Here are some frequently asked questions and answers.
All THX Certified receivers have internal test noise that THX verifies during the certification process. When using the test noise in a THX Certified receiver, the volume level is automatically adjusted to the THX Reference Level when utilizing the test noise. If you have a different receiver, it should feature an internal test noise though you may have to select an arbitrary volume level. Likewise when utilizing a test noise track on a DVD or Blu-ray.
When calibrating using the internal test noise in a THX Certified receiver, you should target 75 dB on your SPL meter. If using a test disc, it may be 75 dB or 85 dB, depending on how the tracks were mixed. The disc should provide instructions.
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, the exact volume level used by the moviemakers and sound artists in the studio.
Achieving the THX Reference Level is no simple task for receivers or loudspeakers. It requires a tremendous amount of power to drive an audio system effortlessly without clipping or distorting. To ensure the audio products reach this peak performance THX developed a set of standards as part of its THX Dominus, THX Ultra, THX Select, and Integrated System certifications.
Noise Criterion – NC – level is a standard describing the relative loudness of space within a range of frequencies. It was established in the U.S. for rating indoor noise such as the noise from air-conditioning equipment or similar. In Europe, it is common to use the Noise Rating Curve – NR.
The method consists of a set of criteria curves ranging from 63 to 8000 Hz and a tangency rating procedure. The criteria curves define the limits of octave band spectra that must not be exceeded to meet the occupant’s acceptance in the actual spaces.
NC-30 represents a specific noise curve that provides a comfortable level of noise of any given environment.
There is a downside to watching all of your films at Reference Level—it is often too loud for your neighbors. With lowered volume levels, bass sounds, surround effects and other sound elements can be lost or perceived differently.
To correct this, THX developed a technology called “THX LOUDNESS PLUS”, which lets you experience the rich details of a movie or game soundtrack without upsetting your neighbors.
Outstanding sound is not just about having great speakers. The integration of acoustic-enhancing elements in a cinema such as absorptive paneling and isolating wall structures provide significant improvement in clear, immersive audio.
Having to ask the person next to you “What did they say?” is never fun. Sounds bouncing and echoing off surfaces around the room confuse the ear and can make dialogue difficult to understand. Eliminating these audible reflections helps optimize audio clarity.
A THX Certified Cinemas is a quiet, pristine audio sanctuary because it features massive wall structures to isolate the cinema from the outside world. 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.
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.
THX Certification confirms background noise meets NC-30 at all octave bands. This ensures exterior noise from air conditioning units and projection equipment does not mask the subtle effects in a movie’s soundtrack.
A well-crafted loudspeaker layout and baffle wall help produce the unique, powerful sound expected in a cinema. This type of speaker configuration is behind the most captivating movie screenings.
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 large wall of speakers housed in an acoustic baffle. This is called the speaker system enclosure.
The baffle wall is approximately the same size as the screen, providing a solid, smooth 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.
The relative positioning of the screen and projector along with the size of the image are essential components of the best cinema experience. When correctly installed and well-designed, viewers can enjoy a mesmerizing image free from distortion.
To ensure the best possible viewing and listening experience, THX recommends having a well-designed room with an impressive screen size and a 36 degree viewing angle from the farthest seat in the auditorium. A larger screen allows for a wider placement of left and right audio channels, enhancing room acoustics and creating a more accurate audio experience.
Prior to construction, THX advises cinema designers and architects to accommodate for the 36 degree horizontal viewing angle, which provides a broad field of view as well as a wide listening space. THX also provides guidance to partners to make sure that every seat has an unobstructed view with clear sight lines.
To achieve THX certification, the cinema projection booth must be accurately placed in relation to the screen for the best viewing experience. If the projection booth is not correctly positioned and installed, the projected image will have a keystone or trapezoid effect.
WELL-DESIGNED PROJECTION SYSTEM
In a THX Certified Cinema, the projection booth is accurately placed in relation to the screen – delivering an image with little or no distortion.
PROJECTION SYSTEM DESIGN RESULTING IN DISTORTED IMAGE
Improper projection booth and screen placement results in many viewing issues, including a severe keystone or trapezoid effect. THX Certified cinemas must be designed with the most optimal framework possible for the room
A testing program at the THX Office prequalifies the equipment used in the sound system of a THX certified cinema. Component approval is based on a series of tests that verify the applicability of the product design, performance, and ability to be easily integrated and installed with other components on the THX Approved Equipment List.
All acoustical or electrical measurements are included to ensure that the equipment provides the features necessary for motion picture playback systems.
The THX pre-qualification testing is designed to confirm the performance levels of the equipment under actual operating conditions. It is considered necessary due to the special demands the THX system places on equipment.
*[CONTACT US TO REQUEST THE APPROVED EQUIPMENT LIST / EMAIL: firstname.lastname@example.org]
Components for the auditorium sound system are selected from the THX Approved Equipment List and integrated into the auditorium by the THX Design Office. THX inspects the equipment installation for the correct placement and aiming of loudspeakers. A THX Certified auditorium’s sound system is calibrated to THX and industry standards using THX approved audio spectrum analyzers and test equipment.
The projected image quality must meet THX specifications. Screen luminance, image contrast, color calibration and accuracy, and focus resolution are evaluated by THX by using standard industry test equipment, test images, and proprietary test patterns. The projected image is measured and evaluated to verify the entire image size is projected on the screen with minimum cropping and distortion.
Every auditorium is tested to ensure that noise sources such as adjacent auditoriums, street traffic, and concession equipment do not distract the moviegoer from enjoying the movie.
The background noise level from the auditorium HVAC unit is measured and cannot exceed NC-30 at any octave band. High levels of background noise can mask subtle effects in the film soundtrack, which is not acceptable in a THX Certified auditorium.
Reverberation is the presence of sound after the source has stopped – similar to an echo. In movie theaters reverberation often builds when sound is reflected off walls, floors and ceiling surfaces.
For example, with action films there are typically loud action sequences, immediately followed by quieter, more dialogue-driven moments. In a THX Certified Cinema with tightly controlled reverberation, the sound of explosions ends immediately and never bleeds over into the next scene.
To control reverberation, THX cover the rear wall of the auditorium with thick, absorptive material which 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 which reduces sidewall reflections.
WITH ACOUSTIC PANELING Acoustic paneling controls reverberation, or echo effect, in a THX Certified Cinema.
WITHOUT ACOUSTIC PANELING Sound bounces off the walls without acoustic paneling, interfering with the movie’s soundtrack.
The best mixing studios in the world are THX Certified. These include Skywalker Sound at Lucasfilm’s Skywalker Ranch, Peter Jackson’s Park Road Post in New Zealand, and Twentieth Century Fox in Hollywood. By focusing on room design, acoustics and the quality of the studio production equipment itself, THX provides filmmakers and recording artists the best possible environment to mix their motion picture soundtracks
Studio acoustics, optimized speaker layouts, THX Approved equipment, and calibrated audio/video systems combine to create an ideal environment for sound recording, design, and mixing.
Creative and quality control:
Provides filmmakers confidence that what they are hearing during mixing sessions will translate the same to the cinema and home.
THX ensures a transparent environment where the room has minimal effect on the mix
A THX Certified Cinema is built to replicate the acoustics and ambiance of the THX Certified Studio environment.
From the surround sound speakers and screen placement to the acoustic baffle wall and sound isolation, THX Certified Cinemas allow moviegoers to be completely immersed in the storyline, exactly as it was produced in the studio.
The Studio certification program focuses on the following areas:
LISTENING AND VIEWING ENVIRONMENT
SELECTION OF AUDIO AND VIDEO EQUIPMENT
LAYOUT OF THE WORKING AREA AND EQUIPMENT
CALIBRATION PROCEDURES FOR THX CERTIFICATION
THX Certified PM3 Studios are ideal for motion picture premixing and producing television programs, music, video games, and other content for non-theatrical release. THX sets very high standards for pm3 studio acoustics, noise levels, and production equipment performance, resulting in the best possible production environment for capturing multichannel soundtracks and high-definition visuals.
THX works with architects and designers throughout studio construction to ensure every detail of the room, as well as the equipment, is performing to its potential.
THX TESTED AND APPROVED:
All components in a THX pm3 Studio must be selected from a list of “THX Approved products.”
All THX Approved mixing consoles and speakers incorporate parameters for the proper playback of multichannel audio in bass-managed consumer systems.
CONSISTENT VISUAL QUALITY:
Colors, black and white levels, and textures are maintained as projects are transferred between disparate THX pm3 Certified Studio locations—providing editors and producers the confidence to make critical editorial decisions.
A THX Certified pm3 Studio is designed for the creation of optimum sound and picture presentation for many different types of media:
AUDIO MIXING AND MONITORING
Authoring and mixing of game soundtracks
Premixing and sound design for motion pictures
Authoring and remixing of Blu-ray and DVD soundtracks
Audio quality control for Blu-ray and DVD
Broadcast master control rooms
5.1 and 7.1 music – high resolution playback for DVD-A and SACD
Calibrated game workstations and presentation rooms
Movie to video telecine and video editing for Blu-ray and DVD
Video quality control for Blu-ray and DVD
Video broadcast production”
SELECTION OF AUDIO AND VIDEO EQUIPMENT
LAYOUT OF THE WORKING AREA AND EQUIPMENT
CALIBRATION PROCEDURES FOR THX CERTIFICATION
THX Certified Screening rooms blend the acoustic performance and aural impact of a THX Certified Cinema in a smaller room—ideal for critical screenings, business presentations, focus groups and editorial reviews. THX defines every aspect of sound and picture quality in its screening room program, from sound isolation and reverberation management to room acoustics and projected image.
Throughout the screening room construction process, THX provides extensive design consulting services. In addition, THX conducts onsite calibration to ensure the equipment is performing to its full potential.
THX does not specify room size or address the visual appearance of the room unless it adversely affects sound and picture quality.
The size of your living room or home theater plays a big part in what kind of system you should consider purchasing. A good surround sound system needs to be powerful enough to fill your room with crisp, clear sound. If you get one that doesn’t have enough horsepower, it can distort when playing at higher volumes.
THX has created “room size categories” to help you find the right products to accurately reproduce movies, music and video games in your home.
When choosing an audio system for your home, first ask yourself what you are going to be listening to. Are you looking for an audio system to connect with your laptop? Is it for multi-channel movies or just improving how your TV sounds? If you want to watch movies, TV, or play games in surround sound, then you should consider a 5.1 or 7.1 surround sound system. If you are looking to improve how your music sounds in your bedroom or desktop, consider a 2.1 or 5.1 multimedia system.
The numbers 5 and 7 correlate to the number of audio channels used to mix the film, music, or video game. They also refer to the number of speakers in the home theater system. For example, a 5.1 surround sound system typically has 5 speakers and 1 subwoofer, and a 7.1 system has 7 speakers and 1 subwoofer.
You will need an AV receiver to experience the best surround sound. The AV receiver is the hub of your home audio system. Receivers accept all audio and video sources, including satellite and cable TV, DVRs, DVDs, and Blu-ray players, as well as gaming consoles. It then distributes the sound from these sources to your surround system, accurately powering all of your speakers.
THX Certified receivers range in price from $500 to $5000. The price difference is often defined by product features and technologies. High-end receivers feature a number of listening modes, calibration technologies, and video processing. Higher priced receivers may also be upgradeable via firmware updates in case a new technology appears on the market.
When deciding on the right AV receiver for your system, start by making sure there is enough amplifier power to drive the speakers for your particular room size. Then, evaluate the various processing modes. If you play video games or enjoy movies in surround sound, THX Listening modes, and THX Loudness Plus will greatly improve the experience. In addition, you should try to pick a receiver with enough inputs (HDMI, component, etc.) for your home entertainment system.
Speakers can be purchased as a package (5.1 and 7.1) or separately. There are a lot of brands to choose from, each with its own unique sonic signature. Depending on the aesthetics of your home theater or living room, you can pick between traditional box speakers that are visible to viewers, or choose in-wall and in-ceiling speakers that disappear into the ceiling and walls. If you choose the latter, some drilling, cutting and running speaker cable is required. If this sounds overwhelming, don’t worry. A THX Certified Professional can help with speaker installation.
Today, there are a number of great THX Certified in-wall and in-ceiling speakers that deliver the same, solid performance as THX Certified box speakers.
You need to make sure that the box speakers you purchase are actually designed for wall mounting. A wall creates an acoustic boundary that reflects low frequencies (bass). If you mount traditional box speakers (not designed for wall mounting) the result could be a very bass-heavy sound.
The size of your speakers makes a difference in performance. While many well-known speaker brands push smaller speaker concepts, THX® recommends resisting the temptation to go too small. The smaller the speaker, the more you may compromise in terms of output and low-frequency performance. Try to find a balance between the size you desire and the sound quality you expect. THX® Certified speaker brands are renowned for their design aesthetic, creating high performing speakers that blend with any décor.
Yes. Don’t think about getting a home theater system without a subwoofer. THX recommends getting the biggest subwoofer that your living space and budget will allow. In the world of THX Certified speaker systems, typically a 12-inch or 2×10-inch subwoofer is a minimum requirement.
Yes. Mixing and matching speaker brands and styles is fine. In fact, the whole concept of THX certification is based on the idea of being able to mix and match components from different manufacturers. The THX certification process standardizes all electrical and output parameters so that all THX Certified speakers and receivers work together.
You can potentially have box speakers for the Front and in-wall or in-ceiling speakers for the Surrounds. However, THX recommends that you keep groups of speakers similar. This means the Front speakers should be from the same manufacturer and designed to work together. Surround Left and Right speakers should also be identical to each other, as should the Surround Back speakers.
Sound is fifty percent of the entertainment experience. Great sound can bring out the power of high definition video. Speaker placement is essential to experiencing the true impact of movies, music, and games.
The best placement for the speaker bar is your bar right below your TV. We don’t recommend placing the speaker bar above your TV or somewhere else in the room. For the optimal sound experience, it should be right below your TV set, should not be tilted, and it should align and face vertically with your TV screen.
We suggest performing a manual loudspeaker calibration instead of automatic setup. There are two parts to the calibration, distance and level.
For distance, simply measure and record the distance from each loudspeaker to the primary listening position. Enter these distances in the loudspeaker setup menu.
To set levels, you will utilize the receiver’s internal test tones and an SPL meter. There are a number of SPL meter applications for both iOS and Android. They may not be as accurate as a standalone, dedicated meter but they’ll certainly work for this.
Position the meter/phone near the ear level of the primary listening position. Start the test tone level calibration in the loudspeaker setup menu and adjust the level up or down for each loudspeaker so that the SPL meter reads ~75 dB SPL, C-weighted. Let the system cycle or manually cycle through each of the loudspeakers. When calibrating the subwoofer level, it is beneficial to move the meter/phone across multiple seating positions near primary as the bass level typically varies by location in the room.
As an aside, THX recommends setting all loudspeaker sizes in the menu to Small as the receiver will perform the bass management and route appropriately to the subwoofer.
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® Spatial Audio is a flexible positional audio solution that delivers pinpoint audio accuracy to provide the listener with a heightened, realistic and immersive entertainment experience. Using real-time rendering and spatial positioning of stereo and multichannel content, THX Spatial Audio can be optimized for playback across all devices (speakers, headphones, laptops and mobile phones), content types, and listening genres.
THX® Spatial Audio enhances stereo and surround sound to deliver the highest level of audio that intensifies soundscapes in all forms of entertainment.
THX® Spatial Audio can be optimized for playback across all devices (speakers, headphones, laptops, and mobile phones), content types, and listening genres. You can find the current THX Spatial Audio products here.
THX Achromatic Audio Amplifier (AAA) is an analog amplifier technology that combines the qualities of the finest Class A amplifiers with greatly reduced energy consumption. It has the ability to drive heavy and difficult headphone and loudspeaker loads to full output while maintaining impeccable performance. THX AAA™ produces the purest performance of any amplification technology now available, ensuring that the art of musicians and filmmakers can be experienced as close to the original as possible.
PATENTED DISTORTION-REDUCTION TECHNOLOGY.
As part of THX’s ongoing pursuit of excellence, our engineers focused on ways to minimize distortion in the audio electronics chain. The THX patented technology uses a unique combination of feedback and feedforward error correction to make the distortion vanishingly small, even with minimal bias current.
Our engineers then used this patented distortion-reduction scheme to reduce some of the common sources of distortion in amplifiers in a variety of ways — the result is an amplifier topology with unparalleled performance and benefits for the audiophile.
Crossover distortion occurs in many amplifiers when the audio signal is “handed off” from an amplifier’s positive-going output device to its negative-going device and vice versa. This transition is never perfect, resulting in crossover distortion that is spiky in nature and rich in high-frequency distortion products. This is easily heard.
Moreover, the problem becomes more audible as the signal level decreases. The more delicate the music, the more it will be masked and obscured by crossover distortion. THX’s patented distortion-reduction circuit reduces crossover distortion to vanishingly low levels (less than 0.0001% @ 1 kHz), resulting in a more accurate reproduction of the original content.
The distortion reduction in the THX AAA™ technology has an additional benefit: it dramatically reduces power supply-induced distortion and noise — a high PSRR (power supply rejection ratio). This means it can achieve exceptionally low noise and distortion floors.
In any amplifier, when the power supply works hard under heavy load conditions, it can sag and ripple, introducing unwanted distortion and noise in the amplifier output signal. The THX patented solution is particularly effective in blocking power supply ripple from reaching the output.
That means more of what you hear is music, and less of what you hear is the character of the power supply noise associated with the amplifier.
Combining this with meticulous layout and design, the THX AAA technology delivers a signal- to – noise ratio (SNR) in excess of 130 dB — this is 30 dB greater than most amplifiers. That’s 30 times less noise than typical amplifiers — the perfect amplifier for a high-resolution audio playback system.
One way to reduce amplifier power consumption is to reduce the bias current flowing through the output devices. This has two effects: it reduces the idle dissipation (good) but increases the crossover distortion (bad).
By applying the THX patented circuit, it is possible to virtually eliminate the crossover distortion while retaining the benefits of lower power consumption.
For portable devices with AAA, this means unlocking a Class-A experience with long battery life and small form factor.
For desktop devices with AAA, this means cool operation and minimal carbon footprint.
THX Loudness Plus™ is a volume control technology featured in THX Certified Dominus, THX Certified Ultra and THX Certified Select Certified AV Receivers, preamplifiers and amplifiers that automatically adjusts the front-to-back speaker level relationship as you turn the volume down.
With THX Loudness Plus, audiences can now experience the rich details of surround sound at any volume level.
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 the 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.
THX Loudness Plus maintains the integrity of soundtracks when listening below Reference Level. The technology compensates for the tonal and spatial shifts that occur when the volume level is reduced. By automatically raising the levels of the ambient sound, you experience the true impact of movies, music, and games regardless of the volume setting.
THX Loudness Plus incorporates two THX Technologies. As the user changes the volume with multi-channel source content, THX Multi-channel Spectral Balancing™ and THX Dynamic Ambience Preservation™ automatically and seamlessly apply for the appropriate compensation. This delivers a more accurate listening experience at any volume level.
THX Multi-channel Spectral Balancing™
Adjusts frequency response to counter the perceptual loss of low and high-frequency sound in all channels. It begins with a flat response at Reference Level, and continually adjusts the response as the user selects lower listening levels. The equalization is applied to all channels in a multi-channel listening environment.
THX Dynamic Ambience Preservation™
Adjusts the surround channel processing to preserve the spatial detail that is lost when listening below Reference Level. It automatically shapes the output on surround channels to maintain the perceived balance in the original mix.
T.A.S.A. stands for Trailer Audio Standard Association. It was created in conjunction with studios and the National Association of Theater Owners to create a level playing field for trailer audio and reduce excessively loud trailers. TASA Certification means a trailer has been independently verified to comply with the TASA standard and does not exceed the TASA upper limit.
The MPAA requires all domestic (U.S.) trailers that they rate to be TASA certified.
The maximum turnaround from receipt of completed TASA form and trailer files is 24hrs, excluding holidays and weekends. If a trailer is received by 4pm, it is typically completed the same day.
The fee for TASA Certification is $550 for standard audio trailers, and $780 for immersive audio formats such as Atmos.
A trailer must be measured from the first audible sound of the trailer after the sync pop to the last sound, excluding any silence before or after. It must be measured on a TASA approved meter. The LeqM measurement is a whole number. Meters that have a decimal point readout must be rounded up to the next whole number.
If you have any questions regarding the THX form, measurement, or process in general, please contact us.
To learn more about the TASA Standard, including the technical document, visit tasatrailers.org.
Leqm measures decibels averaged over time with a weighting curve that is more sensitive to annoyance frequencies: breaking glass, explosions, and other piercing sounds. This allows for trailers to have loud explosions with enough quiet parts to balance it out so as not to fatigue or annoy the audience.
TASA approved LeqM meters:
The current TASA upper limit is 85 LeqM measured on a TASA approved meter.
Trailers that are non-compliant (exceed the upper limit) will need to be adjusted and resubmitted with a new form. An email will be sent to the client and MPAA notifying them of the trailer and its measurement. The revised trailer will be measured with a reduced retest fee of $280.
A Blind Trailer Check ensures compliance by measuring the trailers that are sent to the theaters to check against the certified measurements. BY participating in the TASA program, studios grant THX the ability to randomly check trailers of theatrically distributed DCPs.
For further information, you can find the TASA Standard Technical Document on the official TASA website.
For optimal viewing, you want your line of sight to be more or less aligned with the center of the screen. We suggest 15 degrees or less, above or below the center, as seen in the image below.
For 4K or ultra-high definition (UHD) TV models, they have various layers of LCD enhancement that focus light in specific ways. If you elevate your TV, you’re going to distort the picture quality.
A good rule of thumb is to divide your screen size by .835. This will give you the ideal maximum gap (in inches) between your couch and your 4K set.
To determine what size TV you should purchase, we recommend you measure the distance between your couch and where your TV will be located (in inches). Then multiply that number by .835, and that should help you determine what screen size you should get.
But for 4K or UHD TV sets, the process is a little different since the nearer you sit to these models, the more detail you’ll be able to pick up.
Different content requires different needs from your display. Many TVs include viewing modes optimized for genre-specific content. THX® Certified TVs offer THX Cinema Mode, THX Game Mode, and THX Bright Room. Read more about viewing modes here.