Acoustic guitar require a rather different approach from electric guitars. For example when recording an acoustic you rarely would send it thru an amp. A much more common way would be to run the signal through a DI box, Mic or both
One thing that makes the acoustic guitar different from the electric is the character of the sound starts with the source. It maybe plain and obvious but it is the reason why when recording the acoustic you do not throw it through an amp for it tends to sound artificial.
From the strumming, the picking of the strings, the air floating in and out of the sound hole, the type of strings even the pick all help to create the sound even the wood which is probably the most important but that is another discussion all together. It is better for you to take the time and experiment with the placements of the mic’s then trying to figure that you will fix it in the mix.
Some cool things you can do to try to capture the essence of the acoustic guitar in recording would be as follows. Start by investing in new strings! Take care to set the action and tuning right for your guitar. If you are trying to capture a great rhythm or strumming groove to make a main music bed, try using a thinner pick. If you want to capture the guitar solo or lead use a thicker pick.
When you are ready to record the guitar, start by placing the microphone close to the sound hole. A small diaphragm condenser is ideal, such as Audio-Technica’s AT3031 or a studio condenser like RodenNT1-A both are excellent and fairly affordable choices and will work well in working in recording other instruments as well as vocals.
Place a mic around 16 inches or so (40cm) from the guitar, aiming it towards where the neck joins the body. It usually gets you a full bodied sound. It will capture some of the dynamics coming from the sound hole but yet will also pick up the sounds evolving else where from the guitar.
What I would suggest is moving it around to find that sweet spot. If you move up the neck you tend to get higher frequencies lower towards the body emphasizes lower frequencies. You will want to experiment for the dynamics of the room your in, placement of the microphones, strings all the stuff just mentioned will depend on the tone you capture.
If you are able and have the finances to I would get two microphones set up. Set one up on the sound hole and another directional microphone aimed at the neck near where your hands play. You will capture separate styles and tones when balanced right will actually bring out the best. You can also place the one microphone in front of the sound hole and another one down deep below the body of the guitar which will emphasize the deep tpnes as well. All I can say is experiment to find out what works best.
The greatest thing is nothing you will be considered strange I have set up my amp in the closet of my apartment and placed a mic in front of it, ran the chord all the way down the hall into where I was playing. I had all kinds of clothes hanging in there. The clothes acted like sound proofing in a way. A poor mans version lol. It isolated the tones and you did not hear the fret buzzing or any other oddities. I also placed an amp in my shower stall,(remember to not turn the water on!) the tile in the bathroom acted like a natural reverb of sorts.
Something I have been experimenting as of late has been combining a DI signal (from a DIRECT BOX) as well as including the several different mic placements. When you mix them all together in the mixing portion you can find a nice balance between the both to create a sonic palette that may just be what you are looking for.
I hope some of these ideas may help you out in your quest in finding that all illusive number one hit. One thing I cannot stress enough is you are only limited at times by your own imagination. Just because some producer or famous engineer has not thought of it first does not mean it cannot work for you. The greatest thing in making music is YOU are the painter that is holding the brush on the mind of your listeners.
- Big body, big bottom. You’ll get your low-end (as well as boomy, so be careful) and a general warmth of the wood in this area well behind the bridge, but not too close to the edge. The clarity of all the notes are not as… clear… here, however, so don’t rely on it to get everything you need. Try placing your mic off axis to decrease the proximity effect of the cardioid microphone.
- Twang between bridge and sound hole. Closer to higher strings for more of the brightness. The string sound here is tight and twangy. Off axis will slightly decrease the harshness, as well as pulling it further away by inches. There’s a “solid” sound to the wood as well in this area. If you lower the mic below the strings so it’s approaching the edge where the guitar starts to narrow you’ll get less string twang and more of the “tight” sounding wood tone.
- Sound hole balance. Angling down towards the lower strings (again, angled of off axis to help control any boom from close mic’ing). You should get a fairly balanced high to low tone here, but depending on the guitar will lose some of the high-mids.
- Bony Shoulders. I’m sure you’ve tapped and slapped the wood at various places on acoustic guitars. Start there to help understand what the sound will be like placing a microphone at position four. The wood is tense and there’s not a lot of space for it to resonate and release, so it’s got some tight mids and a solid woody tone. Of course, being close to the strings and neck, you’ll get a decent amount of pick attack as well.
- 12 fret subtle and smooth harmonics. Great place for a small diaphragm mic, angled inward to get a balanced string tone with all of the complimentary harmonics from the string vibrations at that position. If you EQ out some of the more harsh (1-3k) attach sounds, you can get some good sounds here that balance with any other mic placement on the body.
- “over the shoulder” as a possible microphone placement
A cool link to find some other interesting ideas as well as some test and sound samples of various other microphones and placements that you might find helpful in other areas. I do not know much about the website but I found this page to be a great resource and thought heck you might as well if you came this far your into what I am trying to share with you and your a pretty serious dude or dudet. Check it out here.