Stream Basics | Audio
Lets talk about the basics for audio for your next live stream.
Because there is so much information and depth for audio, we will focus on the most common parts of each section. The following items outline the essential gear for the basic audio kit:
Cables connect devices together and transmit information.
Connectors are the heads of those cables.
Microphones capture sound that can be recorded or broadcasted.
Sound Isolation minimizes background noise.
PA systems amplify your sound.
Capture devices change signal into something your computer can understand.
Recorders write data.
Mixers combine inputs for your final sound.
There are two main reasons to invest in quality equipment when it comes to audio. The first is durability and the second is signal fidelity. More expensive parts generally last longer, and having that audio equipment that is properly shielded from other electronic devices is important for the highest quality broadcast.
Cables
Microphone or Audio cables (used most with 3 pin XLR or 1/4 inch TRS connectors)- are more commonly used in stage and live performance environments. These are a balanced signal which captures less background noise than an unbalanced signal.
Pro Tip: Microphone cables can send either a balanced mono signal (with the noise cancelation we talked about) or an unbalanced stereo pair (recommended for less than 20ft).
Instrument cables (used most with 1/4 Inch TS connectors)- These cables are unbalanced meaning there is limited noise protection built into this cable. It is best to keep these under 20 ft. away from your talent.
Connectors
XLR (3 pin)- These connectors have a balanced signal and offers both male and female style plugs on their respective ends. There is a locking latch that clicks into place when connecting the male to the female ends. In most applications the male connector transfers it’s signal to the female.
1/8 Inch (Mini plug, 1/8 inch Jack, Headphones)-These plugs are 1/8 of an inch thick at its tip. Such connectors are used on older phones and are the primary size for many headphones. These cables can have “Mono” or single signal but generally come with TRS (tip ring sleeve) ends. Some headphone cables have a microphone build in so the sleeve has an extra break. This is called a TRRS and the wire has 4 wires going through it for left, right, ground, and microphone.
Nickel, Silver, and Gold plated-The ends of these connectors have tips plated in nickel, silver, gold, or other conductive materials. Silver has the best connectivity even though it needs to be cleaned regularly. Most prefer gold because it has great connectivity but is more expensive. Your most cost effective cables will be nickel which as decent performance and stellar cost.
Microphones used for Live streams
There are several different types of microphones with a variety of applications. The focus for most live streaming are lavalier (or Lav), Boom, Headset (Modonna), and handheld (HH) microphones. Microphones can be wired or wireless. Wired mics give you more reliability in sound and performance while wireless mics give you a bit of flexibility in movement.
Lavalier (lav)-typically clips onto a shirt and is small enough to hide in clothing or even in hair. These mics allow a hands free operation but the sound quality changes depending on the direction your subject is looking.
Boom-This Microphone is very directional and is often held overhead by an operator or stand. The boom mic can gives a rich sound and can capture more low end frequencies compared to a lav. Because the microphones are so directional, they help minimize background noise and are often used on film sets.
Headset (Modonna, earset microphone)- These microphones are closest to the source (the mouth) and allow hands free operation like the lav but offer a more consistent sound since the microphone turns with the head. Such microphones are seen in live music performances where the singer does lots of dancing or movement.
Microphone characteristics
Let’s look at a few elements that separate Microphones.
Condenser Microphones- Condensers need phantom power which is used to power the internal components. They are used for more delicate sounds, higher frequencies, and are often found in studios.
Dynamic Microphones-Better for capturing loud dynamic sounds. They use a wire coil to capture sound and do not need a strong pre-amp to power the mic unlike a condenser mic.
Pickup Pattern- This is the zone or area that the microphone accepts sound.
Proxy effect- This causes bass frequencies to become more pronounced as the source moves closer to the microphone.
What the Specs Do not Tell You- The metals and other material of a microphone contribute to the characteristics and sound of the microphone so its fair to say that price itself is a significant specification in most cases. The higher the price, the higher the quality.
Signal Type
Line level (+4 dB for pro gear and -10dB for consumer gear) is the standard for professional audio. This is used for mixers, recorders, and other pro devices.
Instrument level ( around -20 dB) use a direct box (AKA a DI) to boost it’s signal. Guitars, basses, and pianos are generally instrument level.
Mic level (-40 to -60dB) needs a preamp to boost it’s level to line level.
Sound isolation
In recordings and broadcasts we want to try to isolate the sound being produced and lesson or take away as much of the background noise as possible. The best way to do this is to get the microphone as close to the source as possible paired with sound isolation. Carpets, rugs, and other material designed to absorb sound waves can help reduce the amount of echo or reverb heard in a room.
PA system
PA system is a speaker system to help amplify and project the sound created by your speakers or performers. PA systems come in a wide variety of sizes and are designed to fit the needs of the space acquired. If you have a large room, your speaker system may be larger.
Capture Devices/Audio Interface
A capture device turns an audio signal into something a computer can understand. This helps us either record that sound to the computer or to broadcast it out to our audience. Referring back to the workflow article, it is very important to know where everything is routed so that you can troubleshoot in case something pops up. Some video switchers and some video encoders have audio in ports, so they can serve the same purpose as a stand alone audio interface or capture device. If your switcher or encoder has those ports, you may not need an audio interface.
Recorders
Similar to capture devices recorders allow you to save recordings. Some mixers have built-in recorders and some need a separate dedicated device to record. If you are able to have a dedicated recording within the mixer, do it! However, be sure to also send audio to the backup video recorder so that audio recording is taking place in two spots.
Mixers
Audio mixers can be its own series because there is so much content that can be addressed. However the following is a general overview. There are a multitude of options out there for mixers and range from fitting the needs of stadium-sized set up down to a four track mixer. Modern digital mixers allow for added effects like delay, reverb, compression, and limiters. For a simple presentation, only compression and limiters will really be needed.
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We’ll talk about lighting!
