Quote:
| like multichannel audio, but it isn't the same as stereo was to mono. |
Probably posted on this before but if not then here is my experience with multichannel audio FX in general from the 1970s until the present time.
[size=small]
THE MINI HISTORY OF MULTICHANNEL AUDIO[/size]
*****WARNING : Very long and very boring descriptions to follow.Read this at your own risk but do not say you were not warned so if you b*tch I am not listening.I also realise I more than likely have numerous spelling and grammatical errors to follow but my brain works faster than my typing skills.This is far too much for me to even contemplate an edit
Three Channel audio :
All early integrated amplifiers and preamplifiers had a L/R sum center channel output.There were no three channel amps that I know of but all line level control devices were so if you wanted three-channel stereo a basic mono amplifier was needed plus an additional speaker.
the reason for this "third channel" was twofold :
1-many recordings
were three channel recordings and the only way to accurately reproduce what the recording engineer heard in the home was to recreate the same type of setup.three mics=three loudspeakers (see my previous point about mutli-channel audio reality).
2-Most loudspeakers of the day had very limited high frequency dispersion and in fact beamed the high notes over a fairly narrow range.This "fix" was to simply toe in the loudspeakers through trial and error until the image was locked.
In a large room where the speakers would be placed at the extreme left and extreme right the distance would be so great that no amount of toe in would help so the solution was to add a third identical loudspeaker to fill in this "hole" in the middle of the stereo image.Adjusted properly this was the best solution and is the method used in the movie theaters since the 1930s.
Ambience Extraction :
David Haflers Dyna-Quad ,DIY version.This simple device is one additional loudspeaker connected between the + speaker terminals of the L and R channels on the amp.One one connection a 25 ohm rheostat is added for controlling the volume of this rear channel.
What this matrix does is to extract the L-R out of phase ambience information that may or may not be present in the recrding so it adds nothing artificial but simply extracts what is already there-----or not.
With live recordings it was a very nice add-on but with studio recordings not so good.
Downsides ? The rear speaker needs to have more distance between the speaker and the listener than doers the main left and right channel speaker pair or it will be the first signal heard and dominate the soundfield.This "dominance" totally blows any shot at a good stereo image so it is essential to get distance.
Problem #2 is the rear signal is full range and should have a falling frequency response at the high end of the scale as in real life where high frequencies have a greater attentuation with distance than do low frequencies though back then we did not know this (at least I did not.Hell,I was only friggin' 14 and there was no internet for information dispersal ).So because I had no clue I ran this puppy flat out and full range which in hindsight was another reason for the front image to wander of point with certain recordings.
Flaws and all it was a keeper and stayed "in system" to be used mainly with live recordings.
Second generation dynaquad circuits used two rear speakers instead of the one though the single rear device worked more than well.
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SIDEBAR
Highly recommended for "poor mans" surround but I would add a 7khz low pass filter to the rear channel feed and instead of aiming the additional speakers directly at the listening position aim them at each other across the room.This make for a far more realistic and diffuse sound fileld.One that adds and blends but does not draw attention as a source of sound,as it should be.
Add in the above three channel stereo matrix and you have a totally passive surround sound system on the cheap ! One that will in many cases blow the DSP/active circuit based device right out of the water though it is very placement sensitive.Since you no longer have all the "artificial" controls manipulating the soundfield you need to do it the old school way ositioning and volume attenuation.
The ONLY thing missing to have a true surround matrix is the 20-30 ms audio delay but if you happen to have a room that has a back wall 20 feet away,rare but not unknown,you have in effect just added a 20ms delay and you will be right on spec without adding a single active device ! |
Quadraphonics :
STAGE #1
So I am reading all the articles on quad sound,followed and tried to understand all the technobabble,attempted to make sense of all the graphs showing direction cues and degree of change,was swamped in all the graphs saying why "this" matrix was better than "that" matrix and there being so damn many choices I had no idea which way to jump or even if i wanted in but seemingly THIS was the way of the future.After all,the experts said so so it must be true right ?
Format wars V-1 !
So when my copy of Popular electronics arrived in the mail and the cover story was "Build This Universal Quadraphonics Decoder" I was in !
Hell yes ! The "Universal" part said i did not have to crap or get of the pot but could actually get my hands dirty building something and listening for myself.Life was very cool in ricksville that day.
The device was an Electro voive EV-44 Universal Quad Decoder and from memory build price was like $50.Actually a lot in 1974 dollars considering minimum wage was like $1.50/hour (from memory and may not be exact
).
So I order the chips but not the pcb deciding instead to do a perf board version so I an update later (damn good thing too !),i build the sucker but when I go to test it no damn quad recordings !!!!!!!
I was so into the build I forgot to purchase a recording that I could use it with ! (later this became a non issue when ALL LPs from CBS/columbia were matrixed quad LPs as were many other labels offerings.This said to me and others that we had a standard but that was dead wrong as I/we all know now)
Eventually I get everything going and am prepared to be "wowed" but man,what a frikkin rip ! It was no beeter than my passive Dynaquad !
What ????????????
Later I found out that in reality this and most other "Quadraphonic Matrix Decoders" were in fact glorified Dynaquads but at the line level and active rather than at the speaker level and passive.This is progress ?
Stage #2
Popular electronics to the rescue again :
[size=small]"Add Logic Steering to your Universal Quad Decoder"[/size]
COOOL !!!!
Maybe now this puppy will live up to the hype.This "upgrade" added a logic steering chip to the basic matrix chip and in theory would move the dominate directional sound encoded into the disc to that speaker at a higher volume thus enhancing the effect.
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SIDEBAR #2 : for the "tech heads"
This was simply an additional chip on the output of the original matrix chip.This add-on took the input signals and pssed them to both the input of an FET and also rectified each of the four audio line level outputs making the signals a DC voltage (Audio is AC) which was then used as the control signal for FET VCAs.Once a certain threshold was reached at the rectified input the output signal was increased by a gain factor of X2 making the FET audio output of that channel play louder than the other three.This is how it was done then,this is how it is done now. |
and to be honest it did all it said it could but still it sucked.
Matrix surround was becoming a damn gimmick and once logic steering introduced this "gimmick" even more transparent for what it was.The promise of increased "realism" never actually happened because the idiots in charge had no freaking idea.what they had was a toy without instructions so the attitude was
anything goes and it did.
NO stereo image to speak of,directionals making no sense at all,bleed through from one channel to the other screwing with the image even more,a fkn nightmare though a fun toy at parties to show off how cool you were.In the closet it went,back in went my simple "extra two speakers and a pot" hafler setup
STAGE #3
Matrixed Quad was slipping even though every major manufacturer of note was pushing the technology and some major record labels were making ALL offerings in matrixed Quad even though they never asked the consumer if they wanted in (sound familiar ?).The real problem was the sheer amount of proprietary decoding methods which if the manufascturer was also hooked up to a record label (CBS SQ/Columbia records) you
had to have a compatible decoder just to play the recording back as intended.
CBS had SQ,Sansui QS (
),Electro Voice EV44,and on and on.All claimed cross-platform "universal" compatibility but since they were both pushing their own version and had no access to the intellectial property designs of a competing manufacturer this was a total comprimised and not a true universal solution so the only way to actually play back your record collection as intenede by the record company was to go out and purchase a decoder of each type !
Then the real fun would start.Upon purchasing a new record you had to read the back fine print so you knew exactly which method was used for the Quad encoding so you knew which decoder to actually use.Bypass decoder-A,bypass decoder- B.decoder-C "in".FKN nighmare but what choice ? the discs WERE encoded and if you wanted to play them back as intended you needed to decode them
So no decoder was actually a "Universal" decoder except for one.yup,the original Hafler dynaquad which all matrixed decoders were based on.My simple little DPDT toggle switch/25 Ohm Rheostat/Extra speaker Pair accomplished the same thing as all the various decoders/extra stereo amplifier/extra stereo speaker pair !
something like $50 vs. $500 when it all added up so i sold everything but my little Radio Shack project box decoder
Stage #4
Matrixed Quadraphonics was losing steam and no amount of last gasp efforts by the record labels or equipment manufacturers was going to save it.No one was able to justify the added expense and system "sprawl" for such a flawed technology until......................
DISCRETE FOUR CHANNEL !!!!!
Yeah Baby ! This is the one ! Right ? I mean jeez.we have all these geniouses telling us quad is the future and that we need to get on board or be left behind so get with the fkn program jerky ! The future is NOW !
OK.So now I need to sort out this "new" technology but upon doing the research it comes to me this is not only nothing new but something we "audio geeks" (and yes,card carrying baby since the age of 13
) always had right there in front of us.
The "Four Track Reel-To-Reel Record Deck".
Only now instead of mixing those four tracks down to a single stereo track we would use those four tracks going to four "discrete" channels.that is four amp channels and four speaker channels.These guys were not going out without a bang and they were determined to sell you and extra stereo power amplifer and an additional set of stereo speakers no matter what !
Sounded good on paper but the problem here was that not everyone had or wanted an open reel deck.Unlike the LP you had to go through steps to not only load up the tape but to set bias levels according to the tape formulation,had to demagnetise the heads from time to time,had to run periodic maintainance on the deck,etc.In a word "WORK" was involved and we all know humans are a lazy beast at heart so while those of us who tried to buy into the matrixed quad revolution already had the extra amp and speakers and being geeks had a four track recorder front and center gave it a shot,Joe main street took a pass.It also should be noted that the equipment manufacturers never really got behind this one on a large scale.They were too busy scheming on..........
Stage #5 !
CD-4.discrete four channel sound for the LP record !
Now here wwas something the equipment manufacturers could get behing because in order to buy into this one you not only needed a CD-4 decoder ($$$$) but you also had to replace your phono cartridge with one that could pick up frequencies in the RF range off the disc ($$$$$) ! (for those of you who think the LP has limited frequency resp[onse think about that one for a minute).
This "new" cartridge meant for the first time in many years there was some actual serious research into the stlus tip shape and the first (from memory) that came out was the "Shibata" stylus tip to be followed by the "stereohedron" and other such designs.The DID get nore information out of the groove but at what cost ?
Record wear is what !
Because they so closely modelled the original record cutting machine cutting lathe tip these new cartridges were on the edge of play/cut at any given moment and that is not good in a medium that depends on a mechanical interface to produce sound (as in the original edison discs) but at reduced wear for disc longevity.They worked as advertised flaws and all but by this time most were just flat out disinterested due to the long term format wars and the industry indecision (again,sound familiar ?).New LP discs were offered in either "stereo" (sneakily still matrixed quad but no labelling saying this) and "CD-4" but this also was a big time mistake.Too many choices,consumer distrust,gimmicky sound.manufacturer in fighting,a mess and the Quad Era was at an end.Back to my little box
BTW-My CD-4 decoder was again a Popular electronics project but this time the decoder was a kit by SWTPC.This POS I actually tossed out the window of my Barracuda on a back country road.always wondered if someone found it,took it home,then gunned ot right out the door after trying it out
BTW #2-I still have a CD-4 version of Apostrophe' kicking around here somewhere though i presently have no way to play the disc in quad so more of a curiosity/reminder from a bygone time when the equipment manufacturers and record labels got just a bit out of hand and tried to force feed the public a technology that was not close to ready for prime time.This particualr recording is one of those "gimmick" recordings and has content that comes from strange directions and has zero connection with reality.fun and exiting on the first few plays,boring as hell after a while and very tiring to listen to for exteneded periods.
Exhibit "A" in the archives of "don't give me no artificial speacial effects,just gimme the damn music straight jerky"
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SIDEBAR #3
The only good thing to come from the Quad experiments was the wealth of research into multichannel audio by some damn smart folks and the research into phono cartridge stylus shape and with it information retreival from the grooves of the LP disc.Once the problem of wear was recognised this new tip shape was modified into what is now used in damn near ALL high end cartridges so the overflow technology from quad actually had some real world use. |
Ambience Extraction :
With Quadraphonics being a rapidly fading memory I was very surprised when I opened my just arrived issue of Popular Electronics (yes,same rag folks.At one time if you wanted the straight poop this was the place to get it and I still miss the magazine immensely,but not "computers and electronics which it became before it died,along with Audio Magazine.The other cutting edge Audio electronics/DIY/Tecnical background/product review rag of the era) and right there on page 12 or something (right after the "NEW" section though the name of the column eludes me right now) was a photo off a wall of AR speakers and the caption "New Frontiers in multichannel sound" (or something like that.It WAS over thirty freakin' years ago so cut a little slack
).
The article went on to explain how research up at Cambridge Mass. into bringing the concert hall experience into the living room determined this could be accomplished by using 16 discrete electronically delayed channels scattered throughout the room,placed according to that individual channels delay time (length of distance path) and bandwidth (high frequency rolloff).They came to this magic number of 16 through long term experimentation but hinted that a so far unknown company by the name of Audiopulse was at that time in the process of designing a device that would come damn close using only two addtional channels (sounds like quad to me dammit !These knucklheads are like a damn dog with a slipper,never let go !
).
So I read the article and am interested.This is
not quadraphonics revisited but an entirely new thing and from the article all reports from some highly respected folks is a consensus positive.full thumbs up.Now i want in but I had no clue at all how to go about building such a device.one that they kept some of the details on just for that reason with everything being almost comical in the "if we tell you we have to kill you" tone but that is for the civilians.Those who know circuits and understand the "why" could get enough information to fill in the blanks solo and without the added fluff but that still was no aid.
In order to emulate what was being done you had to have access to the technology and at that point digital audio was non-existant so parts not available.to try and use individual logic chips to construct a digital audio delay line was off the "to do" list because it was not a workable solution.Interest peaked but figuring it will be a blip and pass into memory like so many other things and I will just go back to my dynaquad box and listen to music instead of sweating the details.
But it was not a "blip".At that time i subscribed to Popular Electronics,Radio Electronics,stereo review and a few other and across all these magazines a common theme was starting to come .
"Get ready because digital ambience extraction is coming to a living room near youi soon"
The first product was the Audiopulse model One.Push button delay level selection,rear channel high frequency cut selection (woke me up to the fact that I needed this on my D-box),rear channel level controls,$1,000 out the door !
Over my head at the time though from reading all the background i wanted in.There were "hints" that a model 2 was being designed that not only would be cheaper,not only would the controls be easier to use but it would also add a two channel power amp for the added speaker channels !
and all for "only" $500 ! (I purchased one and still have it
)
What this device was is a digital delay line that delayed the audio signal by a certain amount that relatd to distance or "hall size".
50ms=50 feet,100ms=100 feet etc.
Additionally it had "taps" at various increments along the line of the delay which were mixed together as one at the output.what this did was to simulate the "16 channel wall of sound" by adding all those additional shorter delays formerly using discrete speakers in the original AR setup.This part is very important because with a single delay representing the longest path you end up with reverb or echo which is no more than an effect but with multiple taps representing various levels of delay you fill in the "gaps" between the direct sound of the front stereo pair and the full delay representing the back wall of the original venue of the performance.
The audiopulse Model One was in some ways a higher end machine but the Audiopulse model 2 more of a "finished" product so it sold fairly well and this was noticed by other equipment manufacturers.
In rapid succession products were being offered by Advent in their "Sound Space Control",by ADS and several others and the product sold.Many already had an additional stereo amp and speakers kicking around from earlier Quad experiments so system integration was easy plus here finally was a product that
added nothing to the sound that was not already there but only extracted content present in the recording (L-R mono delay channel with selective phasing to decorrelate the left and right delay channels
).even an audio purist could get behind this one becuse it did absolutely nothing to the main stereo signal so when it was off was
totally off and had zero effect on stereo reproduction.
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SIDEBAR
KOSS came out with a version that was actually pretty good but the cool part was KOSS being predominately a headphone manufacturer added two front panel "4CH Mix" jacks that took the front and rear channel content and mixed it down to a 2CH signal for headphone monitoring.It worked and sounded pretty much better than any "headphone surround" I have heard to date other than my own DIY efforts.There was no center image but since there was no known "surround sound" at the time you did not miss something not yet invented. |
Drawbacks ? It only worked well with live recordings that already have this L-R content inherent to the recording and some studio recordings also having this content though this part was more crap shoot than anything so results all over the map.
We finally a medium that would expand the space of the home listening environment that did more good than harm.Not perfect but not too shabby either.all that original quad research did not go to waste and was in fact brought forward and "tweaked" while the lessons of the format wars V1 not fogotten.
WRONG !
Not happy with fine tuning and extending/improving this new concept that for the first time (well since Hafler D-Q anyway
) extracted ambient content without harming the original stereo signal these as*holes could not leave crap alone and just had to go muck it up.
Extracting ambience was not enough.Oh Nooooo.They needed to
sythesize ambience for those recordings that had zero L-R content.why settle for part time ambience when you can have your cake AND eat it too ?
So generation ll ambience ambience simulation machines were born.This is where things got screwy.Not learning crap from the former
Quad-Wars there were now machines from maybe twenty or so major manufacturers but some were "Ambience Recovery",some were "Ambience Simulation" and some were "All Purpose ambience recovery and Simulation" machines.Now we had a very confused consumer,
still gun shy from the quad experience they were slow to take things on face value again just because the ad copy said they should but if they just stayed with one method maybe there would have been a standard that could have grown into a staple but by having too many options,too many decisions left to the mostly non technical ignorant consumer and a too complicated cotrol structure this also went the way of the dinosaur even though a good idea and with good intent.The idiots were on to something but they fked it up and lost big when the consumer said "No thanks.I'll keep mine stereo dude"
Another possible class of product shot down in flames for this time no good reason other than greed and idiocy but now I had
two devices in my system that i could play with while still retaining the basic purity of two channel audio :
1-Passive ambience extraction :Hafler device
2-Active ambience extraction : Audiopulse Model 2 (Line level dynaquad with delay.That is what ALL multichannel ambience/quad units really are at the core
)
So multichannel audio in the home was a dead subject and the public fed up with all the manufacturer lies/formats/indecision.They wanted no ore and even the thought or mention of multichannel audio would get you laughed at at best and not taken seriously or at worst the idea met with anger and derision.Fool me once shame on you.Foll me twice shame on ME but the problem was we were ALL folled too many times to count and first offered no choice then too many and combined with the ad copy a very confusing state even for thosde who knew what was actually what.
I could go into the various decoders/methods.Mention that the benchmark was the best out there,that the Tate Steering logig a huge step foward,mention the competition between digital delay and analog "bucket brigade" delay,etc.,etc,.but to no point other than to cloud this present post and in the end confuse as much as it clarifies-as was with the manufacturer ad copy.No matter what feature are touted it still comes down to in house listening so reading all the detils mostly no more than self serving to the company wanting you to buy their product.Never will you read "the other guys product is far better but I still would like you to buy mine so I can make a buck or two also considering how much loot is out there to be had from suckers...um I mean customers......"
So four channel audio is finally dead and buried .Long live stereo !
Oh wait ! What's that I hear ? you say something man ? sounds like it is coming from behind me !
Surround sound
Marketing genious but nothing new in technology.
Take the original Hafler Dynaquad L-R ambience extractor,mate it to an Audiopulse type digital delay but at a single standard of delay time,toss in a center channel as has been done since the very beginning of theater sound and for good measure toss in a Dolby NR circuit for a solid rerar/side channel noise spec
SIDEBAR :
At the recording end
But do NOT aim this at the audiophile or equipment geek,not even Joe Public but aim it squarely at Mrs.J.Public ! you get the woman of the house interested and the man has no choice but to fall in line if only to keep the peace and have a harmonious family experience !
Not just that but who does not like the movies ? How many do not enjoy the spectacle of "larger than life" sound and vision ? how many do not leave the theater after being to a srriouslyt good action/adventure flick and everyone chatting about it ?What is not to like ?
well you have to go to the freakin' movie theater and deal with idiots is what !
Well boys and girls.you too can have that experience and all in the comfort and porivacy of your own living room !
Yup.I am deadly serious.all you need to do is add some really tiny and really crappy low cost speakers to your suytme along with this little black box that includes everything else.
Hook it up and sit back and get ready to be dazzled and amazed !
HELL YES ! HEAVEN ON EARTH !
Pure marketing genious and nothing new had to be "invented" .
Just take the best of everything that went before,toss the rest,tweek it,standardize it so every movie will be compatible and all manufacturers can get to building and selling PRODUCT (liscence fee paid of course
),aim the ad campaign at "everyman" instead of the audiophile nut jobs and we have a "winnaaah".
What could be simpler ? You want something to come from the rear ? Just mix it to the rear channel by making it a L-R signal.Front ? Pan left,pan righ pan equal depending on where you want the sound FX "position" to be.Dialog on the screen must be centered ? Hell boy.Do nothing jerky ! The L+R mix that goes to the center channel has that under control and you only need to pan the signal equally left and right as in a regula stero signal !
You say you have no center speaker ?
no problemo pedrone.Just leave your television speakers "on' boy ! They sound like crap you say ?
OK just for you we will toss in a siomple little L+R blend and mix it back to the leaft and right channels at a reduced level.Just for you.say thank you.
thank you
Bottom line is
Hell Yes I know all about multi-channel audio.Not only do I know about it but i understand it.The details,the how and why and so I
know what does and does not work.
Not from reviews.Not from reading articles or from reading manufacturer ad copy but because I
lived it from the very beginning before any had a clue what it was or where this was/is all was headed.From my personal experience the new attempt to get multi-channel
audio into the living room is just chapter three of quadraphonics.
Home Theater Surround said there was a market for multichannel sound in the home and because most already have the additional channels integration is simplified but they still just do not get it !
If you want to convince us to buy into something you say is great and a must have you first need to get your own crap together and offer
one single format that we the consumer can either fall for or take a pass on but have your own little format war,a war that lasts for years and all the while having the "experts" tell us poor ignorant savages why it is we who are foolish for not buying in and you are totally fcked from day #1.
Check the history of your own industry and learn the damn lessons of that history then go figure out something that not only works,not only works consistantly but does not impose and entire system revamp just to have an in to the club.
The rickmonster will take a pass until something comes along that impresses me.Until then I am quite happy with my Dynaco QD-1 MK ll "passive ambience recovery system" for ALL my loudspeaker listening be it music or movies because it imposes NOTHING on my two channel audio.It only adds but subtracts nothing.For headphones I will continue to use my own little DIY passive headphone surround decoder until or if I am impressed by something better.That something also needs to be a device that imposes nothing.Does not cause me to run an analog signal through
someone elses choice in ADC/DAC,that is fully defeatable and bottom line sounds better than what I presently have and use.
I don;t see that happening in my lifetime and i plan on living for a very long time.the term "been there and done that" should have a picture of my mug right along side the text
Rant over ('bout time too.Anyone actually get through all this without falling asleep or going mad ?)
***Disclaimer***
The above is strictly from memory and based on my personal experience so if I have a sequence or two wrong or maybe my facts not exactly correct down to the last detail all I can say is crap happens
in the sound!
