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Mic Proximity

A cheap mic near the audio source is better than an expensive mic far away

Environment

Look at where you’re recording and listen to your environment. Watch out for small rooms with hard, parallel reflective surfaces. Treat the walls with acoustic blankets. Turn of a humming fridge and put your car keys inside. Be cognizant of how audio’s physical needs affect blocking when planning shots.

Approach

Is production audio run straight into camera? Is it dual system? 


Microphones

The most common microphone types include:


Dynamic Mics

Generally speaking, more durable. 

Condenser Mics

Require power. Potentially more fragile. 

Ribbon Mics

Not often used in video production. More delicate.

Shotgun mics or “boom mics” are directional mics that are usually positioned just outside the frame.A receiver (Rx) and transmitter (Tx) can be used to send audio signals wirelessly, though it’s never as reliable as a wired connection. It’s important to monitor a wireless connection as interference is a very common occurrence.

Lavalier

Also called “lav mics”. Small microphones, usually condensers, that clip onto the talent and can oftentimes be hidden. Because these are often times condensers, they will require power. I generally suggest avoiding lavalier use if you have the alternative of a mic with a larger diaphragm. The lav’s sound is simply inferior.Why do some lav mics need a battery and others don’t?”There are two powering systems in general use today:1) Consumer/Prosumer Mic Power, exclusively used with 3.5mm connections & other small connectors to wireless body pack transmitters. Nominally 5 volts dc, varies from 3V to about 7. This power can directly bias (“bias” power or “plug-in power”) a condenser mic, no preamps or other electronics in-line.

“USB microphones”Some microphones will do their own “Digital to Analog” conversion meaning they simply plug into your computer via USB rather than requiring a D to A converter box.

Wireless Mics”Virtually all pro wireless systems operate on either the VHF (very high frequency) or UHF (ultra high frequency) bands. VHF wireless systems generally operate within the 174 to 216MHz range (the range of TV channels 7-13), while UHF uses the 470 to 805MHz range (the range for TV channels 14-69).”Both of these bands are becoming crowded though UHF is generally still considered superior. The analog signal can be “companded” to reduce its dynamic range/signal bandwidth or can be converted to digital before transmitting. These tricks help make the most of a crowded spectrum, but this conversion can increase latency as it has to be reversed by the receiver. Lectrosonic and Zaxcom, Audio Limited A10, are the higher end of the “industry standard”. These systems are built for reliability and rigorous production use. Sennheiser “G” series has been historically popular for more budget-friendly (sub $1000 options).

The 2.4GHz LineupThese use the same frequency band as WiFi and bluetooth. This is nice in that you can use your gear internationally without a problem, but bad in that you’ve got major competition from lots of consumer gear. Generally speaking, this ‘digital range’ doesn’t penetrate walls as well as the lower frequencies historically used in ‘professional’ audio gear will. RODE Link Wireless Filmmaker KitDeity ConnectThe latest to keep an eye on in 2019. Looks like it’ll be good competition to G-series and XSW-D Sennheisers with a decent blend of features.Sennheiser AVX (Pro version of XS below)Sennheiser “XS” seriesNew Sennheiser XSW-D series operates (like RODElink) on 2.4GHz (aka WiFi) spectrum. Great review here.The system is smart about jumping to available WiFi bands quickly. Its one-button approach is great for new users intimidated by gain staging and pairing, but it’s a limitation in that there’s no gain control should your camera have a hot input.Built-in battery lasts around 5 hours per charge.The upgrade ME2 version II lav mic is much better than the original (bundled with G3 kit).Latency is great for a digital system.XLR transmitters available but they don’t provide phantom power.

Disclaimer on spectrum availability: Anyone with systems that operate above 608 MHz must discontinue use and migrate to new frequency ranges. Sennheiser’s G4 series is future-compatible. Older G2 and G3 systems using the “A” range below 600 MHz may still be compatible. It’s not likely the FCC police will be after you unless you’re using these devices at extremely popular sporting events, but you may find your device subject to so much interference (from T-mobile traffic) it becomes problematic. See here for FCC details.

The RodeLink runs on the same open frequency band as wifi networks (2.4GHz). It shares bandwidth with a LOT of consumer devices so you’re going to get more interference and less range due to the higher frequency and increased RF noise. A more recent announcement, at a price point that’s hard to compete with, is RODE’s new “Wireless Go” system. It’s also a 2.4GHz system, but it’s very clever about scanning available frequencies and quickly adapting to best use what’s open. It’s not going to be nearly as reliable as the non-digital, lower frequency band units, especially when the transmitter and receiver don’t have line-of-sight between each other.  


Standalone Recorders

These are small units featuring both microphone and recorder in a single package. Though you can plug an external mic (typically a lavalier) into them, that’s not their primary use. Here are two popular units:Zoom H1

Tascam DR-05

The Zoom F1 is quite an innovation. It can act as a recorder for a variety of devices: lav mics, shotgun mics, etc. It has a headphone out so you can record to the camera and it also works as a USB interface for recording on your computer.


Professional Field Recorders

Professional sound recording on-location is usually done with a dedicated device like these. The recorded audio can be recorded to onboard memory (SD and micro SD) or piped back into the camera so you don’t have to sync in post. The high end devices will even use AES outputs for sending a digital signal to the camera so you bypass the camera’s cheaper A>D conversion and don’t require sync in post. Make sure your camera’s own “input level” is set quite low so its inferior pre-amps aren’t doing any of the heavy lifting. Many of these also act as USB interfaces (analog to digital converters) for plugging into a PC. They also feature compatibility with third-party physical controllers (and regular USB keyboards) and app support (not so handy for adjusting gain but very nice for metadata entry). The high end versions of these have cool features: Zaxcom: Dual A>D converters for “never clip” feature; remote levels control of wireless transmitters;Sound Devices 633, a $3500 field recorder.

Recently, Zoom released their F4 which represents the best value and pro-level feature set to date for $500:Low noise, high quality and high gain pre-amps and impressive dynamic rangeAccurate internal timecode clock and ability to jam syncFalse Take feature (Press rewind)Dual record feature for safetyAlso acts as a USB audio interface

Gain Trim = Input Level

One of the primary levels you’ll set repeatedly is the amount of gain the pre-amplifier is using to boost the mic’s signal. This is your “gain trim” or “input level”.Set it  so you see peaks around -18 dbfs on a high dynamic range recorder with at least 24 bit depth recording and low-noise pre-amps. The headroom is useful in case of a loud laugh or unanticipated performance.


Phone Recorders

You can buy microphones that plug into your phone, making the phone the recording device.Zoom iQ7 (≈$95)Shure MV88 (≈$150)


Polar Patterns

A microphone has increased sensitivity to a certain area around it.

OmniCardiodSuper Cardiod

No Shotguns Indoors

Just like you wouldn’t operate a traditional shotgun indoors, don’t try it with the microphone version. Hyper-cardioid pencil mics don’t use interference tubes and are better for small indoor spaces. A shotgun mics interference tube uses phase cancellation which creates problems with early reflections. A shotgun mic is often a hyper-cardiod pattern with the interference tube to reject off-axis and rear sounds–this makes the shotgun mic more directional.


Physical Connectors

TRS

TRS connectors are common 3-conductor setups which can be used for a mono or stereo mic. “Tip Ring Sleeve” comes standard in 1/4″ and 1/8″ varieties. The 1/8″ is also known as 3.5mm or just a “regular headphone jack” and it’s the one you’re most used to seeing on your consumer audio device.

XLR

The most common professional audio connector you’ll see used with microphones. It’s a balanced connector meaning positive, negative and ground are separated.

For much prosumer work, at short runs, XLR/balanced audio isn’t as big a deal as some make it out to be. You’re audio quality doesn’t immediate drop when being passed through a 3.5mm connector vs. an XLR. Once you’re past six feet you may experience issues. Definitely don’t try taking unbalanced audio runs over twelve feet.

Mic Power

A twelve foot stereo headphone extension cable is frequently used to provide convenient distances from subject to camera for wired mics.This only works with cameras, recorders, or mixers that provide mic power on a 3.5mm jack. Audio Technica (others?) supply a similar mic with a couple button-size batteries in-line for power. There are “power box” suppliers, too, typically a 9v battery system. All of these are based on 3.5mm connectors, except in the case of wireless mic body packs, which can have any of a variety of small connectors. This is called “plugin power”.

Prosumer/Professional Phantom power is nominally 48v. Some systems only supply 24 or 28v, which doesn’t work on all mics, especially large-diaphram condensors. A mic’s specs will state what’s required, a camcorder’s, mixer’s, or audio recorder’s specs will state what they supply. Phantom is (almost) entirely a XLR connector system. Such balanced systems can usually run a few hundred feet when properly wired.””All condenser microphone elements need a few volts of bias voltage, which is often derived from phantom power but need not always be. Many condenser lavaliere microphones these days are used with wireless bodypacks, and those usually don’t supply phantom power (but do supply a bias voltage). There have also been various condenser microphones made over the years that require a separate battery rather than phantom power.” “Bias is a dc voltage (1.5 – 9 volts typically) that is provided on a single conductor. Unlike phantom power, bias does not require a balanced circuit.” “not all external microphone powering is phantom power. The term “phantom” refers to the invisibility of Phantom power, which does not need a dedicated power wire but rides invisibly on the two balanced mic cable conductor wires. When you need it, it is there, when you don’t need it, it isn’t (barring problems with cables or connectors). Mic powering that is delivered on balanced cables in this manner is correctly identified as phantom, regardless of the voltage. “To confuse this understanding, very often ANY powering of condenser microphones is incorrectly called “phantom” even when it is delivered on a dedicated wire or via a battery.Many lavs designed for video/film include a preamp body that can be powered off a single 1.5v AA battery and/or phantom. A few shotguns, too.It takes a converter to plug a lav mic into an XLR input. Though it appears to be just an simple adaptor, the MZA900P converts Phantom Pwr. to a usable ‘bias current’ ( sometimes referred to as ‘Plugin Power”) Using the mic with just a cheap 1/8″ to XLR adapter with Phantom Pwr. could permanently trash the mic.


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