Beginners Guide – Microphones

Being the Second part of my Beginners Guide, we shall focus at the start of the Signal Chain, and later posts will focus on later items.

As stated in the previous post, Microphones and Speakers are both Transducers, converting energy from one form to another. Microphone transfer Kinetic (movement energy) to Electrical energy, where as Speakers transfer Electrical energy back into Kinetic energy.

Something to note is that all microphones do not all work in all directions. Some may be best to pick up sound from in front and behind equally, while others reject sound from the rear. he way mics are split up into these categories is by their Polar Patterns (directionality).

Polar Patterns

Please forgive my artwork! These sketches show (roughly) how each mic responds in directionality. The closer the Red Line is to the outside of the circle, the louder it will pick up from that area.

Cardioid

This is by far the most common at the moment. The Mic picks up from the front, while rejecting / ignoring sound present behind it.

Super (Hyper) Cardioid

Slightly more directional than the Cardioid pattern, this is shown in the pattern being narrower, allowing a more isolated sound to be acheived. This pattern also picks up a small amount from behind the mic.

Fig 8 (BiDirectional)

My wonky Fig 8 diagram shows how the microphone picks up equally whats in front and behind it. This can be useful for getting a Stereo Image over a drum kit with 1 mic, or more complex Studio Techniques like Mid/Side and Blumlein Pair!

Omni

This simply picks up equally from all angles, and is used most in Lapel Mics. Which useful for getting the vocals, but will also pick up jangling bracelets!

Types

The diagram above shows a cut through of two different mics. The Dynamic mic has very little to go wrong, as it’s just the mic capsule and XLR output. Condensers on the other hand, house a circuit to power the mic, hence needing power to come from the desk.

Dynamic

Dynamics are the simplest of all mics to use. Just plug in and play. Physical strength and durability (withstanding high sound levels), along with a punchy warm sound are some great aspects of these mics. They range in price, but for a industry standard dynamic your looking around £100.

Super Cardioid Shure Beta57a – This is a great mic for many applications, be it Snare Drum, Guitar Cab, Horns or Vocals. This is one of my favourite all round mics.

This is a Large Diaphragm Dynamic Mic. Also a SuperCardioid pickup pattern. The flat silver side allows it to be placed next to Guitar Amps, meaning less hassle with stands. Its Diaphragm is also larger than the Beta 57’s, allowing more low end information to be captured.

Condenser

More fragile than Dynamic Mics generally, and require ‘Phantom Power’ (+48V) to power their circuitry. High quality clarity to these mics, and able to withstand more SPL than Ribbon mics. Price wise they range from £100 to £10,000+, so suited to every budget.

Within the Condenser Mic range, there are Small Diaphragm and Large Diaphragm mics. Small Diaphragms are under 1 inch, while the Large Diaphragm are 1 inch upwards. This small difference has a big effect on the performance characteristics of the microphone.

Small Diaphragm Condenser (SDC)

Because of its smaller diaphragm, these microphones respond quicker to short sounds than an equivalent LDC. This makes an SDC a good choice whenever you are trying to capture quick attack sounds cleanly, for example an acoustic guitar, metal percussion, or cymbals.

Large Diaphragm Condenser (LDC)

This is a budget LDC, and its easy see the Diaphragm shining through the Pop Shield. A LDC has a larger surface area for the vibrations to hit, meaning that more detailed representation is recorded. In general terms, a LDC is more sensitive than a SDC, and gives a larger output from the same source signal. Its more sensitive because Condenser are made of conductive materials, both the diaphragm and the backplate. This makes a Capacitor. The larger the plate and Diaphragm, the larger the change in capacitance is produced by the vibrations hitting it, the more voltage is outputted!

Ribbon

Uses a thin ‘ribbon’ as a diaphragm, which vibrates a magnet. These are used most in Studio’s as they are fragile, don’t handle loud sounds well – as it can damage the ribbon. Breath or sudden movement of air from a drum kit can also cause damage to the ribbon. Have a warm & natural sound quality that gives them the price tag! Sadly I don’t own any Ribbon mics, as I can get by without them, here is a pic of one anyway!

Wireless vs Wired

The main reason for using a Wireless System is to allow more freedom in performances. Not that people cannot present with a wired mic, but that its easier and less restrictive not to. That being said, it they don’t move around and are stuck to a Lectern, maybe a Lectern mic would be a better alternative.

With Wireless Systems, not every single microphone is represented.

The Shure range is greatly reduced to SM58 / Beta58A / SM86 / Beta87A’s, Headsets, Lapels, and guitar packs. Meaning that my Beta57 isn’t available in a wireless form. This is not a big deal, but if your artist has a preferred mic, its worth mentioning.

It is possible to get Neumann Heads for Sennheiser Systems, allowing you to swap out their standard 845 head for a Neumann 104, 205, etc.

I’ve seen worship leaders with a wireless microphones standing motionless in front of their floor monitor. Are they really able to move in this scenario? Not really, as they’re basically tethered to the wedge in order hear the mix.

If you want the talent to be mobile, complete the circle by making everything wireless. Give them wireless in-ear monitors, wireless guitar and wireless microphones. Now they can move wherever they need to while playing, singing and hearing their mix.

Wireless vs Wired – ShareFaith.com

This is a great quote, hence why i didn’t try to rephrase it. All too often I have seen this happen, where people have insisted on Wireless mics, only to stand perfectly still beside a comfort monitor, or wedge. These people generally think that they need a wireless mic, as they see others use them to their full potential, whereas in reality they could get away with a less complex and far cheaper alternative.

You really have to weigh up the pros and cons for each usage.

Wireless = more expensive, need to buy batteries / frequencies, for more mobile needs (pastors, soloists, dancers).

Wired = cheaper, more durable, for more fixed requirements (band, singers with mic stands, choirs).

Some may say that Wireless is quicker to setup, as you don’t have to run a multi to stage, etc, but factor in the time spent checking frequencies, sorting any issues that arise from crosstalk and replacing batteries can make the time difference negligible.

The wired version will also always sound better.

This is because the signal isn’t being compressed to be sent over Analogue routes to the receiver, to then be Uncompressed. This is a process is called Companding.

Digital Wireless Systems (Mics / InEars) don’t use this process, though cheaper versions will suffer with Latency – which its Analogue counterparts aren’t affected by.

Noticeable Latency hits around the 20ms mark, but for conferences / solo presentations, this is usually acceptable. For Worship / Rock & Roll purposes, that can be a hinderance.

Thankfully the technology is getting better all the time, and our system (Shure’s GLX-D) has a max latency of between 4.7ms and 7.3ms depending on amount of units involved.

When purchasing Wireless Mics or Inears, its worth going for a reputable company like Sennheiser or Shure, and not going for their most basic range. Meaning ensured reliability and longevity.

Frequencies – without going into too much detail, you NEED to check that the mics you purchase are LEGAL to use! If they aren’t then you could face fines, along with Interference from other Radio Users (Taxi Firms, etc). Check out Shure’s article about how the frequency range is changing to give 3G / 4G more room.

New digital wireless systems use Wifi (essentially) to send the signal to the receiver. This way there’s no issue with interference. A drawback is that Wifi networks can become clogged.

So what are the main advantages of having a wired mic, except for the price?

Wider selection of mics to choose from. There are some great microphones that just aren’t made in a Wireless form. There are ways around this, but I don’t really rate the ‘plug a wireless transmitter in’ approach – and it looks ugly!

Higher quality audio, as stated earlier with Companding and Latency issues that crop up on Wireless Systems. Its very much a what you hear is what you get scenario.

Reliability, the microphone itself is pretty difficult to break, its normally a loose connection in the wiring or the cable attached to it that breaks. You do not have the stress of seeing that half way through a preach / presentation the mic goes to Low Battery and starts flashing at you! The issues of Radio Interference and RF Dropout don’t exist either.

For the record, I love both Wired & Wireless mics, and use them both daily. For church work, we use 1 Headset, and 1 HandHeld, with the rest made up of Wired mics in various forms. Professionally I normally have 8+ Channels of Wireless, with a couple of wired lectern mics or such like.