David's Take: The Reasons I Love Parametric EQ and How Theory Audio Design Implements It

David Susilo

Published: 10/25/2018 07:30:01 AM EST in Sound

David's Take: The Reasons I Love Parametric EQ and How Theory Audio Design Implements It

Unlike many audiophiles, I like equalizers. Not as a tone control, but as an actual tool to flatten the frequency response in a given listening environment.

Equalizer, or EQ, is a filter that allows you to adjust the volume level of a (range of) frequency, of an audio signal. An EQ will let you turn the treble and bass up or down, allowing you to adjust the sonic profile of, let's say, your car stereo or your television. Seeing an EQ as a tone control is wrong because then you're adding extra ketchup, salt, and other ingredients while eating at a 5-Star Michelin restaurant. In professional audio circles, be it in a studio or with live applications, equalization is a highly sophisticated art that can be used to build the tone of instruments in a mix, counteract anomalies in a room, or just pump up the bass.

Regardless of its application, however, good equalization is critical. When used correctly in a reproduction environment such as in a home theatre or monitoring room, an EQ should only be used to adjust a sound system to account for the frequency response of a listening environment.

The two of the most common EQs in use in modern recording and live sound are Parametric and Graphic (Shelving).

Graphic EQs are most common because they are easier to use. They are also less accurate, but they're so easy to use to the point that it is actually more difficult to mess up.

Parametric on the other hand, requires white glove handling and deep knowledge of acoustics in order to use this style of EQ properly. It's so extremely easy to fall into the proverbial rabbit hole if you don't know what you're doing. This, and the higher cost of implementing parametric EQ, makes it more expensive and difficult to find.

At CEDIA 2018, I was shown a line up by Theory Audio Design. Looking under the hood of Theory's loudspeakers, you'll find 1.4-inch aluminum diaphragm compression drivers on proprietary Theory ImpedanceOptimizer waveguides that achieve 110dB of SPL with just 1W input. That's highly efficient for any home speakers. For the bottom-end, Theory loudspeakers feature reflex-loaded carbon fibre woofers which generate 95dB - 100dB SPL per watt depending on the model.

As for looks, the company claims that its design can be considered "audio jewelry," or at least not just another black box. While I disagree with the former, I'm in complete agreement with the latter.

Constructed from custom aluminum extrusions that are only 3.6 inches in depth, and available in black or white, Theory loudspeakers feature clean lines, rounded edges, machined aluminum accents, and configurable decorative trim to suit any d├ęcor. Finish options for the trim pieces include carbon fibre (my favourite) white, grey, or black gloss, natural and black aluminum, brushed stainless steel, and matte pewter (also my favourite).

However, that still doesn't excite me. What excites me more is the Theory Amplified Loudspeaker Controller.

The core of every Theory system lies with a 96kHz / 24-bit DSP processing engine called a Loudspeaker Controller. Theory's ALC-1508B and ALC-1809B eight and nine-channel Amplified Loudspeaker Controllers create an entirely new product category by combining the functionality of a multichannel DSP processor, high-power multichannel home theatre and distributed audio amplifier, multichannel mixing amplifier, high-resolution loudspeaker processor, and, for the first time, multichannel bass management - all packed into a single, stylish, 1U package. There's no more need for a (usually) 2U-6U space being used for EQ and 3U space (minimal) to fit the multi channel amp enclosure.

Theory Audio Design ALC-1809B nine-channel Amplified Loudspeaker Controller

For the power amps, the fan-less, 1U ALC-1508B and ALC-1809B models offer two and three 300W high-current amplifier channels for subwoofer drive respectively, plus six 100W bridgeable amplifier channels to drive full range loudspeakers. As such, the ALC-1508B can support 5.1, 5.2, 7.1 surround sound formats while the 1809B, with its additional 300W channel, adds support for 5.3, 7.2, and the new 5.2.2 Dolby Atmos format.

Multichannel DSP Processor: Both Amplified Loudspeaker Controller models include 80 user-programmable 10-channel PARAMETRIC EQ filters, plus the obligatory gain adjustment, source signals for system diagnosis, and delay of up to 75msec per channel for on-site system-wide optimization and calibration.

High Resolution Loudspeaker Processor: At the heart of the ALC lies a 96kHz/24bit DSP engine for all Theory and Pro Audio Technology loudspeaker and subwoofer products, with over 160 IIR filters, eight FIR filters, intelligent power-limiting, and delay. It is this processing engine that makes Theory's thrilling sound possible.

Mixing/Distributed Audio Amplifier: The ALC-1508B and ALC-1809B each include a full 8x8 matrix mixer, mic input, all-channel priority ducking/paging, four stereo plus mono-sum inputs, bass and treble controls, and up to 75msecs delay per channel - useful in today's large distributed outdoor systems. The ALC ducking feature and mic input enables priority paging in commercial distributed audio installations. In residential systems, 8x8 automatic ducking allows new voice-activated control devices such as Amazon Alexa to page any or all of the audio zones within a distributed system. When Alexa speaks, the audio is immediately reduced in volume, or "ducked," allowing Alexa to speak clearly over a distributed loudspeaker system. When Alexa is done talking, the audio content gradually rises to full output once again. Since any or all inputs can duck any or all output channels, complex systems with many distributed voice control devices can speak over the audio system globally or locally or any combination in between.

Bass Manager: Theory Amplified Loudspeaker Controllers can steer low frequency energy of any of the eight balanced analog audio inputs to any of the two or three subwoofer amp channels, enabling distributed bass management in home theatre and distributed audio applications, such as a subwoofer.

With the entire suite above, not only you can create a professional sounding sound in your house, but also the most sonically neutral listening environment.

Article Tags:  parametric, eq, equalizer, david's take, theory audio design, home theatre, hifi, audio


David's Take: The Reasons I Love Parametric EQ and How Theory Audio Design Implements It

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