AIM Basic Audio - NOTES - Microphones (for training purposes)

BASIC AUDIO NOTES

The image above shows the equipment we will be working with over the next four weeks. The gear on the table is as follows (TL to LR)*:

We will be using this gear to record interviews and ambient sound, add some basic audio effects to recordings, recording testimonials in “the field”, and more.

*not pictured Hindenburg Pro Audio Editing Software (app)

AKG C214 Studio Mic

Dead Cat Windscreen

Audio-Technica AT 897 Shotgun Mic

Pop Filter

Desktop Mic Stand

Zoom H5 Handy Recorder

Shure SM58 Handheld Mic

Sony ECM-44B Lavalier Mic

SD Cards/Micro SD Cards

Sony MDR-7506 Stereo Headphones

Rode R0DECaster Pro II Integrated

Audio Production Studio

Trigger grip mount for shotgun mic

XLR cables

A microphones (mic) sensitivity to various sounds and the direction from which the sound is coming is called its pickup pattern.

Omnidirectoinal

Omnidirectional Pickup Pattern

Cardioid

Hypercardioid

Sound is picked up equally from all directions. The sound is picked up in a circular pattern so that the front, back, and sides of the microphone can pick up sound clearly.

Unidirectional Pickup Pattern

Unidirectional microphones pick up sound from one predominant area. They pick up audio only from the direction that the barrel of the microphone is pointing.

Cardioid Microphones

•slightly omnidirectional microphone

•has a pickup pattern that is heart-shaped

•capture audio mostly from the front of the microphone

•excellent general use microphone

•capture everything in front and block everything else

•front-focused pattern

• ideal for live performance and other situations where noise reduction and feedback suppression are needed

Hypercardioid Microphones

• unidirectional microphone related to the cardioid, but with a more exaggerated front-end pickup pattern

• this type eliminates almost all sound from the sides and back

• Most often, these pickup patterns are used while recording instrumental audio

• typically long and thin

• sometimes called shotgun mics

• typically used for recording dialogue on set due to their ability to accept audio directly on axis with the microphone while still cancelling sound on the sides

Dynamic VS Condenser Mics

Dynamic mics reliably capture sound and can do so even at high sound pressure levels. That said, you can use them for recording loud sound sources like bass and guitar amplifiers, and even drum kits without worrying about unwanted distortion or damage. They also work well in quieter settings.

Example of a Dynamic Mic

The Shure SM58 Microphone is a dynamic microphone with a cardioid pickup pattern

Use this mic when recording vocals, primarily in a studio setting. However, you can use this mic in the field and still generate desireable audio.

Condenser mics have a thin conductive diaphragm that sits close to a metal backplate. This configuration improves fidelity and sound quality, making these mics ideal for precision recording in the studio.

Note:

These type of mics require power, so you’ll need a mixer or direct box with phantom power (except in cases where batteries are used).

Also, remember to handle them with care as they are not as sturdy as dynamic mics.

Example of a Condenser Mic

The Sony ECM-44B Microphone is a condenser mic that has an omnidirectional pickup pattern.

Use this mic when recording vocals, primarily in a studio setting.

Hypercardioid Pickup Pattern

Hypercardioid patterns are similar to cardioid patterns in that the primary sensitivity is in the front of the microphone. They differ, however, in that the point of least sensitivity is at the 150 – 160 and 200 – 210 degree positions (as opposed to directly behind the microphone in a cardioid pattern).

Hypercardioid microphones are considered even more directional than cardioid microphones because they have less sensitivity at their sides and only slightly more directly behind.

Example of a Condenser Mic with a Hypercardioid Pickup Pattern

The Audio-Technica AT897 Shotgun Microphone is a condenser microphone with a hypercardioid pickup pattern

Use this mic when recording ambient noise, primarily in a outdoor setting. wind screen

Basic Audio Equipment Guide - Microphones

XLR cable is used for connecting mics to mixers (such as the R0DECaster Pro II), preamps, audio interfaces and recorders (such as the Zoom H5 Handy Recorder)

• XLR stands for EXternal Line Return

• identify an XLR cable by its circular design with 3 pins • one for positive polarity, another for negative polarity, and a third as a chassis ground (cable shield)

Plug the “female” end of the XLR cable into the “male” end of a microphone.

Plug the “male” end of the XLR cable into the “female” recepter on a mixer, preamp, or recorder.

female

male

male

Phantom Power - a term given to the process of delivering electric power to microphones to drive active circuitry. Condenser microphones all have active circuitry and require phantom power or some outside power source to run them (such as batteries or a DC power supply).

Phantom power sends a DC current from a preamp or mixer, through the XLR cable, and to the condenser microphone to power the internal active circuitry.

You can also power a condenser microphone with batteries.

AKG C214 Large-diaphragm Condenser Studio Microphone is used in AIM’s Audio Production Studio.

The mic kit consists of:

Other components for use with the C214 include:

• Table Mic Stand

•

1. the microphone

2. a shock mount

3. a windscreen

XLR cables

• Pop filter

C214 set up

1. Place the windscreen on the microphone and leave it in the kit (for now)...

2. Remove the Shock mount from the kit and screw it onto the stem of the table mic stand.

3. Move the shock mount into the open position

4. Insert the mic and windscreen into the hole at the center of the shock mount from the bottom up

5. Move the shock mount into the closed position

6. Attach the female end of the XLR cable into the male end of the C214 microphone

Here is the process for connecting a Pop Filter to the a desktop mic set up (stand and mic):

Obtain a Pop Filter from the console area in the Audio Production Suite

Unscrew the clamp on the filter until it fits onto the stem of the desktop mic stand

Adjust the flexible arm on the filter so that the screen rests approximately two or three inches away from the C214 mic

This set-up should help remove most of the pops that you may be getting in your recordings!

Secure the clamp onto the stem of the mic stand (secure...not death grip tight)

Now you are ready to connect the desktop mic set up(s) (mic, pop filter, and desktop mic stand) to either a mixer, preamp or recording device.

To connect the mic set up to a R0DECASTER PRO II: Plug the power supply into a wall outlet

• staff recommends plugging into a surge protector

Connect the power supply unit into the USB-C Power Port next to the red power button on the back of the R0DECASTER PRO II unit

Insert the Micro SD card into the card slot on the back of the R0DECASTER PRO II unit until it clicks into place

NOTE:

To eject the card, gently push the card in and release the pressure.

Connect any/all headphones you wish to use into the jacks located on the back of the R0DECASTER PRO II unit

• numbers correspond to the mic input signals (Input 1 = Output [channel] 1, etc.)

Connect the mic you wish to use for your host into Mic Input 1

• Connect the mic(s) you wish to use for additional talent into Input 2 -4 as needed

NOTE: A good workflow when using multiple mic inputs on a mixer is to put the host in the first mic input and then the guest(s) in the inputs that follow

Turn on the R0DECASTER PRO II unit by pressing the RED POWER BUTTON located on the back of the R0DECASTER PRO II unit

you may want to connect the desktop mic set up(s) (mic, pop filter, and desktop mic stand) to a recording device like the Zoom H5 Handy Recorder!

Here’s how to connect the mic set up to the “H5”: Insert two AA batteries into the back of the recording device

• remove the battery cover, insert the batteries and replace the battery cover

Connect the XLR cable of the host mic into INPUT 1

• staff recommends putting the host on INPUT 1 and the guest/talent in INPUT 2

Open the SD card slot cover and insert the SD Card into the card slot on the side of the recording device until it clicks into place

• Close the SD card slot cover

Connect headphones to the jack located on the left side of the recording device

NOTE: The jack for the H5 requires an 1/8 inch plug...not a 1/4 inch plug

Power up the recording device by sliding the Power/Hold switch to the right

• hold the switch until the LED screen turns on and displays the “SD card access...” message

Basic Audio Equipment Guide - Microphones

Gain VS Volume

What is Gain?

Many devices at AIM, such as audio interfaces, mixers, preamps, etc. have a gain knob. When you increase the gain, you will often note that is seemingly a direct correlation between this and the volume increases.

With gain, you are looking at the input stage of anything being processed, so nothing has happened yet, and gain is one of the adjustments you can make before playing with the volume controls. If you are using a microphone preamp, then gain will increase the input signal (so if someone is singing or speaking more quietly, you can increase the gain to up the input).

So although gain affects the final output, it is a different concept from volume. An excellent allegory would be if you purchase something (this represents the vocals or instrument being processed) and then decide to sell it, but at a higher price to make a profit (this would be like turning up the gain). Therefore if I have an input and increase the gain, my output can be magnified.

Gain is the level of capture of the signal from the source.

What is Volume?

Volume is the output level of any particular sound signal after the processing of the file or input has been completed. When it comes down to it, the loudness of what you can hear and perceive with your ears is what we call volume.

While mixing, for example, the level that you send from any particular channel to a stereo output is volume. A more straightforward example would be when you turn up sound on the television or adjust the volume knob on your car’s stereo or radio system.

Volume is what your ear can hear.

Some differences between Gain and Volume

There are some particular distinctions between gain and volume. Here is a closer look at some fundamental differences between the two:

• Gain can be equated to an amplitude knob that is the gatekeeper at the input level of any piece of hardware (or software). It controls the amount (loudness) of whatever you are processing before it continues through the rest of any of the system. Volume, on the other hand, is what controls the loudness that comes out after it has gone through the system and is what you hear coming from your headphones or speakers.

• Gain will affect the tone and overall quality of the sound; if your gain is set too high and the vocalist, for example, projects too loudly, then turning down the volume is not going to help if you had clipping when adjusting your gain. Volume will not alter the quality or tone of the sound; instead, it increases the loudness of the sound coming from the entire system.

• There is no limit to the output on a system when it comes to volume (bearing in mind the quality of your sound system and what sort of output it can provide). Gain, however, DOES have a limit and if you set your gain too low, your final output may be very faint regardless of how much you turn up the volume.

• If the gain is set too high and you encounter clipping, that is going to carry over and will undoubtedly come through and be apparent in what comes out of your sound system, even if you turn the volume down.

• Your instrument or vocals will feed into your preamplifier, and gain has a direct influence and is an integral part of the preamplifier before you start looking at altering it further with the EQ and effects. Volume then comes into play in the power amplifier component of the system and then feeds the sound to your output (speakers/ headphones).

• Gain has influence over your tone and can cause distortion, which you may or may not want in your final product. Conversly, volume controls the “power” of what is sent through to the speakers.

clipping - a form of waveform distortion that occurs when an amplifier is overdriven and attempts to deliver an output voltage or current beyond its maximum capability. Driving an amplifier into clipping may cause it to output power in excess of its power rating.

Best Practices when using a microphone

Lavalier Mic

• Avoid wearing a necklace...they tend to rub against the microphones

• Do not wear low-cut shirts

- The microphone may not be close enough for clear audio

• Make sure the microphone is pointing towards your mouth

Handheld Mic

• Hold the microphone by your body and point the microphone end towards your mouth - sounds like a no brainer, but you’d be surprised

• Speak over the top of the mic, not directly into it

• Have the mic aimed towards the audio source (person, instrument, etc.) and at a 45° angle

Shotgun Mic

• Shotgun directional microphone must be pointed directly at its target sound source for proper recording

• make sure there are no objects directly in between the microrphone and the source

• use a trigger mount whenever possible