Monday, October 27, 2008

Technical Data For New Song Underground

Because of some questions that have come up in recently in booking discussions, my inner audio nerd decided to get me busy with doing with a technical overview of New Song Underground.  There is quite a bit of "audio nerd content" in this, and some of the language may be unwieldy to parse - but I'm trying to be something that reasonably approaches precise.

Maybe it works, maybe it doesn't.

Anyway, here it is:

Technical Data for New Song Underground

This document is an attempt to provide meaningful, quantitative data regarding various aspects of New Song Underground. It does not (and can not) address every possible situation encountered, and the testing discussed is not infallible. However, this document may still be interesting and useful in various cases. Please excuse any spelling or grammatical errors.


PA Equipment


FOH PA System:

Two stacks, each biamplified, consisting of one subwoofer enclosure of one direct radiating 18” low frequency (LF) driver, and one mid-high enclosure of one direct-radiating 15” LF driver, one direct-radiating 15” mid frequency (MF) driver, and one horn-loaded 1” exit high frequency (HF) driver.

The FOH stack style is parallel (one stack on either side of the stage, with the stacks radiating on a line perpendicular to an imaginary, vertical plane intersecting the proscenium).

The FOH PA is configured to operate as a monaural source. One channel is reserved for the mid-high amplification, and one channel is reserved for the subwoofer amplification. These channels are fed from the output of the mixing console in such a fashion that an audio technician can allocate signal between the mid-high and subwoofer systems by way of the pan controls on each mixing console channel.

FOH PA management consists of one “equalization (EQ) emphasis” loudspeaker management system, and one “crossover emphasis” loudspeaker management system, in series.


Stage Monitor System:

Four monitor wedges, each biamplified, each being a mid-high enclosure of one direct-radiating 10” LF driver, and one horn-loaded 1” exit HF driver.

One drum fill, comprising two stacks, each triamplified, each stack consisting of one subwoofer enclosure of one direct radiating 18” LF driver, and one mid-high enclosure of one direct-radiating 15” LF driver, and one horn-loaded 1” exit HF driver.

The stage monitor style is wedges across the downstage lip, and the drum fill centered near the upstage wall.

The stage monitor system is configured to operate as five monaural sources. Mixes for the sources are derived from the first five auxiliaries available on the mixing console channels, typically using console channels configured to be independent of channels used for feeding the FOH PA. (Channels used for feeding the FOH PA can be used to drive the monitor mixes, if independent EQ and compression for monitor sources is not required.)

The stage monitor system's management consists of one parametric equalizer for each wedge, and one graphic equalizer and “crossover emphasis” loudspeaker management system (in series) for the drum fill.


Mixing Console:

One digital mixing console with 32 channels and 16 physical inputs (one usually reserved for a submix of talkback and house music). Typical configuration is channels 1-16 feeding the FOH PA, each channel having four bands of parametric EQ, a gate, and a compressor available. Channels 17-32 are used to derive monitor mixes, each channel having four bands of parametric EQ, and a compressor available. Gates are not available on channels 17-32.


Performance Measurements

Warning! Performance measurements are made in open-loop (no possible feedback) conditions, using pink noise. It should not necessarily be expected that maximum performance can always be obtained in closed-loop conditions, for example, with a microphone, or indeed in any performance situation where multiple, unforseen and potentially uncontrollable factors exist! Also, please be aware that these measurements were not taken using “scientific grade” instruments, and so may not stand up to measurements made with full scientific rigor – they are a guideline only.


Maximum continuous sound pressure level (SPL), FOH PA:

For an observer approximately 1.676 meters (5.5 feet) above the floor, on a line perpendicular to the fourth “panel” from the front on the south wall, and intersecting a plane perpendicular to the floor and the FOH PA stacks, emanating from the south edge of the bottom stage step:


104 dB SPL A (mostly emphasizing midrange) weighted

107 dB SPL C (more low frequencies measured compared to A) weighted


Method:

Pink noise was introduced to a console channel, with the panner centered. Pink noise was increased in level until the “crossover emphasis” system management system was indicating intermittent limiter operation on the high-frequency output. Limiter operation was approximately 5 times per second. Amplification for mid-high enclosures was steadily indicating onset of amplifier limiter operation and/ or clipping.


Maximum continuous SPL, single monitor wedge:

For an observer approximately 1.676 meters (5.5 feet) above the floor, and approximately 1 meter (3.280 feet) from the monitor on a line parallel to the floor and emanating from the approximate geometric center of the monitor's front face:


113 dB SPL A

114 dB SPL C


Method:

Pink noise was introduced to a console channel. Pink noise was increased in level until the monitor's clip/ limit indicator illuminated, and then decreased in 2 dB increments until the indicator no longer illuminated.


Maximum continuous SPL, drum fill:

For an observer approximately 1.676 meters (5.5 feet) above the floor, centered between the drum fill stacks:


110 dB SPL A

115 dB SPL C


Method:

Pink noise was introduced to a console channel. Pink noise was increased in level until the mid-high enclosure's clip/ limit indicator illuminated, and then decreased in 2 dB increments until the indicator no longer illuminated.


Environmental reverb time, full bandwidth:

For an observer approximately 1.737 meters (5.7 feet) above the floor, on a line perpendicular to the fourth “panel” from the front on the south wall, and intersecting a plane perpendicular to the floor and the FOH PA stacks, emanating from the south edge of the bottom stage step:


1.536 seconds


Method:

Pink noise generated from a “region” inside a recording program was introduced to a console channel, with the panner centered. Pink noise was set to an average of 100 dB SPL C as measured at FOH, with both the FOH PA and the monitor system being audible to the observer. A recording was made of the pink noise ending, and the subsequent reverberation. The recording was analyzed to determine the length of time between the end of the pink noise, and the point where the recording level decayed beyond -55 dBFS (decibels referenced to full scale, or the maximum possible input level for the console channel). The PA system was equalized as normal.


Environmental reverb time, in half-octave bands (spectral decay):




Method:

Pink noise generated from a “region” inside a recording program was introduced to a console channel, with the panner centered. To generate the noise passbands, a multiband compressor (set to a 1:1 ratio) was set so that each passband could be reproduced in isolation. Each passband of pink noise was set to an average of 100 dB SPL C as measured at FOH, with both the FOH PA and the monitor system being audible to the observer. A recording was made of the pink noise ending, and the subsequent reverberation. The recording was analyzed to determine the length of time between the end of the pink noise, and the point where the recording level decayed beyond -55 dBFS (decibels referenced to full scale, or the maximum possible input level for the console channel). The PA system was equalized as normal.

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