Performance Hardware Tutorial

Public performances of karaoke songs require the ability to monitor, modulate, and output audio from multiple sources and to multiple destinations. Specialized audio equipment designed to facilitate the management of audio sources is necessary when managing multiple microphones, computer audio, and output to speakers or other audio receiver.

While there are many brands and countless models of hardware available for consumer/prosumer purchase with many differences in their operation and features, most if not all of them use the same limited set of industry-standard in/out ports and basic audio engineering components.

This article will go over a specific set of hardware as an example, but much of the knowledge gained by understanding its operation can be applied to any audio hardware you might purchase for use in a karaoke DJ physical performance set up. When there is a feature proprietary to the model or relatively uncommon amongst other hardware, it will be noted.

Description of Hardware
A typical DJ or KJ setup consists of several pieces of equipment.


 * 1) Computer with  karaoke show presenting software, from which there are several to choose.
 * 2) *The computer must be installed with an operating system capable of running the presentation software of your choice.
 * 3) *The computer must have either a motherboard with an on-board sound card or a separate sound card fitted to the motherboard in its PCI(e) slot. This sound card must have an audio port capable of receiving the input from an audio input device.
 * 4) Hardware mixer, or software mixer installed on the computer.
 * 5) *In the case of a software mixer, a simpler hardware audio input device is still required if microphones are to be used, as there needs to be electronic adaption of microphone output to a format that a computer sound card can receive.
 * 6) Speakers with associated cabling to transmit audio output from the hardware mixer, or sound card in the case of a software mixer.

Example
The Yamaha MG10XU is a capable hardware audio mixing console at a reasonable price relative to other mixers. It comes with 4 stereo multi-input channels, 3 stereo single-input channels, 24 audio effects, and high levels of control on audio modulation separated into each channel using individual control knobs and switches. Channels are arranged vertically, with the input at the top and the control dials in a single vertical channel as indicated by the blue lines separating the channels painted on the mixer board.

It features multiple audio standards, including XLR connectors, phone connectors, RCA connectors, and a standard USB input. The job of a mixer is to combine all the input channels' audio signals into one output signal. On the MG10XU the input channels are on the left side, and multiple styles of output channels are located on the right side.

A typical mixer, such as this one, will also provide other functions, such as power for condenser microphones and audio modulation. On the MG10XU, each input channel comes with its own array of gain control, compression, frequency modulation, effects level, and pan control.

Understanding how every component is used with perfect knowledge is not necessary for adequate performance sound. Audio enjoyment can be a relatively subjective and varying experience. While having fundamental knowledge of audio engineering concepts would help to understand why each component does what it does, understanding the how and how much each component plays a part in the final sound can only be achieved by synthesizing this knowledge with experience; know that the specifics of audio engineering are available to read in detail, but be sure to experiment in practice to get a good feel for what sounds good in what environment.

Audio Standards
Audio standards have been used commercially and in the home since the late 19th century. Many standards exist and are still in use in modern hardware today. Each have common uses, usually playing to the strengths of the standard.

XLR Connectors
The XLR audio standard is today the most widely used professional audio standard. Most hardware devices will have at least one input channel and one output channel using the XLR standard input jack (or less commonly an XLR and phone connector combo jack). It features three pins arranged in a triangular pattern, sheathed by the casing of the connector or jack, one pin each for left and right audio and one for the ground.

Further Reading
 * XLR connectors on Wikipedia

Phone Connectors
The phone connector is the oldest currently used audio standard. It is still in regular use with modern electronic instruments such as guitars and their amps, as well as commercial radio equipment. The phone connector is suited for easy and repeatable removal and reinsertion, which is the main reason it was invented. When human phone operators still existed, this type of connector was used to make live connections between a caller and their requested destination, requiring frequent extrication and insertion and spurring the development of a hardy and effective design.

Of particular note for applications in live DJ sets, phone connectors come in mono and stereo versions. Take careful note of which one is necessary in your audio setup. There are other types of phone connector standards not typically used in live audio performances.

In the industry these connectors are commonly referred to by their length, i.e. quarter-inch connector.

3.5 mm Connectors
The phone connector miniature, more commonly referred to as a 3.5 millimeter connector, is the miniaturized version of the original phone connector, developed many decades later as electronics decreased in size and ubiquity. The 3.5 millimeter connector was extremely popular in mobile electronics uses such as iPhones and CD players for many decades, but has been supplanted by the Bluetooth standard for mobility. These also come in many styles, but the most useful ones for audio performance are the mono and stereo versions.

Very antiquated styles of devices can be damaged by using the wrong type of connector in a jack, but this is rarely an issue in modern hardware.

Further Reading
 * Phone connectors on Wikipedia

RCA Connectors
RCA connectors, created by the Radio Corporation of America, were designed to transmit electrical signals for home applications, such as audio/visual component connections between the television and AV receiver. In the original and most common style, audio signals are transmitted across the red (right) and white or black (left) component connectors, while composite video is transmitted over yellow.

Further Reading
 * RCA connectors on Wikipedia

Speaker Wire
Speaker wires are plain copper wires sheathed in a plastic insulation. The bare copper on either end of the speaker wire is inserted into a receptacle containing a metal conductor plate, and typically clamped down by a spring-loaded clip on the hardware itself to maximize connection between the plate and the copper. They typically come in zip cord style, allowing for custom lengths to be made from a large spool and for tight cable management. However, care needs to be taken to get the right wire for your use case.

You can use the following equation to determine what gauge speaker wire you will need:

$$L*\pi r^2 = I$$

where:
 * $$L$$ is the length of the wire you need
 * $$I$$ is the impedance/resistance of the speaker wire
 * $$\pi r^2$$ is the cross-sectional area of the speaker wire, $$r$$ being 1/2 the diameter of the wire

The typical industry guideline for the maximum amount of resistance before quality loss occurs is 5%.

There are arithmetically taxing equations you can use to figure out precisely what speaker wire gauge you should get using the American Wire Gauge (AWG) system, but that kind of precision is almost never necessary in practice. A simple guideline to use is to simply use 16 gauge speaker wire for wire runs less than 50 feet, 14 for runs less than 100 feet, and 12 or lower gauge for more than 100 feet.

Further Reading
 * Speaker wire on Wikipedia
 * Handy guidelines for using speaker wire
 * Less handy but very detailed Wikipedia article on AWG

Individual Component Breakdown
Each channel on a mixing console takes input from a single audio standard line in. Each channel also has various adjustment knobs and switches that changes various characteristics of the signal. In the sidebar on the right is a single channel. You can see that it has the line input jack at the top, in this case an XLR + 1/4-inch combo jack, followed by two switches, then several knobs before finally ending with the volume control and peak LED.

Each audio effect is applied from top to bottom in order, inclusive of the volume. So, for example, the gain knob increases the volume of the incoming line at all of the audio spectrum passed through, but the level knob increases the volume of the resulting audio signal after having been modulated by any of the knobs above it. So the level knob increases the perceived effect of each of the knobs before it and sends that signal to the output of the mixing console.

Each of the knobs also has a zero indention. You can feel this indention by moving the knob to the triangle along the border of the ruler for each knob. The frequency modulation and pan knobs zero at no modulation, while the effects and level knobs zero at what the manufacturer perhaps feels is a good baseline level for the knob.

Peripherals
Peripherals are a highly-visible and recognizable set of equipment with many technical and artistic considerations to choose from. Below is some very basic and general guidelines on what to search for and how to pick an audio setup that is right for you. In the spirit of brevity, more specific concepts and in-depth analysis of specific styles or brands will not be covered here. After reading through the basics here, if you have more questions or would like opinions on models you are considering, you can join us in #sound-check on the Global Karaoke Community Discord server.

Monitor Headset


Headsets using some audio standard are used to monitor the output of a mixing console while eliminating difficulties in judging the output audio in the open air. This can help you discern if a voice or instrument is too quiet or too loud relative to the rest of the mix, or more accurately perceive if settings for a particular channel should be tweaked.

Considerations for a monitor headset should be fairly limited for a live DJ. There are hundreds of models and styles of headset that you can use, and almost all are designed to work with the output channels on a mixing console.


 * Choose a headset with an audio input appropriate for your mixing console. Note in the technical specifications of your headset what audio standard it has and make sure that it is compatible with the phone out or monitor out of your mixer. For example, many headsets will come with a 3.5 mm phone connector, while mixing consoles frequently output to 1/4-inch phone connector. There are very cheap 1/4-inch female jack to 3.5 mm male phone connector adapters that will solve this issue.


 * Look through the reviews of the headsets and pay particular attention to the ear padding. Acids and oils on the skin are particularly prevalent near your head and ears and can eat through padding material over time. Choose a headset that comes with pads that last a very long time. Beats, for example, are notorious for cutting manufacturing costs by reducing the quality of the padding, which crack and wear out over a relatively short time.


 * Since this audio application is live performance and not studio recording, if you want to use ear buds or basic earphones, then that is fine. It may be preferable in some cases to have cheaper audio monitoring because operating as a karaoke DJ can come with the danger of being in a bar around people who have been drinking and are more like to accidentally damage your equipment. Plus unlike a music DJ you will likely be talking with your clients more frequently and won't be operating with your headset on the whole show, which diminishes the need for a high quality headset.

Most other choices in the headset department are personal preference. Remember that the headset is a recognizable symbol of a DJ; as such, the headset is part of your image and brand. People are likely to see your headset before your face if you aren't looking directly at them, so considering the implications of that will impact your recognition in a public setting. After checking the boxes on the technical specifications, choose a headset that represents your style and brand in a way that your clients will appreciate your particular KJ presence.

Speakers
This is a very enjoyable basic breakdown of how speakers and stereo sound works.

Speakers connect to your mixing console's output channel. As with headsets, make sure your speakers have audio inputs to match the output audio standards of your mixing console. Many are XLR/1/4-inch compatible, ideal for live settings.



Loud speakers are directional; in other words, they should be placed such that the focus of the sound coming from the speakers converges on a center point that is most likely to be heard by the maximum number of people, typically the center of the listening area. Imagine perpendicular lines drawn out of the speakers in the direction their drivers are pointing: those lines should meet right at the center of the listening area for optimal audio experience.

Sub-woofers, on the other hand, are non-directional. Very low frequency sounds are "felt" more than they are heard, so directional considerations are less important. One trick to optimally placing a sub-woofer is to play music with heavy bass and place the sub-woofer in the center of the listening area. Walk around the bar until you feel as though you can best hear the lows and feel the beat. The subjectively best spot is where the sub-woofer would optimally be set. Hopefully this is in an area that would be appropriate to set a speaker, but if not get as close as you can to it.

In practice, picking a set of speakers that is right for your show comes down to a balance between size, diaphragm types, and affordability.

In a karaoke setting, the mid-range frequencies are the most important as voices tend to be in the 200Hz to 8000Hz range. Singing is typically in a slightly higher frequency range than simply speaking. Make sure you pick a loud speaker that has good output in the vocal range.

In live settings where music is being played, you'll want to consider your audience. If your audience frequently pick music that makes heavy use of bass, drums, or low instruments, a large woofer may be preferable as listeners will be able to "feel the beat" of the song. In this case you'll want a set of speakers that address low sounds with large woofers, but this may require a mid-range driver to efficiently cover the vocal range as these large woofers and the small tweeters don't reproduce those sounds as well, and this will increase the relative cost of your speakers.

One compromise here is to get standard loud speakers with a woofer and tweeter that cover the full range of human-detectable audio frequencies, while supplementing the low sounds with a separate woofer or sub-woofer. Typically in a system like this the stereo outputs of your mixing console will be daisy-chained through each speaker, or alternatively a main speaker will connect to your mixing console and other speakers will connect to it.

Before you bring all of your speakers to a live setting, make sure to site-check the location for technical reasons ahead of time. Many bars with stages have audio systems already in place that you can simply plug your stereo out into. If this is the case, you will likely not need to bring your own speakers into the bar (though it might be prudent to have them on hand in case of equipment failure or inaccessibility during the performance). The downside is that an extra set of audio controls to account for are now part of the audio system, and may be handled by another person. Make sure these things are accounted for prior to your first performance.

Microphones
Microphones come in just as many varieties as speakers do because they are they exact inverse of speakers: In a dynamic microphone, a diaphragm moves in response to audio hitting the diaphragm which is converted into an electrical signal down the wire to your mixing console. In this case, however, because they are directly handled by clients these will not be the focus for audio quality.

The two most common microphone types are dynamic and condenser.


 * Dynamic microphone example
 * Condenser microphone example

Dynamic microphones are frequently seen in live settings. These are designed to be hardy and resistant to damage, and capture sound directionally. In the above example, sound is best captured by speaking directly into the top of the microphone rather than the sides, sometimes referred to as "eating the mic". In practice, non-professionals will need minor instruction on using microphones, but are very likely to move the microphone closer and further away from their mouths while performing. Make sure to use your compression knobs, if you have them, to account for the dramatic changes in volume.

Condenser microphones are more frequently seen in studio settings. They require phantom power to work as they are constructed with capacitors to more accurately buffer sound signals, and thus have superior audio recording capabilities to dynamic microphones. However, this construction makes them quite delicate; dropping one from waist height will very likely destroy the delicate capacitors that allow it to function. Use these in controlled settings where capturing high quality audio is critical to your use case, such as live recordings in a studio or podcasting.