Unraveling The Great Quad Debate

Unraveling the Great Quad Debate

What is the deal with quadrophonic sound? Is it just a gimmick being pushed to sell more products or is there really an advantage to four channel separation? What about the battle between Matrix and Discrete? In looking into these and other questions, the SUN discovered that much confusion abounds about quad. With X-mas Hi-Fi buying in full swing, we commissioned an electronics engineer to shed some light on the subject.

A real good place to start with quad is about 35 years ago or when the Japanese became an issue in WWII. The Japanese had a curious device capable of scrambling radio signals in such a manner that only someone with a special receiver could unscramble the transmitted messages. If we replace the terms scramble and unscramble with the new terms encode and decode we have the same machine present today in the form of a matrix quad system.

The war ended and we forgot about the matrix system, but some wise guy decided one channel was not enough for our hi-fi systems. Everybody thought stereo was, bluntly, dumb! Without thinking we tried to throw legs in the path of development with such questions as, "'How are you going to broadcast stereo? How are you going to get a reasonable amount of playing time on a record and TWO channels? Where am I going to get the money for a second amplifier, another speaker and who wants to buy my mono tape recorder?" I'm sure any of you could answer all of these questions now. At least you could answer with "It's obviously better!" If you are under 50 you might not still hold a grudge against the wise guy who decided two channels are better than one.

The same wise guy was definitely smart enough not to try the same trick twice. So we have a new wise guy who's trying to tell us that four channels are better than two. And we have a whole new batch of legs to toss in the way, replacing the word stereo with the new word ... quad in each of the above questions. Quad is better, but only if you're willing or able to afford it.

                                                                       ORIGINS OF QUAD

As far as the recording industry is concerned four channel has always been around as well as 8 and 16 channel. Thank God they're not trying to press that on us! The industry has been using all those channels and more to make the types of STEREO records we're used to. What they do is attach a microphone or a cable to anything in the studio that moves and record it. The fun part comes when the engineer (butcher) comes along and decides which and how much of all those channels are going to be heard on your sound system. With all due respect to the recording engineers this process requires a terrific amount of skill. A good engineer can make a poor group sound better and a good group sound worse. To the engineer two channel or four channel doesn't make that much difference. Actually, four channel gives the engineer more room in which to work with more imagination. The problem comes in trying to put four channels of information into the two sided groove of the record. Obviously, the left and right channels of stereo go on the left and right walls of the groove.

What is the best way to put four channel information on two walls of a record groove? Currently the discrete (RCA) and Matrix (CBS, Sansui) are battling it out for mass acceptance.

In 1969 the first four channel systems were introduced to the public. Basically, these systems derived four channel sound by enhancing existing stereo records. This meant that the rear channel music was only very slightly different from the front music. What the public wanted was music that sounded as different front to rear as it did left to right, hence, front to rear separation.

The industry was forced to give us a dramatic increase in front to rear separation in order to continue to gain acceptance with four channel. This didn't pose too much of a problem if you were willing to invest in a four channel 8 track or reel to reel tape deck as well as two more speakers and two more amplifiers. Prerecorded 8-track tapes are expensive and prerecorded reel to reel's are even more so. And to the real sound buff (audiophile), these tapes were usually not very good sounding for various reasons. The best way to get four channel sound, then, is through records. That also poses the best question; how do you get four channels onto two walls. With tapes you simply narrow down the existing two channels and add two more.

                                                             MATRIX EMERGES

The Japanese being as conservative as they are, brilliantly remembered a discarded piece of equipment which they immediately dusted off and dragged into their neat little laboratory. They had to drag it because it weighed about three hundred pounds and was about three feet tall. This was their original WWII secret code box. Remember the device capable of scrambling radio messages. The only trouble was they had to make their secret code box the size of a secret code ring. Of course this was no real problem either since they fully realized the advantages of some new devices called transistors and integrated circuits. They had other technical innovations, such as OCL and P11 IC and even FET's. These are the technical jargon of secret code ring and wrist TV manufacturers. Anyway they managed to get the four channel music scrambled onto the record and a descrambler into your four channel amplifier. This was the first matrix decoder. They called it that because no one wants to listen to scrambled records through their descrambler, but everyone wants to listen to their encoded records through their matrix decoder. Definitively, a matrix is an ordered array of numbers. In this case the front and rear channel info is orderly arrayed onto the disc by the encoder and when the decoder hears this it puts it back into its four channel form and transmits that to each of the separate speakers

                                                       ENTER "DISCRETE"

Somebody decided that matrix quad was not good enough and that another system was far superior to the matrix system. RCA and a Japanese company got together and decided to call themselves the Japanese Victor Corp. or JVC. They say the matrix system is less than effective because the decoder doesn't know the difference between a four and a four (that's not a misprint) i.e. a 3 plus 1 four is different from a 2 plus 2 four and even a 1 plus 3 four.

Let me give you a picture of what these numbers indicate. Let's say in this case the four indicates a four piece band, i.e. keyboard, drums, lead guitar, bass guitar. Let's say the engineer wants a 2 + 2 format in the rear channels. This could be the two guitars on one side and the keyboard and drums on the other side, thus 2 + 2. Half-way through the song, the engineer may decide to leave the keyboard man by himself on one side and bring in the other three on the other channel, hence 1 + 3. Then he decides to switch them or do a reverse. Now we have a 3 + 1 . What the matrix does is give a combination of all these additions of four which means that you can't get the desired perfect separation.

JVC says that modulation is better than encoding. Modulation means that they put an inaudible sound at the bottom of the groove as well as the total four channel should on the walls of the groove. What that inaudible sound at the bottom of the groove does is carry the difference of the front and rear channels. In simplified form it tells each of the fours on the walls of the groove exactly what kind of four it is, i.e. a 3 + 1 four or a 2 + 2 four or a 1 + 3 four. This gives a very obvious improved front to rear separation and distinction and was therefore termed discrete quad.

Let's go through it once more and make sure you understand this exactly. Now you're a matrix decoder and the music you receive behaves like the number four. Immediately your decoder has to determine what numbers added together make four and which of those numbers go in the front or rear speakers. You decode, 3 in front and 1 in back; or, 2 in front and 2 in back; or, 1 in front and 3 in back. You can see you have a one in three chance of getting it exactly right. You don't have enough information here to tell you which of the music is supposed to be in the front or the rear. What this means is that quite a bit of the music that's supposed to be in one part of the room will end up in a different part. If you're standing in the middle of a quad system a given instrument will sound primarily in one corner, but quite a bit of that instrument will bleed through to the rest of the room and cause somewhat of a sense of misdirection. To a lot of us this wouldn't make much difference, and actually a little bleeding is necessary to give a feeling of presence. Too much bleeding is confusing.

Now you're a discrete demodulator and you're given the musical information in the form of a four again. This time, however, the walls of the groove of the record say four, but the bottom of the groove, i.e., the modulated portion says 1 . That means 1 is in front; what 's in back? You're demodulator thinks 4 minus 1 equals 3. Aha! Three's in back. Now the modulated portion says 2. No sweat, 2 in front and 2 in back. The modulated portion says 3. You know now that 3 goes in front and 1 goes in back. You've eliminated the 1 in 3 possibility of getting it right. Now each instrument comes from wherever it's supposed to with the correct amount of bleeding. Armed with this information you know more than 90% of the audio salespeople know about quad. Try it. Go to any audio store and ask a salesperson what the difference is between discrete discs and matrix discs. You've never have had so much fun in your life.

                                                             WHICH SYSTEM IS BETTER?

You're next question is, "What's all the confusion about?" From what I've just told you, it's obvious that discrete is the best way to go. This would be true if discrete didn't develop some problems of its own. First, the modulation used up more record space and your LP became an SP. Then they found out some of the higher frequency notes didn't come through too well. Also you were told you had to buy a new more expensive needle that would be capable of that ultra high frequency modulation. Then the discrete demodulator had to be tuned to whatever needle you bought. Finally after you had everything all set up and you were ready to listen to some fine discrete quad sounds, you found that records had a tremendous degree of quality. Some records would put the piano in one corner, place the bass in another, the horns in another, and the tympani in the last corner. Great! But other records would get maybe two or three corners right but the remaining corners would go fzz spsst zap pop etc. No one wants to listen to a recording of Rice Krispies backed up with a piano and horn section.

The originators of matrix decoding made everyone aware of this and claimed superiority. Discrete modulator manufacturers came out with improved demodulators and cheaper needles. RCA held up their end with improved records. Decoder manufacturers decided they had a fight on their hands and came out with improved decoders claiming better separation. Everyone had their own ideas and between 1971 and 1974 the consumer was bombarded with SQ, QS, Vario Matrix, Regular Matrix, SQ logic, SQ full logic and Vario Matrix from the decoder manufacturers and CD-4, s Quadra-disc and Discrete from the demodulator manufacturers. To make things worse compact manufacturers came up with quatra-sound, quadra-play, quadaptors and other quad sounding paraphernalia that has no more to do with true quad than Evel Knievel jumping a canyon on a motorcycle. No wonder we were all confused!

                                                                    DISCRETE/MATRIX 1974

The manufacturers seem to be getting it together. Most quad units can now be purchased with both a demodulator and a decoder built-in that work. Decoded FM is quickly becoming available also. Detroit was one of the last metropolitan areas to introduce FM matrix quad. Soon there may be a discrete FM quad method of broadcasting. (There is some controversy concerning the quality of quad broadcasting on two Detroit stations in particular. Look to a future SUN for a report on the various claims being made.) The question now if you want to go quad is what equipment to buy. If you're looking into the possibility of a sound system you will first have to determine how much you can spend. This is when you will decide if you can afford a quad system. A reasonable one can be had starting around $500. [f you need to spend less than that, I would consider a good stereo system capable of being adapted to quad as your interests increase in the future. Good stereo is better than cheap quad.

When you do find yourself in the quad category, be very careful in your selection. Some good name-brands to look into are: Technichs; Sansui; Pioneer; Harman Kardon. All these brands have both matrix and discrete quad built right into the unit. Technics is a good unit to look into if you're hovering right around the S500 mark. If you're looking a little higher the other three brands offer exceptionally good value. The Pioneer QX-949, for example, is an extremely well accepted unit. However, that receiver combined with speakers and a turntable will bump you over the SI 000 mark. What you can do with this unit is set it up as a stereo system with only two speakers and have enjoyable sound until you're able to purchase two more speakers. At that time you would simply flip a switch on the back of the '" QX-949 and away you go with a whole new quad system. The same goes for the Harman Kardon and the Sansui units. You may think there's no difference so why worry what kind of unit you get. The trick here is to shop the shop. Find a dealer that you trust and stick with him or her. Tell

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Through quad's early development a variety of systems were introduced and then abandoned, leaving the consumer holding the bag. Now it appears the manufacturers are getting it together.....

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the salesperson what you want to do and how much you want to spend. Make sure your dealer has a good return policy and they're willing to help you even after you've given them your money. A good policy is to get the dealer to come out and hook up your unit for you. That way if there are any problems they can be solved for you on the spot. Unless you're an expert in electronics, no one knows more about the individual components and how they hook up than your dealer. You won 't be surprised at how agreeable a salesperson is before you hand over your money; so get the store to agree to deliver the equipment and hook it up for you before you pass the bread. This will not only aid you initially, but in the future the salesperson will be totally familiar with your system and will know exactly what when you give the store a call concerning a problem.

So now you have some idea of just what quad is about. If you don't dwell too much on the small stuff you won't be confused. Make sure that you understand exactly what you're getting into and double check with your salesperson on the details. If you have any doubts concerning quad or any of the aspects have the store supply it in writing.

If you have any questions at all concerning quad or any aspect of sound equipment, write a letter to the SUN. Give us a tough question or one that everyone seems to have and maybe we'll print it with an answer .

Thanks for your time.

--Lou Severino

What is the best way to put four channel information on two walls of a record groove? Currently the Discrete (RCA) and Matrix (CBS, Sansui) systems are battling it out for mass acceptance. Through quad s early development a variety of systems were introduced and then abandoned, leaving the consumer holding the bag. Now it appears the manufacturers are getting it together . . .

SILENCING HUM: HOW TO TELL YOUR CONNECTIONS TO HISS OFF!

Glen Gould may hum along with Bach, but but your hi-fi system shouldn't get away with it. Still, the chances are a little better than 50-50 that your system hums more than it should, despite the fact that hum is as easy to cure as any hi-fi ill. And spending a couple of bucks (at most) and maybe an hour of your time will do more to improve the sound of your hi-fi system than anything short of a hot new amp or pre-amp. 

Why care about hum if you can barely hear it? Simply because even a little hum not only places an added load on your system's ability to reproduce music but also mixes with low frequencies causing muddy base. Removing hum and base notes will gain a new clarity and a well-defined spacious texture.

Ultimately, hum arises from the fact that almost all hi-fi equipment is powered from the AC line. In each component there is a power supply which converts AC to various direct-current DC voltages needed to run the device. This power supply can be designed to work very well with (and expensively) or to operate in a so-so fashion that will allow the manufacturer to sell his product at a higher profit. Given the choice of gorgeous performance or a couple cents profit, the average hi-fi manufacturer will take the money and run; the business isn't known for charity.

In addition to cutting corners on the power supply, many manufacturers are just careless and do things such as route the leads from the phonograph past the hum-inducing fields of the power transformer. They know what they are doing; hum is well understood and there are lots of reasons for it--but few excuses. 

Fortunately, there are some things you can do at home on a rainy day that will minimize your system's hum. First, the obvious things.

Space out components. Since the phonograph cartridge will pick up hum from the magnetic field around the transformer in your components, put some distance between it and them. A few inches often make a difference, since the strength of a magnetic field (and therefor the amount of hum it can induce) drops as the square of the distance from its source. Obviously, long phono cables are not necessarily bad. 

Keep power and signal lines separate. It may be neater to bundle these together as they run between components, but it greatly induces hum and noise.

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The chances are a little bit better 50-50 that your system hums more than it should, despite the fact that hum is easy to cure. Spending a couple of bucks (at most) and maybe an hour of your time will do more to improve your system's sound than anything short of a hot new amp or pre-amp.

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circuited phone plugs look like one end of a phono cable without the cable. They are for sale at most local hi-fi stores and are one of the few bargains in the business.

Shorting plugs are inserted in unused pre-amp or receiver inputs to cut noise and they work. For proof you can hear disconnect from your present phone cables, switch to this input and listen to it with and without shorting plugs in the jacks. Sometimes, shorting plugs in open phono will even cut hum on other inputs.

Shorting plugs are especially useful in systems with several low-level inputs--for example, a system with two phono inputs or an additional microphone or tape-head input. If your system has more than one low-level input, short any that aren't in use.

Ground the turntable to your pre-amp. If you have just put your system together and the phono does nothing but buzz, you haven't followed directions. Run a ground wire of heavy lamp cord between your turntable's motor board and your pre-amp. If you have already done this and you still have too much hum, look for a better spot on the turntable assembly to connect to the ground.

Do this by connecting one end of the lamp cord to your pre-amp or receiver and then by touching various places on the motor board. Do this while the system is on, and, if necessary, with the bass and volume up (but be careful--not too high). You'll find the connection point that gives the least hum easy to spot.

Ground your whole system. If your home has honest three wire electrical outlets or hand-cold water (not gas) pipes, by all means run another heavy  wire from your pre-amp or receiver to ground. There is one spot within your system that will give the most hum reduction; find it by connecting one end of the ground  wire to the water pipe or screw holding the outlet cover on, and then touching the unconnected wire end to various components and to various spots on each one. Usually, the pre-amp will be the beat connection point.

Even if a system ground doesn't cut hum--and in rare cases it won't---you owe it to your body to reduce any potential shock hazard. Ground your system anyway. 

If you have done all this, you should have a lot less hum than you started with. There's now one final trick that will cut hum to the minimum your system can produce, and it may be the simplest step of all --flip your wall plugs.

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