An Introduction to Live Audio Production
September 29, 2017
At Kittredge Theater on the Warren Wilson College Campus
The class is being hosted by WWC student and Theater Crew member Caroline Daniels
with Weogo directing the teaching.
We will cover the basics of:
Safety, AC Power
Listening, Acoustics, Live Recording
Audio Equipment, from Microphone to Speaker
Decibels, Audio Measurement
This class is for:
) Aspiring Live Audio techs, whether in the concert, wedding, theater, church, dance or corporate world
) Anybody interested in how Live Audio production happens
) Musicians who want to better communicate with mix techs
Bring a notepad
Seeya soon! Weogo
Analog or Digital???
Analog came first.
> All audio equipment used basic electrical principles to convert sound waves to electrical signals, make those signals bigger, and then convert them back to sound waves.
Then came digital audio equipment.
> First were digital effects processors – various flavors of reverb and delay, etc.
> Next were digital recording systems.
> Then came stand alone EQs, dynamics processors, crossovers, delays, or routing devices.
> Eventually many of these processes were combined in to one box, commonly called a DSP, or Digital Speaker Processor, as these commonly go after a mixer, and before amplifiers.
> About the time DSPs were coming out, Digital MIXERS started showing up.
Smaller ones were around $50,000, larger, more complex ones could easily go over $100,000.
Digital mixer prices came down.
The larger digital mixer here on the stage, a Yamaha 01V96 from 2003, cost $2000 new, and pretty much did more than that older $50,000 mixer.
The smaller Mackie DL1608 from 2012 is quite a capable mixer and currently costs $600.
The larger DL32R from 2015 is fairly full featured and costs $1500.
> Digital processing started showing up all over the place.
Amplifiers and self-powered speakers got much of the processing that was in the DSP boxes.
> Digital wireless mics started showing up.
So, is Analog better, or is Digital better?
1.) With Analog, from when a sound wave enters a microphone, goes through all cabling to a mixer, processing, amplifier, and speaker, and is converted back to a sound wave, is essentially instantaneous.
> With Digital, in every device, a digital microphone, mixer, DSP and/or digitally processed amplifier or speaker, there is always a certain amount of computing time, called latency.
Early digital units had lots of latency, newer units much lower. But they will always have some.
How much latency in a system?
3.5ms, digital wireless mic
2.5ms, digital mixer
2.5ms, digital speaker processor
= 8.5ms 9.6′
OR 1.ms for just digital mixer
> Compare to air time for monitor to ear transmission.
> Where this is likely critical is when using IEMS, In Ear Monitors.
+) So, Analog has no latency, Digital does.
Plus 1 for Analog.
2.) Digital devices use converters. Analog to Digital at inputs, Digital to Analog at outputs.
Every time you run a signal through a converter you degrade the signal.
Early converters noticeably degraded signal quality.
Current converters commonly have a measurable, but tiny effect.
But if you add lots of conversions, the changes to the signal do add up.
+) Analog has no converter degradation.
Plus 2 for Analog.
3.) When patching Analog equipment you go from a real, physical connector to
Finding patch errors is fairly straight-forward – just follow the cable.
With Digital, patching is done on one or more patch screens.
Finding a patching error means knowing the program/app pretty well.
+) Plus 3 for Analog.
Analog is repairable at a fairly basic tech level. This could be very useful in a lower-tech future.
So why use Digital?
Look at these processors. Imagine having multiple racks of processors like this.
1.) All this extra Analog EQ and dynamics processing requires patch cabling to connect.
Connectors get dirty and can have intermittent, hard to find issues, or can have a continuous buzz, or not work at all. Lots of connections, means lots of points of failure.
With analog mixers, dirty linear faders and rotary potentiometers can have issues similar to those noted for connectors above.
Digital allows you to do some things that you can’t do in the analog world, for instance remote control of preamp gain. This allows for placing a mixer on stage and mixing remotely, without running a snake or power to an analog mixer.
Digital allows you to mix not just where the mixer is, but where the audience is. Very useful for dances, where you can’t have a mixer on the dance floor.
2.) Some of this equipment is expensive, some comes with only a modest price tag.
But even with the modest cost items, when you start adding up ten or twenty units, it can get pricey.
3.) All these processors require power. More AC draw might mean you need a larger AC service to run your system.
4.) All electronics create heat. If you are outdoors in the sun, you may need rack fans to keep equipment cool.
5.) All these processor take up space. Four racks this size would not hold all the processing in this little DL1608 mixer. Since they take up so much space, in the past we just made do with less, and had to really think, which channels are ok without a compressor, which ones really would benefit from having one?
6.) Big analog mixers and racks can take up a lot of venue space. They definitely take a lot of truck space and added weight carrying capacity. Equipment storage space is large.
Mixing speed is a TIE:
Analog mixers and processors have all possible controls at your finger tips.
Digital mixers use various layers on hardware and software.
The fact is, some adjustments are faster on an analog mixer, others on digital.
The real factor here is knowing really well what you are working with.
In reality, a competent tech can walk up to a good analog or digital system and do a good mix.