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What is an XLR microphone and why would I like one?

  An XLR cable
Cameron Summerson

Recently, microphone maker Blue announced a professional studio microphone for $ 1

00, the Ember. So the question arose: What is the XLR thing and how do I use it? Let's talk about what XLR is and why you might want to use it in your studio.

XLR is Pro Audio. This is what all recording and radio studios use, and live performers are used on stage. This is because XLR cables contain balanced audio, which is essential for a clean sound.

What is XLR?

First of all: Define what XLR means. It is a fairly straightforward abbreviation for X Connector, L Oocking Connector, R Ubber Boot. However, the "rubber boot" section of the connector is not always part of the equation today because it is no longer required. Despite the minor design change, the name has remained the same.

Different versions of XLR cables with different additional pins (XLR3 – XLR7) are currently available, but this is about the XLR3 or XLR3 three-pin cable style. This is by far the most common type of cable.

In short: XLR is the standard for high-quality audio inputs, such as B. microphones. This is because they send a balanced signal that isolates noise. It's just a better connector type for this type of application, but it's also so robust that it's not necessarily something that the average consumer needs to really think about unless it's for audio recording or streaming in high quality thought

In addition to an XLR microphone and an XLR cable, you need an audio interface or a mixer so that your computer can see the microphone. A decent audio interface can be found for only $ 40-50, but nicer devices can offer much more. The average enthusiast will probably want to spend somewhere in the range of $ 150-200 for a good interface – for example the Focusrite Scarlett 2i2 is a good entry, for example.

If you're planning home recording, you may also need a DAW – a Digital Audio Workstation – to record your recording. You can use something as free as Audacity, but there are also excellent options that do not cost much, such as Reaper. You can read our pictures for the best DAW here.

The technical side of what makes XLR so much better than other audio inputs is quite technical. Continue reading for all the juicy details.

The Balancing Act

If you've ever changed the batteries in your flashlight, you've probably noticed that the battery has a positive (+) and a negative (-) side. If you connect only one side of the battery to the bulb of your flashlight, nothing happens. You need both the positive and negative terminals for the lamp to light up. This is an electrical circuit. The electrons must form a complete loop from the negative pole of the battery through the wire, through the light and back to the battery. Audio is no different: you need the positive and negative sides of an audio signal for something to happen. A microphone pushes electrons to one side of the cable, the electrons are routed to an amplifier and then back to the other side of the microphone.

The problem is that most audio systems treat the circuit as if there were only one cable. usually the center conductor in one piece of coaxial cable, and they just combine the other wire with all the other electronics in the system. This provides the possibility of various types of noise entering an audio signal chain:

  • Ground Loop Noise: In my 35 years of experience with professional audio and video systems, this is especially the most common and annoying problem when using a computer involved. Most of the time you hear this as a quiet hum, although it can also occur as static or irregular buzzing sounds. Ground loops occur when the audio signal goes to the amplifier in two different ways: a path through the audio cable and a second path through the wiring of your building.
  • EMI and RFI : Transformers, Motors, and High-Frequency Electronics May Create Magnetic Fields That Induce Current in Your Audio Cables. This creates a humming and hum and can even transmit audible wireless signals if you are too close to an AM transmitter.
  • Crosstalk : This happens when a signal from the same system changes to another.

How do you fix this? The solution seems pretty obvious in hindsight: they insulate both wires in the signal chain so that the positive and negative signal halves are carried separately from the other signals. The main advantage of having a balanced audio signal (when done correctly) is that the audio signal never touches the ground plane of the amplifiers or other instruments in the system. So there is no possibility for crosstalk or ground loops.

For example, I work with a live band, and a few weeks ago we had a problem with the "click track" that was created by the musical equipment of one of the performers used. The sound from the click track penetrated to the other outputs of its audio interface, so you could hear a beep in the PA system. It was quiet, but there. We disconnected the unbalanced audio cables he used and switched them to balanced XLR cables. The problem went away.

The other advantage is the noise reduction. EMI and RFI work because a moving or changing magnetic field creates a voltage across a wire. For unbalanced signals, the magnetic field generates a voltage on the positive side of the signal, but not the negative (or vice versa). With a balanced cable, the wires are directly next to each other and thus a magnetic field generates the same signal on both sides.

  Audio Wavelengths
Inverting the copy of the waveform removes the interference, and we get the same signal we put on the wire. Tom Wilson

On the sender side, an XLR device makes a second copy of the audio and inverts it. On the receive side of the signal, the inverted copy of the signal is summed up again in the original copy of the signal. And just as in mathematics, where -2 + 2 = 0, a symmetric audio signal rejects the noise from the outside.

Finally, your chances for crosstalk are significantly reduced if the signals do not share a ground plane signal. High-end devices that use a fully balanced audio chain internally have virtually no crosstalk.

Use for Use

How do you practice all this? What does it help?

If you look at the Ember, you may think of streaming to Twitch, recording a podcast, or listening to music. Either way, you can connect this ember to a USB mixer (such as the Mackie Pro FX8) and use the mixer as an amplifier for the microphone and a USB audio interface. You can also add another microphone for your Internet Co-Star and connect other devices – such as a musical instrument, another computer running Skype or Discord, or just your smartphone.

The most important aspect you should keep in mind is that you need a mixer or microphone phantom power audio interface (this is often indicated by a switch with + 48V). Since the microphone needs to be powered, you need something that can produce that power. This is one reason why a mixer is a good choice for an audio interface because it integrates phantom power directly into the device. High-end mic preamps may also have phantom power, and some XLR computer audio interfaces incorporate phantom power supplies.

Other options

Finally, there are other options for sending balanced audio as an XLR plug. [19659031] TRS phone plug "width =" 352 "height =" 385 "data-credittext =" Tom Wilson "src =" /pagespeed_static/1.JiBnMqyl6S.gif "onload =" pagespeed.lazyLoadImages.loadIfVisibleAndMaybeBeacon (this); " onerror = "this.onerror = null; pagespeed.lazyLoadImages.loadIfVisibleAndMaybeBeacon (this);" />

Tom Wilson

TRS telephone plugs can also carry balanced signals.Cable plugs are commonly used in professional audio equipment to connect mixers and amplifiers, as well as for connecting external effects devices such as reverb processors, equalizers, compressors, and audio recorders.The plug looks and is the same as the plug used in high quality headphones, but the ring is for the negative side of the audio signal

You can also use some of the benefits of a balanced audio cable with a device called a ground loop isolator like a small box with two cinch sockets or sometimes a mini headphone plug. Ground loop isolators have a 1: 1 audio transformer that breaks the earth loops. When you connect a computer to a mixer or cable box, you are almost guaranteed to hear earth loops and humming noises. This almost always fixes these noise problems. You may even have this problem in the car when you connect your smartphone to your car stereo, so a ground loop isolator with 3.5mm jack plugs is a great help.

Why not a USB microphone?

In conclusion, you may wonder why the trusted USB microphone is not good enough.

In fact, it's fine if you only have to record one thing at a time. I have a nice Samson USB microphone for podcasting or streaming on my desk, and it works great. The catch with USB microphones, however, is that you can not use more than one microphone at a time. USB audio devices each have their own clock to control the digital audio converters. If these clocks are out of sync, pops or dropouts will appear in your recordings because the software on your computer is trying to correct those errors.

It's also harder to mix this way because these physical buttons are not available. So if I want to do something with more than one person at a time, I reach for my desktop mixer and my familiar studio microphones connected to an XLR.

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