When recording music, “room microphones” are often positioned away from the musicians and instruments in order to capture the “sound of the room” and/or a more developed and mixed musical sound.
Capturing the sound of the room includes the sound reflections and reverb within the physical confines of the acoustic space. This provides a sound capture that better represents the way we hear sound: from a distance. Close-miking everything would sound unnatural and room mics help to balance a natural and punchy recording.
Another benefit of room mics is that, depending on the context, they pick up a blended sound. In a full band live room, this means all instruments picked up by one or more room mics (again similar to how we'd listen to a live band). More commonly, room mics are used in drum booths in order to capture a full drum kit sound to be mixed with the close microphones for a punchy yet naturally sounding drum kits.
So now that we know the benefits of room microphones, which microphone are best for this application? Here are my top two room microphones:
- AKG C 414 XLS: A pair of AKG C 414 XLSs (link to check the price on Amazon) are an extraordinary choice for room mics. The C414 large-diaphragm condenser is among the most versatile on the market with 9 selectable polar patterns, 2 pads, and 3 high-pass filter options. Whether we decide on a spaced pair, Blumlein pair, or any other stereo (or mono) room miking technique, the accurate and high-quality sound of the AKG C 414 XLS's will sound amazing.
- Neumann U 87 AI: A pair of Neumann U 87 AIs (link to check the price on Amazon) is another marvellous choice for miking a room. The U 87 has 3 polar patterns to choose from: omnidirectional, cardioid, or bidirectional (figure-8), meaning it will fill the role of any stereo or mono room miking technique. The clarity of the U 87 makes it a superb choice for many applications including miking a room.
Let's talk about the C414 and U 87 in more detail after defining what factors makes a great room mic.
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 Makes A Great Room Mic Or Pair Of Room Mics?
- Versatility: There are practically infinite “rooms” and infinite ways to mic them. Having a mic or a pair of mics that are versatile will allow much more flexibility in the various room miking situations you may encounter.
- Flat/extended frequency response: Choose a mic or pair of mics with a flat frequency response across the human range of hearing (20 Hz – 20,000 Hz). Having a flat response will effectively capture the natural sound of a room.
- Sensitivity: Room mics are typically distanced from sound sources and are responsible for reproducing a mix of one or more direct sounds along with the reflections in the room. Selecting a sensitive mic or mic pair will better reproduce the nuances of direct and reflected sound waves in an acoustic space.
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The AKG C 414 XLS
The AKG C 414 XLS is a very popular large-diaphragm condenser. Its low self-noise, high sensitivity, flat frequency response, and industry-leading versatility make it a superb choice as a room microphone in any practical situation.
The AKG C 414 is featured in the following My New Microphone articles:
• 50 Best Microphones Of All Time (With Alternate Versions & Clones)
• Top Best Vintage Microphones (And Their Best Clones)
• Top Best Solid-State/FET Condenser Microphones
• Top Best Microphones For Recording Vocals
AKG is featured in the following My New Microphone articles:
• Top Best Microphone Brands You Should Know And Use
• Top Best Headphone Brands In The World
Versatility Of The AKG C 414 XLS
The AKG C 414 is perhaps the most versatile large-diaphragm condenser on the market today. With 9 selectable polar patterns, 3 different high-pass filters, and 3 different pads, the C414 will work well in any room or acoustic space. Whether we’re using a single C414 or using multiples in a stereo configuration, this microphone works wonders in room miking applications.
Let's quickly list out the AKG C 414's switchable options:
9 Selectable Polar Patterns
- Omnidirectional
- Omnidirectional/Wide Cardioid (intermediate)
- Wide Cardioid
- Wide Cardioid/Cardioid (intermediate)
- Cardioid
- Cardioid/Hypercardioid (intermediate)
- Hypercardioid
- Hypercardioid/Bidirectional (intermediate)
- Bidirectional (Figure-8)
For more information on microphone polar patterns, check out my article The Complete Guide To Microphone Polar Patterns.
3 Selectable High-Pass Filters
- No HPF
- 12 dB/octave HPF @ 40 Hz
- 12 dB/octave HPF @ 80 Hz
- 6 dB/octave HPF @ 160 Hz
For more info on high-pass filters, check out the following My New Microphone articles:
• What Is A Microphone High-Pass Filter And Why Use One?
• Audio EQ: What Is A High-Pass Filter & How Do HPFs Work?
3 Selectable Passive-Attenuation-Devices (PADs)
- Default
- -6 dB Pad
- -12 dB Pad
- -18 dB Pad
For more information on passive attenuation devices, check out my article What Is A Microphone Attenuation Pad And What Does It Do?
I think it goes without saying that the AKG C 414 will fill any roll in any microphone array/configuration when miking a room. When I've used C414's as room mics, I've generally set them as omnidirectional with an HPF at either 40 Hz or 80 Hz with no pad engaged. However, it all depends on the sound source(s), room, mic placement, and sonic aesthetic you plan to achieve.
Frequency Response Of The AKG C 414 XLS
The frequency response of the AKG C 414 XLS is given as 20 Hz – 20,000 Hz. The C414 XLS (omnidirectional position) frequency response graph is as follows:
I chose to show the frequency response of the C414's omnidirectional polar pattern (of the 9 polar pattern options). This is because
The C414 has a very flat frequency response. This means the microphone will reproduce the complex room sound (in the form of a mic signal) with pristine accuracy.
The slight boost of the upper-frequency range helps enhance the “brilliance” or “air” of the acoustic space, adding an extra sparkle to the sound.
As for the high-pass filters (HPFs), find one (or leave them disengaged) that sounds the best in particular room, mic positioning, and sound sources.
For more information on microphone frequency response, check out my article Complete Guide To Microphone Frequency Response (With Mic Examples).
Sensitivity Of The AKG C 414 XLS
The open-circuit sensitivity rating of the AKG C 414 XLS is given as 23 mV/Pa (-33 dBV ± 0.5 dB). The microphone will output a strong signal when subjected to exterior sound pressure.
For more information on microphone sensitivity, check out my article What Is Microphone Sensitivity? An In-Depth Description.
The light-weight large diaphragms of the C414 XLS capsule are very reactive and the microphone has a very accurate transient response. This helps tremendously in reproducing a precise replica of the complex sound waves in the form of mic signals at the microphone diaphragms.
For more information on microphone capsules, check out my article What Is A Microphone Capsule? (Plus Top 3 Most Popular Capsules).
For more information on microphone diaphragms, check out my article What Is A Microphone Diaphragm?
With an extremely low self-noise rating of 6 dBA, the C414 will pick up the slightest amount of sound pressure variation.
For more information on microphone self-noise, check out my article What Is Microphone Self-Noise? (Equivalent Noise Level).
The Neumann U 87 AI
The Neumann U 87 AI is another industry-standard microphone. Though best known for its voice recording applications, the U 87 AI makes an amazing room microphone. This high-quality microphone captures an accurate room sound that is clean yet full of character. The versatility of the U 87 makes it practical in any room.
The Neumann U 87 is featured in the following My New Microphone articles:
• 50 Best Microphones Of All Time (With Alternate Versions & Clones)
• Top Best Vintage Microphones (And Their Best Clones)
• Top Best Solid-State/FET Condenser Microphones
• Top Best Microphones For Recording Vocals
Neumann is featured in the following My New Microphone articles:
• Top Best Microphone Brands You Should Know And Use
• Top Best Studio Monitor Brands You Should Know And Use
Versatility Of The Neumann U 87 AI
Though not as versatile as the aforementioned AKG C 414 XLS, the Neumann U 87 AI has various settings to choose from. At least one configuration of a U 87 AI will fulfill a role in a given room miking array. Let's quickly run through the switchable options of the Neumann U 87:
3 Selectable Polar Patterns
- Omnidirectional
- Cardioid
- Bidirectional (Figure-8)
1 Selectable High-Pass Filters
- No HPF
- 3 dB/octave HPF @ 1000 Hz
1 Selectable Passive-Attenuation-Device (PAD)
- Default
- -10 dB Pad
Having all the above options available in the U 87 makes it an ideal microphone for any room miking techniques. Though I haven't used U 87 AIs as much as C414s to mic rooms (I've only even had access to one U 87 AI but pairs of C414s), I can say that it works wonders as a mono room mic. When miking a room with the U 87 AI (or a pair of them), I would likely start in omnidirectional mode with the high-pass filter and pad disengaged.
Frequency Response Of The Neumann U 87 AI
The frequency response of the Neumann U 87 is listed as 20 Hz – 20,000 Hz. Here is the frequency response graph of the U 87 in omnidirectional mode:
As we can see, the Neumann U 87 AI has an incredibly flat frequency response from roughly 60 Hz to 5,000 Hz. This will accurately recreate the mid-frequency sounds in a room which make up a great majority of the sonic information we process as humans.
We'll notice the increased bump in the upper frequencies. The enriches the brightness of a room and helps to enliven the sound of the acoustic space.
Another important note is that at the very upper range of the U 87 AI frequency response there is actually a roll-off. The roll-off protects the microphone from yielding an overly bright and harsh sound. This is critical in the days of digital recording, where the high-end is often over emphasized.
Note that one of the biggest differences between the U 87 AI and the vintage U 87 is that the newer AI edition sounds slightly brighter than the original.
The high-pass filter of the U 87 AI is designed mostly to counteract the proximity effect when used in close-miking situations. I would not suggest engaging this HPF when miking a room.
Sensitivity Of The Neumann U 87 AI
The sensitivity ratings of the U 87 AI vary depending on the selected polar pattern:
- 20 mV/Pa in omnidirectional mode.
- 28 mV/Pa in cardioid mode.
- 22 mV/Pa in bidirectional mode.
These are typical ranges for a condenser microphone. The U 87 AI will output a strong mic signal when subjected to room sounds.
The U 87 has a superb transient response. The light-weight large diaphragms of the U 87 AI are very reactive to changing sound pressure levels, making the microphone extremely accurate. This helps to capture the nuanced blending of sounds at the position of a room microphone.
The self-noise ratings of the Neumann U 87 AI is also quite low and doesn't overly affect the sound of the room. The U 87 AI self-noise depends on the selected polar pattern:
- 15 dBA in omnidirectional mode.
- 12 dBA in cardioid mode.
- 14 dBA in bidirectional mode.
Recap
When miking a room, care must be taken to find the right microphones. The recommended microphones on this list excel as room mics in any practical acoustic space as singles or in stereo/surround sound microphone arrays. The top two room mics are:
- AKG C 414 XLS: Best large-diaphragm multi-pattern electret condenser room microphone.
- Neumann U 87 AI: Best large-diaphragm multi-pattern “true” condenser room microphone.
For all the My New Microphone mic/gear recommendations, please check out my page Recommended Microphones And Accessories.