A stage monitor system is a set of performer-facing loudspeakers called monitor speakers, stage monitors, floor monitors, wedges, or foldbacks on stage during live music performances in which a PA system or sound reinforcement system is used to amplify the performers' singing, music and other sounds for the audience. Monitor speakers are useful; the sound at popular music and rock music concerts is amplified with power amplifiers through a PA system or sound reinforcement system. With the exception of the smallest venues, such as coffeehouses, most mid- to large-sized venues use two sound systems; the main or front-of-house system is a PA system/sound reinforcement system which amplifies the onstage sounds for the main audience. The monitor system consists of monitor speakers aimed at the on-stage performers rather than the audience and power amplifiers, they are driven by a separate mix from the main front-of-house system. This mix highlights the vocals and acoustic instruments so they can be heard over the electronic instruments and drums.
The sound signal for the monitor speakers may be produced on the same mixing console as the main mix for the audience, the case in small venues, such as pubs where singer/guitarists perform. Monitor systems have a huge range of sizes and complexity. A small pub or nightclub may have a single, 100 watt powered monitor speaker onstage so that the lead vocalist can hear her/his singing, with the "aux send" signal from a small powered mixer plugged straight into the monitor cabinet, the singer setting her/his own levels with the onstage mixer. On the other hand, a stadium rock concert may use a large number of monitor wedges, big racks of power amplifiers with thousands of watts of power, a separate mixing board and sound engineer for the monitors. In most mid- to large-size venues, there is a separate sound engineer and mixing console on or beside the stage creating a mix for the monitor system; the monitor mix is different from the front-of-house mix, because performers may request to hear more of certain accompaniment or rhythm section instruments.
In the most sophisticated and expensive monitor set-ups, each onstage performer can ask the sound engineer for a separate monitor mix for separate monitors. For example, the lead singer can ask to hear their voice in the monitor in front of them and the guitarist can ask to hear the bassist and drummer in their monitor. Without a foldback system, the sound that on-stage performers would hear from front of house would be the reverberated reflections bouncing from the rear wall of the venue; the reflected sound is delayed and distorted, which could, for example, cause the singer to sing out of time with the band. A separate mixed signal is routed to the foldback speakers because the performers may need to hear a mix without electronic effects such as echo and reverb to stay in time and in tune with each other. In situations with poor or absent foldback mixes, vocalists may end up singing off-tune or out of time with the band. For live sound reproduction during popular music concerts in mid- to large-size venues, there are two complete loudspeaker systems and PA systems: the main or front-of-house system and the monitor system.
Each system consists of a mixing board, sound processing equipment, power amplifiers, speakers. The two systems share microphones and direct inputs using a splitter microphone snake. There is disagreement over when to call these audio systems Sound Reinforcement systems or Public Address systems; this distinction is important in some regions or markets, while in other regions or markets the terms are interchangeable. The main system, which provides the amplified sound for the audience, will use a number of powerful amplifiers driving a range of large, heavy-duty loudspeaker cabinets including low-frequency speaker cabinets called subwoofers, full-range speaker cabinets, high-range horns. A coffeehouse or small bar where singers perform while accompanying themselves on acoustic guitar may have a small, low-powered PA system for the "mains", such as a pair of two 200 watt powered speakers. A large club may use several power amplifiers to provide 1000 to 2000 watts of power to the "main" speakers.
An outdoor rock concert may use large racks of a number of power amplifiers to provide 10,000 or more watts. The "monitor" system reproduces the sounds of the performance and directs them towards the onstage performers, to help them hear the instruments and vocals; the monitor system in a coffeehouse or singer-songwriter stage for a small bar may be a single 100 watt powered monitor wedge. In the smallest PA systems, the performer may set their own "main" and "monitor" sound levels with a simple powered mixing board; the simplest monitor systems consist of a single monitor speaker for the lead vocalist which amplifies their singing voice so that they can hear it clearly. In a large club where rock or metal bands play, the monitor system may use racks of power amplifiers and four to six monitor speakers to provide 500 to 1000 watts of power to the "monitor" speakers. In large venues, there are separate monitors for the vocalists and instrumentalists. In most clubs and larger venues, sound engineers and technicians control the mixing boards for the "main" and "monitor" systems, adjusting the tone, sound levels, overall volume of the performance.
Larger clubs and concert venues use a more complex type of monitor system which has two or three different m
R v Sault Ste-Marie 2 SCR 1299 is a Supreme Court of Canada case where the Court defines the three types of offences that exist in Canadian criminal law and further defines the justification for "public welfare" offences. The city of Sault Ste. Marie, hired Cherokee Disposal to dispose of the city's waste; the city built a disposal site 20 feet from a stream which, when filled by the disposal company, resulted in waste seeping into the stream. The city was charged with discharging, or permitting to be discharged, refuse into the public waterways causing pollution pursuant to section 32 of the Ontario Water Resources Act; the issue before the court was whether the city's offence should be classified as strict liability or absolute liability. The Court of Appeal for Ontario held that the charge required proof of mens rea, which on the facts would acquit the defendant. In the judgement written by Justice Dickson, the Court recognized three categories of offences: True Crimes: Offences that require some state of mind as an element of the crime.
These offences are implied by the use of language within the charge such as "knowingly", "willfully", or "intentionally". Strict Liability: Offences that do not require the proof of mens rea; the act alone is punishable. The duty is on the accused to have acted as a reasonable person and has a defence of reasonable mistake of fact; the Court stated that the due diligence defence "will be available if the accused reasonably believed in a mistaken set of facts which, if true, would render the act or omission innocent, or if he took all reasonable steps to avoid the particular event. These offences may properly be called offences of strict liability." The reason for this is that the Court described a need for a class of offence that had a lower standard to convict than True Crimes but was not as harsh as Absolute Liability offences. As opposed to the first category of offences in which the accused is presumed innocent, offences of strict liability presses a presumption of negligence on the accused.
The burden of proving that the accused acted as a diligent person rests on his shoulders and must be demonstrated by preponderance of evidence. Absolute Liability: Similar to Strict Liability, these offences do not require proof of mens rea either. However, the accused has no defences available. To distinguish between these types the Court examines: he overall regulatory pattern adopted by the legislature, the subject matter of the legislation, the importance of the penalty and the precision of the language used will be primary considerations in determining whether the offence falls into the third category; the Court noted that the dumping offences were of a public welfare nature and were from a provincial statute, were Strict Liability offences and do not require mens rea. Absolute liability Re BC Motor Vehicle Act, examined absolute liability in light of the Charter of Rights and Freedoms. R v Wholesale Travel Group Inc Strict liability Full text from CanLII.org