THX Tech Tip

Not Hearing Enough Bass From Your Subwoofer? It Could be your Room

 

 

Your subwoofer is a critical element in your home theater system. The low frequency from the subwoofer is what puts the boom in an explosion, the rumble in a spaceship and the thud in a gunshot. However, even the biggest and baddest subs may not meet your expectations if they aren’t placed and set up properly.

“It’s a classic story amongst Home Theater Professionals – the client spends all this money getting a giant subwoofer to complement the rest of their system. But, when they sit down to watch a movie, the person next to them complains about too much bass, while others feel the bass is too weak.
– John Dahl, Director of Education at THX Ltd.

It could simply be a difference in personal preference, but more than likely it’s the room itself that is the root of the problem.

THX Certified pm3 Studio

THX pm3 Certified DiMAGIC Studio

THX Certified pm3 (multichannel mixing and monitoring) Studios are ideal for motion picture pre-mixing and producing television programs, music, video games and other content for non-theatrical release. THX sets strict standards for pm3 studio acoustics, noise levels and production equipment performance, resulting in a technically flawless production environment for capturing multichannel soundtracks and high definition visuals.
THX pm3 Certified Studios can be found at Sony Computer Entertainment, the Cleveland Institute of Music and Fox Studios.

THX Certified Studio Specifications

THX Certified Studios and pm3 rooms are designed to offer the world’s premier standard for quality.

THX pm3 and Studio Specifications

• Listening and Viewing Environment
• Acoustic performance
• Structural isolation
• Reverberation time
• Preferred dimensions
• Color scheme and ambient light for optimum video monitoring

• Working Area Layout and Equipment
• Loudspeaker position
• Video monitor position
• Optimum listening positions
• Site lines
• Speaker focus angle

• Audio and Video Equipment
• Front and surround speakers
• Subwoofers
• Power amplifiers
• Bass management system for multi-channel monitoring (applies only to THX Certified pm3 rooms)
• Multi-channel equalizers and digital delays
• Video monitoring

• Calibration
• Audio and video calibration
• Specific test equipment and signals
• Performance requirements

THX Cinema Certification

THX Certified Cinemas

Designed to recreate the acoustics and ambience of the studio, our cinemas allow audiences to experience their favorite movies exactly like the director intended.

THX Certified Cinema Reverberation Control

Reverberation is the presence of sound after its source has stopped – much like an echo. In a movie theater, reverberation often builds as sound reflects off surfaces such as walls, floors and ceilings.
For example, in an action film, such Iron Man, there are several instances where the movie’s hero (Tony Stark) is being chased through the sky by two fighter jets, followed immediately by quiet, more dialogue-driven moments. In a THX Certified Cinema with tightly controlled reverberation, the sound of jet engines and explosions ends immediately, never bleeding over into the next scene.
Among the methods THX uses to control reverberation is covering the rear wall of the auditorium with thick, absorptive material. This prevents the direct sound of the screen speakers from reflecting into the seating area. THX also requires the placement of absorptive materials on the sidewalls, down to the audience’s ear level. This reduces the amount of sidewall reflections.

Image caption with acoustic paneling

Acoustic paneling controls reverberation, or echo effect, in a THX Certified Cinema.

Image caption without acoustic paneling

Sound bounces off the walls without acoustic paneling, interfering with the movie’s soundtrack.

THX Auditorium Isolation

THX Certified Cinemas are quiet. They feature massive wall structures to isolate the cinema from the outside world—creating a pristine audio sanctuary. With these walls, audiences can focus on the movie experience in front of them, as opposed to distracting sounds from neighboring cinema auditoriums, outside traffic and lobby activity.

THX Sound Isolation Methods

• Large quantity of building material
• Isolating air gap
• Large quantity of building material

With THX Sound Isolation

The walls in a THX Certified Cinema are constructed to provide sound isolation from other auditoriums.

Without THX Sound Isolation

Without the use of the recommended building materials, thin wall construction allows sound to pass through to neighboring auditoriums.

In Theatre - Speaker Layout and Baffle Wall

 

Unique to every THX Certified Cinema is the THX “baffle wall.” If you were to peel away the screen at any THX Certified Cinema, you will see a massive wall of speakers housed in an acoustic baffle (speaker system enclosure).
The baffle wall is approximately the same size as the screen, providing a solid, smooth and uninterrupted surface to distribute sound throughout the auditorium. It produces a large sound image and accurately tracks sound elements with the onscreen action. This makes panning shots and off-screen sounds more believable and natural, helping to pull audiences into the storyline. Without a baffle wall, sound is uncontrolled – producing a weak, uneven image.

With the baffle wall

The baffle wall in a THX Certified Cinema controls the sound behind the screen – projecting a smooth audio experience out to the audience.

Without the baffle wall

Without the baffle wall, sound is uncontrolled behind the screen – producing a weak sound image that “jumps” across the screen.

THX AV Receiver Features

THX Certified AV receivers and pre-amplifiers feature a number of proprietary technologies, all designed to accurately present movie, music and game soundtracks in the home.

Re-EQ

Many movie soundtracks are mixed in studios for playback in large cinema auditoriums with an array of speakers. When played on home systems, they may appear abrasive and edgy. Re-EQ establishes a more accurate tonal balance when enjoying movies in your home.

Timbre Matching

Your ears hear different tonal qualities in sounds coming from different directions. Timbre Matching restores the frequency balance between your front and surround speakers—ensuring seamless and smooth panning between the front to back of the room.

Boundary Gain Compensation (BGC)

Sitting near a wall may result in distorted bass response. BGC corrects the way low frequency sound is perceived when seated near a wall. This results in a more true and accurate bass response.

Adaptive Decorrelation

Adaptive Decorrelation changes one surround channel’s time and phase relationship with respect to the other surround channel, expanding the listening position and creating the same spacious audio experience at home as in a movie theater.

Other THX Receiver Technologies

THX Certified Receivers also feature THX Adaptive Speaker Array technology, which establishes surround sound modes for movies, music and games, and THX Loudness Plus for enjoying surround soundtracks at lower volume levels.

THX II Car Audio Features

Technology Advantage

HD Radio™ Technology offers crystal-clear static free sound, more programming choices, on-screen information, iTunes® Tagging and much more.

SIRIUS broadcasts over 130 digital-quality channels, including 69 channels of commercial-free music, plus exclusive channels of sports, news, talk, entertainment, traffic, weather and data.

DTS® Neural Surround delivers immersive 5.1 surround sound from broadcasters and your MP3 player.

Forget about wires altogether and stream your favorite music from your phone or MP3 player.

The intuitive MyLincoln Touch™ allows drivers to engage with the vehicle by the touch screen, steering wheel controls or voice activation to access all system features.

THX Car Surround System

 2011 Lincoln MKT

The THX II Certified 5.1 Surround system is like none other on the open road. Fourteen strategically placed speakers, including a center-channel THX Slot Speaker system, bring out the subtle details of your favorite recordings. Bass notes groove, vocals sing and live tracks put you a few rows from center stage. Hearing is believing.

THX II Car Audio Features

1. A center-channel THX Slot Speaker array produces a wide, spacious sound stage and home theater like ambience.
2. True 5.1 surround sound plays from DVD-Audio discs and DVD Movies.
3. Rip, store and manage 2,400 tracks with a 10 gigabyte Jukebox.
4. Digital media players and flash drives connect via USB port and are voice-activated through the Lincoln SYNC® media system.
5. New DTS Neural Surround™ delivers surround sound experiences from stereo-based music stored on MP3 players and mobile phones.
6. Sophisticated Digital Signal Processing provides spectral balance, wide dynamic range and exceptional acoustic performance.
7. A 12-channel amplifier produces 600 watts of power from 20Hz to 20kHz with a total harmonic distortion of less than 0.1 percent.
8. Rich, deep bass emanates from an 8” rear subwoofer

THX Car Audio

2010 MKT Video from THX Ltd. on Vimeo.

The Speed of Sound

A push of a button fires up your THX surround sound experience in 2011 Lincoln vehicles. Musical instruments dance about, and a powerful sound stage rises, pulling you into a space that feels bigger, more impressive. The quiet acoustics of the cabin bring out every nuance of your favorite music. Bass notes thump, vocals sing and the noise of the road is left a few exits back.
THX and Lincoln are transforming your daily commute. THX II Certified Audio systems in 2011 Lincoln vehicles start with the quietest cabin in its class. From there, THX builds a system rivaling all others with strategically placed speakers, optimized acoustics and advanced THX sound technology.

Why is a THX Certified Car Audio Surround Sound System Better?

Lincoln and THX offer something for everyone. Audiophiles can enjoy true 5.1 surround sound from DVD-Audio discs and DVD Movies. CDs deliver uncompressed music that mirrors the recording studio, and USB-connectivity brings your digital music library to life.
Home theater-like sound is provided by a 12-channel amplifier that delivers more than 600 watts to precisely places speakers. A center-channel THX Slot Speaker array provides a broader sound image and better control of how music is distributed throughout the vehicle’s acoustically engineered cabin.

THX Certification Performance Categories

You have plenty of choices when it comes to selecting a surround sound system, yet many speakers and receivers fall short in terms of power output and performance. THX believes that having the right components is just half of the equation. The other half is how the components are placed and calibrated, and how room size and acoustics affect performance.

To help match the best speakers and receivers for your listening needs, THX has established certification categories to ensure your home theater system can deliver crisp, clear THX Reference Level sound in the room size you desire.

Which THX Certification is Right for You?

THX Ultra2

THX Ultra2 Certified products bring the cinematic experience to larger home theaters, 3,000 cubic feet in size, with a viewing distance of 12 feet or greater from the screen.

THX Select2

THX Select2 Certified products are for medium sized rooms, up to 2,000 cubic feet in size, with a 10-12 foot viewing distance from the screen.

THX I/S Plus Systems

Certified Systems (AV Receiver + Speaker Bundle) have the power to fill a small home theater or dorm room where the viewing distance from the screen is 6-8 feet.

THX Certified Multimedia Products

THX Certified Multimedia Products are designed and engineered for PC gaming and multimedia on the desktop.

THX Surround Sound Speaker Set Up

Sound is fifty percent of the entertainment experience. Great sound can really bring out the power of high definition video. And speaker placement is essential to experiencing the true impact of movies, music and games. THX offers speaker set up and positioning tips for 7.1, 5.1 and desktop speaker systems.

7.1 Surround Sound Speaker System Set Up

 

 A 7.1 surround system has seven discrete audio channels, Left, Right, Center, Left Surround, Right Surround, Left and Right Back, and of course, the Subwoofer.

• Front Left & Right Speakers (L & R): Place the Front Left and Right speakers at ear height, producing a 45° angle as viewed from the main seat. This delivers a wide sound stage and precise localization of individual sounds.
• Center Channel Speaker (C): Place the Center channel speaker either above or below the display. Then, aim the speaker either up or down to point directly at the listener. If you have a perforated projection screen, center this speaker both horizontally and vertically behind the screen.
• Surround Left & Right Speakers (SL & SR): Place the SL & SR speakers between 90° to 110° to each side and 2 feet or higher above the listener. The SL & SR speakers recreate the enveloping sound and intense special effects that you experience in the cinema.
• Surround Back Left & Right Speakers (SBL & SBR)*: The SBL & SBR speakers should be the direct firing type and placed together on the back wall. This allows the THX Advanced Speaker Array, or ASA technology to deliver its maximum effect. If the SBL and the SBR speakers can not be placed together, refer to your THX Certified Pre-amplifier or Receiver’s “THX Set Up” menu for alternative configurations.
• Subwoofer (Sub): There are a few variations for subwoofer placement, depending on how many subwoofers you have in your room. If you have four subs, place one in the middle of each wall. If you have two, put them in the middle of opposing walls. If you have one, place it in the middle of the front wall.

 

5.1 Surround Sound Speaker Set Up

 

 

A 5.1 surround system has five discrete audio channels: Left, Right, Center, Left Surround, Right Surround and the Subwoofer.

• Front Left & Right Speakers (L & R): Place the Front Left and Right speakers at ear height, producing a 45° angle as viewed from the main seating position. This delivers a wide sound stage and precise localization of individual sounds.
• Center Channel Speaker (C): Place the Center channel speaker either above or below the TV. Then, aim the speaker either up or down to point directly at the listener. If you have a perforated projection screen, center this speaker both horizontally and vertically behind the screen.
• Surround Left & Right Speakers (SL & SR): Place the SL & SR speakers between 90° to 110° to each side and 2 feet or higher above the listener.
• Subwoofer (Sub): If you have two Subs, put them in the middle of opposing walls. If you have one, place it in the middle of the front wall.

 

Dolby® TrueHD or DTS-HD Master Audio™ Set Up

 

 

If you use Dolby® TrueHD or DTS-HD Master Audio™, your back surround speakers should be separated to produce a 60° angle from the main listening position. In addition, you should go to the “THX Set Up” Menu in your THX Certified AV Receiver/Pre-amp and set the ASA Surround Back Speaker setting to “Apart (greater than 48).”

Desktop System Set Up

 

• Monitor Viewing Distance: There should be a 28 inch viewing distance from your desktop display to your seating position.
• Front Speakers: If you have a 5.1 desktop system, the Front Left and Right speakers should be placed to the side of your display, with the Center Channel Speaker either above or below the display —aimed at the listening position.
• Surround Speaker Set Up: If you have a 5.1 desktop system, the Surround speakers should be positioned 56 inches from your seating position.

THX Certified Acoustic Materials

Ambleside Advanced Screening Room showcasing THX Certified Acoustic Materials

THX Certified QuietHome Door

The QuietHome Door delivers exceptional movie, music and video game experiences by ensuring exterior noise is kept out, and the soundtrack kept in.

Key Benefits of THX Certified QuietHome Door:
• Delivers an STC rating of 50.
• Reduces noise 70-85 percent compared to a solid core door.
• SRP is 30-50 percent lower than competing products.
• The only THX Certified acoustic door on the market today.

QuietRock 545THX is a THX Certified, internally-damped CPG composite drywall designed specifically for high-end home theater, studio and other commercial applications.

Key Benefits of THX Certified QuietRock:
• Delivers STC ratings of 56-80.
• Highest total loss factor across all frequencies from low to high.
• Installed just like standard drywall.
• Low frequency isolation up to 50dB; high frequency up to 90dB.

THX Certified Microphones

 

THX started in the studio with young, maverick filmmakers pushing the limits of new technology to help shape their stories. Today, THX Certified USB Microphones provide a new generation of aspiring artists and storytellers the tools to capture podcasts, voice-overs and other recordings for digital distribution.
The THX Certified Yeti USB mic from Blue Microphones is a recording solution that combines quality, usability and convenience for a wide range of audio applications. A rigid THX testing process ensures the fidelity of the recording always remains true to its source, allowing you to accurately capture voice-overs, interviews and other sound elements with confidence.

 

Why does THX Certification Sound so Good?

• Ultimate recording and playback fidelity: Superior design, quality and rigorous lab testing by THX affirms the best possible recording and playback fidelity.
• Superior recording results: Four patterns (Omni, Cardioid, Stereo, Bidirectional) for incredible versatility and superior results in any situation.
• Powerful studio quality performance and features: Minimal Latency, amplified headphone monitoring, microphone-mute and hardware-based gain adjustment.

THX Certified HDMI Cables

Connecting your home theater components together is the last step before enjoying your favorite movies, music and games. When upgrading your system, it is critical to make sure every home theater component is performing to its fullest.
THX HDMI cable certification includes a series of electrical tests to ensure the integrity of the HD signal is maintained from device to device without introducing digital artifacts and noise. This protects you from any unexpected surprises once your home theater system is installed, connected and engaged.

 

What are the Benefits of THX Certified HDMI Cables?

• Pristine source signal: Ensures the source signal is never degraded.
• Thoroughly tested: Ensures the highest standards for quality and usability across specific cable speeds and distances.

THX Certified Receivers

Filmmakers and musicians take you on a journey, pulling you into the story and evoking emotions through dialogue, music and sound effects. THX Certified receivers, amplifiers and pre-amps are designed with exclusive home theater technologies and features to bring out every nuance of a storyline, with the raw power of a surround sound cinema experience or live recording session.

 

The Benefit of THX Certified Receivers

• Crisp, clear sound fills your room: THX Ultra2 Plus, THX Select2 Plus and THX I/S Plus certification categories deliver amazing performances based on your room size.
• Powerful studio volume: Set your THX Certified receiver to “0” on the volume dial, and experience the exact Reference Level volume used in the movie theater.
• Effortless performance: THX performs more than 2,000 Bench Tests, to ensure that your receiver plays effortlessly with plenty of power and low distortion in your home theater.
• Loudness Control: THX Loudness Plus lets you catch every detail of a surround sound mix when the volume is lowered.
• Easily mix and match brands: With a single standardized bass configuration, you can easily and confidently use any THX Certified product together.

 

THX Certified Speakers

Teufel System 5 THX Select Speakers

A deep understanding of the filmmaking process and surround sound is at the very heart of every THX Certified 2.1, 5.1 and 7.1 speaker system. Engineered with design characteristics of professional studio speakers, THX recreates the tonal balance of the filmmaker’s final mix in your living room. The result? Action sequences are impactful, and dialogue-driven moments are natural and engaging.

 

THX TruStudio Software Suite

Creative's WOW Headphones featuring THX TruStudio

Today’s movie fans and gamers expect their sound experience on PCs and Netbooks to be on par with other home entertainment devices. Whether playing the latest first person shooter or watching a Hollywood blockbuster movie, THX TruStudio provides the tools to accurately process and reproduce movie, music and game soundtracks and effects for PC platforms. The result is an immersive sound field that puts you in the middle of the action.

Razer Mako

Razer Mako 2.1 Desktop Audio System

THX is redefining desktop speaker performance with its THX Ground Plane and Slot Speaker technologies combined for the first time in the Razer Mako 2.1 THX Certified Multimedia System. For PC gamers and music lovers, the THX Slot Speaker and Ground Plane Technologies create a spacious soundstage with room filling sound.

THX Slot Speaker

THX II Certified Car Audio System using THX Slot Speaker Technology

THX Slot Speaker technology redefines how speakers look and sound, transforming traditional circular speakers into narrow slot openings that can distribute sound to wider listening areas. Featured in 2010-2011 Lincoln cars, the Slot Speaker technology enables the THX II Certified 5.1 Surround system to widen the range and directivity of sound within the car’s cabin—without cluttering the dashboard with audio components.

THX Slot Speaker Advantage

• Modify directional characteristics of sound
• Simplify packaging
• Reduce grille area
• Opportunity for new speaker styling ideas

THX Slot Speaker and Ground Plane

When listening to traditional PC speakers, sound reflecting from the desktop surface can add to the audio experience at low frequencies, but also cause interference with the direct sound at higher frequencies. The THX Ground Plane and Slot Speaker technologies make use of the desktop surface to improve the overall sound presentation across all frequencies.

THX Reference Level

THX Certified Audio products are designed to let you experience movies the way they were meant to be heard. On every THX Certified AV Receiver the “0” on the volume dial represents THX Reference Level, a setting designed to mirror the exact volume level used by moviemakers and sound artists in the studio.
When you are watching a movie with the playback volume set to “0” on a THX Certified Receiver, you experience every sound element exactly like it was produced by the filmmaker—with the same fidelity, detail and clarity.

 

What is Reference Level?

Manufacturing receivers and speakers that can achieve THX Reference Level is no simple task. It requires a tremendous amount of power to drive an audio system effortlessly without clipping or distorting. To ensure the audio products can reach this peak performance, THX developed a set of standards as part of its THX Ultra2, THX Select2 and I/S Plus certifications.

• Experience Studio Clarity: THX Certified Receivers reproduce studio Reference Level, 85dB SPL with 20dB of headroom.
• Reference Level for your Room: THX Ultra2 Plus, THX Select2 Plus and THX I/S Plus certification categories deliver Reference Level performance in your specific room size.
• Distortion-free Playback: THX Certified Receivers and speakers are designed to recreate Reference Level with minimal distortion.

THX Surround Sound Modes

THX Advanced Speaker Array (ASA) recreates the 5.1 studio surround sound field in your home by digitally reconfiguring the surround channels for the type of media you are enjoying. Featured on all Certified Receivers, THX ASA establishes THX Listening Modes, making it convenient to have one speaker set up for movies, music and games.

What is THX ASA?

Today, movie, music and games are created in different types of studio environments, with multiple speaker configurations. The dilemma? Finding a single listening solution for playing different types of media, without physically moving your speakers. THX ASA addresses this by providing the following Listening Modes:


THX Cinema Mode

Recreates the ambiance of the movie theater by positioning the 5.1 mix to immerse you in the movie’s soundtrack.

THX Games Mode


 

Distributes the sound effects and dialogue generated by the game engine, placing the audio from a 5.1 mix source to the appropriate “action” location – creating 360-degree gaming experience.

THX Balanced Bass-Line

Most of us have experienced deep bass rattling walls, windows and doors in the home and car. THX Balanced Bass-line provides the ability for speaker manufacturers to deliver big-box bass performance—minus the vibrations.

THX Balanced Bass-line breaks the mold of traditional subwoofer designs—getting the sub out of the big box. The technology places small, micro-precision woofers face-to-face, arranged in balanced pairs. This approach force cancel vibrations, ensuring deep low frequency performance without vibrations discoloring soundtracks or intruding into adjacent rooms.


THX Balanced Bass-line Features

Tight Bass Performance: Experience natural sounding bass exactly like it was recorded, without shaking the walls loose.

Shape Shifting Designs: THX Balanced Bass-line allows speaker manufacturers to produce very natural, vibration-free bass from smaller, more stylized systems.

THX Loudness Plus



Loudness Plus™ is a new volume control technology featured in THX Ultra2 Plus™ and THX Select2 Plus™ Certified Receivers, pre-amps and amplifiers. With THX Loudness Plus, home theater audiences can now experience the rich details of surround sound at any volume level

What is THX Loudness Plus?

All movies, music and games are mixed at Reference Level in the studio, to be played back at the same Reference Level in the cinema or home theater (0 db on the volume dial for THX Certified Receivers is equal to the studio Reference Level). However, many of us find Reference Level is too loud for our homes. But, turning the volume down often means that elements of movie, music and other soundtracks are lost or perceived differently from the original sound mix.

How THX Media Director works ?

Content Creation


From capture to post-production THX Media Director metadata describes specific creative and technical characteristics of audio and video content

Distribution

THX Media Director metadata is associated with each program and is distributed with the content

 

 

Playback


THX Media Director enabled devices, such as Blu-ray players, AV receivers, and 3D TVs, act upon the metadata to automatically select appropriate playback settings.





THX Media Director

THX Media Director™ simplifies the entertainment experience, allowing your TV and home theater system to automatically select the appropriate playback settings and modes when you are watching a movie, playing a game or listening to music.

Today’s entertainment experiences come in many shapes and forms, with blockbuster movies on your mobile phone, broadcast programs streaming on the Web, and 3D TV in the living room. As the sheer number of media devices and delivery formats grow, you can often be overwhelmed with choices. THX Media Director addresses this challenge.

What are the Benefits of THX Media Director?

Dolby Pulse





The Ideal HE AAC Codec for Broadcast

Assures content creators that consumers receive consistent content precisely as intended

Delivers high-quality stereo and 5.1-channel audio at the lowest data rates

Provides full compatibility through the complete broadcast chain

Supports industry-standardized Dolby metadata to ensure consistent audio delivery

Meets Dolby’s high testing standards

SDDS, THX, DTS, and Dolby Digital in Brief

The purpose of this page is to explain THX, DTS, and Dolby Digital in the context of movie theatres. These terms are relevant to home theatre systems as well, but there are important differences. A future page or set of pages on home theatre systems may be created that will explain these terms in the home theatre environment. 




First, people tend to put THX, DTS, and Dolby Digital into one "basket", and attempt to compare them. I am going to try to eliminate some of the confusion that results when people do this.
I have heard these types of (incorrect) comments on many occasions:

• "THX is better than DTS."
• "Dolby Digital is not as good as THX."
• "Theatres with DTS cannot be THX certified. Only those with Dolby Digital can be." (from a guy who wired some THX auditoriums, some of which use DTS!). 

Standard 35mm Film Audio

A photo of a 35 mm film print featuring all four audio formats (or "quad track")- from left to right: SDDS (blue area to the left of the sprocket holes), Dolby Digital (grey area between the sprocket holes labelled with the Dolby "Double-D" logo in the middle), analog optical sound (the two white lines to the right of the sprocket holes), and the DTS time code (the dashed line to the far right.)