This is nothing new. There was Quad(4 channel) in the 1970's. There was rear speaker setups like the Hafler circuit for rear ambience sound. There were rear digital and analog delay units. It was all crap.
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see Dolby Digital 5.1 channel sound
see DTS surround sound
see DVDa multichannel sound
see SACD multichannel sound
All of these formats are competing for the multi channel music market (Dolby Digital 5.1 is mainly for movies).
Anyway, my biggest argument against multi channel music is all of the speaker cable or interconnect involved. Your either going to have to run some very long interconnects or very long speaker cables to 2 sets of speakers. This can have a serious impact on the sound quality of those speakers. Why would one want to listen to 3 premium sounding speakers then 2 speakers that were producing noticeably less quality of sound.
This dimished sound quality for rears is not as evident in movies due to the fact that most rear channel sounds are really not recorded terribly well. Most of the Movie sound comes from the L/C/R/ speakers.
I'm not sure this thread is exactly about quad... but that was certainly an attempt at this.
In my personal experience, I listen to (what I would like to call, if such a thing can exist) "4-channel stereo" much of the time. The only company I'm aware of that explicitly offers such a mode (5-channel stereo, just lose the center) is Adcom, and I haven't much enjoyed what I've heard or owned from them. I have an Acurus Act-3, which I purchased ONLY because it 1) will allow independent volume control over front vs. rear via a balancing adjustment, and 2) will allow me to hook everything up to it, HT (seldom-used) included. That said, I don't really like this unit much either.
I am definitely *not* a pre/pro expert (I try to pretend they don't exist) and that's the one place I always run and hide in this hobby... it's hard for me to select a pre/pro because all I really want is 4 channels (front + rear) with independent volume control to move the emphasis forward and backward, as needed. HT capability is also a nice thing to have, but in every unit I've researched, the HT angle seems to be all they are paying attention to, and good 2 or 4-channel non-altered playback is either impossible, or an afterthought. All the pre/pros I've ever looked at seem to display an enormous HT bias. I would rather have a pure 2x2 setup without all the delay and echo and who knows what these systems always seem to force one to use.
Are there any units out there that offer HT capability while offering a good 2x2 (stereo front + rear) mode without all the HT echo party/arena/stadium/jazz club hoo-ha? I'm ignorant in this arena, let that be said. Last time I looked, I was very, very discouraged.
Let's take a look at what's going on in the concert hall, and then come back and look at speakers that bring some of those elements into the listening room.
In the concert hall, the direct sound from the instruments arrives first (naturally), from which we get our directional cues. Then there's a bit of a delay before the reflections start to arrive. There is a great deal of diffuse energy in the reflections, which set up a very powerful reverberant field that actually contains many times more energy than the first-arrival sound (although the first arrival sound is louder, its presence is brief).
This powerful, diffuse reverberant field contributes to the rich timbre we experience in a concert hall. There is a tradeoff relationship in halls between precise localization of sound sources and ambience, just as in the home. Most concert halls excel at rich timbre and luscious ambience rather than "imaging".
Okay, now let's step into the typical listening room. Just as in the concert hall, the first arrival sounds give us our directional cues (and primary timbral cues). But then there is relatively little delay between the first arrival sound and the onset of reflections. And typically, the reverberant field in the home has a very different tonal balance than the direct sound (unlike in the concert hall), because loudspeakers' directional characteristcs change with frequency. Compared to the concert hall, the typical reverberant field in the home arrives too soon; often contains undesirable strong, distinct early reflections; isn't powerful or diffuse enough; has too much bass relative to the midrange and treble energy; and decays too quickly.
A surround sound system seeks to approximate the concert hall by reproducing delayed ambience energy from the rear speakers. Whether or not this is more realistic than a comparably-priced two-channel system is debatable.
The problem with using a second pair of speakers to the sides, without delay, is that the ear localizes sound primarily by arrival time, and secondarily by intensity. Unless the path length to the second pair of speakers is at least a foot longer, they will be perceived as distinct sound sources. And even if they are a little farther away, their "reverberant" energy arrives way too soon, and will still cause image shift. Unless the signal to the second pair of speakers is delayed, in practice it will probably do more harm than good.
Some speakers are designed to put a great deal of energy out into the reverberant field. Omnidirectional speakers do so, for instance. You might look at designs by Shahinian, Wolcott, and MBL, for example. The bi-polars from Mirage and Definitive Technology also generated well-energized reverberant fields.
If placed fairly far out from the wall, dipole speakers can create a good sense of ambience because the backwave contributes to the reverberant energy in the room, and the farther out the speaker is from the wall the longer the delay before the onset of that additional ambient energy.
Treating the first reflection points is a good idea, whether with absorption or diffusion. Remember that in a small room a little absorption goes a long way (because sound waves will bounce it many times in fairly short time interval), and that in general diffusion is the better approach because it preserves the reverberant energy as long as possible instead of swallowing it up.
I hope this helps a little.
Mythtrip, it sounds as if you and Dr Amar G. Bose have visited the same concert halls : )
Honestly though, his published theory as to how he came up with the design for the original Bose 901's is very similar to some of what you stated above. The main problem with his design is that it uses multiple drivers and suffers from severe comb filtering. In effect, the design creates almost as many problems as it tries to address.
As Duke stated, omni's are capable of producing a very expansive soundstage but are also more susceptible to reinforcement / cancellation from room boundaries. If you can get a good pair of omni's properly set up, the soundstage is pretty amazing. I have a pair of point source ( one driver per cabinet ) omni's and they produce a soundstage that literally "wraps around you" and "engulfs" you on some discs. I have never heard any other speakers ever do this. To be honest though, the electronics in this specific system also play a key part in this as these speakers have not always produced this effect. This is true even though i have not altered their position over the course of many, many component / cable changes.
Dipole's aka "planar's", "stat's", "ribbon's", etc... are capable of doing this, but not to the same extent ( at least in my experience ). They do tend to sound far more open and less "congested" than what most "boxes" are capable of as a general rule. The problem with a dipolar design is that the rear wave is out of phase with the front wave, creating an instant problem with cancellation. In comparison, the specific omni's that i have radiate in a 360* pattern while keeping the signal in phase. So that you have a better idea of what i'm talking about, here's a picture of what they look like. The specs as published are VERY incorrect though, so take them with a grain of salt. The only thing that the manufacturer got right is that you need AT LEAST 100 wpc to drive these. I have two pairs of these with one looking like the picture and the other having a slightly different design.
All i can add to the above is that once you experience a system that has a very expansive ( wide, deep and tall ) sound stage, you will find it hard to listen to "boxes". They will, for lack of a better term, sound very "boxy". Obviously, some designs are better at "disappearing" than others, but much of that will also be up to the electronics that they are connected to. Sean
I suspected all along that people who insist on the importance of cables would simply freak out at the thought of adding channels. Yippers! Imagine having to have the best Siltech all around! Imagine having to cryo the lot! Mythtrip, better ring up some other site if you want to have anyone consider for a nanosecond the benefits of more than two channels. There is more chance to find some guy extolling the virtues of mono, horns and SETs being fed ticks and pops here than anywhere else. I assume you are relatively new to audio. Multichannel in various guises has been around for a mighty long time. Attempts were made at quad sound, with LPs, decades ago and foundered, inter alia, on the problems associated with stores keeping multiple formats. Even before that, Dynaco had some primitive form not requiring any special recording using four speakers and changing phase in the rear ones, if I recall. Not a great proposition, but showed some imagination and low cost implementation at least. Another approach, which for many years I felt could provide quite good result if properly implemented, was to synthesize effect channels from stereo records. At the outset these could be divided into two distinct lots: analogue, which sounded like s...t (remember SAE?) and used bucket brigade circuitry which should have given analog a bad name forever, and digital, which, because of the name had to be given short shrift by the analogue maniacs. These digital time delay units by doing the signal processing in the digital domain did not introduce a lot of noise or distortion compared to the analogue units. Audio Pulse, long defunct, was the first to come out with digital delay units. Many moons ago I bought their model 1000 and used it for a number of years. Primitive, noisy, but effective, if used in small doses. For a number of years companies such as Yamaha, Koss and JVC brought out improved models. I used the JVC XP-1010 for many years and, as were certain reviewers at Stereophile, was quite pleased with the results. Now comes multichannel SACD and DVD-A. This looks a bit like the four channel wars of yore, were two different incompatible systems, requiring separate inventories of software clashed. Add to that the intervening wave of multichannel HT and you have a messy situation, which will be very difficult to solve. The standard chosen for multichannel SACD is difficult to fathom in that it calls, if done by the book, for five identical full range speakers (see the problem with high-enders wondering how to finance five Grande Utopias or Soundlabs and fit them in their rooms) fed by five equally powerful amplifiers (ditto the remark on speakers, Wolcotts or Halcros all around please). You would sit in the middle of these speakers, three at the front, two to the rear, in an arc type set-up, and for good measure add a sub-woofer. Quite a menu, I think, when all you should want is to reproduce ambiance. Yes, multichannel is probably as big, if not a bigger, an improvement over two channel stereo as the latter was over mono. Don't expect any positive comments on it though from the cable sniffers, and believers of "micro-dynamics" (something like noise within noise, I guess), the absolute virtue of analogue, cryoed dipsticks, the microphonic nature of solid state circuits, and the Great Pumpkin. From the mid-fi trenches, I remain just a two eared guy. Good day..
I think I should chime in here, all of the above makes perfectly good sense and that was also the reason why I refrained from any experiments into that direction until I heard that Quad's Peter Walker had a speaker setup ( a wall of his stators) not unlike the one I had arrived at PLUS Quads (don't know how many though) arranged along the side (not back) of his listening room. When I had managed to obtain a pair of ESL63 from ebay at a very good price I started experimenting and finished placing the speakers at right angles from the main speakers halfway between them and my listening position fairly close to the side walls, firing at each other and giving them a dedicated amp and preamp, fed from the tape out of my main preamp, a Jadis 200. I have the dedicated preamp close to my listening position, so I can dial in the exact dose of side information for every piece I am listening to. The dialing in has to be done in very, very tiny increments and what is most important, seperately for the left and the right side, in order not to ruin sound stage information and the placement of instruments and voices therein. However if done right, it will give back ambience to overly dry recordings and add width and depth and a sense of immediacy to good ones. I will never go back to the classic setup and found this to be a great step forward in my personal enjoyment of my rig. However the step between enhancement and ruin of a presentation is very slight and it is frankly even more difficult than properly dialing in a subwoofer. I also think, that it is essential with such a setup, that main and side speakers should be of the same make, or at least similar in their voicing and characteristics and all this should not be attempted for the very reasons given above, if the auxiliar side speakers cannot be dialed in exactly for each LP, Cd or master tape being played. Cheers, Detlof
In the mid-'80s Sony put out a $600 ambiance/delay unit, the 505ES, a digital unit based on a combination of the features of two '70s analogue units by companies named Sound Concepts and Benchmark. The Sony unit delays and rolls off the sound to the rear speakers within programmable parameters, and the rear speakers have to be similar to but can be much smaller and less expensive than the front speakers. The real key, however, is that nothing requires you to run the front speakers through the unit. The result is convincing hall sound with no gimmicks, and nothing fouling up your megabuck front channels. Within a year Sony had screwed up later models with more bells and whistles, requiring you to run the front channels through the unit, and inflating the price. Then Lexicon came along and went even further. Fifteen years later, several friends and I have kept our old Sony units, had them rebuilt as to connectors and some wiring, and treasure them. In the meantime my front channel components have increased astonomically in price as I upgrade, and not one audiophile who has dropped by for a visit hasn't first questioned my sanity for keeping the rear channels in the system, and then been shocked at how much they contribute when I turn them off. Four speakers, yes, it can work wonders. Without a delay, I doubt it would help much. As to what's possible or available now, who knows what the right manufacturer has done or could do if someone could just keep it from mucking it all up with more "innovations"....
Plato, thanks for the address. This method has been widely discussed in Europe and widely acclaimed by the critics, but also here the public did not really respond in sufficient numbers, to make the whole project commercially viable.
Pbb, fankly I don't understand your attitude. Your post is full of interesting information. But then, why all that gall? If you find us here all so ridiculous or impossible, why bother with us? Shakespeare comes to mind, to me you have, what he calls a "jaundiced eye". Well on second thoughts, perhaps you need us, to get rid of your "humours", to quote him again. Hope you felt better after you had written that post. Only it is now us, who have all that bad air. (us = people, who think cables important.)Why punish us, if you are not interested to hear what we can? I don't get it. Respectfully,
I'll admit to using the Dynaco-style L-R rear speakers scheme in my reference rig. I have a 6x8 pass-through library just behind my listening chair, and mounted small monitors high up on the sidewalls, facing each other, using barely visible AWG20 black hook-up wire, and of course a nice wire-wound 40 ohm pot. I rarely use it on classical works, but on some jazz and rock it's a great way to provide ambience and wider stage for lean or dry recordings. Plus it subtlely fills that walkway with enough sound so that it doesn't sound like a big "null" as I walk through it to sit down in the sweet spot.
My system consists of a 7.5' equi-triangle in a 24' long room, so I have lots of room behind the speaker plane, thus providing a VERY deep stage. However, dialing in these rears progressively shortens the stage depth as the rears fill in! It's almost like having my listening chair roll forward on rails! Not at all an improvement on great classical recordings, but fun for multi-mono rock and jazz.
The solid copper Radio Shack AWG20 and small bookshelf monitors (Super-Zeros, Atoms, etc.) are fine for this, as one is only trying to dial in a bit of L-R ambience, so perfect timbral matching and low-frequency extension are NOT important, unlike true digital surround matrices.
I just set up such an HT system in a larger, livelier adjacent family room from mid-fi NAD receiver and Spendors, and with NAD's EARS 5.1 synthesis from FM 2ch or TV 2 ch. the fake-surround is fun. But there's NO question that the ultra-deep stage I get from my 2ch ref rig is much preferable for serious classical and jazz listening. I'm glad I didn't try to make an all-purpose music-and-HT system...I think digital surround has a long way to go in soft-ware development before it becomes an efficient, viable alternative to nearfield 2 channel in a well-damped room!
Detlof: sorry about my poison pen (hmm, keyboard?) coming out again. Some time, when the moon holds water, I revert to my true nature: that of a curmudgeon. No excuse, but I guess TWL's early post is what prompted my barbs. Again, what bothers me the most is the knee jerk reaction to whatever new, large electronics companies propose, that I have come to expect from a lot of audiophiles and, you will have to admit, the vast majority here, contrasted to the ready acceptance of products that come from so-called designers, that actually offer nothing or next to nothing but are hailed as major breakthroughs. Just read the comments on the sound quality of SACD or the need for such a format posted on A'Gon. It has not been out that long and a lot of people here have already relegated the whole thing to the trash bin of audio history. Since SACD is a double barrelled approach, in that it is both a high resolution format (in answer, I guess, to all those who have criticized Red Book CD into disrepute) and a multi channel format, it is difficult to comment on one and not the other. The reaction to the better resolution is to say that it is good, but not as good as "my vinyl rig" (Geez I wish I could hear such a rig). The reaction to multi channel is to say that the whole thing is not worth considering even for a moment since the pinnacle of sound reproduction has been reached with two channels ("you know we only have two ears") and since multi channel, whether synthesized or brought about by multi channel software, is only really feasible in the digital domain, the same people have to slap it down hard, especially in answer to a neophyte, so that the one and only true virtuous analogue road to sound Nirvana is safe. Not to draw lines in the sand, but why not ask the dyed-in-the-wool analogue/vinyl people to refrain from commenting on the new formats, if after the most cursory listening they pronounce it as mediocre compared to their technology of choice and also to refrain from commenting on multi channel if all they have to say is that it a good idea whose time will never come? Sorry for the rant, I would have a number of questions on setting up a multi channel system based on the ITU Standard recommendations for SACD reproduction. I hesitate to ask them in this forum, as its membership (at least some of its most vocal portion) appears at best totally uninterested, and at worst quite hostile, or at least cynical, to anything that really changes their beloved paradigm. My most basic recommendation at this point is the following: buy the cheapest Sony SACD player you can find, buy the Vaughn Williams "A Sea Symphony" on Telarc and tell me that it can be bested by another recording available in another format, even in two channel mode (for sake of diplomacy, I refrain from using the usual "at any price" taunt here). I can only guess how wonderful it should sound when I have the extra channels connected. By the way, the term "micro-dynamics" seems to me to be an oxymoron, unless one believes that every part of infinity is also infinite in itself... Regards and salutations from the mid-fi trenches.
Pbb, thanks for the lengthy remarks from one curmudgeon to the other. Can't say that the quality of my reply -at least there where it was personal - was any less curmudgeonlike than your scorn, which promted it. You're right, must be a lunar influence. Cannot find any fault in anything you had to say in your last post, in fact I find that it makes very good sense, only the trenches you aim your fire from, don't seem mid-fi at all, or shall we say, your amunition certainly isn't. I'm a vinyl freak, but all the same, I cannot fault you in what you have to say about certain opinions here on A, which are indeed less than tolerant and abound with rash judgings. I've read TWL's post and just ignored it, because I knew he was wrong. But then perhaps the moon wasn't yet high enough.
Do you have a better word for micro-dynamics by the way? I think there is a difference between components, which swing the range between a fff and ppp very well, whereas there are others, which cannot do this, but excell in getting the difference between a pp and p or an ff and an f just right. Perhaps one should properly speak of the "rendering of micro steps within the dynamic range at the ff or pp level", or something like that. The term may be an oxymoron, but it is handy and it describes a bit of aural reality to my mind. Well, enough already, cher confrere, lets go out and enjoy the moon drawing water, or play football between the trenches, as they used to do on occasion during WW I on the Western Front, very sensible at that. Cheers!