Audio Production

Audio Production

This PowerPoint presentation was prepared by David Christensen, Technical Director for Centrum. www.david-christensen.com for use class presentations during Centrum’s Blues and

Chamber Music workshops in 2007.There are two files…the MHTML file made from PowerPoint, which you of course have found. (Note: Click “slide show” in the lower right for full screen viewing.) There is limited audio in the presentation, so turn up your volume. There is also a file called samples of A.wav If you load this file into any audio editing program (including Audacity a free program you can download)

you will see the wave forms for a pure 440 Hz tone (A) and the wave form for the note A from a human voice, a flute, a guitar and a piano. This helps in understanding harmonics/overtones.

The program will suggest when you want to look at this file.I hope you find the program of interest. I’d love to hear your comments.

David Christensen [email protected]

http://www.david-christensen.com/

mailto:[email protected]

Audio ProductionBasics

&

Techniques for Demo

Recording

David Christensen, Technical Director for Centrum

www.david-christensen.com

Prepared for the 2007 Port Townsend Jazz and Chamber Music Festival


Goal: Make someone's ear drum move.

Side view of an ear drum



Creating a wave form

Time

Frequency

Volume

Creating a wave form

Time

Frequency

Volume

Simple wave form – A 440

Time

Frequency

Volume

(click the speaker icon to hear tone)


Just what do we hear

and

how loud is too loud

What can we hear?

• Frequency Range:• From Approximately 20 cycles (Hz)


(You probably won’t hear much from these two samples…chances are your speakers can’t reproduce 20 Hz and you can’t hear 20,000 Hz!)

What can we hear?

• Frequency Range:• From Approximately 20 cycles (Hz)• To Approximately 20,000 cycles (Hz)


(You probably didn’t hear much from these two samples…chances are your speakers can’t reproduce 20 Hz and you can’t hear 20,000 Hz!)

What can we hear?

• Frequency Range:• From Approximately 20 cycles (Hz)• To Approximately 20,000 cycles (Hz)

• Volume Range• From 0dB• To Approximately 120dB (considered threshold of

pain!)


How does this relate to what we want to record?

So…What is it that creates the Timbre or Uniqueness of a

Sound• The attack or how the sound is created



• The release or how the sound is terminated.



• The release or how the sound is terminated.

• The overtones or harmonics

Overtone Progression

• 440hz Fundamental

• 880hz First Overtone

• 1320hz Second Overtone

• 1760hz Third Overtone

• 2200hz Fourth Overtone

• 26 40hzFifth Overtone

• Etc.(click the speaker icon to hear tone)









































• For a given note, the overtones are always the same (for most sounds)…voice and instruments.


• What gives the note timbre (what make it a violin or a clarinet etc.) is


• What gives the note timbre (what make it a violin or a clarinet etc.) is

•

The relative volume

of those overtones


What does sound look like?

• Let’s look at the wave forms of different sounds in Sony Media’s Sound Forge.


Analog

vs.

Digital

No…we are not going to discuss which is better!

Analog vs. Digital Audio

• Analog audio is all the audio we listen to…

(You can’t hear digital audio)




• Digital Audio– To create digital audio you first must convert analog

audio to digital.




• Digital Audio– To create digital audio you first must convert analog

audio to digital.

–To listen to digital audio you must first convert digital audio to analog.

• To Record Digital Audio– You must first must convert analog audio to digital.

• To Playback Digital Audio– You must first convert digital audio to analog.


• To Record Digital Audio– You must first must convert analog audio to digital.

• To Playback Digital Audio– You must first convert digital audio to analog.

• Not all analog to digital (A to D) and digital to analog (D to A) converters are created equal.


Digital File Formats

• Wav or aiff file. CD quality is 44,100 samples per second with 16 bit words.

These files are the product of most professional digital recorders and computers. Files can be created in CD quality or even higher resolution files.



Let’s go back to Sound Forge to actually see the samples!



• CD format: wav or aiff files written to a music cd.




• MP3 format– Most MP3 files are 128kbps– High almost CD quality are aprox 360kbps




• MP3 format– Most MP3 files are 128kbps– High almost CD quality are aprox 360kbps

• Other formats (for streaming etc.) *.rm (Real Media) *.wma (Windows Media) *.mov (Quicktime)


What do you need to know

about

recording digitally?

Ideally

• When recording digitally you should be creating *.wav or *.aiff files.

Ideally


• You should (at least) be recording at a sample rate of 44,100/sec and with word length of 16 bits (not bytes)

Ideally


• You should (at least) be recording at a sample rate of 44,100/sec and with word length of 16 bits (not bytes)

This will give you files that can be made into any format, and can be easily edited and mastered.


Best ways to record

Record to what?

For this discussion we will only talk about recording two channel in real time…which is stereo.

Most classical music is recorded in stereo using two mics.

Multi-track recording much more complex and beyond what we can talk about here.

Record to what?

To a Computer:

For a usable recording you will need software and an interface between your recording gear and the computer.

Software:

ProTools

Sony Media Vegas/Sound Forge

Audacity (free)

Many others too.

Record to what?

To a Computer:

Digital Recorder: Many available– Hard disk recorders – Masterlink by Alisis– Memory chip recorders – M-Audio Microtrack,

Sony PCM


Recording volume level

Set record level so the loudest sounds

are down 10dB from 0

When recording digitally DO NOT allow the volume

level to exceed 0dB


Once you arrive at a recording level for a piece, do not change it

for different movements!


Microphones


MicrophonesThe Microphone Book

John Eargle

Microphones

Without a good mic, you can’t have a good recording.

Microphones

• 2 types of mics:– Dynamic/moving coil mics.

Most common and least expensive of good mics.

Microphones

• 2 types of mics:– Dynamic/moving coil mics.

– Condenser micMore expensive and all things being

equal, better. But they require some sort of a power supply.

Microphone Characteristics

• Pickup (or polar) pattern–Omni

–Directional– (Cardioid)

–Bi-directional


• Pickup (or polar) pattern–Omni – good for recording groups in

a good room. Also great when put in the middle of a drum kit. Can be used as excellent vox mic.

–Example: Earthworks QTC1




–Bi-directional


• Pickup (or polar) pattern–Directional (Cardioid) – pickup

pattern helps isolate the sound and avoid “bleeding” Usually used for VOX and close micing instruments

–Example: Shure SM58




–Bi-directional


• Pickup (or polar) pattern–Bi-Directional (Figure 8)Known for a smooth sound. Common in

the 30s and 40s. Often used with vocalists on each side of the mic.

–Example: RCA 44, Royer 122, AKG 414


Mic placement

(a good mic in the wrong place sounds like _ _ _ _!)

Mic Placement

• Voice

Mic Placement

• Voice

• Guitar

Mic Placement

• Voice

• Guitar

• Piano

Mic Placement

• Voice

• Guitar

• Piano

• Chamber ensemble

Mic Placement

• Voice

• Guitar

• Piano

• Chamber ensemble

• Orchestra


Is Stereo Important?


Is Stereo Important?

Yes!

Stereo Preception

• How we perceive stereo

– Volume difference: It’s louder in the right ear than the left ear.

Stereo Preception



– Time arrival: It gets to the right ear before the left ear.

Stereo Preception



– Time arrival: It gets to the right ear before the left ear.

Stereo perception for frequencies below 700hz is primarily through time arrival.

Stereo micing for groups

• X-Y (note: must use directional mics)



• Spaced Pair 15” to 36”



• Spaced Pair 15” to 36”

• NOS/ORTF (note: must use directional mics)


Post Production

(or OK, it’s recorded…now what?)

Post Production Options

• Equalize: Adjusting the volume of different frequencies.





• Compression: Reducing the dynamic range of the recording.










• Normalize: Adjusting the volume so that the loudest sections are using the full dynamic range of the media.

Before Normalizing

Normalized

IMPORTANT

Adjust volume equally for all cuts of a classical recording.

Normalizing

Track 1 - 6 dB

Track 2 - 12 dB

Track 3 - 5 dB

Track 4 - 4.5 dB

Raise volume of each track 4 dB leaving .5 dB headroom.

Normalizing


Ways to get your demo

where you want it.

What format for your demo

• Standard CD

The usual form for audition and demos.


• Standard CD

• Streaming on your web site

You will need to prepare the files in *.wma, *.rm or *.mov format. You may also need help in creating the streaming format using meta files.


• Standard CD


• Downloadable from your web site

You’ll need MP3 files (128bps) for this


• Standard CD


• Downloadable from your web site

• uTunes, MySpace etc.

Your files have to be compiled for these sites.

Preparing your demo disk

• No more than 3 or 4 selections

Select carefully and put your best cut first!



• No longer than 30 sec. each

Note: You don’t have to start at the beginning. If you have a hot 30 seconds embedded in the cut, use it!




• If you want to include full cuts put them after all the 30 sec. cuts.

(Be sure to note that on the label)





• Prepare a good looking disk label with:– The group name

– The contact name and address, phone numbers and email address

– Web address

– Musicians name(s) and instrument(s)





• Prepare a good looking disk label with:– The group name

– The contact name and address, phone numbers and email address

– Web address

– Musicians name(s) and instrument(s)

• Put in jewel box. Label inserts are optional and can include bios of the musicians and group activity.


Questions – Discussion – Experiment?

Audio Production

Education

hz tone

digital audio digital

overtone progression

digital audio analog

hzfirst overtone

limited audio

cycles hz volume range

audio editing program