Where to Place the Microphone when Recording Acoustic Guitars

As Mike said in the previous post, things have been a little hairy on this side, so I must apologise for the lack of new content over the last few weeks. With the formalities out of the way, let's get started with the good stuff...

When recording acoustic guitars, it is typically best to use a microphone rather than its built in pickup. The reason for this is that an acoustic guitar is known for its acoustic sound (i.e. the "natural" sound it makes in a room) rather than for the electronically reproduced sound its pickup would create. However, the quality of the recording is also highly dependent on the quality of the mic. So, this leaves you with two options: either buy a decent mic (preferably a condenser mic), or use the built-in pickup if it sounds better than your cheap mic.

Okay, so I've now convinced you to get a decent mic, and you probably think that it makes no difference where the mic is placed, as long as it's fairly close to the guitar. Well, that's simply not true, your mic placement is extremely important. Let me explain...

If you place the mic far from the guitar you will get more of a room sound than a defined guitar sound. In other words, your guitar track will sound quite spacious, as if there was a reverb effect on it. On the other hand, if you place your mic close to the guitar, you will get more guitar sound than room sound. This seems pretty obvious, and it is... but sometimes it's good to hear the basics. I can see you're a bit disappointed, so let's go a little deeper...

If you place your mic close to the bridge, you will get a very twangy sound (i.e. loud mid to high frequencies with little bass) and you will also hear the pick hitting the strings. However, if you place the mic close to the bottom of the neck, you will get a bassier/warmer sound. The reason for this is that the strings have more room to move on here than they would at the bridge, meaning that the higher frequencies of the note are produced where the string is tight and the lower frequencies are produced where the strings are loose. You may not want to place your mic right by the sound hole because it is typically too bassy and loud there, so your mic will start clipping.

You can see from the pictures below, that I like to place my mic by the bottom of the bridge, but aimed towards my strumming hand. By placing my mic here, I will get a warm mix (meaning a mix with a fair amount of bass but still with a defined mid and high tone). By aiming the mic towards the strumming hand, the sound of the pick hitting the strings will become clearer, which most artists consider to be a good thing because it adds definition. The nice thing about this setup is that if you want to remove bass later, it is simple to add a high-pass filter in Ardour (or any other DAW) to get a thinner and clearer mix.



I have recorded the sound of the guitar whilst moving the mic from the nut to the bridge and whilst moving closer to and further away from the guitar. Once you hear this, you will understand completely what I've been trying to get down in writing. The MP3 is available from the link below:

AcousticMicing.MP3 (1,619 kB)

Other posts you might find interesting:
What Gives a Guitar its Tone?
Microphone Review: Shure's SM57
Sound Proofing and Room Acoustic Basics
Sound Mixing Tips: EQ vs Volume
Stereo Panning Tips: Panning for Gold

Sound Proofing and Room Acoustic Basics

Ah, sound proofing... a term which is thrown around by newbie sound guys who have heard of it but don't necessarily know what it means. They may have heard something about egg boxes, seen really expensive studio setups or heard of some funny stuff like bass traps, suspension ceilings and the like. This one's for you little ones (Don't be offended - I was in your shoes just a few years ago).

First off, let's define the difference between sound proofing and room acoustics.

• Sound proofing: This is essentially the method of isolating any sound from getting in or out of a space/room.
• Room Acoustics: This deals with getting a room to sound good by using materials within the room to dampen reverb/echo and flatten out the room's frequency spectrum.

I hope you're starting to see the difference, a sound proof room can sound really bad inside and a room which has been acoustically treated can still let sound leak in and out of it.

With that said, let's ask the next question: How can I improve sound proofing and room acoustics cheaply and effectively? To answer this, I will start with sound proofing and then deal with room acoustics separately.

Sound Proofing

The only way of stopping sound from escaping or entering a room is to isolate the room from the noise source. Sound can escape from a room in two ways: either directly through an air gap or indirectly by vibrating the medium between the room and the noise source (i.e. a window vibrates quite easily and thus even when it is closed will still transfer some sound). The best sound proofing method which is used by most professional studios is to build double walls with an air gap between them. This is also expensive and thus not relevant to cheapos like us. A cheaper way of doing this is to modify an existing room by sealing all the doors, windows and anything else which provides a gap for sound to travel through. Sound is able to get through very small gaps so covering the bottom of the door and even keyholes can make a significant difference. I have sealed my doors and windows with a weather proofing foam tape. The idea is to seal any gaps which connect the inside and outside of the room. It also helps to use really think curtains or wood to cover the windows as this will also create an air gap between the windows and the room.

Room Acoustics

Sound proofing is the easy one, because it is just about sealing things and going big. Room acoustics is more difficult because if you go too wild, your room will sound bad.

There are two major materials used to better a room's sound: absorbers (soft things like mattresses, carpets, sofas, etc) and diffusers (rough things like egg boxes, randomly loaded bookshelves, etc). Absorbers stop reflections by absorbing the higher frequency sound energy whilst diffusers still reflect sound but the reflection is scattered, making it harder to hear it as a defined echo. The easiest way to think of it is to use the analogy of light. A beam of light will reflect clearly off a straight piece of tin foil but when the same beam is shone onto a crumpled piece of tin foil, the light is reflected randomly around the room. In the case of the crumpled tin foil, the whole room should become brighter just like when you use diffusers, the room fills with a warm sound as opposed to a clear echo.

With that said, please don't go out and make the same mistake most rookies do. Most rookies hear this and decide to cover their entire room with absorbers and diffusers - i.e. a room covered from floor to ceiling in carpet. This is not ideal, you want your room to sound natural and enhance your recordings - reverb is a good thing if it is controlled. You control the room's sound by placing these materials in planned places around the room. This is a complicated process and I'd bore you to death if I wrote it all in one post, so I will just throw around some thought provoking ideas and then fill in the gaps in a future post. Idea 1: Focus on eliminating the corners, because corners amplify bass and muddy sound. Idea 2: If working in a room with parallel walls, place absorbers or diffusers on one wall only to eliminate sound waves bouncing back and forth. Idea 3: A thick carpet on the floor always helps. Idea 4: A bookshelf loaded randomly with books can act as a cheap diffuser. Idea 5: Read this awesome article: Acoustic Treatment for Home Studios. Idea 6: Keep reading my blog for other tips because I'm not finished with you :).

Other posts you might find interesting:
Monitor/Speaker Placement
Sound Mixing Tips: Bringing an Instrument Out of the Mud
What Gives a Guitar its Tone?
Sound Mixing Tips: High There?!
Sound Mixing Tips: Panning for Gold

What gives a Guitar its Tone?

Hey guys,

I've come across an excellent set of articles all about guitar tone. Have you ever wandered what makes a guitar sound the way it does? These articles deal with exactly that. Each part of the guitar affects its tone. The author cleverly discusses these parts individually. They are:

1. The Strings
2. The Neck
3. The Body
4. The Bridge

The author explains these concepts fundamentally from the types wood to the pickups. I find that the basic idea with the tone of any instruments or a room, is simply that hard surfaces (eg. a brick wall) reflect high frequencies whilst soft surfaces (eg. a soft sofa) absorb the high frequencies.

Using light as an analogy to sound works well because they are both waves and both reflect and refract off materials. Think of hard surfaces like a mirror - they reflect almost all the light. Soft or rough surfaces diffuse the sound, similar to how a glazed bathroom window diffuses light.

You will notice that guitar tone is governed by the same fundamental rules. Hard materials brighten the tone and soft materials seem to boost the low frequencies, creating a warmer sound. All the same, the above mentioned articles are definitely worth a read because they go into way more detail about which woods or materials create which sound.

Other posts you might find interesting:

Microphone Review: Shure SM57 Microphone
Speaker Placement
High There?!
Panning for Gold
Audio Recording in Ubuntu Studio - Part 1: Plan your Project

Speaker Placement

Alright, by now we've probably seen the prices of good quality studio monitors. You may very well be asking: "Why are they so expensive?". To which your smart arse friend probably answers: "Because they are good quality." They are good quality because they have a flatter response than normal speakers, i.e. they output roughly the same power over all the frequencies in the audible spectrum. The more you pay, the flatter the response.

This, however, is not my point... my point is that if you spend all this money and set them up like an idiot, than its a waste. This is because the way they are set up in a room affects the frequency response. Below is a figure showing the correct method for setting up monitors.

In the figure, you are the ugly red thing and the grey squares are your monitors. The room is represented by the outer square. Firstly,you must be the same distance away from each of your speakers as they are from themselves (this is represented by distance X in the figure). Secondly, your speakers must be placed an equal distance from each wall (distance L in the figure). You can choose any distance you like to represent X and L.

Other posts you might find interesting:
Sound Proofing and Room Acoustic Basics
Tips for Recording Drums
Free Drum Lessons
How to Capture Audio from Video
Beginner's Guide to Ubuntu Recording