So, we’re diving into the deep end of the pool with a REL 3D Theater system, which consists of a front subwoofer, a center subwoofer, and a rear subwoofer. Why? Because it allows us to lay out a number of basic principles that operate quite differently from the somewhat dumbed down approach that mid-fi uses to approach home theater. Systems that can do both theater and music well tend to be capable of accurately rendering all manner of vocal timbres correctly—which is necessary for intelligibility—and accurately scaling dynamics in a natural manner, which is again necessary for both genres. These systems are generally capable of safeguarding long-term enjoyment, meaning that the audience isn’t drained from having been sonically pummeled throughout a two-hour long movie—instead having been thrilled, moved, and appropriately emotionally affected by each scene.
We build systems based largely on what a professional transfer studio or screening room would use, meaning using the best practices approach rather than the lowest common denominator approach. Do not, for a moment, presume that this requires driving the cost of building a great home theater crazy. This blog is dedicated to those enthusiasts looking to obtain the highest level of sound quality from their theaters—deliberately intending to maintain high quality, full range, music reproduction as a priority, in addition to creating theaters that are capable of far more than simply utilizing the large-scale bombastic and obvious approach that dominates our industry (although we can bombast with the best of them!). After we get through building out the paradigm, we’ll scale back and look at simpler versions of theater constructs. Here we go:
Content:
- Meeting Dolby Criteria
- How Does REL 3D Achieve Dolby Standards?
- Walking Through REL 3D Set-Up
- Final Thoughts
Meeting Dolby Criteria
REL 3D: REL 3D is the simplest, most cost-effective method we could devise to meet the Dolby criterion for 5.1 systems (and subsequent evolutions) at the lowest price. Dolby is a brilliant company, arguably the smartest of all; they have authored over hundreds of patents over the course of their 50+ year long history. When they created Dolby 5.1, it was an outgrowth of Dolby’s Spectral™ patent that was developed for professional theater applications. Marketed as Dolby Digital (DD), it debuted in the 1994 movie Speed; within one year, three major studios had announced that all future releases would be DD-only, a tradition that carries on to this day. The consumer version (DD AC-3) called for five independent channels with a bandwidth of 20-20,000 Hz along with a Low Frequency (Special) Effects channel with a bandwidth of 20-120 Hz. Later, the frequency range was expanded to include frequencies as low as 3 Hz, although the merits of attempting to deliver frequencies this low in a home environment are debatable. The solution we came up with is REL 3D, ensuring users get the best home theater experience possible at the most affordable price.
Full Disclosure: REL 3D is designed to deliver true full-range performance at an accessible price point, even if that means working within the practical low-frequency limits that real-world rooms impose rather than chasing spec-sheet numbers. Even in the world of expensive subwoofers, true 20 Hz in-room response is rare—and please don’t write to quote some mid-fi company’s nonsensical spec of promising sub-15 Hz bass at $800; it’s a lie. However, real world usable response between 25 and 32 Hz is achievable in the wonderfully accessible T/i range. This means you can explore some pretty epic home theater improvements with reasonable investments. At REL, we took all this in and asked ourselves the basic question: how can we take these daunting standards and deliver the true full range sound for all five channels plus a .1/LFE channel—more on this in a moment—as Dolby intended? Apart from one pair of speakers that, at the time of writing this, sell for $720,000 per pair, we know of no full range speakers capable of flat output to 20 Hz in a real-world setting. Back here on planet Earth, we arrived at the following as the simplest, most effective way to deliver on the promise of Dolby 5.1/DTS. It is important to realize that Dolby ALWAYS conceived of the .1/LFE channel as unnecessary to the story-telling main purpose of a movie and expects the main channels to carry the primary burden of delivering bass—whether there be five, seven, or nine.
From Dolby Labs: To avoid confusion, a clear distinction is made between Low Frequency effects, which may be contained on a separate .1/LFE channel, and the radiation derived from the program content at low frequencies—which is typically reproduced by one or more subwoofers dedicated to this purpose. Although these signals seem to be one and the same, they do not need to be. This confusion about the management of low frequencies causes a large number of problems in practical situations.
From Tomlinson Holman (inventor of Lucasfilm THX sound system): The .1/LFE channel provides non-essential low frequency content, and though many home theater subwoofers focus on only delivering LFE channel bass, a REL subwoofer connected High Level and LFE, (especially in a REL3D system) can deliver more than just the LFE channel. That said, the reproduction of this channel is not essential to enjoyment of the program, leading to the most important recommendation for our moviemakers out there: DO NOT record essential story-telling sound content in the .1/LFE Channel.
Now let's dive deep into setting up a REL 3D system.
What Is REL 3D – And How Does It Achieve Dolby Standards?
Paradoxically, REL 3D is not a visual effect; the “3D” represents the minimum quantity of 3 subwoofers required for all channels to achieve full range—or near full range—capabilities. It’s also a tongue-in-cheek reference to how the sound surrounds you, making it feel immersive and three dimensional. It’s best to think about your theater system in 3 parts: main speakers, center channel, and rear channels. This is the minimum number of speakers required to achieve true surround sound, and any additional channels are derived from these 3 categories. So, to create REL 3D is simple: use a subwoofer to supplement each of these three speaker categories, with one subwoofer each for your main speakers, center channel, and rear channels. Once you have done that, granted your subs are connected to High Level inputs and your processor has been configured as Large for each channel, all speakers will be playing full range—just as Dolby intended.
RELTip: Connection methods differ when using REL’s HT line, because HT models do not have a High Level input. For HT subwoofers, you would need to set your main and rear speakers to Small and utilize a low crossover setting for each channel; anything lower than 60Hz will sound great. The HT subwoofer for the center channel should be connected to the center channel output and set to Large, though please note that a Y-splitter is required to go from a single-ended RCA to a 2-plug RCA to ensure compatibility with a REL. If your processor has multiple subwoofer outputs that you can assign, that’s even better. Please contact REL support if you need any additional help configuring HT into a REL 3D set up.
Walking Through REL 3D Set-Up
Main Speakers
Through no fault of their own, proper placement of main speakers means that few quality speakers deliver output significantly below 40 Hz in room, as opposed to the anechoic chambers that mimic output in free space without the limitations of normal room boundaries. To expand that output to be functionally full range (approaching the 20-20,000 Hz ideal), use one or more RELs connected to High or Low level inputs in a Dolby 5.1 system, with speakers set to Large. This typically allows for the low frequency limit to extend into the mid-20’s.
In REL 3D, these RELs will be your main subs, matching and extending the capabilities of the main speakers. They will generally be the largest, most capable sub(s) in the system.
Placement Guidance: If you plan to use one subwoofer, select the stiffest, structural corner of the front of your theater to place it for the most immersive experience. In our example, the main G-1 is placed in a corner that has an external wall with a thickness of well over 1 foot and is built using solid masonry construction—giving excellent launch characteristics to bass transients. Toe-in—that is, angle inward—all RELs toward listening chairs where possible to maximize sound quality.
Connection: Both the High Level and .1/LFE inputs should be connected; if High Level input is impossible due to the use of some unusual amps, or any similar issues, please use Low Level inputs with .1/LFE.
The Center Channel
The center channel also carries the requirement to be a full range channel, meaning that, generally speaking, we find this to be an area where one of our smaller subs works well—no need to have identical subs at every station. This subwoofer may be and often is placed—for both practical and aesthetic reasons—a bit off-axis from the actual center channel speaker.
Placement Guidance: Place the center channel on the front wall underneath the screen facing forward, within the central two thirds of the room, using standard REL guidance for voicing placement. Use rhythmic, deep bass programming material to best locate the best spot for overall performance. For both practical and aesthetic reasons, this subwoofer is often placed slightly misaligned with the center channel speaker.
Connection: This sub should be connected through High Level inputs only—do not connect this subwoofer to .1/LFE; if High Level input is impossible due to the use of some unusual amps, or any similar issues, please use Low Level inputs.
Surround Channel(s)
The surround matrix is responsible for creating the vast spaces necessary to project scale in all sorts of scenes—which, isn’t it funny that it is sound that is used to convey the empty vastness of deep space? Full marks if you recall that there is no sound transmitted in the perfect vacuum that is space—and per Dolby spec, these surround channels necessarily comprise a full range group of channels ranging 20-20,000 Hz. A fairly large REL(s) is needed to properly convey the sense of scale needed to keep up with state of the art surround sound, meaning this unit should be the second largest model in the REL 3D set-up. For example, if you are using a T/9x as the subwoofer for your main speakers, a T/9x or T/7x are both perfectly adequate for your surrounds—whereas a T/5x would work well, but would result in sacrificing some of the extension that’s important for the rear subwoofer, especially as it supports the .1/LFE channel with the main subwoofer.
Placement Guidance: Ideally, place the surround subwoofer in the diagonal corner on the opposing side of the main sub. If your main subwoofer is in the left front corner, the rear surround sub would be best placed in the right rear corner. Again, carefully toed-in towards the main listening position is preferred if aesthetic concerns can still be met in doing so.
Note: The most common mistake is using too small a sub—or no sub—for the surround channels. This mistake begins with clients thinking they can skimp on surround channels, aided and abetted by similar advice from mainstream media parroting this same nonsense.
Connection: Both High Level inputs and .1/LFE should be connected; if High Level input is impossible due to the use of some unusual amps, or any similar issues, please use Low Level inputs with .1/LFE.
RELTip: Often placement, especially regarding running cables to the back of the room, is difficult. We have taken to highlighting one of our uncompromising wireless systems: Arrow, HT-Air MKII, or Airship Direct. Utilizing one of these, though not appropriate in all circumstances, can also be far less costly than running cables under base boards, down through crawl spaces—so on and so forth.
Master Your Setup
In the past 20 years that we have travelled the world teaching, calibrating and demonstrating the REL 3D approach, the most common experience shared with us is that this approach restores the liquid, full range bass that common mid-fi based systems strip out—placing the theater participant in the midst of a truly 3-dimensional sonic envelope that is highly addictive. Our REL 3D walkthrough, then, outlines the basics of how to develop a system capable of meeting the broad outlines of the Dolby standard, allowing for a few Hertz here and there to permit customers of widely varying budgets and room sizes to still participate in the wonderfully captivating world of high-end theater in one’s home.
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