Best Microphones For Miking Classical Guitar


Classical guitar (when played well) is one of the most beautiful sounding instruments on the planet. There are plenty of microphone placement techniques to capture the beauty of the classical guitar. There are also a plethora of microphones used to reproduce the sound of well-rehearsed classical guitarists. But is there a best microphone for classical guitars?

My top microphone recommendation for recording classical guitar is the Shure SM81 (link to check the price on Amazon). This small diaphragm electret condenser microphone accentuates the sound of the classical guitar in all the best ways. The versatility of this microphone makes it a practical top choice for any playing style, room, or microphone position.

So what makes a great classical guitar microphone and why is the Shure SM81 my recommended choice? Let’s discuss the answer to these questions in this post!


Disclaimer:

“Best” is a dangerous word. There is really no such thing as a “best microphone” for any situation. The microphone(s) listed in my Recommended Microphones And Accessories” page are simply my recommendations. These recommendations are based on my own experience and are mindful of budget. It would be easy to suggest an ELA M 251 or U47 for most scenarios. However, these tube mics are very expensive, putting them out of a hobbyist’s price range and making it difficult for professionals to make their money back on the gear.

Another important note is that the microphone or equipment you choose is not the most important part of recording audio. In fact, there are many factors that are arguably more important than the choice of microphone. These include:

  • Performer (whether a musician, speaker, or otherwise)
  • Instrument
  • Microphone technique/placement
  • Number of microphones used
  • Natural sound of the room
  • Content (whether that’s the song, discussion, or otherwise)
  • Signal chain (including mic cable, preamplifier, console, and/or interface/computer)

With that being said, some microphones and gear suit some instruments better than others, prompting this series of articles under “Recommended Microphones And Accessories.”


What Does A Classical Guitar Sound Like?

When picking the ideal microphone for an instrument, it’s critical that we understand the sound and projection of that instrument. So what does a classical acoustic guitar sound like?

Frequency Range Of Classical Guitar

  • Overall Range: 82 Hz ~ 7,000 Hz
  • Fundamentals range: 82 Hz – 988 Hz (6 string, 19 frets, standard tuning)
  • Harmonics range: 162 Hz ~ 7,000 Hz (upper harmonics are much weaker, though still present above 7 kHz)

Sound Of Classical Guitar

Like a “regular” acoustic guitar, the classical has a top plate, a hollow body and a sound hole that provide natural amplification. The top plate helps to project the higher frequencies of the guitar while the hollow body and sound hole amplify the lower, fundamental frequencies of the guitar. The nylon strings of classical guitars yield a slightly different timbre, however, the overall frequency response is roughly the same.

When miking a classical guitar at a distance, it’s often best to point a directional mic at the body of the guitar. When close-miking a classical guitar, we typically want to point the microphone(s) near the 12th fret rather than at the body/sound hole.

The Shure SM81 sounds superb in both situations!


A Note On Classical Guitar Pickups

Some classical guitars come with electric pickups. Often these are tiny electret microphones just inside the sound hole of the guitar.

In live situations, I’d typically suggest going with these pickup mics rather than external microphones. The pickups “stay put” inside the guitar, providing a consistent capture and no bulkiness outside of the guitar itself.

This article is about the best “outside” microphone for classical guitars without electrical pickups and/or for recording classical guitars in studio.


What Makes An Ideal Classical Guitar Microphone?

Let’s discuss a short list of the critical specifications that make up a great classical guitar microphone:

  • Flat/extended frequency response: Choose a microphone with a flat frequency response to accurately capture the sound of a classical guitar. Although the harmonic content of guitar strings isn’t very strong in the high-frequencies, having extended high-end helps to capture the air and character of the guitar and room. Extended frequency responses allow microphones to capture sound in a way that’s similar to how we naturally hear the guitar.
  • Accurate transient response: It’s always preferable to have a pronounced transient response when miking stringed instruments. There is a lot of information in the transients of the nylon string harmonics and often many strings will be played in short succession.
  • Low self-noise: Condenser microphones are often the best bet for miking classical guitars. These mics are active and therefore have self-noise. Choosing a quiet active microphone will help to further capture the subtle nuances in the sound of a classical guitar performance.
  • Directionality: Select a directional microphone to better suit the various miking techniques used in recording classical guitars.

So the above points should be kept in mind when choosing the best microphone for recording a classical guitar. How, then, does the Shure SM81 compare against the ideal specs?


Miking Classical Guitars With The Shure SM81

Shure SM81

The Shure SM81 is a top choice partly due to its flexibility. It accommodates all playing styles, rooms sizes, and practical microphone positions. Primarily, though, the SM81 just sounds amazing on classical guitars. It reproduces the sound of a classical guitar very closely. When positioned correctly, it’s as if we’re in the room with the guitar when listening back. Let’s talk about this fantastic mic in more detail:

Frequency Response Of The Shure SM81

The frequency response of the Shure SM81 is given as 20 Hz – 20,000 Hz. The SM81 frequency response graph is as follows:

Image from the Shure SM81 Specification Sheet

The first thing we’d notice when looking at the graph is the 3 options we have with the SM81. There are 2 different high-pass filters (HPFs) we may engage: one gentle slope starting around 300 Hz, and a steep slope starting around 120 Hz.

The second thing we may notice is the “1 Meter” written below the line. This is the frequency response graph the microphone portrays at a distance of 1 meter from a classical guitar (or any other sound source). This is important since the proximity effect states the bass response will become more sensitive as the microphone is moved closer to the sound source (this is because the SM81 is a directional microphone. More on this later).

The versatility of the HPFs and the proximity effect make the SM81 extremely flexible with mic placement. Whether you’re planning on capturing the full sound of the guitar with distance miking or a specific timbre with close miking, expect the SM81 to yield excellent results.

The relatively flat curve along the frequency range of a classical guitar allows the SM81 to accurately capture the sound of the nylon-stringed instrument.

Transient Response Of The Shure SM81

When it comes to transient response, ribbon diaphragms are the best. However, small diaphragm condensers aren’t far behind in accuracy! The Shure SM81 is nearly spot on with its responsiveness to transients.

There’s so much information in the transients of guitar strings (both in the fundamental frequencies and harmonics). The SM81 captures this nuanced information accurately and elegantly.

Self-Noise Of The Shure SM81

The self-noise rating of the SM81 is 16 dBA. This is noticeable in the quietest of studio rooms. However, if you’re recording in a hall or chamber, the self-noise shouldn’t be an issue.

Though not the best rating, the Shure SM81 is “quiet enough.”

Directionality Of The Shure SM81

The Shure SM81 is a cardioid microphone with the following polar pattern diagrams:

Image from the Shure SM81 Specification Sheet

Cardioid patterns work amazingly well when miking classical guitars at close range or at a distance.

Pointing the SM81 at an acoustic guitar from a distance will capture a clean, full sound of the guitar with no worries of exaggerated bass response (due to the proximity effect). The SM81 will capture a classical guitar similarly to how our ears would naturally.

When close-miking a classical with an SM81 (or any other directional mic), it’s standard practice to point it at or near the 12th fret. The slight off-axis colouration of the 81’s cardioid pattern will help reduce the sound coming from the sound hole (lower resonances) while still picking up the full character of the guitar. The helps to reduce the proximity effect and capture an accurate sound when close-miking.

When miking a classical guitar in a church, hall, chamber, or other reverberate room, the cardioid pattern will help to capture more of the direct source and less of the reflections and reverb. This may come in handy!


Recap Of The Shure SM81

Regardless of miking technique, performance style, or space, the Shure SM81 is my top recommended microphone for classical guitars. The versatility of this microphone makes it an ideal choice for many applications. The frequency and transient responses make it a go-to for classical guitar.

The Shure SM81 makes a great choice for a full, rich, accurate, nuanced sonic capture of classical guitars!

For all the My New Microphone mic/gear recommendations, please check out my page Recommended Microphones And Accessories.

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