In my first studio session, I decided I would experiment with various techniques to record acoustic guitar. To do this, I placed a variety of microphones in various positions around the body and neck of the guitar whilst playing the same song to ensure that comparisons between the recordings would be easier.

The aim of the session was to find which method of recording I would prefer to use when recording the acoustic guitar in the future.

I carried out my experimentation using the following  microphones and techniques:


Microphones:

AKG C1000 x 2

I used this microphone to capture the following techniques:

  • Close Mic’ing the Sound Hole (Small Diaphragm Condenser)
  • Close Mic’ing Behind the Guitar Body
  • Spaced Pair
  • Mid Side Technique
  • Vertical Spaced Pair

I believed that this microphone was the most suitable for recording these techniques for the following reasons:

Frequency Response – The C1000 had a good frequency response at around 200Hz to capture the “boominess” of the guitar well and also had a good response to frequencies around 2000Hz and 7000-10,000Hz to also capture both the “harshness” and the “cut” of the guitar to a high quality.

Frequency Response Graph:

c1000-freq

Polar Pattern –  The microphone’s cardioid polar pattern and front address design ensured that it picked up sound mostly from the front, which was useful as the microphone was more often than not placed on axis to the guitar making sure that the microphone would capture a clear, strong recording with minimal spill from other, environmental/ambient sounds.

Sensitivity – The C1000 has a sensitivity of 6 mV/Pa (milliVolts per Pascal), which is about a mid range sensitivity for a microphone. This means that it is suitable for recording most instruments of a range of volumes, making it ideal for recording an acoustic guitar as it can be played at various dynamic levels.


Rode NT2-A

This microphone was used in the following recording techniques:

  • Close Mic’ing the Sound Hole (Large Diaphragm Condenser)
  • Ambient Microphone Facing a Reflective Surface
  • Mid Side

I used the microphones to make these recordings because they met the parameters required to record them or because I believed they were the most suitable based on their:

Frequency Response – On the frequency response graph for the NT2-A, similarly to the C1000, there are peaks at around 2000Hz, making the microphone good for capturing the “harshness” of the guitar. Furthermore, there are peaks at around 7000 and 10,000Hz making the microphone suitable for capturing the “cut” of the guitar.

Cardioid Frequency Response Graph:

nt2-a.jpg

Omnidirectional Frequency Response Graph:

nt2-a omni.jpg

Polar Pattern – The Rode NT2-A’s polar pattern can be selected by the user. The three available polar patterns are cardioid, bidirectional and omnidirectional. This was useful as for the recordings I was planning on making, I would need a bidirectional microphone to capture using the mid side technique, a large diaphragm cardioid microphone for recording close mic’ed techniques and an omnidirectional microphone for use as a room/ambient mic. This versatility contributed to my choice of the NT2-A as a utilised microphone in the session.

Sensitivity – The sensitivity of the NT2-A is 16 mV/Pa (milliVolts per Pascal), categorising it as a high sensitivity microphone. I decided to record using this microphone as i wanted to capture the small nuances produces by the acoustic guitar, like the fret noises. I believed that these small parts of the recording would contribute to a more atmospheric recording so wanted to see if they could be captured using this microphone.


Other Equipment:


  • Focusrite Scarlett 2i4
  • Microphone Clips and Cradles
  • Microphone Stands
  • XLR Cables

Techniques:


Close Mic’ing The Sound Hole (Small Diaphragm Condenser):

The first recording technique I tried was close mic’ing using the small diaphragm AKG C1000 condenser microphone. This meant that I had to place the microphone within 30cm of the sound source which, for this recording, was the sound hole of the acoustic guitar.

The set up I used for this recording is depicted in the image below.

img_2787

Please see “Acoustic Guitar – Close Mic – Small Diaphragm Condenser – Sound Hole.MP3” to hear the recording I captured using this technique.

As you can hear, the recording made using the C1000 was very bright and strong and captured the range of frequencies being produced by the acoustic guitar. In addition to this, the recording was articulate and clear and you could hear all aspects of the playing distinctly.


Close Mic’ing The Sound Hole (Large Diaphragm Condenser):

The second recording i made was again a close mic’ed recording, this time making use of the Rode NT2-A  large diaphragm condenser microphone as oppose to the AKG C1000. The polar pattern was kept as cardioid although the microphone offered interchangeability between cardioid and omnidirectional polar patterns as it was the most appropriate for a close mic’ed recording as i only wanted to record from the front of the microphone. This recording was again made on-axis to the sound source. However, for this recording the sound source was the 12th fret of the guitar instead of the sound hole as this is in the middle of the instrument and will allow the microphone to be able to capture both high and low frequencies from the nut and the bridge.

The set up I used to make the recording is depicted below.

img_2784

Please see “Acoustic Guitar – Close Mic – Large Diaphragm Condenser – 12th Fret.MP3” to listen to the recording I captured using this technique.

The close mic’ed recording made using the NT2-A sounds duller than that made using the C1000. Furthermore, the recording captured using the NT2-A was much bassier overall. The recording was also strong and captured the full range of frequencies produced by the guitar when it was being played as well as the articulation in the performers playing.


Close Mic’ing Behind The Guitar Body (Small Diaphragm Condenser):

The next technique I used was close mic’ing the back of the acoustic guitar with an AKG small diaphragm condenser microphone. The microphone was positioned within 30 cm of and on-axis to the  back panel of the guitar.

The setup I used to make this recording is pictured below.

img_2781

Please see “Acoustic Guitar – Close Mic – Small Diaphragm Condenser – Behind Guitar.MP3” to hear the recording I captured using this technique.

When listening back, I found the recording to be very dull and weak.There wasn’t a lot of clarity to the recording as it sounded muffled due to a larger amount of bass and mid frequencies being captured.

A potential issue with using this technique is that, when recording, the guitarist found that the microphone was in the way and that, on occasions would hit the microphone when playing. Additionally, I found that if the guitarist is wearing a jacket it hangs over the area where the microphone would be placed so ensure your session musician/performer removes excess clothing.


Ambient Microphone Facing a Reflective Surface:

The fourth recording technique I tried in the studio was the use of an ambient microphone. An ambient microphone is a microphone that is placed outside a 30cm boundary of the sound source. I decided that I would place my ambient microphone facing a reflective surface, in this case the surface was a window, whilst using the NT2-A’s cardioid polar pattern in a hope to capture reverberated sound waves that had bounced off the window.

The way i had the equipment set up and placed is demonstrated in the image below.

img_2791

 Please see “Acoustic Guitar – Ambient Mic – Reflective Surface.MP3” to hear the recording I captured using this technique.

When listening back to the recording made with this technique, I found that it sounded distant, thin and that it lacked articulation. However, there was still excellent clarity in the recording despite its distance from the sound source. When played back with a close mic, I found that the ambience of the reflected sound made the recording sound more lively and that it added depth to the track.


 Spaced Pair (Stereo Technique):

Next, I decided to try out the spaced pair stereo recording technique. To do this I used two AKG C1000 microphones on axis to the guitar. The first microphone was placed in line with the sound hole and one hand span away from it. The second was placed on-axis, three hand spans up the neck of the guitar from the first microphone and one had span away from the neck. This is known as the 3:1 ratio for spaced pair recording and is a way to make sure the recording has no phase cancellation occurring.

After I had made the recordings, I panned the microphone on the neck to the left and the one at the sound hole to the right using the panning pots on the mixing console to create the stereo image to be as if the listener is playing the guitar.

panhard

Please see “Acoustic Guitar – Stereo Techniques – Spaced Pair – Hard Left and Right – Guitarist’s Position.MP3” to hear the recording I captured using this technique.

When panned in this way, a very good stereo image was created and it felt like I was watching the guitarist live due to the different frequency bands being captured from different ends of the guitar and then played back through different sides of the headphones. This effect added intimacy to the listening experience as it makes the listener feel more involved in the recording.

 

Additionally, I panned the microphones the opposite directions to form the stereo image to be as if the listener is watching the guitarist.

panhardinverse

Please see “Acoustic Guitar – Stereo Techniques – Spaced Pair – Hard Left and Right – Audience Position.MP3” to hear the recording I captured using this technique.

Similarly to panning the tracks hard left and right in the opposite directions, the panning shown above formed a strong stereo image. However, this time, the effect when listening back was that I felt like I was watching the guitarist live as all the high band frequencies from the bridge were being played from the left hand side of the headphones and all of the low band frequencies, from the bridge, were coming from the left side and all the high band frequencies, from the nut, were coming from the right side.

I also experimented with panning the tracks to different degrees:

Firstly, I panned the tracks a quarter turn.

panquarterturn

Please see “Acoustic Guitar – Stereo Techniques – Spaced Pair – Quarter Turn.MP3” to hear the recording I captured using this technique.

I found that panning the tracks in this way had only a slight effect on the listening experience, that was hardly noticeable to the listener. For this reason, this panning configuration formed a weak stereo image and wasn’t favourable to me.

I then panned the tracks a half turn.

pan-half-turn

Please see “Acoustic Guitar – Stereo Techniques – Spaced Pair – Half Turn.MP3” to hear the recording I captured using this technique.

When listening back to this recording I found that a good stereo image was created as frequency bands captured from both sides of the guitar could be heard separately as a majority on each side of the headphones, however, there was also an area of crossover of the frequencies in the center of the headphones contributing to a fuller sound. In my opinion, this degree of panning was the best.

The equipment and microphone placement is shown in the image below.

img_2796

I found that this recording was strong and sounded bright, clear and articulate.


Mid Side (Stereo Technique):

The Final Technique i recorded was the mid side technique, another variation of the coincidental (XY) stereo technique. The mid side technique makes use of two microphones: the ‘mid’ and the ‘side’. The mid microphone is a cardioid microphone on axis to the 12th fret of the guitar, the sound source for this recording,  and the side microphone is a bidirectional microphone that is placed underneath the mid microphone pointing towards the nut and bridge of the guitar at 90º to the sound source. The side microphone is placed to capture the high and low frequencies from the bridge and nut of the guitar whereas the mid microphone is placed to capture the middle frequencies from around the 12th fret of the guitar.

Post recording, the side microphone track should be duplicated along with the recording and the phase should be inverted on that track to represent what both sides of the bidirectional mic were recording. In order to reverse the phase of the duplicated side microphone track, I had to press the phase invert button on the mixing console.

midsidephaseinvert

I than panned the tracks to form a stereo image.

I first panned the original track from the bidirectional microphone hard left and the duplicated microphone track hard right.

midsidehardpan

The stereo image made the listener feel as though they were the performer playing the guitar as all the low frequencies, coming from the bridge of the guitar, came from the left side and all the high frequencies, coming from the nut of the guitar, came from the right side. This effect makes the audience feel more involved and intimate with the recording.

I then panned the original track hard right and the duplicated track hard left.

midsidepaninverse

This panning configuration created an effect opposite to that of panning the original track hard left and the duplicated track hard right. The strong stereo image created made the listener feel as though they were watching the performer as all the high frequencies, from the nut of the guitar, came from the left side and all the low frequencies, from the bridge of the guitar, came from the right side.

When making this recording, I used and AKG C1000 as my ‘mid’ microphone and a Rode NT2-A as my ‘side’ microphone.

The picture below shows how my microphones were set up to make the recording.

img_2795

Please see “Acoustic Guitar – Stereo Techniques – Mid Side.MP3” to hear the recording I captured using this technique before duplicating the side microphone track and inverting the phase of it and without panning the tracks.

Please see “Acoustic Guitar – Stereo Techniques – Mid Side (Phase Inverted) – Performer.MP3” to hear the recording I captured using this technique before duplicating the side microphone track and inverting the phase of it, with the tracks panned as if the listener was the performer.

Please see “Acoustic Guitar – Stereo Techniques – Mid Side (Phase Inverted) – Audience.MP3” to hear the recording I captured using this technique before duplicating the side microphone track and inverting the phase of it, with the tracks panned as if the listener was a member of an audience.

I found these recordings to be very strong and clear, capturing the warmth of the guitar and the nuances in the guitarist’s performance, like fret noise.

In comparison with the other stereo techniques, I preferred this method, with the tracks panned as if the listener was the performer, as the overall recording sounds much fatter, fuller and of a higher quality.


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