The most overrated technologies in the surround sound arena are the 7.1- and 6.1-channel formats (Surround EX, DTS-ES, etc.). These are marketing-driven upgrades that prey on the insecurities of technophiles. There is no reason to go beyond the 5.1 standard unless your home theater is the size of a cavern and has genuine coverage problems in the back rows. An average smallish theater with 3-5 seats per row does not need extra channels in the back (though a larger theater with 10 seats per row just might).
Three speakers in front, four in back -- what's wrong with this picture?!
5.1 forever!
Mark Fleischmann
5.1 versus 6.1 and 7.1
-
ISF Forum
- Archives
- Posts: 83
- Joined: Thu Mar 04, 2004 3:58 pm
- Location: ISF Calibrators Discussion
-
ISF Forum
- Archives
- Posts: 83
- Joined: Thu Mar 04, 2004 3:58 pm
- Location: ISF Calibrators Discussion
-
ISF Forum
- Archives
- Posts: 83
- Joined: Thu Mar 04, 2004 3:58 pm
- Location: ISF Calibrators Discussion
-
ISF Forum
- Archives
- Posts: 83
- Joined: Thu Mar 04, 2004 3:58 pm
- Location: ISF Calibrators Discussion
Hi Guys,I agree completely. Most rooms do not need more than 5.1. Of course I am a video engineer. My fear is that we may sound like the die-hard Two channel guys. (My most expensive speakers and processor are in my two-channel system, not my home theater)
While I can certainly I honestly have to agree with you, and I make my money selling loudspeakers now. No question, maintaining uniform frequency response from the surround speakers to main speakers is important in creating a convincing "sonic landscape." That said, I expect a home theater surround sound system to enhance the viewer's experience with the movie, not provide a separate performance of its own. In the broadest sense, movies are still means of communication. A director or storyteller may have us hung on a character's every word, draw us into the emotions of a situation, or even just give us a unique perspective in a documentary. Probably the first audio concern in communication is the intelligibility of dialog through any condition. Considering 99% of movie dialog originates on-screen or at least in the same plane as the screen, it is pretty clear that the front 3 channels and particularly the center channel should reciever a large percentage of our attention and efforts. Emotion and drama are typically accompanied by dramatic changes in sound requiring seemingly effortless dynamics and power to match the occasion. Even in this case, the surround channels can help envelop us in sound, but the power and drama can certainly be conveyed by a competent set of front three speakers and subwoofer. Even when the surround channels are called to action in transporting us to a very different place than where we are sitting they do so by supporting and augmenting the scene and sound directly in front of you.
Additional rear channels do certainly offer some benefits to many rooms, and when space provides can certainly aid in creating some very interesting effects which were intented, but we need to check our priorities. The marketing side of it serves many well, as it is much easier to just add channels and build more speakers than to improve the quality of the speakers or other components.
Echoing the comments of others, there are many other things to significantly improve before we bother introducing more speakers to the majority of home theater systems.
Mark Seaton
Sound Physics Labs/ ServoDrive
-
ISF Forum
- Archives
- Posts: 83
- Joined: Thu Mar 04, 2004 3:58 pm
- Location: ISF Calibrators Discussion
Let's talk about the front center
I was struck by this sentence in Mark Seaton's post: "Considering 99% of movie dialog originates on-screen or at least in the same plane as the screen, it is pretty clear that the front 3 channels and particularly the center channel should receiver a large percentage of our attention and efforts."
Right on. The front center speaker is neglected and should receive more attention. My take on this is that the horizontal design used for most front center speakers doesn't provide a perfect match for the front left and right. There are a few reasons for this, such as different woofer sizes, and the tendency of dual woofers to cancel each other out, creating an unevenness known as comb filtering.
Every time I review a set of surround speakers, I ask for both the horizontal center plus an extra clone of the front left/right. When I compare the two in the center position, the clone always sounds better, providing a more uniform and involving soundfield.
The best way to improve an average surround system is not to add more speakers in the rear but simply to match speakers all around.
Mark Fleischmann
I was struck by this sentence in Mark Seaton's post: "Considering 99% of movie dialog originates on-screen or at least in the same plane as the screen, it is pretty clear that the front 3 channels and particularly the center channel should receiver a large percentage of our attention and efforts."
Right on. The front center speaker is neglected and should receive more attention. My take on this is that the horizontal design used for most front center speakers doesn't provide a perfect match for the front left and right. There are a few reasons for this, such as different woofer sizes, and the tendency of dual woofers to cancel each other out, creating an unevenness known as comb filtering.
Every time I review a set of surround speakers, I ask for both the horizontal center plus an extra clone of the front left/right. When I compare the two in the center position, the clone always sounds better, providing a more uniform and involving soundfield.
The best way to improve an average surround system is not to add more speakers in the rear but simply to match speakers all around.
Mark Fleischmann
-
ISF Forum
- Archives
- Posts: 83
- Joined: Thu Mar 04, 2004 3:58 pm
- Location: ISF Calibrators Discussion
Ahh the center channel debate... Here's a can of worms which can certainly make for some interesting discussion!
Conceptually we would want the sound to eminate from the location of the image, but a perforated screen allowing this brings in other compromises which have to be dealt with. Once we accept that no ideal will exist, then we are able to better evaluate our options, and decide on a solution.
The common center channel for home theaters started life as a solution to an application, not as an ideal. The problem is simple. We needed a speaker which can fit above or below a video display. The first option was to just turn a speaker on its side, but then things feel rather unbalanced visually, and in many cases were sonically unbalanced as well. Enter the horizontal MTM.
The first question should be "can this be made to work?" Yes, but driver sizes and spacing make things difficult and most solutions require compromises. The most significant problem which a designer needs to work with is the spacing of the woofers and the tweeter in these systems. Two horizontally spaced woofers CAN work just fine, but the distance between the two woofers dictates how high in frequency they can be used. While small problems are observed directly on axis, the majority of problems occur off axis in the horizontal. At crossover frequency, any dome tweeter will have very wide dispersion. The top end of the the horizontally spaced woofers will have a response which changes with horizontal angle above some frequency related to their spacing. Uniform and smooth response can only be achieved in the area where both the tweeter and bass drivers have constant response.
While graphs of this type are not commonly viewed in home audio applications, it quickly lends a visual to what is going on with the interaction between two spaced drivers. While the below example is for woofers at 9' spacing, the effect is directly scalable to a 9" spacing by multiplying the frequencies by 12. The separation distance dictates the frequency at which these effect occur, not whether or not they occur.
Subwoofer Spacing by Charlie Hughes
http://www.mississippi.net/~charlie/Art ... acing.html
If you study the above plots enough it can be understood that for an MTM speaker, the woofers need to be as close as possible, and the tweeter to be crossed over as low as possible. Both of these goals have consequences. Tweeters will have increasing distortion and lesser output capability as the crossover is lowered. Placing drivers close requires modest diameter drivers which will have bass output limitations, and a small face tweeter which further limits options. I recall back when I was still doing the retail thing that some of the first set of front speakers that seemed to actually "gel" together had similar qualities like the NHT VS-2 which used a small face tweeter with the woofers crammed as close together as possible.
As home theater grew attention was finally focused on the performance of a center channel, and we saw the entry of Aerial Acoustics and Revel with larger, 3 way center channels. I do recall the first time I heard a CC-3 with a matched right and left, and thinking "now this is what it is supposed to sound like!" One of the strongest benefits of these 3 way designs is the ability to use the same/similar tweeter and midrange compliment which are also oriented the same as the matching left and right speakers. This way both the on axis sound along with the off axis are quite similar. In these 3 way designs the woofers are only used below a few hundred Hz, where we can see from the graphs referenced earlier that they operate essentially as one source. What we find is that a horizontal woofer configuration results in little difference from a vertical configuration aside from the interaction of each with the room. The room interaction difference cannot really be solved unless you place the speakers at similar locations(relative to height for example).
In defense of using more surrounds, we should acknowledge one definite advantage. Our surround system strives to create the acoustics of a space within our theater. The most significant hurdle to accomplishing this is that the system has to operate in the acoustics of your own space. More speakers in different locations will give the system more dominance over the acoustics in the rear of the room. Of course a little room treatment would probably still provide even better gains... for less money.
Regards,
Mark Seaton
Sound Physics Labs/ ServoDrive
The first thing which needs to be set straight is that there is no such thing as a "no compromise" home theater design. If we did everything possible to optomize the audio performance within a given space, we would then end up messing things up when we have to place that pesky screen at the front of the room.Right on. The front center speaker is neglected and should receive more attention. My take on this is that the horizontal design used for most front center speakers doesn't provide a perfect match for the front left and right. There are a few reasons for this, such as different woofer sizes, and the tendency of dual woofers to cancel each other out, creating an unevenness known as comb filtering.
Conceptually we would want the sound to eminate from the location of the image, but a perforated screen allowing this brings in other compromises which have to be dealt with. Once we accept that no ideal will exist, then we are able to better evaluate our options, and decide on a solution.The common center channel for home theaters started life as a solution to an application, not as an ideal. The problem is simple. We needed a speaker which can fit above or below a video display. The first option was to just turn a speaker on its side, but then things feel rather unbalanced visually, and in many cases were sonically unbalanced as well. Enter the horizontal MTM.
The first question should be "can this be made to work?" Yes, but driver sizes and spacing make things difficult and most solutions require compromises. The most significant problem which a designer needs to work with is the spacing of the woofers and the tweeter in these systems. Two horizontally spaced woofers CAN work just fine, but the distance between the two woofers dictates how high in frequency they can be used. While small problems are observed directly on axis, the majority of problems occur off axis in the horizontal. At crossover frequency, any dome tweeter will have very wide dispersion. The top end of the the horizontally spaced woofers will have a response which changes with horizontal angle above some frequency related to their spacing. Uniform and smooth response can only be achieved in the area where both the tweeter and bass drivers have constant response.
While graphs of this type are not commonly viewed in home audio applications, it quickly lends a visual to what is going on with the interaction between two spaced drivers. While the below example is for woofers at 9' spacing, the effect is directly scalable to a 9" spacing by multiplying the frequencies by 12. The separation distance dictates the frequency at which these effect occur, not whether or not they occur.
Subwoofer Spacing by Charlie Hughes
http://www.mississippi.net/~charlie/Art ... acing.html
If you study the above plots enough it can be understood that for an MTM speaker, the woofers need to be as close as possible, and the tweeter to be crossed over as low as possible. Both of these goals have consequences. Tweeters will have increasing distortion and lesser output capability as the crossover is lowered. Placing drivers close requires modest diameter drivers which will have bass output limitations, and a small face tweeter which further limits options. I recall back when I was still doing the retail thing that some of the first set of front speakers that seemed to actually "gel" together had similar qualities like the NHT VS-2 which used a small face tweeter with the woofers crammed as close together as possible.
As home theater grew attention was finally focused on the performance of a center channel, and we saw the entry of Aerial Acoustics and Revel with larger, 3 way center channels. I do recall the first time I heard a CC-3 with a matched right and left, and thinking "now this is what it is supposed to sound like!" One of the strongest benefits of these 3 way designs is the ability to use the same/similar tweeter and midrange compliment which are also oriented the same as the matching left and right speakers. This way both the on axis sound along with the off axis are quite similar. In these 3 way designs the woofers are only used below a few hundred Hz, where we can see from the graphs referenced earlier that they operate essentially as one source. What we find is that a horizontal woofer configuration results in little difference from a vertical configuration aside from the interaction of each with the room. The room interaction difference cannot really be solved unless you place the speakers at similar locations(relative to height for example).
While two speakers can be "matched" to sound quite similar with careful design, for many speakers this only holds true for a limited angle or area in front of the speakers. Off axis there will be differences, and the differing box sizes cause reflections to occur at different frequencies. The more reflective your listening room, the more significant the off axis response becomes. Using 3 identical speakers insures that the on and off axis response of each speaker is the same. There are still problems that arise from the locations we end up placing the speakers, yet the effect is still much more convincing.Every time I review a set of surround speakers, I ask for both the horizontal center plus an extra clone of the front left/right. When I compare the two in the center position, the clone always sounds better, providing a more uniform and involving soundfield.
When I design a surround sound system I usually first consider the quality and robustness of the center channel and then make sure the right and left match appropriately, followed by examination of the subwoofer which can relieve the workload of every main speaker when of sufficient quality. From there then I will see what sort of solution I can come up with for the surrounds.The best way to improve an average surround system is not to add more speakers in the rear but simply to match speakers all around.
In defense of using more surrounds, we should acknowledge one definite advantage. Our surround system strives to create the acoustics of a space within our theater. The most significant hurdle to accomplishing this is that the system has to operate in the acoustics of your own space. More speakers in different locations will give the system more dominance over the acoustics in the rear of the room. Of course a little room treatment would probably still provide even better gains... for less money.
Regards,
Mark Seaton
Sound Physics Labs/ ServoDrive