The center channel and its unique horizontal design is an unmistakable centerpiece of most multi-channel set-ups. Designed to fit neatly above or below a screen, it’s tasked with carrying a tremendous amount of audio information including dialog, movie sound effects, and music, making it a key piece of equipment. We recently caught-up with Smith Freeman (Director of Product Management, SVS) to discuss center channels, how they should be integrated, and what SVS’s product line has to offer. Smith is a long time audio enthusiast with advanced degrees in Physics and Acoustics from Johns Hopkins University, and is responsible for the engineering and design of all SVS products
. His passion for high performance audio combined with his extensive acoustic and mechanical engineering experience are applied on a daily basis to ensure every SVS product meets the highest standards of design excellence.
Home Theater Shack: What is the primary function of the center channel speaker? How has SVS designed its center speakers to provide optimal performance of that function?
Smith Freeman: Typically a surround sound presentation will have as much as 70% of the key audio information passing through the center channel, as that will contain most dialog, front effects, and music. Likewise, the center channel acts as an acoustic bridge between the Front Left and Front Right speakers to allow acoustic events and objects to move seamlessly across the screen between channels. For those reasons we designed the SVS Ultra and Prime Centers to do those exact tasks effortlessly and with complete balance with the rest of the system. The vertically aligned tweeter and midrange in both models are arranged as such explicitly to present midrange and upper frequency information without any lobing or distortion. We flank the tweeter and midrange with larger woofers to provide low frequency information and deep base, ensuring the speaker performs in a full-range manner when music or sound effects require it.
HTS: Besides form factor, what differentiates a dedicated center channel speaker from a conventional bookshelf speaker? What are the advantages of a purpose-designed center?
SF: Any well designed speaker should be able to perform the duties of a center speaker, but the form factor of a dedicated center speaker allows it have more flexibility with being positioned above or below a TV. While some center speakers are explicitly designed for vocal performance, ours are very musical as well. For that reason we have made our center speakers great for movies, games, and multi-channel music. We also took time to ensure that it performs great above, below, or behind a display. There is no guarantee that a customer will place the speaker perfectly behind an acoustically transparent projection screen, so we have to be sure that our center speakers will allow an acoustic image to track correctly regardless of vertical position. This is another reason why we use a true 3-way design in both Ultra and Prime series center speakers.
HTS: What should enthusiasts look for when buying a new or upgraded center channel? Must they always be looking for a matched system?
SF: We recommend staying within one brand of speaker across the front, if possible. Typically, a brand will also recommend you stay within a product line, but we wanted to make it easy for SVS customers to mix-and-match between the Ultra and Prime product lines. If you have specific space or budget constraint, we’ve made it easy to build the multi-channel system that works best for you. When upgrading a center channel speaker
, you will see the quality of the components and the size of the drivers increase. For example the midrange and bass drivers on our Ultra speaker are larger than those on the Prime, which present deeper bass, higher SPL and an all around higher-grade performance.
HTS: Do you recommend a 3-channel setup over phantom mode for rooms where 5.1 is not possible?
SF: We understand that not every room is destined for a full surround sound system. Each speaker serves its purpose and it often becomes a question of what fits where? While the rest the Ultra and Prime speakers do a masterful job of presenting the “phantom center”, it is still a huge performance increase when a dedicated center speaker is added. This takes a lot of load off the front speakers, and can really enhance the sense of space and depth in a surround sound system.
HTS: If a buyer is looking to add a center to an existing stereo setup, what criteria should they use to achieve the most seamless match?
SF: The most important thing in making sonic cohesion between channels is working with similar drivers, especially between tweeters and mid-range woofers which have the highest impact in determine a speaker’s acoustic signature. Using the same sized and material dome across all our tweeters is how we keep cohesion between the Ultra and Prime Series. Likewise, using the same family of woofer motor parts and driver geometries is critical for family voicing. Internally, we use nearly identical crossover topologies and similar crossover points between drivers to ensure each driver is being used efficiently and in a similar fashion across models.
HTS: What are SVS's priorities when designing center channels? Do they differ from the approach used for bookshelf and tower speakers?
SF: Like any good quality speaker the center speaker also should be acoustically invisible. A proper design should minimize distortion and anything that could color or alter the subject material. Beyond that, a center speaker should absolutely have a wide and flat frequency response and good SPL performance with minimal distortion. Since center speakers are somewhat position ambiguous, it becomes that much more critical to avoid lobing or irregularities in the dispersion characteristics. There is nothing worse for your family, if the center speaker is not presenting the acoustic information evenly throughout the various listening positions.
HTS: In terms of SVS’s center channels, how should owners optimize placement the speaker? Both models are physically large and might not fit in popular AV/entertainment racks…should they be stand mounted?
SF: Stand mounting a center speaker, if there is space, is a great way to ensure you get the best performance from your center speaker relative to your room and listening positions. Likewise, if using a projector and an acoustically transparent projection screen, placing the center speaker at ear-height behind the screen is ideal. If neither of those is possible, our center speakers fit great on top of an entertainment cabinet or easily on a shelf mounted above or below the TV screen. Either way, your ears will easily track the acoustic image.
HTS: Enthusiasts are routinely told to place main speakers so that tweeters are approximately ear height. With the exception of a front projection setup, the same is rarely achievable for a center speaker in an average home. What is optimal center speaker placement under real world conditions?
SF: As I mentioned, the optimal center speaker position would be at ear level, centered in the middle of the screen, and on the same plane as the other speakers. This emulates what is done for both movie theaters and recording studios where the master recording is mixed. Since this is rarely possible in most homes, we all have to find what makes the most sense for our living and family spaces. At a minimum, you will want to keep the center speaker centered vertically below or above your screen. Ideally, you would be able to place the center speaker as close to the screen or close to ear height as possible. Essentially you want the acoustic image to resemble where your eyes are focused as closely as possible, but since we do not localize sound vertically as well as we do horizontally, the vertical position of the center speaker can be adjusted according to the application in the home.
HTS: What frequency does SVS suggest as the crossover setting for systems without a subwoofer? Both the Ultra and Prime claim to extend down to 45-48 Hz respectively; should the center present bass?
SF: While both center speakers could perform comfortably with a crossover setting at 50Hz, we often see that some Room EQ systems like Audyssey, depending on the room, will set the frequency as low as 40Hz or as high as 60hz. None of which should be a problem. If you are not using a room EQ system, we recommend starting at 50Hz and judging the blend with your subwoofer
HTS: Let’s finish up by talking specifically about SVS’s Prime and Ultra center speakers. What are the key differences between the two?
SF: Both Ultra and Prime Centers are designed around a genuine 3-way design with a dedicated mid-range driver below the tweeter in its own acoustically sealed chamber, and flanked by two ported bass drivers, all using premium grade cross-over components to divide the side to its respective transducer. Not to mention the Prime Tweeter is heavily based around the Ultra tweeter, which is a critical way that we keep similar voicing across both product lines. Visually, the Ultra Center Channel Speaker
is a much larger cabinet with more extensive chamfers and internal bracing while also employing beautifully hand machined aluminum trim rings across all drivers. The Prime Center uses a 3.5” mid-range versus the larger 4.5” in the Ultra with a cast aluminum frame, and composite glass-fiber cone. This larger mid-range presents more of the vocal range with greater ease due to its larger size and larger motor. Likewise, the Prime Center uses two 5.25” woofers, which extend the speakers frequency response to about 48Hz. The Ultra Center again increases the size of the flanking woofers to 6.5”, again with cast aluminum baskets and composite glass-fiber cones, which increases the SPL output and the low frequency response to about 45Hz.
Image Credits: SVS Sound