox". From there I solo'd the patch in my headphones and worked the effect parameters and EQ until I had a sound that I thought sounded like a nice and natural acoustic guitar. It’s important to note that I wasn’t looking for a big and beautiful hall reverb, or even a room verb, I was just trying to simulate the sound of an acoustic guitar’s body resonance sound which, in the reverb world, is pretty short. The big room reverb was run on another channel, and had both the normal guitar signal, and my new "resonance verb" running to it.

Resonance Verb EQ
I then took off my headphones and went back to listening to the mix in the room. I slowly brought up the reverbed guitar effect until I felt that it brought the sound of the guitar to a more natural sounding acoustic. This is when I was running out of time with the sound check phase of things so got the voice sounding good and got them to start playing their set. At this point, I don’t think it was perfect, but it sounded much, much better than what I could have got with the straight D.I tone by itself. Because this kind of acoustic music doesn’t require much attention throughout the show, I was free to work on getting this guitar sounding as good as I could get it. So, for the remainder of the set, I worked on very small increments in trying to perfect the guitar sound. There were five guitarists over the night with five different guitars and five different playing styles. So the sound of the resonance, as well as the EQ and compression on the guitar changed for each one, so I definitely wasn’t bored.

The Vocal Point

Vocal EQ
The only other sound source that I had to deal with one this particular gig, was obviously the vocal mic. I didn’t spend as much time on this as I did for the guitar, but I still had some ideas that I definitely wanted to try out. Being an acoustic gig, I had a lot less sound to compete with when it came to the other instruments, and this was a breath of fresh air. It’s common, especially with loud bands in smaller venues, to have half of your decisions are to make the vocal sound good, and the other half are to get them to cut through the mix while not feeding back. Because I had complete control over all the sounds on stage (a luxury that doesn’t come when you’re dealing with drummers or loud guitar amps in the room), I could really sculpt the sound of the vocal to exactly how I wanted to hear it.

As with the guitars, I spent a lot of time changing the EQ and compression over the course of the gig to try to get it to a point where I thought it was near perfect. I also resisted the urge to make an EQ shape that I thought I would need before actually hearing the performer play. Instead, I tried to really listen to the sound of the voice and only EQ anything that I thought was necessary. This meant that I was taking out a lot more high mid and boosting a lot more low end than I would normally do on a live vocal. This was really interesting, but made sense.

The Human ear detects the most detail at around 1000-3000Hz, so when you’re fighting to get a vocalist to be heard and understood in a room full of loud instruments, you’re most likely going to boost some frequencies in this range. The downside to this is that these frequencies also have a tendency to sound harsh. Alternatively, sounds lower down tend to have little detail in the human ear, so if you boost these frequencies, the overall sound tends to just blend in with all the other sounds in the room and create a big, muddy mess. However, with acoustic music, you’re not fighting with many other sounds, and the acoustic guitar is easily manipulated to your will. There is plenty of space in the frequency spectrum to have a vocal that’s up front and easily understandable, without having to pull out the low end body of the singers voice and inject it with harsh upper mids. 

One thing to note, which should go without saying but some engineers tend to forget, is that this is NOT a one-size-fits-all scenario. Every singer, microphone, desk, EQ, PA and room are different, and you should EQ a voice depending on what you’re hearing on the night. The instruments supporting and even the size of the crowd can have a drastic input on what a voice will sound like. Over the course of the night, I changed the EQ shape 5 times, for each of the 5 singers and I urge any budding engineer to resist the urge to jump on a desk and start EQing what they think will make a great vocal sound before they get a chance to hear the raw sound of the singer first.

The Bottom Line

This was a great gig. Because of the simple changeovers there was no stress, the performers were really easy to deal with and the setup at the venue was well kept and simple. This could easily have been a “set and forget” style gig where I got a decent sound and sat back, looking at my phone for the whole gig and the performers and punters wouldn’t have noticed. However, I had a lot of fun with this one. I’d gone in with some ideas and done a bit of research and was interested with the results that I could push out. If you have any questions, feel free to comment or send me an e-mail at I hope you learned something that you can experiment with in your own mixing.

Check out the Video Tutorial I did on how to set up a resonant channel for acoustic guitar using plugins in Pro Tools here:

- Locky

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