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Tech Feature: Subwoofer Ports

Tech Feature: Subwoofer Ports

Figure 1: Simulated relative SPL of a loudspeaker driver vs. port in a vented enclosure. This assumes proper port function.

The majority of low frequency sound reproduction is from vented loudspeaker enclosures – that is, loudspeakers that have a port in the enclosure. Nearly all professional loudspeaker enclosures are vented to improve their low frequency output. Including a properly designed port in a loudspeaker enclosure is a straightforward way of gaining additional low frequency output over a simple closed-box enclosure. Unfortunately, port design is usually a compromise, and this affects how the port functions at high output levels. This article seeks to enlighten the reader about how the port in a vented box operates, and to provide some guidelines for identifying good port design.

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Outline Mini-COM.P.A.S.S. and iSM with iMode

In this age of technology convergence, laptops double as DVD players, video-phones, multi-track recorders and audio analyzers, while cell phones have evolved into Internet-capable computers with thousands of applications. Loudspeaker control and monitoring is also converging. The old modular console-graphic-crossover-amp-speaker systems built from components are merging to become simply consoles and loudspeakers, shedding their outboard racks along the way.

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Waves Plugins, Part 7: H-EQ

I am currently enjoying the singular privilege of being on tour with the incomparable writer, singer and virtuoso guitarist, Joe Walsh. As I write this column, we are on a flight from Cincinnati to Dallas. Joe and the band have just performed two excellent sell-out shows in the home state of the James Gang, propelling us into the final week of this tour leg.

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How SXSW Helps Keep Austin Profitable

Back in July, this column underscored how UK Music, the British non-profit trade and lobbying organization, has been helping that country's live music industry, both by quantifying it and through legislative advocacy. For instance, this year, a UK Music survey found that large-scale live music events, such as festivals, are contributing over £1.4 billion a year – that's nearly $2.2 billion – to the U.K. economy from all sources, including ticket sales and travel to the event locations.

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Filters: High-Pass, Low-Pass and Band-Pass

Among the more useful tools in the audio toolbox are a variety of filters. Some engineers shun the use of filters in favor of EQ, which can, of course, be very powerful, but filters are your friends and can do things that EQ can't. The three most common filters used in pro audio are high-pass, low-pass and band-pass. In case you need a refresher: a high-pass filter cuts low frequencies, a low-pass filter cuts highs, and a band-pass cuts high and low frequencies simultaneously, allowing a midrange band to pass.

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Earning Money in the Worship Audio World

As you know, "Sound Sanctuary" seeks to find common ground between those audio techs who volunteer their services and those who are paid to provide audio expertise. This month's installment only covers those of you who currently make money (or wish to make money) in worship sound. However, if you are an audio volunteer, please read on.

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Relevance

From the Encarta Dictionary: "Relevant (adjective) 1. Connected: having some sensible or logical connection with something else such as a matter being discussed or investigated. 2.Having social significance; having some bearing on or importance for real-world issues, present-day events, or the current state of society."

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Electro Acoustics Redesigns Sound at TCU Stadium with JBL VLA Line Arrays

FORT WORTH, TX – Home to the Texas Christian University (TCU) Horned Frogs' football team, Amon G. Carter Stadium is currently undergoing a multi-million-dollar rebuild, with construction scheduled to be completed in 2012. The stadium's new audio system, however, was completed in time for the 2011 football season. Installed by Fort Worth, Texas-based Electro Acoustics, the system features a variety of JBL loudspeakers, including VLA line arrays.

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Starlike Equips Expanded Korundi House of Culture with Community Gear

ROVANIEMI, Finland – Starlike Oy opted for Community iBOX series loudspeakers to enhance the carefully-designed acoustics within the new 340-seat concert auditorium for the Lapland Chamber Orchestra, part of the expanded Korundi House of Culture. There are L-R clusters of two Community iHP1566, a center cluster of two iHP1266, two 18" i118S subwoofers and four iHP1266 units for moveable fill and point effects, along with 12 I/05 loudspeakers for surround sound. The system is powered by Yamaha P-series amplifiers, with Yamaha DME24N for DSP. The mixer is a Yamaha LS9-16.

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Korean Mega-Church Installs QSC KLA Line Array System

WESTMINSTER, CA – Korean First Presbyterian Church of Orange County, a mega church with more than a thousand members and a 30-year history in the area, recently upgraded with QSC's KLA Line Array Loudspeaker System. Aviwork, Inc. of Fullerton, CA handled the installation and was tasked with designing a sound solution to meet the challenges of the shallow and wide sanctuary, which also has a number of balconies.

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