Recording Acoustic Guitars
Recording acoustic guitar it can be quite tricky to get a great sound. Getting an ok sound can be easy, but to get a really nice sound you need to experiment. What I want to share with you in this article is some of the things I have learnt about recording acoustic guitars, I'm not a mix engineer but I have been recording (and watching other people record my guitar) for a long time, so I think I have a few tips to share! The first thing to think about is the source, getting your sound right out of the guitar is the first and most important step. The best mics in the world are not going to make a bad guitar sound good!
Choose the right type of guitar...
There are a few styles of guitar and choosing the right one for the track you are recording is very important. Large body acoustics (like a Gibson J200) are great for big strumming patterns (think Oasis or Rolling Stones), Dreadnaught style guitars (like my Maton Messiah or a Martin D12) have a rich sound for more intricate acoustic pick or finger work (think Neil Young) and smaller body acoustics (like my Maton 808 series Jester, or Taylor GC series) are generally better for fingerstyle playing (think Tommy Emmanuel). 12 String acoustics have a very rich and full sound that is very distinctive and work great on both rhythm and lead parts (think John Butler Trio). So the style of track you are working on will help you choose your acoustic, if you have a choice of instrument.
The thickness of strings will also impact on the tone you will get. Very think strings tend to have a thinner sound, but are easier to play. Thicker strings have more body and a better defined bottom end. Very thick strings can be muddy and loose harmonic overtones so there is a limit. I use 12 gauge on my Maton Jester which I use mostly for fingerstyle parts and 13 gauge on my Maton Messiah which I use more for strumming. I use 11 gauge on my Maton Mini which I use for tracking an existing part, although that guitar is often left in Nashville tuning for a 12 string effect.
I will usually re-string my guitar right before recording so I get a nice bright sound. Dead old strings will sound dead and old which occasionally will be the sound you want, but I would advise generally to change your strings at least a few hours before you record so the strings have time to settle in, they sometimes sound a little rattley immediately after you have put them on.
Thinner picks will get more click as you play the strings, thicker picks will give more definition to single notes so are therefore usually better for playing lead lines and intricate parts. I usually use a very thin pick for strumming because I like the percussive effect of the pick click and a thicker pick for anything where I am playing single lines or picking out individual notes. It is a mater of preference of course and just depends on the sound you want on your track.
Get in tune...
Before you start recording, tune your guitar carefully. After a few takes, re-tune. Tune up every time you are suspect about a note at all. Playing a perfect take but not being able to use it because of a tuning problem is very frustrating. I think strobe tuners generally give a much more accurate tuning than regular electronic tuners, but are more expensive. Whatever you use, just make sure it is perfectly in tune before you hit the red record button!
As much as it is nice to move around when you are feeling the groove and playing, it can cause big problems if you have just spent ages getting your microphones placed just right. If you tap your foot, get a pillow (or jumper) to tap on because you probably don't want to hear your foot tapping. And while I am on noise, make sure you don't have a belt buckle or necklace that can tap on the guitar because that can ruin a take too.
The sound of the room will also have a big effect on the sound of your guitar. I usually prefer to record in a dead sounding room with a carpeted floor (or use a rug), but it is sometimes better to get a bit of top end life into the sound which can be helped by putting some wood on the floor beneath the microphone and player. The more "live" reflective surfaces in the room, the more that will effect the room sound.
Often the area of the room will play a part too, so sometimes it is worth walking around the room while playing to see if there is better area of the room to record in. In my old flat I found the bedroom had a better sound than the living room where I had the studio so I had long leads running from the studio and eventually we bashed a hole in the wall so we could run mic leads and headphone cables through into the next room! But that technique is not recommended unless you own your own home (or are happy to pay someone to fix the hole when you move out).
Many acoustic guitars have an electric "piezo" or transducer pickups built in. These are great for playing live but you will get a much better sound by using a microphone, even a basic one. For a rough demo or something like that it will be fine to use the built in pickups, but they sound very thin and generally will not sound good in a mix. My advice is leave the pickup for the stage, and use a microphone to record them for demos or records.
That said it can be fun to record the direct pickup as well as a microphone and blend it in a little, sometimes it gives the sound a little zing that the mic might not have. I have also liked putting an effect on the pick up signal and leaving the mic signal dry and close without effects. Remember that experimenting is a great thing to do!
Start with your ears
The most important thing that you can do to start with, is use your ears to find the "sweet spot" to record from. This obviously requires a second person but can make a big difference to your sound, so it is worth doing. Try and get a friend to sit and play your guitar, cover up one ear, and then move your other ear around the body of the guitar and listen to how different the guitar sounds depending on where you are. You will find that it is very different, and that is why the microphone placement is so important.
When I started experimenting with microphone placement I did not have anyone else around to help me so I did it a slightly different way, that worked but was a little harder. I started with the headphones on, so I was listening to the microphone signal and then slowly moved myself (and the guitar of course) around and listened to the effect of the movements and tried to find a sweet spot. Once I had a rough idea I hit the record button and played a couple of bars and then spoke to the microphone to say where I was and then tried the next placement. This way when I listened back I could hear which placements sounded best and use that for the recording. Takes a bit of mucking around, but it is worth spending some time on this, because once you know the sweet spots of your guitar you can use them all the time!
There are many ways to record an acoustic guitar and many different microphones you can use. After experimenting with your ears to find the right place to place your microphone you might like to know about some of the options. One thing that you should be careful about is trying to place the microphone right in front of the soundhole, this will usually give a very boomy sound with a muddy bottom end.
You also need to consider the distance from the guitar, as a very close mic will often sound to boomy, and a distance mic will capture more of the room sound, which will be good or bad depending on how good your room sounds! A good starting point should be 6-8 inches from the guitar.
I have up until a month ago used a two mic set up, but we started using just one mic and it's been the best acoustic sound I have recorded. I think it's a combination of two things: We are using a very nice old Neumann KM86 (no longer made), through a Neve 1073 pre-amp, and I am sure using high quality gear makes a difference. But a major contributor too is having Cesar (my producer and a superb mix engineer) there to place the microphone to exactly the right place to get a great sound. I am sure you will be able to get a very solid sound with any descent condenser microphone if you spend time on getting your placement good. A single mic in front of the soundhole, 8-10 inches away and pointing it toward the part of the guitar where the neck meets the body is a good place to start.
Two Mic Set Up (Stereo Images)
This technique is probably the most common way of recording acoustic guitar which I have been using most of my life and see others doing the same most of the time. It involves using a large diaphragm condenser microphone (like a Neumann U87 or TLM104) pointing roughly between the soundhole and the neck, this would be the "body" mic. Another small diaphragm pencil mic (like a Neumann KM184) is placed pointing at the neck, up around where your fingers are on the fingerboard. This mic picks up the the bright sound that comes of the guitar neck, which when blended into the sound of the "body" mic can give a very accurate sound, you can also play around with panning and put one left and one right and get a cool stereo effect.
Another option is to use two microphones over the 12th fret, one pointing at the body, one at the neck, at a 90 degree angle to each other (this is called a coincident pair or XY mic technique). Panning one left and one right will usually give a lovely stereo image. In my experience it works best with a matching pair of pencil mics (like the KM184). Again the position of the pair is important and it is worth playing around with this until you get the sound you are looking for.
A common variation is the spaced pair where one mic is placed near the neck and the other at the bridge.
There are many other variations on these two techniques that you might like to experiment with, like putting one mic near the ground pointing up - or one from the players ear, there are no rules that can't be broken if it sounds good..
If you use two microphones you will sometimes get what is called phase cancellation. I'm not sure how to describe it, other than some of the notes sounding suddenly thin or wobbly! Most mixing desks or DAW systems will have a phase reversal button, which looks like a circle with a line through it. Try hitting that if you think you might have some phase problems.
The choice of microphone will depend on budget and choice of placement technique. You will generally want to use a condenser mic over a dynamic mic because they capture the high end better and seem to record the air in a way that suits acoustic guitars.
I record a lot of solo acoustic guitar, for which I prefer using a medium to large diaphragm condenser, but in a full band situation you may prefer the sound of a small diaphragm mic, which carry less bottom end. In a band you will probably get rid of most of the low end in the EQ anyway.
If you only have one mic you will probably use a Medium to Large Diaphragm condenser. My personal favorite is the Neumann KM86 but I don't own one and have to borrow one when I can. They are quite expensive (around £1000) and hard to find. I also like the Neumann TLM103 a lot as well. Rode also make some great large diaphragm mics for those on a budget and I've got some great results with their cheapest model, and NT2. AKG 414 is another popular choice.
Small and medium condensers can also sound great. I was amazed at the depth of bottom end in the Neumann KM184. Rode also make one called an NT2 which has a similar sound at a quarter of the price.
Recording the same part twice and panning them left and right is a very common and effective way of making the guitar sound bigger. Even if you don't get it exactly the same both times it will usually sound interesting and well worth experimenting with. Often I will double rack an acoustic guitar just for the choruses of a song to fatten it up a bit!
I often wondered if recording at different sample rates makes much of a difference. Well it does. It is subtle but it is there. I had the please to record in a great studio a few years ago where they had the new Pro Tools HD system with a 192 interface. Just to test it, we recorded some acoustic guitar at 44.1, 96 and 192 sample rate. There was significant jumps in the clarity of the top end with each step up, but the 192 option significantly reduced the track count available. These days I record at 96k if at all possible, I do think it sounds better than 44.1.
EQ and compression for the mix
Using light compression on the way in, is generally a good idea and will stop any accidental peaks in volume. I usually start with a 3:1 compression ratio, 250-300ms release time and 5-10ms attack setting and go from there. If I have the choice I will go for an 1176 or LA2 compressors. Overly compressing the signal on the way in is a very bad idea because it can't be changed later, so start small and then add more compression at the mixing stage if you need to.
Same with EQ - I tend to leave that until after recording rather than doing stuff on the way in. Always better to use mic placement rather than EQ to fix the sound.
If the guitar is solo then you will just EQ it to suit the sound you are looking for. The big rule here is to use your ears, the following are just some suggestions to try out, but make sure you listen because that will tell you the truth!
Many guitars have a "boom" at around 110Hz, so it might be worth cutting that a little to see if it helps clarify the bottom end.
If the acoustic is playing with a whole band including bass and electric guitars it will usually help your mix to remove all the bass frequencies from the guitar, say from 100Hz and down (a high pass filter).
Adding a little boost at 700Hz-1k can a add a little body to the sound.
To get extra brightness and air you might want to add a little 10-18k which is pretty common and usually sounds good - but can also accentuate finger noise if you are not careful.
Hope that helps you get your acoustic tracks sounding sweet. Back with more studio tips soon!