Week 27 - Sound System Design Flashcards
What is the main goal of sound system design?
Provide sufficient, undistorted SPL to every member of the audience
(We are a waveform delivery service)
When setting up a sound system, what 3 main variables must we keep in mind?
Speaker placement
Coverage angles
SPL
Where should we position the PA relative to our microphones, and why?
Always position the PA downstage of your microphones
This will drastically improve the gain before feedback
What concepts do we need to keep in mind regarding clarity when setting up a sound system?
The HF content is the most directional and the most important when we are talking about clarity
Reverberations and indirect sounds bouncing off walls and other surfaces will adversely affect the clarity - discrete reflections will drastically reduce clarity
2 speaker horn designs
Long throw (narrow coverage angle)
Short Throw (Wide coverage angle)
What does it mean to array loudspeakers?
Using two or more speakers to cover a wider area with direct sound
(We can attempt to avoid phase interference by arraying speakers at wider angles)
What are front fill speakers used for?
Often the front section of the audience will be so close to the stage that they are outside of the coverage area of the main PA
In this situation, it makes sense to add a separate zone to provide a direct signal to these members of the audience
The front fill speakers can be a copy of the main PA (matrix output) or can have their own mix created through an aux send (post fader)
What are matrix outputs?
A matrix output is an additional output on a console
Matrix outputs are fed by the other console outputs (main left/right, aux buses, group outputs)
This allows you to send a copy of your mains, monitor mixes, or group outputs to another location I.E. recording truck, DAW, fill speaker/ multiple zones
What are center fill speakers as compared to front fill speakers?
To retain a stereo image (because we can??), front fill speakers will often be split up into different zones to allow for separate control
What are delay speakers?
If the performance space is large enough, it often makes sense to add a second (or more) set of speakers to the PA
They are often called delay speakers, as the signal being sent to them must be delayed to properly phase align with the main PA speakers
How do we calculate delay amount?
Delay speaker distance/speed of sound
Speed of sound is 1130 feet per second
My delay speakers are 50 feet away from my main speakers
Delay time = 50/1130 = 0.044 seconds = 44 milliseconds
What is the HAAS effect and how does it relate to the placement of delay speakers?
When two sound sources are coming from different locations and are between 2-40 milliseconds apart, the perceived location any subsequently arriving sound will be the first arriving sound
Delay speaker distance/Speed of sound + HAAS
We can add up to an additional 40 milliseconds of delay to our delay speakers and the listener will perceive the sound as coming from our main PA
(Taleski trick: distance in feet = approximate milliseconds of delay)
When would we delay our main speakers?
If the sound coming off the stage is very loud, it can interfere with the sound coming out of our main speakers
If this is affecting the clarity, we can delay the main speakers to be in line with the loudest sound sources on the stage
Usually, the snare drum or the line of guitar amps
