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 C414 XLS: A pair of AKG C414 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 C414 XLS’s will sound amazing.
- Neumann U 87 AI: A pair of Neumann U 87 AIs (link to check the price on Amazon) are another marvellous choice for miking a room. The U87 has 3 polar patterns to choose from: omnidirectional, cardioid, or bidirectional (figure-8), meaning it will fill the roll of any stereo or mono room miking technique. The clarity of the U87 makes it a suberp choice for many applications, notable among them is miking a room.
Let’s talk about the C414 and U87 in more detail after defining what factors makes a great room mic.
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.
The AKG C414 XLS
The AKG C414 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.
Versatility Of The AKG C414 XLS
The AKG C414 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 C414’s switchable options:
9 Selectable Polar Patterns
- Omnidirectional/Wide Cardioid (intermediate)
- Wide Cardioid
- Wide Cardioid/Cardioid (intermediate)
- Cardioid/Hypercardioid (intermediate)
- 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 information on microphone high-pass filters, check out my article What Is A Microphone High-Pass Filter And Why Use One?
3 Selectable Passive-Attenuation-Devices (PADs)
- -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 C414 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 a 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 C414 XLS
The frequency response of the AKG C414 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 C414 XLS
The open circuit sensitivity rating of the AKG C414 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 U87AI
The Neumann U87AI is another industry standard microphone. Though best known for its voice recording applications, the U87AI 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 U87 makes it practical in any room.
Versatility Of The Neumann U87AI
Though not as versatile as the aforementioned AKG C414 XLS, the Neumann U87AI has various settings to choose from. At least one configuration of a U87AI will fulfill a role in a given room miking array. Let’s quickly run through the switchable options of the Neumann U87:
3 Selectable Polar Patterns
- Bidirectional (Figure-8)
1 Selectable High-Pass Filters
- No HPF
- 3 dB/octave HPF @ 1000 Hz
1 Selectable Passive-Attenuation-Device (PAD)
- -10 dB Pad
Having all the above options available in the U87 makes it an ideal microphone for any room miking techniques. Though I haven’t used U87AIs as much as C414s to mic rooms (I’ve only even had access to one U87AI but pairs of C414s), I can say that it works wonders as a mono room mic. When miking a room with the U87AI (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 U87AI
The frequency response of the Neumann U87 is listed as 20 Hz – 20,000 Hz. Here is the frequency response graph of the U87 in omnidirectional mode:
As we can see, the Neumann U87AI 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 U87AI 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 U87AI and the vintage U87 is that the newer AI edition sounds slightly brighter than the original.
The high-pass filter of the U87AI 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 U87AI
The sensitivity ratings of the U87AI 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 U87AI will output a strong mic signal when subjected to room sounds.
The U87 has a superb transient response. The light-weight large diaphragms of the U87AI 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 U87AI is also quite low and doesn’t overly affect the sound of the room. The U87AI self-noise depends on the selected polar pattern:
- 15 dBA in omnidirectional mode.
- 12 dBA in cardioid mode.
- 14 dBA in bidirectional mode.
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 C414 XLS: Best large diaphragm multi-pattern electret condenser room microphone.
- Neumann U87AI: 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.