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Blu-Ray Audio: The latest gimmick? - Page 6

post #76 of 129

I haven't had the chance to read through the thread yet, but I just came across this:

https://shop.klicktrack.com/2l/35847/?

Quote:
 Blu-ray is the first domestic format in history that unites theatre movies and music sound in equally high quality. The musical advantage of Blu-ray is the high resolution for audio, and the convenience for the audience as one single player will handle music, films, their DVD-collection and their old library of traditional CD. What we are seeing is a completely new conception of the musical experience. Recorded music is no longer a matter of a fixed two-dimensional setting, but rather a three-dimensional enveloping situation. Stereo can be described as a flat canvas, while surround sound is a sculpture that you can literally move around and relate to spatially; with surround you can move about in the aural space and choose angles, vantage points and positions.

 

 

So it's saying Blu-Ray supports 5.1+ surround sound?

ヽ(´ー`)┌

post #77 of 129
Quote:
Originally Posted by bigshot View Post
 

I started with the auto EQ feature on my receiver. That did OK with EQ, but the volume levels of the channels were all wonky. Next I fine tuned by ear using good classical music recordings. I adjusted everything in sweeps, not all at once. I started with the relative volume levels of the channels, then I adjusted EQ on the mains, then the center, then the rears. EQing changed the overall volume levels, so I swept through that again. Then back to EQing. Back and forth, because each adjustment affected all the other adjustments. I would go through tweaking all the channels, then listen to a variety of recordings for a few days. When I figured out what needed work, I would tweak that and go back to listening. It took dozens and dozens of go rounds over a period of several months with progressively smaller and smaller corrections. Kind of like parallel parking. Lastly, I fine tuned the levels of the 7:1 stereo DSP relative to discrete 5:1 content, found the best multichannel decoder for movies, and worked with the level of the sub to get it to hand off smoothly. It was a very long process. Now that I have it where I want it, I need to go through all the menus and photograph the settings so I can recreate it if the amp loses the settings.

 

What it started out sounding like, and what it ended up sounding like was quite different. Now, just about anything I play sounds good, and the sub never blows the roof off when I put on a modern action movie. The soundstage across the front is very defined, evenly spread across the three channels, and feels like it has depth. When I play a 5:1 movie, the dialogue is perfectly balanced and the rears don't jump out.

 

I have better speakers that I plan to swap in for my rears, but I have to figure out how to mount them on the wall so they won't come crashing down in an earthquake. When I put those in, I suspect it will require a good amount of rebalancing.

 

I can go into more detail on my balancing process if you're interested. I learned an awful lot about how 5:1 and the various DSPs work.

 

I certainly admire the amount of work you were willing to put into this process. Not sure I would care for the result, but I certainly can understand how much you must like it because it bears your taste in sound each step of the way. True enough, I have never heard of anyone setting up a system in this way, generally the technique involves either measurement or auto EQ or both with the idea that objectively "flat" EQ is the way to go, it would appear that your method is basically subjective (I don't mean that in a pejorative way).

 

I still don't think this would be to my taste or jive with my take on how live acoustic music in a concert hall sounds, but I am sure it would be an interesting listen.

post #78 of 129
Quote:
Originally Posted by bigshot View Post
 

 

Actually, it does include many of those. Yamaha has settings for the Vienna and Berlin Philharmonic halls, as well as several clubs and small theaters like the Bottom Line, The Roxy, etc.

 

Not sure I would consider a dozen "many", LOL.

 

No "real" music performance space has all the sounds of the musicians coming from two wooden boxes set ten feet apart. That's basically 2 dimensional sound. Adding rears allows you to create a sound field that allows a 3 dimensional feel. A center channel lets you open up the soundstage wider than just ten feet. That is MUCH more "real" than just 2 channel stereo. Also, any home audio presentation is an approximation, and processing of one sort or another is required to make the presentation as real as possible. It's how you pick and choose how you apply that processing that makes the difference. Yamaha's 7:1 Stereo DSP makes regular stereo sound like a live performance, and that's the ultimate goal I would think.

 

"Real" music of the acoustic sort is not the same as ANY method of reproduction. Live is live and you are just using more wooden boxes*. But to me, in the context of music reproduction in the home, "real" means to try and reproduce, as much as I can, what I would have heard had I been at the concert hall the day the recording was made. Generalized processing may make an effect you like, but that doesn't have much to do with the actual sound at the venue that day. To me, for better or worse, the recording is what we have to work with. Some are very good, some not so good, some poor. But it's the only reality left to us of that performance. If verisimilitude to the original performance is our goal, it's in what was captured by the mics. This may seem old-fashioned and hairshirt to you, but it's what I believe and what has been true in my experience.

 

Just taking a stereo signal and patching direct through an amp to two speakers doesn't guarantee realism. That's a mechanical and dogmatic way of thinking about sound and it just doesn't work for a dozen different reasons. However, multichannel audio is MUCH more difficult to set up and tweak, and it requires a larger space. If a 5:1 system isn't properly set up, it can sound worse than 2 channel stereo. That appears to be what you've heard before.

 

Nothing guarantees sonic realism, real is real. It's just a matter of what one believes gets us closest to that goal. What I believe may be dogmatic, but no more so then your way, which sounds generally like a dogma of your own making. And why not? You don't have to like what the general considered wisdom of music reproduction offers.

 

I agree on one thing, multichannel sound requires a MUCH larger space to even start to come into it's own. Which is a reason it's impractical for most of us. I can afford the audio equipment you disapprove of, but I can't afford a seven-figure home for my surround system  :redface:

 

* Actually, neither the Magnepans I was using at the time or the speakers in my main system now are wooden boxes, come to think of it...


Edited by k3oxkjo - 10/23/13 at 1:30am
post #79 of 129

I don't think auto EQ really works, except in the most general of terms. EQ and channel balances affect each other. If one channel is slightly louder, the EQ is thrown way off. With all the variables with speakers and room acoustics, I just don't think auto EQ does what it is supposed to do very well.

 

A friend of mine is a sound mixer for live shows, and he's worked with installations that were calibrated by extremely expensive pro audio equalization systems. He always runs a tone sweep to double check and ends up making some pretty large adjustments. Apparently most sound mixers just use auto EQ as a jumping off place. They do the rest of the tweaking by ear.

 

My goal is pretty simple. I just want my music to sound good. I've learned through the years that most things audiophiles worry about don't add up to a hill of beans. Recently though, I've discovered something that makes a huge difference... multichannel sound. It gives me the most realistic sound I've ever had... clear, dynamic, and a soundstage that blows away anything I've ever had before. Dimensional imaging is the future of home audio and it's the next big step towards making music in the home sound more like music being performed live.

 

But a lot of people don't set their multichannel systems up properly and don't even come close to taking advantage of what it can do.


Edited by bigshot - 10/23/13 at 10:16am
post #80 of 129
Quote:
Originally Posted by bigshot View Post
 

A friend of mine is a sound mixer for live shows, and he's worked with installations that were calibrated by extremely expensive pro audio equalization systems. He always runs a tone sweep to double check and ends up making some pretty large adjustments. Apparently most sound mixers just use auto EQ as a jumping off place. They do the rest of the tweaking by ear.

 

Sounds like those 32-band "FEEDBACK KILLER" units.. Yugh. Run away! I've seen those units make some pretty fatal mistakes! Your friend is right not to trust them. 

 

Frequency sweeps, and clear, coherent vocal tests are the #1 way to check for feedback problems (IMHO). For resonance issues and room tuning, playing a track you're intimately familiar with, with a large FR range is the way to go.

 

...Sorry, enough about live. Back to home theatre.. 

post #81 of 129

For a dedicated room, and for 5.1 especially, room treatments will go farther to improve the sound than EQ.

EQ is easier. But fix the room problems and things get better fast. Speaker placement also can nip problems

before they happen. In a perfect world the room would start out with speaker placement.

But for most of us speakers end up somewhere by default. I've heard a well set up 5.1 setup in a shop in a dedicated room.

The speakers, the listening position, and the chairs were all in the right place. There were some room treatments as well.

The speakers were Paradigm, middle of the road models. But they did their job well.

I'll go with 5.1 can sound pretty darn good, but for most of us a 2 channel setup is easier, cheaper, and more workable.

The real start of this thread was Blu-ray audio. Like SACD and other formats,my guess is it never catches fire.

The trend seems to be lower res formats and ease of download and storage. It's getting to the point that even

Blu-ray movies have been undermined by lower res downloads.

post #82 of 129
Quote:
Originally Posted by ktm View Post
 

For a dedicated room, and for 5.1 especially, room treatments will go farther to improve the sound than EQ.

 

All speaker installations require a decent room. But there's a limit to what you can do without tearing out walls and replacing building materials. EQ is what you can do easily. It is the best improvement you can make for minimal effort... aside from the effort required to find the proper response curve. It won't help if you live in a train station, but it's the best thing you can do if you have your stereo in a living room.

post #83 of 129

I received Beck / Sea Change disc yesterday. ( The second 5.1 title I now have. ) It's sonically, truly AMAZING !!

The stereo layer is : 2,0 DTS-HD MA 24bit/192kHz & also in PCM. The best sounding stereo title so far....but the 5.1 layer, is on another level !!

post #84 of 129
Quote:
Originally Posted by bigshot View Post
 

Without EQing each channel, the various speakers don't mesh properly. The center channel needs to be perfectly matched to the mains, or the soundstage becomes a triangle instead of a smooth left to right handoff. The same is true of the rears. You can't get a phase mesh at your listening position unless the EQ is balanced all around. That's what made it sound like sound coming from all different directions to you. The channels aren't supposed to be separate. They're supposed to seamlessly integrate with each other, creating a clear sound field. Every room requires EQing for a 5:1 setup. No living room is the same acoustic in front as it is behind. The differences in furniture placement and location of walls make that impossible.

 

We need to be clear here. Yes, EQ'ing your speakers will certainly help and it is the easiest and often the only tool which can be used in practise as the vast majority of home listening environments are not dedicated to listening but have to serve other, usually more important functions, such as a living room or bedroom. However, we must not kid ourselves that EQ can solve the inevitable and severe acoustic problems which exist in every domestic room, it can't, EQ can only marginally improve some of them! In commercial studio design, EQ'ing the speakers is virtually always used as part of the solution but only a small part, the general rule of thumb is that it's about 10% effective!

 

The problem we have is sound waves radiating from the speakers, some of which travels directly to our ears (the direct sound) and some of which bounces off the walls, floor, ceiling and other reflective surfaces in our room (the reflections) and interacts with both the direct sound and with other reflections. The two main problems this causes is the reflections being in phase with the direct sound (or other reflections) and the reflections being out of phase with the direct sound (or other reflections.

 

In the top left image the direct sound and reflected sound are in phase and so at that particular frequency the two will sum together and create peak in the frequency response. In the top right image the direct sound and reflected sound are out of phase and will cancel each other out, resulting in a severe reduction or some cases even a complete elimination of  that frequency from the spectrum. If we have any parallel surfaces in our room, the reflections interact with each other as well as with the direct sound and you get things like standing waves, where the sound reflects in phase, essentially add infinitum, between two parallel surfaces and creates a frequency peak which deviates above flat by 20dB or more! The more parallel surfaces we have, the more standing waves and phase cancellations we are going to get. Therefore, the absolute worst room shape acoustically is a perfect cube, followed by a cuboid (a rectangular shaped room). So as far as listening to sound is concerned, the average listening environment in the average home is pretty close to the worst possible design!! In an average room there are likely to be several areas of the audible frequency spectrum which are massively far away from flat and 10-20 other areas of the spectrum which are only out by 6dB (double) or so. It's impossible to say what those frequencies areas are, as it depends on the dimensions of the room, what's in the room and what the walls are made of. BTW, the control rooms of commercial recording studios ALWAYS avoid parallel surfaces by sloping the ceiling and having the walls at angles to each other.

 

These two main acoustic problems can't be solved with EQ. Obviously in the case of a standing wave, we can apply an EQ cut which will bring the peak at that frequency more in line with other frequencies but all you are doing is reducing the peak, not the additional duration of that frequency caused by repeat reflections, so the average level of that frequency is still way higher than it should be, even if the peak matches. We can clearly see occurring this in a waterfall graph. In the case of the numerous phase cancellations, EQ is of even less help! If we imagine boosting the level of the top frequency (direct sound) in the top right image above, then we are also boosting the level of the reflection (the bottom frequency in the top right image) by the same amount, with exactly the same result. In other words, if the peak value of our top frequency (direct sound) is say 50 and the value of the corresponding trough at the same point in time in our bottom frequency (reflection) is -50; -50 + 50 = 0 (bottom right image)! Boosting our direct sound (top frequency) with EQ to say 100 will also boost our reflection (bottom frequency) by the same amount and; -100 + 100 is still zero! OK, so total phase cancellation is reasonably unlikely to occur at exactly our listening position but even with only partial phase cancellation, the same principle applies and the vast majority of any EQ boost we apply is nullified. The only way to solve these severe acoustic problems is to stop the reflections occurring in the first place by using a material at the reflection points which absorbs those frequencies or redirect (diffuse) the reflections so they don't interact with each other or the direct sound. No one solution works for all the problems so commercial recording studios use a combination of no parallel surfaces, absorption, diffusion and some EQ and even then only usually get very roughly in the ball park of a flat response!

 

I'm posting this so Head-Fi members are hopefully better informed of the basic problems of speakers in a room because I see so much discussion in areas of sound/music reproduction which ultimately affect the frequency spectrum by a tenth, hundredth or thousandth of a decibel and so little discussion in an area of sound reproduction which is hundreds, thousands or tens of thousands of times more significant! I hope from this you also now appreciate that EQ is at best only a partial solution. It's still better than nothing in many cases though.

 

Quote:

Originally Posted by bigshot View Post
 

Secondly, when I'm talking about 5:1 for music, I'm talking about 2 channel recordings run through a 5:1 DSP. That accounts for 90% of my music listening. SACDs and blu-ray audio is fine, but that isn't what most people are going to listen to all the time. The 7:1/stereo DSP on my Yamaha receiver makes a bigger improvement in sound than anything else in my system. It takes the normal 2 channel stereo spread and adds an ambience to it that widens the soundstage, gives it three dimensional depth and fills in the rear with just enough sound to feel live, but not so much you can hear it. The ambience fills in the room and makes the sound good from any listening position, not just the main listening position.

 

Even with a 5:1 recording, there are multiple DSPs for processing the multichannel information. It isn't a "one size fits all" thing. Synthesized environments are *real* environments. My Yamaha has a dozen different ambiences that were taken from measurements of the acoustic in real world venues. It's not a reverb.

 

That is still a reverb! If I've understood your description properly, it's a convolution reverb rather than an algorithmic reverb.

 

I have to say, I'm personally a bit troubled by your position. The acoustic information in a stereo recording has usually been carefully crafted by mixing the inputs of various well placed ambient microphones during recording or adding one (or frequently more) artificial convolution and/or algorithmic reverbs or indeed often a combination of the above to create the desired "feel" and "sound".  By applying a 5.1 DSP process to a stereo recording, your are to a very large extent masking/destroying the intent of the producer. You may very well prefer the result of applying this additional DSP and that's fine but let's not try to kid ourselves or others that it's a more accurate representation. I personally don't see any difference between doing this and using say a deliberately distorting tube in an amplifier, an individual may like the result but it's patently not more accurate, neutral or real, it might just appear that way to an individual who likes the result.

 

Of course, I'm talking here of up-mixing a stereo recording, not of a recording actually mixed and distributed in 5.1, in which case IMHO you still wouldn't want to apply any additional acoustic DSP processes. As we know though, there isn't much specifically 5.1 music. We have to appreciate that virtually all of the popular music genres have evolved in response to two main stimuli, cultural changes and advances in recording technology. The leap from mono to stereo, the advent of multi-tracking, the invention of synths, MIDI, samplers, digital audio and then cheap DAWs, all resulted in the corresponding emergence of one or more popular genres. Rock music for example, is a genre specifically designed for stereo and multi-tracking, without significantly redesigning the genre, it just doesn't work well in 5.1. The possible exception to this is the case of a live performance of rock music or genres based on live performance rather than recording technology, where we can in theory provide some additional information, the reflections of the sound from the rear walls of the concert venue for example. The problem with 5.1 for music is that no one has yet developed a popular style/genre of music designed specifically for 5.1 reproduction. The attempts which have been made have tended to be viewed as gimmicky and relatively few attempts have been made because the music industry is largely driven by radio, streaming and download services who tend not to support 5.1. It could be that bluray audio causes more people to experiment with 5.1 and that one of these comes up with some new genre which grabs the public's attention but I have my doubts as 5.1 has been available to musicians/producers for many years in the form of DVD Audio, SACD and even in a streamable/downloadable format like AC3.

 

I also disagree that a 5.1 system well balanced for music would also necessarily be well balanced for movies. While it might help in some respects, there are a number of  variables to consider here which are being overlooked, not least of which is the fact that the 5.1 systems designed for film operate in very different way to consumer 5.1 sound systems and that 5.1 theatrical sound is deliberately NOT mixed with the speakers all being evenly balanced.

 

G

post #85 of 129

Well I guess it depends on whether you're talking about theory or practice. What makes sense to you in your head doesn't mean a whole lot when you start shoving couches around and slinging wire. It's taken me many months of trial and error to arrive at the sweet spot, but I think with room acoustics and EQ, that's the only way to do it. I could have planned and worked it all out in theory, and I still would have had to completely readjust. There are just too many variables for hard and fast rules. Instead, you have to listen, isolate problems, and apply principles that might solve them. Sometimes that leads you to solutions you never would have expected.

 

The process is the important thing, not the specific solutions.

 

As for speaker installations, the room is part of the sound. You try to eliminate problems, but the goal shouldn't be to remove the sound of the room entirely. No live performance has sound that emanates from two small boxes 8 feet apart in an acoustic void. It sounds better with some life and air around it. Also *directionality* of sound and three dimensional phase are more important than anyone realized back in 1952 when the stereo standard were established. Just like stereo improves both music and movies, 5:1 is a huge leap forward for both too. You don't know until you hear it.

 

The DSP I use doesn't muddy up the front stereo soundstage. It just enlarges it and moves it forward into the room. The relationships between channels on the mains are identical... just wider and clearer, with air behind instead of dead quiet. But it took getting the proper phase match all around before it worked like that.

 

All it really takes to know what 5:1 and EQ add is to press the "direct" button. It strips off all of those settings and presents straight stereo. The sound shrinks, becomes opaque and recedes into the distance. Super clear improvement, and not just personal preference. Even grandmas would say it sounds better with 5:1!


Edited by bigshot - 11/13/13 at 12:36pm
post #86 of 129

By the way, in looking at photos of people's 5:1 setups on the web, I keep seeing the same problem over and over. Apparently, the wives are banishing the sound equipment to the basement, complete with narrow bowling alley proportions, concrete walls and floor, and low ceiling. This is a recipe for reflections all over the place, and cramming a great big system into it and hoping some absorption panels and EQ will help is like expecting a gorilla to do toe dancing to Dance of the Sugar Plum Fairies.

 

CREATOR: gd-jpeg v1.0 (using IJG JPEG v62), quality = 80

 

Here is an example of what I'm talking about. This might work OK for movies if the walls are all covered with absorptive materials, but it would never work for music. Just about every home theater I see pictures of on the web makes the same mistakes... Speakers flat against the side walls, flush with the front wall, narrow long rooms like mall shoebox theaters.

 

A good 2 channel listening room needs space, and 5:1 setups intended for music playback need even more space. The speakers shouldn't be crammed into corners or pushed against walls. They need some room around them. Likewise, the listening position can't be flat against the back wall. You need space around the speakers and yourself for the sound to open up. The important thing for room acoustics is, you need to make sure the main points where sound bounces are blocked with soft furniture or carpeting. It's easy to determine this spot by sitting in the listening position and putting a mirror on the side wall in the exact spot where you can see the speaker reflected in it. You also need something on the front and back walls... I used bookcases... to prevent reflections coming straight back at you. Secondary reflections are exactly that... secondary. Deal with the big stuff first and you probably don't need to sweat the little stuff.

 

Taming room acoustics isn't as complicated as people make it out to be. Like anything else, you start with the big things and work your way toward the less important things. Eventually, you hit a spot where it's both good sounding AND livable. There is absolutely no reason why a good 5:1 listening room can't be a functional living room too. You don't need to upholster all the walls and make it look like the bridge of the Starship Enterprise. It just takes a little experimentation and finessing. The nice thing about a 5:1 system is that it solves some of the problems of off axis listening. My system sounds MUCH better from the side with 5:1 than it does with 2 channel.

 

There is a trick to getting the same system to sound good with both movies and music using a stereo to 5:1 DSP. Movies assume a certain calibration and the decoder isn't adjustable. You are supposed to calibrate to Dolby or THX standard, the same way movie theaters do. So you start by calibrating for movies and get that right first. Yamaha's 7:1 stereo DSP has adjustments for the levels of the various channels. So once your system is tweaked for movie playback, you adjust the levels within the DSP to suit music. The sub isn't adjustable within the DSP though, so it takes a bit of back and forth to find the point where the 5 are balanced to the 1 for both movies and music. If the levels are off between the channels for DSP stereo playback, you get things coming at you from different directions and it sounds muddled, but once you hit the proper balance, it's like the soundstage dialing into clear focus... everything sounds full and alive, but the spread in front of you is crystal clear and wider than the separation of the speakers themselves.

 

700

 

This is my theater/listening room. There are couches on both sides now blocking the primary reflection points on the side walls. The rug takes care of primary reflection off the floor, and the vaulted ceiling prevents reflections from above. There are two sets of mains... JBL towers back where the screen comes down that favor midrange, and custom full range studio monitors from the 70s a little in front. The center channel is right in the middle of the screen. There is about five feet from the front of the front mains to the wall. This solves the problem of associating the sound with the screen, while still having the bulk of it out in the room far enough for it to open up. There's about three feet on either side of the mains, and the listening position is five feet from the back wall. I had to compromise with the speaker placement on the rears- they are against the back wall- but I'm still working on that part of the system. I have some new speakers and a new idea for hanging them that might solve that problem.

 

When I play 2 channel music through the DSP, the soundstage spreads out from wall to wall with no dropouts in the middle (try to do that with two speakers!) and it extends into the room about six or seven feet or so from the front wall. Exactly the size and shape of a typical performance stage. It's very focused, so I can close my eyes and identify instrument placement precisely. The depth cues and placement of the mains give it the illusion of three dimensional depth, like seeing a symphony and hearing the violins in the forestage and horns in the back.

 

Come by and hear it some time!


Edited by bigshot - 11/13/13 at 12:53pm
post #87 of 129

i like it very much,there's no need to do any processing of any kind. Just issue the master's digital copy, there should be plenty of space on these discs.thank you

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post #88 of 129
Quote:
Originally Posted by bigshot View Post
 

This is my theater/listening room. There are couches on both sides now blocking the primary reflection points on the side walls. The rug takes care of primary reflection off the floor, and the vaulted ceiling prevents reflections from above.

These statements along with many others in your post is based on a few isolated facts, some other incorrect facts and all joined together with logical assumption. Unfortunately, by missing many pertinent facts and incorporating some incorrect facts, the logic of your assumptions cease to be logical and you end up with illogical and incorrect conclusions. I'm not trying to be insulting here bigshot, just illustrate for the benefit of others why some of your opinions and advice may not be applicable to them. Let me give you a few examples starting with what I've quoted:

 

Your couches are most definitely not blocking the primary reflection points on the side walls! They are absorbing some frequencies, transparent to other frequencies and reflecting still others and, they are only covering part of the primary reflection points due to their limited height. Depending on the deviation (from flat) your reflection points are creating, depends on whether your couches are helping the room's acoustics, or not. As a generalisation for most living spaces, couches placed as you have done will create an overall improvement, possibly a significant one but it won't solve all the problems and could make some of the problems worse. This is why recording studios and cinemas use specific types of acoustic treatments rather than just nailing couches all over the walls! Also, the rug on the floor most certainly does not "take care" of the primary reflections from the floor. Being relatively thin, it will reduce some of the reflections within a limited range of frequencies, most likely in the mid-high frequency range. It will be almost entirely transparent to many frequencies, including most of the more problematic frequencies in the low and low-mid frequencies. Again, it will almost certainly be better than just having a bare wooden floor and no rug, but it's a relatively small incremental improvement in your floor's reflective properties rather than a "taking care of". Your vaulted ceiling also does not "prevent reflections from above". It eliminates a parallel surface (with the floor) and thereby greatly reduces the likelihood of standing waves (between the floor and ceiling) but it doesn't reduce reflections, it probably increases the density of the reflections and so could be causing other acoustical problems. Again, if solving acoustic problems was as simple as a vaulted ceiling, all cinemas, control rooms and dubbing theatres would have vaulted ceilings but most/many do not.

 

"Just about every home theater I see pictures of on the web makes the same mistakes... Speakers flat against the side walls, flush with the front wall..." :- You are not just describing home theatres here, you are describing just about every commercial cinema and dubbing theatre on the planet because they too place their speakers on the walls and flush with the front wall.  So are you right and the rest of the world is wrong or do you think it's possible there's some practical applications of room acoustics you're missing?

 

"Taming room acoustics isn't as complicated as people make it out to be. Like anything else, you start with the big things and work your way toward the less important things" :- But this is obviously not what you have done! What you appear to be doing is: Improve the biggest things you are able to identify by 10%, 20% or whatever is practical, then move on to the next most significant things you are able to identify and easily improve and ignore everything else. As general advice to someone who hasn't considered acoustics before and whose listening environment has to fulfil other functions, I would say what you have done is reasonably good advise and will likely result in considerable enhancement of their listening experience. But this advice will not of course result in a flat or good listening environment, just one which is more to your personal liking given your circumstances and equipment. If you are after something particularly good and accurate though, then "taming room acoustics" is far more complex than you seem to realise/appreciate.

 

"There is a trick to getting the same system to sound good with both movies and music using a stereo to 5:1 DSP. Movies assume a certain calibration and the decoder isn't adjustable. You are supposed to calibrate to Dolby or THX standard, the same way movie theaters do. So you start by calibrating for movies and get that right first". :- Again, what you are saying/assuming, does not correspond in anyway to what you are actually doing! Have you calibrated your front speakers to 85dBSPL(C), your rear speakers to 82dBSPL(C) with Dolby pink? Have you calibrated your sub to +10dB relative to your front speakers with an RTA? Have you applied the cinema x-curve to your room's response? Is there at least 18ft between your left front and centre speakers and do you have the appropriate baffling/isolation between all your front speakers. Are all your front speakers full range (20Hz to about 18kHz) or do you have to employ some form of bass management (which is unacceptable for Dolby of THX theatrical specs)? I think we can safely say that your system is not even vaguely in the ball park of Dolby and/or THX theatrical standards. Even if it were, it still wouldn't sound as intended, as Dolby and THX specs are designed for large room acoustics and are not applicable to small rooms/home listening environments. We also have to consider the fact that many (but not all) DVDs/Blurays are remixed specifically because home listening environments and equipment are not the same as cinemas and, films broadcast on TV often have another remix again. And lastly, I hope it's obvious after this, that a system which is well calibrated for movies is not flat or balanced appropriately for the ideal playback of music in 5.1. If it appears that it is, that's a fair indication that something is wrong somewhere in the calibration!

 

"Also *directionality* of sound and three dimensional phase are more important than anyone realized back in 1952 when the stereo standard were established. Just like stereo improves both music and movies, 5:1 is a huge leap forward for both too. You don't know until you hear it." :- I think the importance of phase and directionality were well realised in the 50's but it's certainly NOT correct to say that stereo improves movies, it doesn't, it makes them worse! So much so, that stereo has never been one of the accepted audio formats for movies and indeed, it's not even possible to put stereo sound on the standard digital movie distribution format (DCP)! 5.1 was certainly an improvement over the LCRS format it replaced but it's not the huge leap you are stating and of course 5.1 itself has now been superseded by another step forward, with systems such as Dolby Atmos. BTW, careful about saying things like "you won't know until you hear it", as you don't know what I've heard or what I'm used to hearing!

 

"When I play 2 channel music through the DSP, the soundstage spreads out from wall to wall with no dropouts in the middle (try to do that with two speakers!)  and it extends into the room about six or seven feet or so from the front wall."  :- OK, this is particularly troubling! There should absolutely not be any dropouts or even the slightest loss in the middle with a stereo system. What you are describing is either a fault/incorrect setting with the stereo panning law of your amp or far more likely, some fairly serious phase issues between the left and right speakers (and/or the room acoustics). Amp DSP effects use phasing/reverb as part of their processing, this is corroborated by the fact that you describe the sound as extending into the room by 6 or 7 feet. A phase based effect is by far the most obvious explanation of this observed phenomena. You also mention the separation being wider than the speakers themselves and as phasing effects are the only way to achieve this, I think we can say with a high degree of certainty that your DSP is using some form of phasing in it's processing. It's not entirely uncommon in some music production to use similar phased based effects to create a stereo image wider than the speaker placement. However, it's generally avoided because: 1. When played back on a mono device there is virtually always considerable phase cancellation and 2. Even in stereo the results frequently don't work as intended because they depend on good speaker placement and relatively little phase discrepancies in the playback chain/environment.

 

At an educated guess, it would appear that you have got some quite serious phase issues in your room. Applying the DSP effects in your amp has altered the phase of your outputs which has changed the phase relationship in your room and evidently reduced at least some of your room's/system's phase issues. I could be wrong, but I don't believe the DSP in your amp is designed to make the sound stage appear wider or extend 6 or 7 feet into the room, as both (and particularly that latter) would be fairly unpredictable from room to room and system to system. It's likely just a consequence of the DSP phasing interacting with the phase issues in your room which is causing this effect. This would explain why the precise balancing and tweaking of your system makes such a significant difference and why you are hearing a distinct improvement in clarity and positioning when engaging the DSP. Normally the applying of amp DSP effects would cause different phenomena from the ones you are describing and exactly the opposite in some cases! It would also explain your observations when listening in standard stereo, as well as most of your other related comments, such as your perceived improvements not being present unless the right balance/EQ is applied to each speaker.

 

If I am correct (and you have supplied quite a bit of evidence to suggest that I am), then many of your assumptions and a fair amount of the opinions and advice you have provided in this thread will only be applicable to you and the current state of your listening environment. It's almost certain that if your phase issues could be accurately identified and solved that your opinions (and future advice) would change significantly.

 

I'd love to "Come by and hear it some time!", I'd like you to hear my environment too, unfortunately that's not practical due to my current location. I'd post a picture of my room but most of what's there would not be obvious from a photo and I wouldn't want my posts or this thread to descend into a "mine is better than yours" debate, even though we are admittedly already quite a way off topic!

 

G

Edited by gregorio - 11/14/13 at 8:45am
post #89 of 129

Maybe it's magic. Come by and I'll play it for you and you can tell me why it sounds so good when it shouldn't!

 

I salute your absolutism!


Edited by bigshot - 11/14/13 at 9:38am
post #90 of 129
Quote:
Originally Posted by gregorio View Post
:- OK, this is particularly troubling! There should absolutely not be any dropouts or even the slightest loss in the middle with a stereo system.

 

Disagree. The phantom center produced by a stereo setup definitely has its flaws. First, the room and the listeners distance to each speaker has to be absolutely symmetrical in order for dual mono to be perceived dead on center.

Secondly, comb filtering is a physical necessity with stereo. When both speakers play the same signal, the sound of the right speaker will arrive slightly delayed at the left ear and vice versa. This results in multiple frequency response dips (comb filtering). That's one reason why stereo sounds crap if there are no reflections from the room (they partly fill in the comb filtering gaps).

 

With a center channel you get a real center that is more stable, accurate and sounds better (flatter FR).


Edited by xnor - 11/14/13 at 10:29am
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