World-renowned for their accurate, full-range sound, Blue Sky is pleased to introduce its newest critical listening component to its full line of monitoring solutions: the SAT 265 High Output Near-Field Active Studio monitor. Blue Sky’s fresh approach to studio monitor design delivers the highest possible ratio of performance to cost, in turn providing the highest value to our customers. US MSRP: $1500.00 (USD)

Blue Sky | SAT 265

By Diane Gershuny:

Blue Sky’s SAT 265 is a 2-way, tri-amplified, 300-Watt, High Output Near-Field Monitor which features two 6.5” high excursion hemispherical woofers and a 1” dual ring radiator tweeter with integral waveguide, for superior off-axis response. Powered by a dedicated low distortion 100-Watt amplifier for each of the 6.5” woofers, it also features a low distortion 100-Watt amplifier for the tweeter. The SAT 265 effortlessly delivers clean and accurate sound with a frequency response of 80Hz to 30kHz +/-3.0dB (200Hz to 15kHz +/-1.5dB) for full compatibility with Blue Sky’s SUB 15 Universal, SUB 212, SUB 12 and BMC (Bass Management Controller). The rear panel also has controls for “full space” (placement in a room) or “half space” (mounted in a baffle wall) operation, along with HF level trims, as well as controls for variable gain settings.

Blue Sky | SAT 265

“The Sat 265 was the logical step in the development of the Blue Sky monitors,” said Blue Sky Vice President Chris Fichera. “The only thing we could do to make the Sat 6.5 (Sky System One) better was to make it play louder, so that’s what we did.”

Making the subwoofer an integral part of the monitoring system design enables the SAT 265 studio monitor to be positioned for the best imaging, and the SUB to be positioned for the best bass response. Relieving the SAT 265 studio monitor of the requirement to reproduce the low frequencies means that the uncompromising sealed-box design can combine with sophisticated bass management electronics, to provide a seamless transition between the SAT 265 and SUB. It all adds up to accurate, full range sound.

Blue Sky | SAT 265 - Back Panel

The SAT 265 has been designed to integrate perfectly with Blue Sky’s new SUB 212, a sealed box, push-pull, 400-Watt subwoofer. The push-pull configuration reduces distortion, provides increased output, and features an anechoic frequency response of 25Hz to 200Hz, +/-3dB. In addition, the SUB 212 also has built-in 2.1 bass management electronics with both a 4th order 80Hz Linkwitz-Riley low-pass filter and a 2nd order 80Hz high-pass filter that is perfectly matched to the response of the SAT 265 (the SUB 212 is also compatible with the SAT 265, SAT 6.5 and SAT 5). When combined, the SAT 265 and SUB 212 provide a stunningly accurate and engaging, full-range monitoring system.

Blue Sky | SUB 212

About The SUB 212

Blue Sky’s SUB 212 is a sealed box, dual 12”, push-pull, 400-Watt subwoofer. It features an anechoic frequency response of 25Hz to 200Hz, +/-3dB. In addition, the SUB 212 also has built-in 2.1 bass management electronics with both a 4th order 80Hz Linkwitz-Riley low-pass filter and a 2nd order 80Hz high-pass filter that is perfectly matched to the response of the SAT 8 (the SUB 212 is also compatible with the SAT 12, SAT 6.5 and SAT 5).

The SUB 212’s unique “push-pull” configuration is designed not only to increase output, but also to reduce distortion. A push-pull subwoofer uses two drivers: one mounted facing forward, the second mounted backward with the magnet facing out. Utilizing two drivers doubles the maximum output, while the push pull configuration reduces even harmonic distortion. Typically, in a more conventional design, at high output levels, second harmonic distortion dominates the distortion spectrum of most subwoofer drivers and is caused by asymmetric operation of the suspension and magnetic structure. In simple terms; the output of the driver is slightly different when the cone is moving away from the magnet, as compared to when it is moving toward its magnet.

Push-pull operation reduces this even harmonic distortion in a clever application of physics. As mentioned before, push-pull uses two drivers, one reversed from the other. The bottom driver has its magnet facing out of the box and is driven electrically out–of–phase from the front driver, which keeps both drivers acoustically in phase. However, when the front driver’s cone is moving away from its magnet, the bottom driver’s (reversed) cone is moving towards its magnet. This puts the even harmonic distortion components of the bottom driver out-of-phase with the front driver. When you combined the outputs of both drivers, the even harmonic distortion of both drivers cancels, reducing the overall distortion of the subwoofer.

About Blue Sky:
Blue Sky International was founded, and is jointly owned by Group One Ltd. and Audio Design Labs Inc. The company was established by combining the marketing, sales and distribution expertise of Group One Ltd. with the knowledge and experience of Audio Design Lab’s award-winning design team. more »

For more information about Blue Sky International, please visit: www.abluesky.com

By Diane Gershuny

Up until about a dozen years ago, the idea and implementation of production sound recording was virtually non-existent in India. As a film school graduate from India’s Film School Institute in 1985—and with inspiration from Spielberg to Lucas—Resul Pookutty aspired to change all that. Riding the wave of the massive success from his work on 2008’s international indie blockbuster, ‘Slumdog Millionaire’ (and subsequent sound design awards including an Oscar, BAFTA, MPSE, CAS, and others), the mixer/sound designer and colleague Akhilesh Acharya launched Canaries Post Sound outside of Mumbai in late ’08. The studio’s main sound design room is built around a Blue Sky 5.1 Sky System One.

“If you look at the history of mainstream Hindi filmmaking in the last, say, 10 years, it was in the mid-90s was when Hindi films were being compared with Hollywood and European cinema. We had to change how the films have been portrayed (it’s not all about song and dancing) and how the production planning has been done, and the process has benefited. We as new production technicians get to put our stamp on our work, and to also say that this is how it has been traditionally done, but it is not how it should be done. Especially with the Oscar that I received with my work in ‘Slumdog Millionaire’, there is a new energy, a new enthusiasm, and a new awareness about sound. So with that, I’d say we are going through a golden period of the changing face of Indian cinema.”

With the launch of Canaries Sound Post, Pookutty is determined to change the way production sound is traditionally handled in India. With the spotlight on Indian cinema globally, thanks in large part to ‘Slumdog’, the timing couldn’t be better.

“To understand how sound functions in Indian cinema, you must understand that production sound recording was virtually non-existent until 13 years ago. In India, in its true essence of how sound has been handled, there are no sound editors or no supervising dialog editors like we have in Los Angeles or any other part of moviemaking industry. Here, we end up doing everything as one person in postproduction—so I myself handle everything from recording production sound, dialog editing, sound design, supervising of the mixing procedures, and most of the time I do the Foley recording, sound music mixes and extras. Also, there are no specialized film post-production facilities specializing in India where can handle the sound and production process. What usually happens is that I work on my production recordings here and then fly off to London, Australia, or LA for executing better mixes. That’s been my modus operandi up until now. Early in my career, I realized that good soundtrack of a movie was the result of how you handle the raw material that was recorded. That’s why we thought about having specialized post studios where we can handle the sound and production process. That’s how Canaries has come into existence.”

Seeing, and hearing, a Blue Sky ‘Sky System’ in action at Skywalker Sound, he was convinced to install a Blue Sky 5.1 Sky System One into the main sound design room at Canaries, with an Audient ASP 510 surround encoder in conjunction with a Digidesign HD Pro Tools system. Two smaller 2-track cutting rooms are outfit with Blue Sky ProDesk systems.

“A close associate in Italy talked to me about Blue Sky,” Resul recalled, “and that’s how the name came to me. I was working at Skywalker on a sound effects session and was immediately impressed with its response and power and the way sound is being reproduced. I have used Dynaudio, Genelec, and HHB monitors, and no one is good over the other; certain qualities that one has, the other doesn’t. In a film and sound design environment, working with all the music, sound effects, dialog, and background ambiences needed a certain quality in a reproduction system. The Blue Sky systems gave me a very wholesome listening environment and are very spot-on. The fact that it gives me true monitoring in a small room impresses me a lot. I’m hearing everything that I’d be hearing in big room; I’m listening to all streams of sound, which are going to be mixed to the film format in its true sense. And I really love the bass management system. It’s a very cool concept and absolutely essential in a small room. I can hear the true color of my sound, which was misguided and misleading in other monitor systems. In other words, Blue Sky made something that was very intangible, tangible.”

Moving forward, Pookutty is putting finishing touches on 3 major Indian movies including ‘Pazhassi Raja’, a biopic historical film and one of the most expensive Hindi movies ever produced, and ‘Blue’, an underwater treasure hunt movie which re-teams Pookutty with his ‘Slumdog’ composer, AR Rahman. Pookutty went on location to the Bahamas to gather underwater sounds (the first time in Hindi cinema) and is gearing up its major launch this fall.

All of this momentum is not lost on Pookutty. Not only did the success of ‘Slumdog’ open new production opportunities for him and other like-minded production folk, but also shed new spotlight on sound in film.

“In the 80 years of Oscar history, no one from India has won a technical award in the film industry,” he states. “And apart from that, the Oscar has created a lot more awareness about sound. One thing that touched me very deeply was at the Motion Picture Sound Editor Awards this February. Ben Bertt was receiving the Career Achievement Award and both George Lucas and Spielberg were there. I realized that this is something we are lacking in India: mentorship. There was nobody to guide me when I was starting out. I don’t want my own generation or the one after me to go directionless, so I am building myself up to cater to a new breed of enthusiastic film technicians and film people. I’m hoping that the Canaries Post of tomorrow will be the Skywalker of India.”

For more on Canaries Post, go to: www.canariespostsound.com

ABOUT BLUE SKY
Blue Sky International was founded, and is jointly owned by Group One Ltd. and Audio Design Labs Inc. The company was established by combining the marketing, sales and distribution expertise of Group One Ltd. with the knowledge and experience of Audio Design Lab’s award-winning design team. more »

For more information about Blue Sky International, please visit: www.abluesky.com

The SAT 8 and SUB 212’s Sealed-Box Design, Combined With Sophisticated Bass Management Electronics, Provides A Seamless Transition Between SAT & SUB. The End Result Is A Stunningly Accurate Full-Range Monitoring System.

By Diane Gershuny:

World-renowned for their accurate, full-range sound, Blue Sky is pleased to introduce two new critical listening components to its full line of monitoring solutions: SUB 212 400-Watt Push-Pull Active Subwoofer and the SAT 8 300-Watt, Compact Mid-Field Monitor. The SUB 212 is designed to be an integral part of the monitoring system, enabling a studio monitor, such as the SAT 8, to be positioned for the best imaging, and the SUB to be positioned for the best bass response. Relieving the studio monitor of the requirement to reproduce the low frequencies means that the uncompromising sealed-box design can combine with sophisticated bass management electronics to provide a seamless transition between the SAT and SUB. When combined, the SAT 8 and SUB 212 provide a stunningly accurate and engaging, full-range monitoring system.

“Our customers were asking for a powerful system that was similar to the Sat 12 and Sub 15, but in a smaller package,” said Blue Sky Vice President Chris Fichera. “The Sat 8 and Sub 212 will address those applications.”

SUB 212 | Shown with Grille

About The SUB 212

Blue Sky’s SUB 212 is a sealed box, dual 12”, push-pull, 400-Watt subwoofer. It features an anechoic frequency response of 25Hz to 200Hz, +/-3dB. In addition, the SUB 212 also has built-in 2.1 bass management electronics with both a 4th order 80Hz Linkwitz-Riley low-pass filter and a 2nd order 80Hz high-pass filter that is perfectly matched to the response of the SAT 8 (the SUB 212 is also compatible with the SAT 12, SAT 6.5 and SAT 5).

The SUB 212’s unique “push-pull” configuration is designed not only to increase output, but also to reduce distortion. A push-pull subwoofer uses two drivers: one mounted facing forward, the second mounted backward with the magnet facing out. Utilizing two drivers doubles the maximum output, while the push pull configuration reduces even harmonic distortion. Typically, in a more conventional design, at high output levels, second harmonic distortion dominates the distortion spectrum of most subwoofer drivers and is caused by asymmetric operation of the suspension and magnetic structure. In simple terms; the output of the driver is slightly different when the cone is moving away from the magnet, as compared to when it is moving toward its magnet.

SUB 212 | Back Panel Electronics

Push-pull operation reduces this even harmonic distortion in a clever application of physics. As mentioned before, push-pull uses two drivers, one reversed from the other. The bottom driver has its magnet facing out of the box and is driven electrically out–of–phase from the front driver, which keeps both drivers acoustically in phase. However, when the front driver’s cone is moving away from its magnet, the bottom driver’s (reversed) cone is moving towards its magnet. This puts the even harmonic distortion components of the bottom driver out-of-phase with the front driver. When you combined the outputs of both drivers, the even harmonic distortion of both drivers cancels, reducing the overall distortion of the subwoofer.

SAT 8 | vertical configuration

About The SAT 8

Blue Sky’s SAT 8 is a three way, tri-amplified, 300-Watt, compact mid-field monitor which features an 8” high excursion hemispherical woofer, an ultra low distortion 4” hemispherical midrange driver, and a 1” dual ring radiator tweeter with integral waveguide, for superior off-axis response. To reduce destructive cabinet diffraction reflections, Blue Sky has developed and incorporated into the baffle, the proprietary “Multi-Aperture Acoustic Diffraction Absorber”, which helps to maintain smooth on and off axis frequency response throughout the critical MF and HF frequency range, without the need for a large wave-guide or horn.

SAT 8 | Back Panel Electronics

The SAT 8 is powered by a dedicated low distortion 100-Watt amplifier for the 8” woofer, a low distortion 100-Watt amplifier for the midrange, and a low distortion 100-Watt amplifier for the tweeter. The SAT 8 effortlessly delivers clean and accurate sound with a frequency response of 80Hz to 30kHz +/-3.0dB (200Hz to 15kHz +/-1.5dB), for full compatibility with Blue Sky’s SUB 15 Universal, SUB 212, SUB 12 and BMC (Bass Management Controller). The rear panel also has controls for “full space” (placement in a room) or “half space” (mounted in a baffle wall) operation, along with individual HF, MF and LF level trims, as well as controls for variable gain settings.

The SAT 8 is designed to operate both vertically or horizontally, thanks to the rotatable MF/HF plate.

To read about and see pictures of the first installation of Blue Sky’s SAT 8 and SUB 212, follow this link.

About Blue Sky:

Blue Sky International currently markets a wide array of award-winning, full-range monitoring systems. The Blue Sky core philosophy is the utilization of bass management technology with subwoofers to satisfy the demanding requirements of audio professionals. These systems are also ideally suited for those home audio enthusiasts looking for a superior sound experience.

Blue Sky International was founded, and is jointly owned by Group One Ltd. and Audio Design Labs Inc. The company was established by combining the marketing, sales and distribution expertise of Group One Ltd. with the knowledge and experience of Audio Design Lab’s award-winning design team. more »

For more information about Blue Sky International, please visit: www.abluesky.com

Read the complete press release by following this link to the Blue Sky website. »

Blue Sky International was founded, and is jointly owned by Group One Ltd. and Audio Design Labs Inc. The company was established by combining the marketing, sales and distribution expertise of Group One Ltd. with the knowledge and experience of Audio Design Lab’s award-winning design team. more »

What is the .1 / LFE Channel and why does it exist?

The .1 or LFE is a channel which is exclusively used for frequencies below 120Hz (below 80Hz for DTS). It is therefore a bandwidth limited channel, but it is not the same as the subwoofer, which is the speaker that typically reproduces the LFE channel in a home audio or studio monitoring system (more information is provided below). The purpose of this channel is to provide an additional 10dB of electrical headroom, for low frequencies, above the main channels. This is done by calibrating the acoustic playback level, so that it has 10dB of in-band gain above the other channels (fronts and surrounds).

Blue Sky | SUB 15 Universal

Click this link to view an image showing how the LFE is calibrated relative to the main channels.

The LFE channel was officially launched as part of the film version of Dolby Digital, although its lineage actually dates back to six track 70mm soundtracks, and was mainly designed to enhance low frequency sound effects, such as large explosions and other low frequency content, which exceeded the headroom of the main channels. Hence the name LFE, or Low Frequency Effects, and not low frequency bass channel. It is important to note that all of the five main channels in a 5.1 delivery format, such as Dolby Digital or DTS, are capable of handling full-range audio (20Hz to 20kHz) on their own, without using the LFE channel. Because of this, the LFE channel isn’t always used, as it is not required for full-range audio.

Typically, unless the recording is something like Tchaikovsky’s 1812 Overture and is recorded with REAL cannons, the LFE doesn’t need to be used in most music applications, but can be useful in film and multimedia applications where dramatic low frequency effects are often important (explosions etc.)

AN IMPORTANT NOTE: Depending on the playback system, such as when a two channel system is being used instead of a full 5.1 system, the Dolby Digital decoder may drop the LFE channel completely (poof!).  Therefore persons creating a Dolby Digital mix should not put relevant audio content exclusively in the LFE channel.

OK, so if the LFE is a channel and the subwoofer reproduces this channel, what is bass-management and how does it fit in to the equation?

Bass management uses filters to extract low frequency information from the five main channels and then reroutes that information, along with the LFE Channel in a 5.1 system, to a mono subwoofer (multiple SUBs can be used for higher SPL, or to improve frequency response over a wider area).

A ‘typical’ bass-management signal flow diagram can be seen by clicking this link.

Bass-management is a function of the playback or monitoring system, in the same way that a crossover inside a speaker is part of the playback or monitoring system. It is a somewhat confusing name, for something that is basically a summation and crossover network – no more, no less.

The reasons for using bass-management are pretty simple:  It extends the frequency response of speakers that are not capable of reproducing full-range audio.  Since most 2-way speakers and studio monitors aren’t full-range and most modern recordings are, we feel bass-management, in combination with a subwoofer, is an extremely useful technology.

Click this link to again view the calibration diagram, which was also linked in the previous section. This time take note of how the bass-managed subwoofer signal is calibrated to splice in and extend the response of the each of the main channel speakers.

So what is the correct bass-management crossover frequency for my surround system?

Because bass-management is a function of the speaker system, determining the best bass-management crossover frequency for your audio system is completely dependent on the type of speakers and subwoofer you are using.   If you are using a THX Certified home theater speaker system, or a THX pm3 approved studio monitoring system, then an 80Hz setting is typically desirable.  This is also the default setting for THX receivers, THX controllers and Blue Sky’s BMC MK II.

If you are not using a THX Certified or pm3 approved system, then you will need to check with the manufacturer of the speakers you are using to see which crossover frequency setting is correct. 

Additional notes:

• Certain receivers and controllers offer expanded options with regard to filter settings.  These settings may include individual controls for high pass and low pass filters.  For a THX Certified speaker system, or THX pm3 approved monitoring system, these should be set to; 80Hz, 12dB per octave High Pass and 24dB per octave Low Pass.   Again, if you don’t have THX certified or pm3 approved speakers, check with the manufacturer of your speakers to see which settings you should use.
• For additional information about the benefits of using bass-management and why it is incorporated into every Blue Sky monitoring system, please follow this link.
• For more information about Dolby, please visit www.dolby.com
• For more information about DTS, please visit www.dts.com
• For more information about THX, please visit www.thx.com

If you have comments, questions or suggestions, please don’t hesitate to contact ADL, or post them below in the comments section.

The reasons for the lack of improvement are complex and often vary depending on the content creator, broadcast network and even differences between national and local broadcast networks. To help understand what is causing these ‘issues’, it is probably best to first review one of the key technologies that is available today, to help mitigate this problem.  Dolby Digital, which is currently used as the preferred audio delivery format for many HDTV broadcasts, includes several unique features which are designed to help improve consistency between various broadcasts and other audio sources.

Dolby Laboratories realized a long time ago, that there can be radical differences between different types of sources, channels and content, and that it would be extremely inconvenient for a TV viewer to continually have to adjust the audio level while watching TV.  Because of this, Dolby Labs decided to implement a feature called “Dialogue Normalization”.  Dolby includes this feature in what is known as the “Metadata” of any Dolby Digital bitstream. Metadata is non audio information, which helps to describe the audio content in the bitstream to the Dolby Digital decoder in your HDTV, home audio receiver, etc.

Dialogue Normalization works by assigning a relative numerical value to the average dialogue level of a given program, commercial, movie etc.  This numerical value should be calculated using hardware or software tools offered by Dolby and is then encoded into the Metadata by the content creator or broadcaster.   The graph below (credit www.tvtechnology.com) shows some of the typical relative levels between different types of source material.  The black line and the numerical number next to that line, would be the dialog normalization level.

This numerical value is used by the Dolby Digital decoder to automatically adjust the level of the audio, so that during playback all these different types of program material have the same average dialog level.  The graph below (credit www.tvtechnology.com) shows the resulting adjusted level, which is automatically implemented by the the decoder.  Theoretically, and in practice when done correctly, the consumer would now not need to adjust the level between these different types of program material and they would perceive a very consistent level across all of these different types of program material.

So if Dialogue Normalization is such a powerful tool, why hasn’t the situation gotten any better, especially with the advent of HDTV and Digital Broadcast Television? The answer is complicated and there are many different possible causes.  Below are some of my theories:

• Certain content is purposely mixed to be perceived by the listener as being louder: Commercials have for a long time been mixed so that their average level is much higher.  Although the peaks are technically not louder, the content is compressed and the dynamic range of the content is very low, so it is perceived as being much louder by the listener.  This is often done by the creators of commercials so that their commercials ‘stand out’. Although dialogue normalization, when properly implemented, would address this problem, it is easy to manually assign a dialogue normalization value which would make the decoder play it at any relative level the content creator, or broadcaster would want.
• Lack of consistent production and delivery standards between TV broadcasters: Unlike the film industry, which has very rigorous calibration, production and playback standards & practices, many broadcasters have very unique delivery specifications, which can impact the accuracy of the Dialog Normalization levels and audio levels in general.
• Local broadcast affiliates: Although the major national broadcasters are improving their implementation of dialog normalization, during a national broadcast the local affiliates and cables systems play their own local commercials, which are inserted during the broadcast.  Often, and particularly in smaller markets, there is a lack of expertise and more often than not, a lack of hardware to properly support dialogue normalization.  If this is the case, the local feed may not be broadcast in Dolby Digital and there can be huge differences in level between local and national broadcasts.  This also applies to locally produced TV shows and news broadcasts, which in these smaller markets may not take advantage of Dolby Digital and its features.  With the transition to DTV in 2009, this particular issue should improve over time as local affiliates continue to upgrade their hardware and gain experience with these new tools.

So, how can we consumers, the content creators & broadcasters improve this situation:

• Complain: The first thing we can do as consumers is to complain to the local affiliates, cable systems, broadcasters, etc. Broadcasters won’t know about, or deal with a problem, unless they are receiving complaints. Many broadcasters, especially at the national level, want your feedback and this will add to the internal pressure to resolve these types of issues.
• Education: The industry as a whole needs to do a better job of educating themselves on the proper setup of audio systems, using recognized standards, and also learn how to properly implement features such as Dialog Normalization.
• Industry Wide Production, Delivery and Broadcast Standards: The film and movie theater industries used to have a tremendous problem with the sound level of movie previews, in much the same way as consumers do with TV commercials.  The typical way this was handled by the movie theater operators was to turn down the level of the previews, when someone inevitably complained.  Unfortunately, the level would rarely be turned back up for the feature and this often left the viewers with a less than engaging audio experience.  Producers & directors, upset about their movies not being presented at the proper playback level, along with the National Organization of Theater Owners, began to complain about this problem and the industry as a whole took steps to address the issue. The industry implemented a set of standards, through an organization called TASA, and today all previews are tested to conform to a certain playback level standard.  Previews that don’t conform to this standard are typically not shown in a movie theater. The lesson from the film industry is clear; broadcasters and content creators need to work together, with manufacturers and industry organizations, to develop standards and practices to address this problem.  Doing so will result in a much more engaging experience for consumers and will reduce their frustration with this annoying problem.

For more information about Dialog Normalization, please follow these links (updated 7/23/2008):

• A Closer Look At Audio Metadata, by Tim Carrol | www.tvtechnology.com
• Estimating Dialogue Loudness with Leq(A) or ITU-R Rec. BS.1770 | www.dolby.com
• Managing DTV LOUDNESS with dialnorm, by Jim Starzynski | www.broadcastengineering.com
• Dialogue Normalization: Friend or Foe, by Brian Florian | www.hometheaterhifi.com
  

This article was also published in the October 2006 edition of Resolution Magazine. You can download a PDF copy by following this link to the Blue Sky website (143KB Adobe Acrobat PDF).

Intro

About 8 years ago, my business partners at Blue Sky and I had a number of meetings to discuss designing a new series of studio monitors. After much debate, we decided there was little point in building another set of “me too” monitors, in the typical 5”, 6” and 8” 2-way configurations. What we felt was needed was a different approach that overcame some of the limitations of current monitors and provided tangible real world benefits to the recording engineer.

So where did we begin?

When creating the requirements for Blue Sky’s nearfield and mid-field studio monitors, we decided to start at the end of the chain and work backwards to the beginning.

Over the last 25 years audio technology has changed and improved dramatically. 25 years ago, people in their homes were listening to scratchy vinyl records and watching movies on analog cable or VHS, in mono. The speakers they used were what came built into their TV, or at best, stereo 2-way ported bookshelf speakers. In their cars, they had a choice of AM radio, FM radio, cassette tapes, or eight track tapes, which were played through 6 x 9 speakers with whizzer cones. Back then the typical 2 way studio monitor was much better than what the typical consumer had available to them for playback.

However, things have changed greatly since then and today’s consumer now has a dizzying array of choices, such as HDTV, digital cable, satellite TV, DVDs, MP3, video games, etc. All these sources are capable of high bandwidth, wide dynamic range stereo or multi-channel audio. Likewise, speaker technology has also improved with the utilization of stereo and 5.1+ speaker systems, with integrated subwoofers. Similar technology advances have occurred in the car audio world. Drivers now have access to CDs, DVDs, digital satellite and HD radio. And like the home, many autos now have complete, factory installed, stereo and 5.1 bi-amplified speakers systems, also with integrated subwoofers.

Following a parallel course, most studio equipment has improved much over the last two decades. With the introduction of digital audio workstations, hard disk recorders, digital mixers, all of which include high performance 24 bit ADCs and DACs, studios today can essentially record DC to daylight. Unfortunately, studio monitors in many studios have not kept up with this trend and in many cases seem to be stuck an infinite time loop. Like 25 years ago, many professionals are still mixing content for today’s consumer systems, on a set of conventional 2-way ported monitors, which tend to exhibit poor low frequency extension. Looking at this situation, we felt that there had to be a better way.

The ‘typical’ studio monitor, in a typical studio

So next we moved one step up chain, to examine the precise reasons why a typical 2-way nearfield monitor is no longer suited to the task of creating mixes destined for today’s consumer.

Almost all 2–way nearfield monitors are ported, use a 5”, 6”, or 8” woofer and have a low frequency cutoff between 38 and 65 Hz. Since ported designs roll off at 24 dB per octave, or greater, these monitors are incapable of reproducing much of anything from 20 Hz up to their lower cutoff frequency. This kind of performance was perfectly acceptable when consumer playback systems had similar performance limitations. However, since many of today’s consumers have full-range speaker systems with subwoofers, the typical 2-way ported design, just doesn’t cut it anymore.

The other problem is what happens when you place these monitors in a typical recording studio. Although major movies have their final mix completed on a large dubbing stage, typically with a volume of 20,000 cubic feet or greater, a lot more material is mixed in studios with an internal volume closer to 3000 cubic feet, especially for music, radio and TV applications. Unfortunately, as the physical dimensions of the studio get smaller, the acoustic conditions change as well. The biggest change occurs at low frequencies, which in a large space is an issue relating to low frequency reverberation time. When you move into a smaller studio, the main acoustic factor at low frequencies is room modes, or standing waves. Room modes occur in all rooms / studios at frequencies where the wavelength of sound is an integer fraction (i.e. 1/1, 1/2, 1/3, 1/4, etc.) of the distance between two walls, or the distance between the ceiling and floor.

Whenever you place a speaker in a small room or studio, its measured low frequency response will be altered by the boundary effects and room modes that form in the studio. This means that invariably some frequencies are reinforced and some frequencies are canceled, resulting in peaks and dips in the frequency response at the listening position. These frequency variations change depending on the location of the speaker and where the listener is located in the studio relative to the speaker and boundaries of the studio. Because of this, bass reproduction from multiple speakers in a studio can be very inconsistent. To add a further complication, the speaker location that is best for imaging is almost never the best place for bass reproduction. So given little choice, recording engineers choose imaging over low frequency performance.

Granted, the use of broadband absorption, which we consider very important, can reduce the effect of studio / monitor interaction to a degree and absorption can definitely be utilized to improve low frequency performance. But, in a typical small studio, broadband absorption will not a fully address these problems.

So what is the solution?

True full-range monitoring, is the phrase which best describes our goal. Not just full-range monitoring for those willing to spend huge amounts of money on large in-wall monitoring systems, but true full-range monitoring for all applications, from the desktop on up. The technologies we employed to achieve this goal are based on well understood principles of physics, are relatively simple to implement and deliver superior real-world results.

First, to provide real low frequency reproduction, reduce intermodulation distortion and to reduce the influence of the studio on low frequency reproduction, we decided to incorporate a subwoofer as an integral part of the monitoring system. This is in sharp contrast to an optional subwoofer added on to an existing “quasi full range” 2- way monitor.

The second improvement was to eliminate ports or passive radiators and go with sealed box designs. There were three reasons for doing so: One, sealed box speakers have superior transient response when compared to ported or passive radiator designs. Two, satellite speakers using the correct sealed box design integrate much better with a subwoofer than typical ported speakers. Third and last, the 12 dB per octave roll off of a sealed box subwoofer provides a better match to the rising low frequency characteristics of small rooms / studios. This ‘room gain phenomenon’, which was documented in an AES paper by Louis D. Fielder of Dolby Labs, shows that smaller sealed rooms, such as the typical music studio, exhibit a 12 dB per octave gain below 30 to 35 Hz. This ‘room gain’ response perfectly matches the sealed box response of our subwoofers, allowing for incredible in-room low frequency extension, down to below 20 Hz. Compare this to a typical ported or passive radiator roll-off of 24 dB per octave, or greater, and you can see why the sealed box response is a much better choice for accurate full-range monitoring in a typical recording studio.

The third improvement was to tie this all together with a technique called bass management or bass redirection. Bass management uses filters to extract low frequency information from two or more main channels and redirects that bass to one or more mono subwoofers. This is the same technique that is used in virtually all consumer home theater systems and many high-end car audio systems. Bass management when used in conjunction with satellite and subwoofer speakers provides a number of advantages. First since the satellite speakers do not have to reproduce low frequencies they can be smaller, which make them easier to place in the environment, and they can be placed for best imaging without worrying about how that would affect their low frequency performance. Second, since bass reproduction is coming from a mono subwoofer, the subwoofer can be placed in the optimum position in the studio so as to offer the best overall low frequency response. Thirdly, because low frequencies from multiple channels are now summed electronically, instead of acoustically in the studio, low frequency phase issues between channels are resolved in the most absolute and accurate way possible – electrically.

The critical final step

Now that we have a monitoring system which has the bass being reproduced by a separate source, we have to find a way to ensure repeatable and accurate setup of the system. We have found that many listeners can actually do this very effectively by ear, when using familiar broadband source material. However, to make this process a little more foolproof and repeatable, we provide a free set of wav test files which allow the end user to quickly adjust the electro-acoustic level of the system. These test files can be downloaded from our website. To use them, you just need an inexpensive SPL meter.

The purpose of calibration is to adjust the relative level of the SUB and SAT, along with the overall electro-acoustic system gain, so that 0 dB VU equals a certain acoustic level at the listening position. Since most recording media is now digital, the reference electrical signal level is typically around –20 dBfs with 20 dB of headroom. The acoustic calibration level may vary, depending on the application and standards being used. For film applications this level is typically 85 dBc, but because music is typically more compressed, a lower level, often around 78 or 79 dBc, may be more appropriate.

Once the calibration procedure is completed, the end user has a system which provides extended bandwidth, seamless summation between SAT and SUB, along with an overall more accurate and repeatable system response. We believe this new methodology, which is based on simple and proven technology, makes for a clearly superior monitoring system. This true full-range monitoring system design allows the engineer to create more compelling full-range mixes that translate exceptionally well to the wide variety of modern consumer playback systems currently available on the market.

click to download (Adobe / PDF)

To find out more about Blue Sky’s complete line of studio monitoring systems, follow these links to Product Reviews and Blue Sky News on the Blue Sky website.  To learn more about how ADL designs speaker and studio monitors, please follow this link. If you have any questions, or would like to find out what ADL can do for you, please don’t hesitate to contact us.

This article was also published in the October 2006 edition of Resolution Magazine. You can download a PDF copy by following this link to the Blue Sky website (143KB Adobe Acrobat PDF).

Instructions for electro-acoustic calibration of a professional stereo, 2.1 and 5.1 studio monitoring systems (speakers) using a SPL meter and ADL’s test files.  If you are interested in calibrating a home theater system, we recommend using the test signals and procedures included with your home theater receiver.

Before starting, download the ADLTestFiles.zip (15 MB). To download the zip file, “Right Click” and select “Save Target As” and the file will begin downloading.

Once downloaded, either burn the test files on to a CD or import them directly into your DAW and follow the instructions below.

Additional Required Items

• Stereo, 2.1 or 5.1 Monitoring System
• SPL Meter – such as the SPL meter sold by RadioShack in the U.S.

ADLTestFiles.zip Includes 4 files:

• 1000Hz SINEWAVE -20dBFS.wav – a 1kHz file recorded at -20dBFS for electrical calibration
• 40-80Hz PINK NOISE -20dBFS.wav – a 40Hz to 80Hz bandwidth limited pink-noise file recorded at -20dBFS
• 500-2.5kHz PINK NOISE -20dBFS.wav – a 500Hz to 2500Hz bandwidth limited pink-noise file recorded at -20dBFS
• Pink Noise full bw -20dBFS.wav – a full-bandwidth pink-noise file recorded at – 20dBFS

All the test signals were created and measured on the Prism Sound dScope III and conform to the AES 17 guidelines for digital audio measurements. Because pink noise has a high crest factor, the levels of the pink noise signals were made using a time averaging technique, where multiple time samples are captured and averaged over a ten second interval to calculate the RMS level. These test files are all mono files. Please make sure you hard assign them to the left and then the right, not both channels at the same time. If you are using a CD / CD player, use only one channel of the CD player.

Theory
The purpose of calibration is to adjust the overall electro-acoustic system gain so that 0dBVU of electrical signal level equals a certain acoustic level at the listening position. Since most recording media is now digital, the reference electrical signal level is usually –20dBFS with 20dB of headroom. The reference SPL  however can vary based on the delivery media and speaker type.

Please note that the bandwidth limited signals that have been provided, limit many of the room interaction affects often associated with measuring SPL and broadband pink noise.

*Also note that the LFE channel gain in 5.1 formats varies from 0 to +10 dB depending on the encoding format used.  This level is referenced to the bass-managed subwoofer level, which is listed as “SUB” in the chart below. Since the LFE channel is not calibrated as a separate entity, the LFE gain will not affect system calibration.  It is important not to confuse the bass-managed subwoofer calibration level with the LFE channel.  For more information about bass-management and the LFE channel, please follow this link.

The common calibration levels are listed below:

**IMPORTANT: When compared to movie soundtracks, music tends to be much more compressed, with reduced dynamics and greater overall level.  Because of this, music mixes may seem too loud when played back on a system calibrated for an 85dBc reference level. If this is the case, we recommend calibrating for a lower reference level, such as 78dBc.

All test signals are recorded at –20dBFS including the 1 kHz sine wave tone. The sine wave tone is used to set the electrical output level throughout the signal path, right up to the point you get to the speakers. While the various pink noise signals are used for acoustic measurements and calibration.

The following procedure assumes you are calibrating the system to 85dBc SPL. If you are calibrating to TV, etc. substitute the appropriate level from the above chart.

1. TURN OFF THE MONITORING SYSTEM (until step 4)
2. Remove all eq and dynamics from the signal path and set all controls to zero / unity gain. Play the 1kHz Sine Wave, hard assign it to the left channel only, and adjust the output fader so the so the output meter reads -20dBFS. If you are using an analog console or measuring the output of your D to A, set the output level to 0dB VU (typically 0dB VU is equal to +4dBu / 185 nanoWebers per meter / 1.23 Volts RMS – using a true RMS volt meter). Then hard pan the signal to the right channel output and repeat for the right channel. For a 5.1 system assign the channel to each output and repeat the adjustment procedure. Once calibrated do not move the output faders.
3. Mute everything and make sure the 1kHz tone is OFF.
4. Now that the system has been electrically calibrated, turn ON the SUB and SATs.
5. Assign the 500-2.5kHz pink noise signal to the left channel only. Make sure there is nothing coming from the right channel (or any other channels). Because this signal is bandwidth limited, you don’t have to worry about turning the sub off. There are two methods of setting the levels.
   1. If you have a master monitor controller, with individual channel calibration adjustments (such as Blue Sky’s BMC), you can set the monitor gain controls on each speaker at the reference / max gain position and then adjust the master level control for 85 dBc. Then mark that master monitor level as your ‘reference position’ and use the individual channel calibration adjustment on your controller, to calibrate the rest of the channels, as outlined below. This method may not always be practical and if your monitors have too much gain, may result in a in poor signal to noise ratio.
   2. The other method is to set master monitor level to the position you want as a reference level and then use the individual monitor gain controls, until you measure 85 dBc. If you use this method you should mark the knob position, on each monitor, with a grease pencil so you can always go back to the reference level if the knob gets moved.
      For either method:
      SPL should be measured at the mix position, with the SPL meter at arms length, with the microphone at seated ear height, angled at approximately 45 degrees, and pointed at the center point between the left and right speakers.Once the left channel is set to 85dBc, repeat this step for the right channel (and C, LS & RS in a 5.1 system).
6. Feed 40-80Hz pink noise signal to the left channel only. Adjust the subwoofer level control until the subwoofer reads 85dBc (slow) at the mix position. The meter will bounce around a little, so you will need to do a mental average (I tend to filter out the peaks in my mind, so I don’t set the sub too hot). The right channel should measure about the same and no additional adjustments need to be made.
7. You can play the full-bandwidth pink noise, assigning it to the left and then the right channel (not at the same time). You should measure about 85dBc. It may be a little higher, because below 30Hz the room may have a little extra gain.No adjustments should be made with Full Bandwidth pink noise, unless you have an RTA (real time analyzer).
8. You are finished and the calibration process has been completed – enjoy!

If you have any questions, please don’t hesitate to contact us, or leave a comment to this topic.