Microphone placement on a speaker is a crucial aspect of shaping the sound of an electric guitar. Different sounds can be produced based on factors such as the distance from the speaker, the characteristics of the microphone, and the acoustic properties of the room. To investigate these factors, a project at Hochschule Düsseldorf involved professional guitarists playing various guitars, and students recording the sessions. For the purpose of this article, the recorded DI tracks were reamped.
Reamping refers to the process of re-processing a guitar track with an amplifier after the live recording. This process allows a band to send their guitar tracks to a producer, who then has the freedom to edit the sound.
In the first step, a dry guitar signal is recorded, which is split from the guitar-amp-cabinet signal path using a DI box. In the second step, a reamping box takes over the task of presenting the previously recorded signal with the correct impedance and level, making it suitable for connection to a guitar amplifier input. The signal can then optionally pass through effects devices before reaching the amplifier. In the final step, it is routed to a guitar cabinet equipped with microphones to capture the resulting sound.
This way, a guitarist can still reshape their sound and influence it with new effects even after the recording. For the purposes of the investigations in this article, reamping was chosen as the recording method because it eliminates the variable of playing technique and allows for a more straightforward comparison of microphone sounds.
Equipment
Five microphones were used in succession to record the amplifier. The microphones include the Shure SM57, AKG C414EB, Royer-121, Sennheiser MD421 II, and Sennheiser MKH800 PH48. The guitar was a Music Man Luke II (Stratocaster-type). The amplifier used was the Marshall JVM410H guitar head in its 50th Anniversary edition, the loudspeaker was the Celestion G12 Vintage 30. The effects devices included the Ibanez TS808 Pro overdrive pedal and the reamping box from Radial Engineering.
Details and Specifications of Equipment
Microphones
Shure SM57 The Shure SM57 is a dynamic microphone with a cardioid pattern. It is frequently used in the studio for recording percussion and guitars and is known for its powerful and clear sound and robust construction. The frequency response ranges from 40 - 15.000 Hz, nominally.
AKG C414 The AKG C414 is a condenser microphone with a selectable four-pattern switch. In this case, it was set to the cardioid pattern. It features a fairly linear frequency response which captures a very realistic sound. The frequency range is nominally 20 - 20.000 Hz.
Royer 121
The Royer 121 is a ribbon microphone with a figure-of-eight pattern. Its sound is somewhat grainy and warm, making it well-suited for distorted electric guitar. The frequency range is 30 - 15.000 Hz, nominally.
Sennheiser MD421
The Sennheiser MD421 II is a dynamic microphone with a cardioid pattern. The built-in selectable bass filter provides good flexibility for both vocal and instrumental recordings. The frequency range is nominally 30 - 17.000 Hz.
Sennheiser MKH800 P48 The Sennheiser MKH800 P48 is a condenser microphone with a switchable polar pattern in five settings. Here, it was set to the cardioid pattern. The particularly wide frequency range of nominally 30 - 50.000 (!) Hz makes this microphone especially suitable for recordings with a broad frequency spectrum.
Amplifier and Loudspeaker
The Marshall JVM410H guitar amplifier head in the 50th Anniversary Edition was chosen for its ability to produce the appropriate sound for the Metal-style audio samples. The amplifier is a tube amp with 12 different core sounds, including Crunch, Clean, and Overdrive.
For reamping, the amplifier was set to the medium-strength preset on the "Overdrive Two" channel with the following control settings:
The Celestion G12 Vintage 30 loudspeaker has been a leading choice in speaker chassis for Metal for many years. Frequency Response
Guitar, Cable, and Effects Pedal
The Music Man Luke II is a Stratocaster-style guitar and, like many other Music Man guitars, is popular in the metal genre. For more information and sound comparisons of the pickups, see the partner article on guitar and pickup comparisons.
TS Pro TS808 Overdrive Pedal The cable run between the studio's wall outlet and the amp was 7.5 meters, and there was an additional 6.25 meters between the amplifier and the speaker. More information on the topic of cable lengths, can be found in the companion article.
The TS808 Pro Overdrive pedal is used to make the guitar's distortion even richer. This setting is preferred by many modern metal producers and guitarists.
Microphone Comparison
Setup
In the following microphone comparison, the microphones were placed in different positions in front of the speaker and the signal was recorded anew.
Position 1: 9 cm distance between the center of the speaker and the microphone Position 2: 9 cm distance between the center of the speaker and the microphone, and shifted 6 cm to the side Position 3: 18 cm distance between the center of the speaker and the microphone Position 4: 18 cm distance between the center of the speaker and the microphone, and shifted 6 cm to the side Position 5: 3 mm distance between the center of the speaker and the microphone
Each video features a single microphone. Each video includes six repetitions of each position. Additionally, there is variation between two pickup settings on the guitar and three versions of the mix. The first version is with full production, the second with no additional effects, and the third has only the first equalizer.
To ensure that the comparison of the microphones is not affected by different volume levels, all tracks were normalized to the same loudness.
The closer the microphone is to the speaker, the more bass content you get (-> proximity effect). When the microphone is placed further away, the sound becomes more balanced. Additionally, with increased distance, the microphone captures more of the character of the room.
Lateral displacement results in less high frequency, more midrange, and reduces the attack, giving a more controlled and softer sound.
Other placements that were not examined here include angling the microphones for a slightly more indirect sound (the effects are minimal).
In general, it’s best to first try to create the desired sound in the room before attempting to modify it through microphones. This will help ensure that the player feels comfortable because it sounds “right,” and it can save a lot of time in post-processing.
Production
The following effects were applied uniformly to all microphones in the full mix as a 'send effect' to a group track.
