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CD History - Digital Audio Compact Disc


25 Years CD: August 17, 1982 - August 17, 2007 and turned 30 in 2012

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EARLY HISTORY
DEVELOPMENTS
IN THE 1960s
DENON PCM
SONY
SOUNDSTREAM
JVC
THE INDUSTRY - COMPETITION AGREEMENTS AND DEMONSTRATIONS
CD IS THE
SIMPLE LINEAR FORMAT
EXPENSIVE HIGH RESOLUTION FORMAT
SOUND IMPROVEMENTS
THE BENEFITS OF
THE VINYL LP
   
THE CODES:
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ADD - DDD

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How Does It Work...

Reading the signal of a Compact Disc and converting it to analog

Edited image. Oiginal image taken from the brochure issued by Philips in 1981 at the Festival du Son in Paris. The added schematic diagram indicates the functioning of the laser pick up, the conversion, and the amplification of the signal.

The engineers in the world famous Philips Physics Laboratory (NatLab) start working on digital techniques around 1967. A few years later they research the feasibility of the laser video disc combining images and sound. That brings up the idea of making a laser disc just for music and speech with no images added.

The final outcome is a disc of 12 cm in diameter which is read by a laser beam. The disc has a reflective layer, covered by a non reflective layer with holes of various lengths which measure mere micrometers. These holes represent the recorded music. Only when the laser beam is reflected by the disc, the beam is read by a photo cell and the data which it represents are converted into an analog signal.

Although the resolution of the signal and the depth of the sound are very low in quality, relative to the analog tape and LP, this disc is to be the modern substitute for the vinyl long playing stereo gramophone record.

The first Compact Disc, as the disc is called, is pressed on August 17th, 1982, in the Polygram pressing plant near Hannover, Germany. In 2007 the format was 25 years old.

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History Starts In 1967

Early design and final appearance of the label of the Compact Disc

Analog Sophistication
By the end of the nineteen seventies designers of high end amplifiers are concerned about an extreme large bandwidth, they are investigating all sorts of distortions in order to further improve the reproduction. Not just the values of the Total Harmonic Distortion (THD) and how to handle these, but also the newly discovered Transient Intermodulation Distortion (TIM) and Dynamic Intermodulation Distortion (DIM). Digital formats will make all further research for improvements in these fields practically obsolete.

Sound Premonition
In the late nineteen seventies digitally recorded sound is being demonstrated at the big audio fairs: Funk-Ausstellung (Berlin), CES (Chicago and Las Vegas), Heathrow (London), Firato (Amsterdam), Festival du Son (Paris), etc.
Many discriminating music lovers and audiophiles are not too enthusiastic about digital sound. For many it is not difficult to hear that the resolution (specifically of the high frequencies) is extremely low and that the bandwidth is restricted. This is the more apparent if the exhibitor in the next stand demonstrates music coming from analog sources.

Digital Fear
Many do fear the arrival of a digital format with such a low resolution. Especially those who have invested in high end turntables, expensive cartridges, in tape recorders with professional qualities, in esoteric amplifiers and grandiose loudspeakers. They have brought the reproduction of the analog Stereo LP to an extremely high and refined level and are enjoying pure music, reproduced from records pressed from high grade vinyl with silent surfaces.
Are the fears justified?


"This day will be a memorable day in the history of sound. For the first time music will sound in the living room as pure as in the concert hall: without the extra noise of the needle in the groove, without dust particles, scratches or dents."

These are the first lines of an advertisement introducing the CD to the music loving public. The advertisement appears in Dutch newspapers on the 1st of March, 1983.
The first CD is pressed on August 17, 1982, in the Polygram factory in Hannover, Germany.
In Japan the Compact disc is introduced
on November 1, 1982.

Successor to the Stereo LP
Thomas Alva Edison is the inventor of the Phonograph and the vertical engraving of the signal on a cylinder. It is the so called hill and dale technique which is later used in a disc proposed by Edison himself and by Pathé in France.
Emile Berliner proposes the horizontal, meandering groove. Edison's hill-and-dale is soon outmoded. But it comes in handy when the stereo long playing record is designed and officially is introduced in 1958.
After the launching of the stereo LP, manufacturers of consumer electronics and a few record companies start thinking about the next step of improvement. Some start thinking of a completely new recording system, a new sound carrier.

The Beginning
In 1966 audio journalist Leonard Marcus of High Fidelity Magazine investigates the future of recording in a very interesting article called 'The Prospects in Audio'. He writes that CBS Laboratories are developing a new analog disc. It is Dr. Goldmark himself who demonstrates this new format. It is a 7 inch record with an extremely fine groove. It turns at 8 RPM and can contain the same amount of information as a 12" LP. It shows that CBS is a firm believer in their own invention: the analog long playing record.

RCA
In that same article in the April 1966 issue of High Fidelity Magazine, RCA's Dr. Harold Olson tells the readers that the record of the future will be completely different: ''There will be no music on it, only a binary code''. He adds that only a very small disc will be necessary. The way the code will be read is also completely different. No needle or other mechanical devise will be used. Olson: ''The record could be read by an electron beam.'' It will be possible to record half an hour of music on a disc as small as the size of a quarter dollar (according to Wikipedia the quarter dollar measures 0.955 inches = 24.26 mm in diameter).
The carrier is not necessarily a disc. The encoded information can be printed on a metal bar, or a piece of paper (as was demonstrated later by Soundstream), or whatever object. In 1966 this means an upcoming revolution. It is the dawning of the age of the computer.
Futuristic
In the April 1966 issue of High Fidelity, pianist Glenn Gould writes an essay on
''The prospects of Recording''. He goes even further and predicts that the listener will have a console with a keyboard in his listening room. After typing the title of the work he wishes to hear, say Beethoven's Emperor Concerto, he can choose from a list of available recordings. After entering the selected performance, the music signal will be sent by cable to his hi-fi set and a small sum will be deducted from his bank account.
The prediction is that it will also be possible to store the entire performance in a chip (today that would be a memory stick , or a memory card) which can be bought in the "record shop".

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Working On The Future

Ampex
Tape recorder manufacturer AMPEX is experimenting with a digital tape format. IBM is computing with big machines using reel to reel tape recorders and connecting their clever Selectric typewriters for printing the data sheets. However designing a digital tape recorder for sound is a complicated affair. The marketing of such a recorder is impossible as the cost is $150.000 per unit.

Bell Laboratories
Bell Laboratories are concentrating on the idea of the Vocoder. The Vocoder divides the frequency band in several sections. Each section is represented by a code (which is a single frequency, akin to FM and the carriage frequency in Quadro). These codes can be transmitted via telephone lines, as transmitting speech is the original idea of the inventor. Naturally these frequency codes can also be stored on a disc. The transmitted or stored single frequencies can be translated again to the original sections of the audio band which, together, form the complete, original audio spectrum. The inventor of this method is Homer Dudley. He devises this system in 1928! Now Bell assesses if a further development for recording purposes is possible.
There are more people working on "the system of the future", mostly in secret.
In Japan new ways are being contemplated upon in the laboratories of giants like Matsushita, Nippon Columbia (Denon), Kenwood, Pioneer and Hitachi. And in Europe by Telefunken and Philips.

Telefunken Video Technique
Telefunken Video with tangential arm reading and inscribing the video and audio signals

Telefunken: 'Vinyl' Video Disc
In Germany, in 1965, Telefunken starts working on the development of a new carrier which is much larger than Dr. Olson's quarter dollar. Telefunken's laboratory system consists of a 12 inch disc. It contains digitally encoded signals for video and audio. It is a floppy disc made of thin PVC. The information is written in a vertical script with varying depth, akin to Thomas Alva Edison's hill-and-dale, so to speak. The variations are mere micrometers. The disc turns at 1500 RPM. That is 25 turns per second. Each turn represents a video image. In order to have equal density for every turn, only a small area of the disc can be used. The total playing time of an entire disc is 12 minutes. If the disc can contain images and sound, it sure will be possible to make a similar disc with sound only.

Primitive
In the Telefunken system the information can not be written at the high playback speed, so it will have to be "recorded" at a tenth of that speed and takes 2 hours to be completed. The disc rests on an air cushion. The differences in pressure are sensed by a piezoelectric pick up system which moves in a tangential arm. The diamond prism ensures the correct distance between pick up and record. The down force is 0.2 gr. The use of a carrier wave of 6 MHz is possible. This proposition is a rather primitive one. It still reminds one of the vinyl gramophone record. This mechanical method with the usure of disc and diamond (enabling 1000 playings), is certainly not the way.
In the nineteen seventies JVC is designing a numerical system. This time with a sapphire connected to an electrostatic pick up system, also moving in a tangential arm.

Philips Video Disc system is called LaserVision

Philips Video Disc: LaserVision.

Philips Video Disc: LaserVision
Around 1967 the engineers of the famous Philips Natuurkundig Laboratorium (Philips Physics Research Laboratory - Natlab) start researching the development of a video disc. It is an optical system instead of a mechanical one. Around 1980 the system will be ready for introduction and is named LaserVision. In 1967 the engineers realize, that, when omitting the images, they may have the possible successor to the LP, the long playing record.
In 1970 Wireless World reports about such a digital sound system. There are other magazines that publish more than once articles about the numeric formats of the future. For example Jean Hiraga writes in La Nouvelle Revue du Son about the systems that are being developed by manufacturers in Japan and Europe.
In the nineteen seventies manufacturers do agree on the basic features and solutions for storing sound and images in a digital format. For the digital audio disc these are the features that have to be agreed on: maximum bandwidth (frequency band), number of bits, the physical aspects of a disc, and the ways of storing and reading the information. But a player is not yet in sight.

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The 1970s: Developing The Standard

Denon PCM Logo
Japan Broadcasting Corporation
In 1969 the Technical Research Laboratory of the Japan Broadcasting Corp. demonstrated their digital system known as Pulse Code Modulation which was looked at with great interest by large electronic companies in Europe and the USA Billboard reported: "Nippon Columbia (Denon, Ed.) earned the cooperation of the laboratory and (...) came up with a PCM recording system which opened the door to noiseless and distortion-free recording."
Denon professional PCM recorder

Sophisticated Recording Equipment
Denon produced PCM recordings as early as 1973 of artists like pianist Takahiro Sonoda, pianist Yuji Takahashi, harpsichordist Zuzana Ruzickova, pianist Annerose Schmidt, pianist Deszo Ranki, pianist Zoltan Kocsis, etc. The recordings of Mozart's Complete Piano Sonatas by Maria João Pires won several awards.
These recordings could only be proliferated by means of the vinyl record as the laser disc and the compact disc were not yet created. For the recordings extremely sophisticated equipment was built. At left the recorder based on a video-recorder for television stations. The image of the Denon recorder is taken from one of the inserts of Denon PCM LP discs and includes the technical details as well as a catalog of available recordings.

The specifications of Denon's PCM recording system:
Pulse Code Modulation: 44.1 kHz/14 bit
Dynamic Range: > 89 dB
Distortion: < 0.1 % at 0 dB level
Crosstalk: < -80 dB.
Frequency characteristic: DC - 20 kHz, +/- 0.2 dB

Telarc claims on their web site: "Even before the public had heard of the digital process, they were embracing the sound of Telarc." This is of course not correct. Telarc was founded in 1977, while from 1973 on Denon released their vinyl Digital PCM Discs.

Denon 14 bit PCM recording on vinyl disc
Denon (Nippon Columbia)
By the end of 1974 the world wide adopted digital format is the 44.1 kHz/14 bit PCM format. PCM stands for Pulse Code Modulation. The sound is measured at specific intervals by a pulse. A higher sampling frequency than 44.1 kHz. and a higher quantization than 14, are not yet feasible.
From then on Nippon Columbia (Japan) produces digital recordings and releases these on the Denon PCM record label. The relative low quantization and bandwidth and the ringing of filters to prevent the mirrored audio band (aliasing) from interfering with the musical signal, prompt many audiophiles to say jokingly: "You can hear the switching." As if the variations of the samples and bits is the same as the shifting of gears in a race car. What they actually mean is that they are aware of the fact that the sound shifted from one dynamic level to another, from one bit to another. The later recordings done with 16 bit quantization are of course of a much higher quality and some are quite stunning in sound if compared to the later CD releases. Why? That will be explained later in this article.

Large Catalog
A gradually growing catalog is offered to the record buying public with popular music, jazz, folk, and classical music. The classical recordings feature flute player Jean-Pierre Rampal, the Josef Suk Trio, the Tokyo Metropolitan Symphony Orchestra conducted by Louis de Froment, the NHK Symphony under Otmar Suitner, the Berlin Philharmonic conducted by Kurt Sanderling; pianists Maria Joao Pirez, Anne Rose Schmidt, Vlado Perlemuter, Deszö Ranki; cellist Janos Starker; violinist Josef Suk; organist Helmuth Rilling. From 1982 on many of these recordings are made available on Compact Disc also.


The A & R Department
The people of the Artist and Repertoire Department of the Denon PCM label (Nippon Columbia) knew well their way around and with taste. One of the many fine recordings was the performance of Mussorgsky's Pictures from an Exhibition played by the Tokyo Metropolitan Symphony Orchestra conducted by Louis Fremaux (X-7072).
It was Mercury who set the standard of demonstration in 1951 with Mussorgsky's Pictures At An Exhibition with Rafael Kubelik. Since then the orchestration by Maurice Ravel has proved to be a score that shows all the dynamics and refinement of the instruments of the orchestra as well as the capabilities of a specific recording format, a well cut laquer and a perfect vinyl pressing. Of course it served to demonstrate the technique of Pulse Code Modulation and it is an exceptional dynamic recording which dates from December 1972! Like Antal Dorati also Louis Fremaux serves the music to the full one hundred per cent. Another noteworthy recording is the 3 LP Box with the complete Sonatas for Unaccompanied Violin, performed by Jean-Jacques Kantorow. The recordings were made in November, 1979, in the Arakawa Public Hall in Tokyo. But here the PCM technique may show its restriction somewhat regarding the upper harmonics.
Denon PCM sample record
Denon's PCM LPs Reassessed
At left you see the cover of LP ST-6007 from 1979. It contains excerpts of the Denon catalog of PCM recordings. This promotional release and other records from the nineteen seventies show all to clear the quality of the recordings made before the advent of the Compact Disc.
In the audiophile set ups of today the Denon PCM discs have a very realistic dynamic sound, a deep and large soundstage, when an orchestra is recorded, and they often are a pleasure to listen to.
It was Mercury who set the standard of demonstration with Mussorgsky Pictures At An Exhibition with Rafael Kubelik in 1951. Since then the orchestration by Maurice Ravel has proved to be a score that shows all the dynamics and refinement of the instruments of the orchestra as well as the capabilities of a fine recording, a well cut laquer and a perfect vinyl pressing. The reference number of the performance conducted by Louis Frémaux is X-7072.
Varese-Sarabande digital LP
Japan Victor Company - JVC
Another developper is JVC, the company known for their consumer products and the CD-4 Discrete 4 Channel Quadraphonic sound recording system. In 1980 JVC's digital format has the standard 14 bits and sampling frequency of 44,056 kHz. At left the cover of The Devil's Trill, a Varèse-Sarabande LP featuring violinist Vlaclav Hudecek and pianist Josef Hala who have been recorded using the JVC VP-1000 Digital recording system.
Miller & Kreisel 16 bit LP
Miller & Kreisel and Sony
In the beginning of digital recording Sony U-Matic recorders in conjunction with separate converter modules are being used. Sony develops the PCM 1600 Digital Studio Recorder which becomes very popular. When the 1600 becomes available, more labels start recording digitally. Miller & Kreisel is such a label. The recordings are made with a Sony PCM 1600 with a sampling rate of 44.1 kHz. and the dynamic gradation of 16 bits. Jonas Miller and Ken Kreisel design their own electronics and modify the microphones. Their objective is to achieve a recording with the least phase shift and name it M&K RealTime Recording Process. Sony soon replaced the 1600 by their PCM-1610 Digital Audio Processor, a recording tool that - if used intelligently - can outperform many a modern low bit processors.
Soundstream LP with a recording using a higher sampling frequency

Soundstream, Telarc, Digitech, a.o.
The producers and recording engineers of Telarc, and Digitech use a different digital format. It is devised by Soundstream and has a sampling frequency of 50 kHz. which results in a slightly wider frequency band of theoretically up to 25.000 Hz. before the phase (time coherent) destroying brickwall filter comes into action. But what is a high resolution PCM recording format? The format of the Compact Disc with its 16 bit and 44.1 kHz. or the 48 kHz. of the digital audio recorder (DAT) can hardly be called high resolution formats, nor can the Soundstream digital technique. They only get a widfer frequency band and a higher resolution when two converters are used by Pioneer in their
Wide Range DAT.

Specifications for the Soundstream Digital Recording System:
Frequency Response: Flat from 0 to 21 kHz.
(- 3dB at 22 kHz.)
Total Harmonic Distortion: At "0" VU, less than 0.004%
At peak levels, less than 0.03%
Signal to noise: 90 dB RMS Unweighted
Dynamic range: 90 dB RMS, Unweighted
Sampling Rate: 50.000 samples per second
Digital Format: 16 bits linear encoding/decoding
Wow and Flutter: Unmeasurable

Data taken from Digitech DIGI 103 with Anthony Newman on the Historic Hilborne Roosevelt Organ (Great Barrington, Massachusetts.)

DMS Delos used Soundstream Digital Recording System

DMS-Delos
Right from the beginning of the digital era the Delos label released the recordings with clear and crisp string sound of the Sequoia String Quartet made when using the Soundstream digital recording system. These performances were masterfully cut and pressed on perfect vinyl. At left the cover of D/DMS 3004 cut in the groove by famous Stan Ricker who was the chief engineer for this recording which was produced by Amelia S. Haygood. Stan Ricker used a transformerless cutting system of JVC and he used Pyral lacquers which were still available in 1979 when these sides were cut.

CBS Recordings
For most recordings CBS used the Sony PCM 1600 converter/video adaptor which was connected to a Sony U-matic video recorder. When the 1610 was available, the sound engineers used that device. Many recordings were mixed and mastered on the CBS DisComputer. There are also a few CBS recordings done using the Soundstream System. The performances of Beethoven's Cello Sonatas Nos. 1 & 2 by Yo-Yo Ma and Emanuel Ax were recorded with the Sony PCM 1600 (CBS D 37251). For their recording of Sonatas Nos. 3 and 5, the Soundstream system was used (CBS IM 39024). And for Sonata No. 4 and Seven Variations WoO, Sony's PCM 1610 was the converter/video adaptor.
Mixing to Two Channels on the Spot
The new digital format confronted any producer and any sound engineer with quite a few difficultes. Apart from the limitations of the digital format, the biggest problem was that multitrack recorders - if available - were very expensive. So the sound picked up by the various microphones had to be balanced on the spot, and the signals had to be mixed down then and there to the two channels of a stereo recording. These signals were then converted by a Sony PCM-F1, or a PCM 1630, and recorded on a U-matic or even a Betamax video recorder. No re-mixing at a later date was possible. That is what "direct to digital" in most cases meant.

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The Industry: Agreements and Demonstrations

Prototype of Sharp 13 cm digital disc player

Sharp's prototype of a digital audio disc with 16 bit quantization and 44.1 kHz. sampling rate, stored on a 13.5 cm disc.

Pioneer and Sharp
In 1980 a committee discusses the standard of a future digital disc once again. Pioneer proposes a digital audio disc with a diameter of 13.5 cm instead of 30 cm (12"). The sampling frequency shall be between 44.1 kHz and 50.4 kHz. It will be a linear format with 16 bit. The maximum playing time will be 60 minutes. The disc shall be playable in their Laser Video Players made for 12" video discs as well.
Not much later Sharp presents a prototype in accordance with the format proposed by Pioneer. The actual digital format of Pioneer and Sharp is incompatible with the disc Philips and Sony are working on. However, the presentation by Sharp of their PCM digital audio disc, makes it all too clear that if Sony and Philips want to set the world standard, their cooperation better be successful.

Philips CD-Video Disc

The development of the Philips Laser Video Disc (LaserVision) and its player led to the creation of the CD-Video Disc and Player (introduced in 1987) thus paving the way for the DVD.
Picture taken from the brochure introducing the CD-Video format.

Sampling Frequency
Also the format Philips is working on is a linear format and not on a logarithmic format. It means that the number of samples vary with the frequency. The higher the frequency the fewer the samples. It also means that the width of the frequency band for audio depends on the chosen sampling frequency.
In order to measure sound one sample is not enough. It is necessary to have at least two references, or samples, as I.S. Reed and G. Solomon had made clear.
If we want to use the audio band of 10 to 20.000 Hz. we need at least two samples measuring the top frequencies. The result is that a sampling frequency of 44.1 kHz. gives a frequency band extending to half of that frequency, namely 20.500 Hz.

Bandwidth and Transient Response
A higher sampling frequency will result in a wider audio band. The later adopted 48 kHz. for the Digital Audio Tape Recorder (DAT) means an audio band extending to 24.000 Hz. A sampling frequency of 400.000 Hz. would mean an audio bandwidth from DC to 200.000 Hz. and practically no phase shift, and a fast risetime which is in fact hampered by the 20 kHz of the CD format. A large bandwidth is necessary to produce a true to live transient.
The maximum resolution of a system is dependent on the clock frequency which in 1980 is rather low. A higher clock frequency gives a higher bit rate. They eventually do not offer a better alternative. The later SACD is not an alternative. It is based on low bit conversion and does not have the dynamics of Pulse Code Modulation (PCM) which is the format of the CD.

That is the time when computer freaks are working with a Sinclair, a Commodore, an Atari, with 8 bit and a CPU with 4.43 MHz., storing data on a cassette tape with time consuming writing and reading.
Petition
When word gets around that Philips will propose a digital disc with the 14 bit/44.1 kHz format, editor/publisher Peter Aczel inspires the readers of The Audio Critic to send postcards to Philips in Eindhoven, the Netherlands, to urge the engineers to choose a sampling frequency of at least 50 kHz.
But in fact even a sampling frequency of 50 kHz. would not be high enough to satisfy the discriminating listener, as only a much higher sampling frequency can produce upper harmonics and a true transient response.
Further Development together with Sony
After consultations with Matsushita (Technics) and Sony, it is Sony who joins Philips to finalize the development of the Compact Disc. Philips has a 60% interest and Sony 40% in the joined venture. Apparently Philips is mainly responsible for the laser technology and Sony for the correction codes. You all have heard the story that Herbert von Karajan was happy that the capacity of the CD could contain the complete recording of Beethoven's Ninth Symphony. All physical and digital specifications and data are contained in The Red Book. But you only need ears to be able to judge the benefits and the less positive aspects of the medium.
Prototype of CD in cardboard sleeve

Prototype of the CD. Like the LP it has a paper label and the cover is a sleeve of thin card board. The jewel case has yet to be designed.

1981: Festival du Son in Paris
In the Spring of 1981, well before the official introduction of the CD, Philips demonstrates their newly developed Digital Compact Disc at 'Le Festival du Son' in Paris. People are elbowing their way into the small auditorium to witness this historic event. When a Philips engineer needs to check the equipment and lifts part of a long and wide, gray curtain, it is immediately clear that Philips uses stacks of electronics: amplifiers and cabinets filled with digital circuitry for converting and correcting the signal. The interconnecting cables are thick and heavy. It shows all too well that at that time the elaborate circuits and complicated modules for conversion and correcting any mistake made while reading the disc, has not yet been reduced to a few ICs, chips and a couple of operational amplifiers. The cabinets filled with components recall pictures of a demonstration at a World Fair in the early years of the past century. There is something primitive about it. But there is also the thrill of witnessing the beginning of a new era: sound recording and reproduction by means of a computer. The development of tiny converters and operational amplifiers is certainly on its way. But no risk shall be taken during such an important demonstration. Yet it will not take long before electronic circuits and converters are reduced to the size of a mere IC.
The difference in size between LP and CD
Louis Armstrong and Mussorgsky
Many do remember the demonstration of Louis Armstrong's digitally remastered trumpet, sounding round without a chiseled top. Also an original digital Philips recording of Mussorgsky's "Pictures at an Exhibition" performed by the Concertgebouw Orchestra, conducted by Sir Colin Davis, can be heard. The introductory trumpet sounds indeed unstable, is shifting in intensity from bit to bit, as it is recorded at a low level. Apparently no dither is added as it is not yet en vogue. The recording is also issued as LP with reference number 9500 744 and a few years later as CD 411-473-2. When listening to this recording in whatever format, it is clear that the recording technician is still "thinking analog".
The reason for the less than precise reproduction during the demonstration is not because the new constructed format does not work properly. It certainly works as correctly as the format dictates with the components of that moment. The actual reason is that the format is too restricted to really render the nature of the trumpet. Philips demonstrates with 14 bits converters, eventually enhanced with the technique of noise shaping. Only much later pure 16 bit conversion in combination with oversampling is applied in the Philips CD players.
Yes, the demonstration shows that the sound is as clear as light. That is true. But the demonstration makes clear that the sound is also incomplete.
And when two years later the first Philips player, the CD-100, is introduced, many a music lover can hear this "clear'' sound in their own listening room.

Remarkable Feat
No doubt, the creation of the Compact Disc is a technical feat of the highest order.
Taking the given format of 44.1 kHz. and 16 bit, designing a method for storage, incorporating algorithms with the codes for the signal, the correction of the signal, for the steering of the disc's speed in order to ensure the same density of information at every diameter, adding calculators for restoring the signal if a reading would be incorrect, and finally putting the audio signal plus this extra information in a series of pits on a very small disc instead of a heavy, 12 inch silver disc as other manufacturers propose... that surely is a technical miracle.
And do not forget about designing and building a pressing plant where all vital aspects of the production in a dust free surrounding are attended to (though in the first years many discs show imperfections and cannot be played entirely).
And finally the development of the design of a container (jewel case) which protects the CD, makes the product complete.

Denon PCM LP OX-7072-ND

Sir Colin Davis on CD and LP with Mussorgsky

The digital recording made by Philips of Pictures at an Exhibition as performed by the Royal Concertgebouw Orchestra conducted by Sir Colin Davis transferred to LP 9500 744 and later available on CD 411-473-2. At left the Denon PCM recording with Louis Fremaux and the Tokyo Metropolitan Symphony Orchestra (OX-7072-ND) from 1972. The different approaches by the respective producers and recording engineers are clearly audible.

Point of View
But that is looking at the medium from a technical point of view, that is looking from the point of view of the proud engineers of the Philips Research Laboratory, the point of view of the Sony engineers, the point of view of the marketing people and the record companies who - first reluctant - finally will accept the new world standard, a format with a channel bit rate of 4.3218 Mb/sec and a data bit rate: 2.0338 Mb/sec. Yes, there is no dust in the groove, there is the absence of the sound of the stylus in the groove, there are no scratches, there are no dents, no pressing bubbles. But there is the lack of resolution, and there are the anomalies (differencies) in the clock frequencies of player and DAC, the importance of which are gradually being discovered by engineers and designers. Serious music listeners who knows how acoustic instruments do sound, hear these technical aspects without knowing the technicallities by name or effect. They are judging the new medium with cautious ears. It is said that the late Jaap van Ginneken (long time producer at Philips' Phonografische Industrie - PPI, later to be named Phonogram and Polygram Records) did express his doubts, if not to say that he was against this limited format.`
 

Comparing Apples to Oranges
In the early days of CD, one journalist noticed that there were readers of his magazine who did not like the CD. He compared the attitude to that of the music listeners in the early years of the LP. They did not like the dull sound of the (early) LP if compared to that of the 78 RPM direct to disc recording. That journalist made of course a mistake. The change from 78 RPM to LP cannot be compared to the introduction of the CD. Both shellac and vinyl in the nineteen fifties had high resolution analog sound, restricted by the bandwidth of the respective carriers. And that is completely different from digital encoding and the problems it poses. It is not only the resolution but also the phase which is incorrect because of the CD's restricted bandwidth.

However, it is the convenience which leads to the general acceptance of the CD format and this prevents the inventors to develop another PCM format with a much higher sampling frequency, higher quantization and consequently a higher bit rate. There is no alternative!

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16 bit and 44.1 kHz.

The Linear Recording System

Bandwidth
The chief determining factor of the linear recording system is the sampling frequency. In case of the CD it is 44.1 kHz.
In order to measure a frequency (sound), at least two samples are necessary. This means that the maximum frequency of the audio band is 22.050 Hz. (in theory).The higher the sampling frequency, the more extended the audio band will be. For example: 48 kHz. as applied to the DAT recorder sets the upper limit of the audio band at 24 kHz.

700.000 Hz. Sampling Frequency
Already in the early nineteen eighties I remember fantasizing with John Watson (of Mission Electronics at the time) about a very high sampling frequency of say 700.000 Hz. well knowing that this will result in a high resolution sound recording. Or take the sampling frequency of 400.000 Hz. as is the argument of designer Tim de Paravicini in the nineteen nineties. That frequency will give an audio band extending to 200.000 Hz. This means that the number of samples at 20.000 Hz. is 8. And this brings about the resolution of a professional reel to reel tape recorder. Furthermore a 6 dB filter - which is phase coherent - can easily be applied at 20.000 Hz. To some the 200.000 Hz. bandwidth may seem rather far fetched. In the analog days a basic bandwidth of 400.000 Hz. for sophisticated phono stages was not at all uncommon.

Aliasing the audio band up to 22050 Cycles
Aliasing
The format of the linear CD has a theoretical bandwidth of 1 Hz. to 44.1 kHz. In practice however the audio band of 1 to 22.050 Hz. can only be used. The frequency band from 22.050 Hz. to 44.1 kHz. cannot be used. It is the mirror of the 1 H - 22.050 Hz. band. In other words it is the alias. Not a bit of the 22.05 to 44.1 kHz. band shall interfere with the music. In order to prevent a mix up, the insertion of a steep filtering by means of a so called brick wall filter, is applied. In theory the slope of that filter should be 96 dB. That is a very difficult value to implement with an analog filter. That is why sometime later the filtering will take place in the digital domain. This makes it possible to insert a less steep filter in the analog domain.

 

Samples
The number of samples in the audio band is frequency dependent. The lowest frequencies are being measured many times more than the top frequencies. The frequencies from about 11.000 Hz. to 20.000 Hz. are sampled only 2 times.
There is another important trait of the CD format. The highest resolution of the sound is attained at the loudest level, that is at 0 dB recording level. 0 dB gives also the least distortion. At lower levels, the resolution is less and is not in line with that of the 0 dB level. The lower the level, the less the resolution.
Every bit measures 6 dB. 16 bit means a dynamic range of 96 dB, no matter if the original recording was made at 20, 24, 32 or even 64 bit.

Linear Format and Oversampling

Oversampling fakes a higher resolution

Refining
The computer of the PCM recorder has a steep filter otherwise recording was not possible. The same goes for the CD Player. There is however a way to avoid such a filter with a very steep slope. The Philips engineers introduce the so called oversampling. This is a very clever technique. By multiplying the sampling frequency by 4, the sampling frequency will be seen as 176.4 kHz. instead of 44.1 kHz. and an audio bandwidth of 88.2 kHz. is suggested. This also means that the aliasing is far away from the music signal, the actual audio band of 10-20.000 Hz. Yes, 176.4 kHz. would be quite an ideal sampling frequency. Such a high frequency does not need a steep filter. This multiplication has the benefit of "interpolation". Steps between one level (bit) and the next level (bit) are being generated. This results in a more analog like sound wave.

The problem with the bits

Resolution of analog and digital are not in the same class

16 Bits
The 6 dB per dynamic step does not promote refinement.
A sound that is not at the exact measuring level, will be given the value of the nearest level. The drawing above shows how a specific loudness is attributed to a lower or higher step/level of 6 dB. without the use of interpolation. In other words, if no interpolation would take place, a sound of 2.9 dB above -6 dB would be attributed the value of - 6 dB. A sound of 2.9 dB below 0 dB would be attributed to 0 dB. That is why people, especially in the beginning of the CD era, would say: "It is a violin, but not exactly a violin." Every pianist knows that a digital recording of a piano has less "depth" than an analog recording can have. In other words: the deep sound of the singing of the strings is less.

Reverberation and Depth
This is also true for recordings of orchestral music. In the beginning the recording equipment was not as sophisticated as it is today. In order to give the sound of the recording of Symphony No. 4 of Anton Bruckner with Bernard Haitink conducting the Vienna Philharmonic Orchestra more depth and concert hall atmosphere, recording engineer Volker Strauss took the ready tape to a little church in a small village in the Veluwe region (the Netherlands), played the music and added a well chosen amount of the natural reverberation of that church to the final tape from which the master was etched for the CDs to be released. It was a sort of acoustic feedback so to speak. Without this measure the music would have sounded less agreeable, would have less depth, would have a dry characteristic. Volker Strauss said so when interviewed for Dutch opinion weekly "Vrij Nederland".

96 dB
Because there are 16 bits, the difference between silence and loudest music (the dynamic range) is 96 dB. The quantization of 16 is a rather low number. At the time of the development of the Compact Disc a higher number of bits was not feasible. Today 64 bit can easily be applied when designing a format. But in 1980 16 bit is the maximum and already superior to the 12 bit/32 kHz. which is then used in broadcasting transmissions. And it is very superior to the 4 or 8 bit of a simple computer. The higher the quantization, the more depth the sound has. (Note: This adagio is also true for images made with a digital camera and with a scanner.)

Restriction
You can make a recording at 20 bits, 24 bits and even 32 bits and storing them on a digital tape recorder or a hard disk, if you have the appropriate converters (preferably of the multibit design). Or make an analog recording with 700 "bit" (so to speak, or gradations) if we don't count with the fact that a bit is 6 dB and not 1 dBb.
Fact is that the CD has no more than 16 bits. In whatever format you are recording, the result will be transposed to 16 bit and 44.1 kHz. sampling frequency in the end, that is the unchangeable format of the CD. As the CD-Player is in fact a computer system, all sorts of calculations, multiplication, additions and subtractions in the algorithm are possible, after the recording has been made in the standard format of 1982. Oversampling and upsampling are blessings for the manufacturers and recording companies, because these manipulations give the idea of a higher resolution and are appreciated by the the lovers of the convenience of the Compact Disc. For a higher resolution a higher sampling frequency is necessary and - if you like - more bits. More bits means that the lowest bits do not have to be used, nor dithering has to be added.

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High Resolution Sigma Delta

Keep your brain from shrinking. Read.

High Resolution Digital
There is another way of devising a digital format. It is a system by which every frequency is measured with the same sample rate. It is, like the analog recording technique, a logarithmic sound recording format. That is what originally is called the sigma-delta method. The name is later used for high quality linear converters.
This way of encoding and decoding gives an analog like sound reproduction as the resolution is very high, also of the high frequencies, and there is no need for oversampling. No need for filtering to prevent aliasing because there is no mirror image. And at every dynamic level the resolution is the same.
However, with this method the resulting frequency characteristic is not a linear curve. A correction over the entire audio band has to be applied in order to arrive at a linear curve for frequency and dynamics, somewhat similar in nature of the RIAA curve. A wide frequency band can be chosen. In theory there is no limit to the audio band. But it is, of course, wise to chose an upper frequency that can be handled well, and implement a filter at 20kHz. The advantage of such a format is that there is no phase shift. The disadvantage is that such a format is rather complicated and as a result extremely expensive.

Sigma Delta explained

All drawings Copyright by Rudolf A. Bruil

Sigma Delta: Natural Harmonics
As the number of samples is the same over the entire audio band, there is the same resolution and depth at every dynamic level: the same high resolution with every bit. While the linear digital formats suffer from inaccuracy at low recording levels, the resolution of the nonlinear (delta sigma) format is the same at all dynamic levels, loud passages or soft music. The harmonics are therefor very natural and logic. (Note: Digital photography suffers from the increasing inaccuracy at each lower level as the linear digital audio formats do.) Needless to say that the sigma delta asks for extremely clever calculations and corrections in order to have an impeccable, linear audio band in the end. In 1980 - let alone in 1967 - such a complex method is only a theoretical option and if put into practice, it would need a completely different sound carrier instead of the CD.

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Sophistication

The importance of the Most Significant Bit MSB

PCM: ln the Beginning
In the beginning, the CD is not at all the sophisticated medium as we know it today. In the first years the percentage of rejected CDs with pressing faults is high. The spiraled track with the small pits has less than 1.6 micro meter room.
Also problems in connection to the conversion and the precise reconstruction of the wave form, the filtering and the further refinement of the sound have to be addressed to. Yes, the sound quality is related to the recording equipment, the amplifiers used for the transfer of the data, and the CD mastering.
The consumer however is concerned by the quality of the CD-Player. It is possible to encounter players with converters for the left and right channel which are not exactly the same. It is possible that they do not give maximum stereo, or deliver more than the advertised distortion, or have a less perfect frequency curve.

Most Significant Bit
Important in this respect is the precise adjustment of the Most Significant Bit (MSB). As the bits are 6 dB which is a rather large span, a small irregularity does impair harmonics.
The manufacture of converters and the precise adjustment of the MSB are expensive. This eventually leads to the appearance of low bit converters. By he way they function, the error is reduced to a small percentage. But they shows other less agreeable aspects.
In
the first years of its existence, the anomalies and imperfections are not generally accepted and many articles are written and published about the "digital sound" of the Compact Disc.

Philips CD 100 top loaded player

CD-100 by Philips

Sony CDP-101 front loaded player

CDP-101 by Sony

Acceptance
Not only high end magazines like Stereophile and The Absolute Sound, a.o., also Stereoplay and Audio in Germany, IAR in Canada, HiFi News in Great Britain, in fact all over the world audio journalists are reviewing the players and are coming to grips with the benefits and the anomalies of the new format. They report on every little improvement.
Also manufacturers of electronics have difficulty in optimizing their amplifiers. Designers of loudspeakers are also doing their best in striving for a precise reproduction of the high frequencies. There are loudspeaker systems that cannot handle the fierceness of the treble and tweeters are easily blown up. And those who do not see the signs of the time see their position and rank in the market going down.

Thorens
Armin Graf, managing director of Thorens A.G., publishes a magazine article with the meaningful title: "CD, A Misperformance" (CD, eine Fehlleistung). He argues that most people have never heard the high quality reproduction of the high resolution analog black vinyl disc. He is right of course, as only 5 to 10% of people have ears and probably have invested in some sort of quality audio. And the rest? It is true that many a lover of pop music, often does not care whether the disc is slipped back into the cover when partying. Some seem to use the LP as a Frisbee. Many forget about checking the diamond tip at regular intervals, unaware of the significance of maintenance. For those the CD is a blessing. However, many fans of classical music and serious collectors of jazz do care about maintaining the high quality of the LP. Armin Graf certainly writes the article also because Thorens is afraid to loose their market, which they eventually do before starting anew.

Beard Digital Audio Converter DAP-1  uses tubes and four converters in line
Solutions and Improvements
Various manufacturers of CD-Players and converters try to improve the reproduction of digital recorded sound. They incorporate valves in the amplifier stage: California Audio Labs, Luxman, Sonic Frontiers, Musical Fidelity. Beard produces the DAP-1 with 3 sampling frequencies, three 16 bit converters applying 4 times oversampling. Filtering is practically unnecessary. The DAP-1 works fantastic with the Philips CD-822 unit, illustrating that not every DA-Converter gives the same performance with every player. Cambridge Audio places up to four converters in line to eliminate the brickwall filter (Cambridge Audio).
Many hear the restrictions in the top frequencies and many argue that the reproduction of frequencies beyond 20.000 Hz. is necessary for the perception of the complete nature of the sound of acoustic instruments. Some manufacturers do recognize this and start devising specific ways of conversion in order to suggest an extended frequency band.
Marc Guisto designs a system for connecting the CD to the Phono Input
Guiston CD Converter
In the nineteen eighties it is Marc Guisto from France, designer of the remarkable Guiston tube amplifiers and loudspeaker systems, who uses the capabilities of the RIAA phono stage: a minute signal is presented to an amplifier stage with a wide frequency band for optimum harmonics and transient response. He designs his "convertisseur numerique-analogique", which of course is not a DA-Converter in the strict sense.
He applies a correction to the mostly 150 mV output signal of the analog stage of the CD Player and brings the level back to a few milli Volts, changes the characteristic slightly (which is different for every type of brand of player), applies a filter (-3dB at 20 kHz.), and applies the RIAA correction for the LP. Now the outgoing signal can be connected to the RIAA stage (phono inputs) of the preamplifier and a clear refinement of the digital sound is the result. Click on the image to see a larger picture.
Pioneer has Legato Link to improve the phase and bandwidth of the CD

Pioneer: Legato Link
When listening to old records pressed in the nineteen fifties and sixties, the hiss and surface noise do suggest a wider frequency band than the actual recording has. The noise mixes with the sound of the instruments. This is the principle Pioneer uses in their "Legato Link" conversion introduced in 1992. They use the noise above 22.05 kHz. which normally is being filtered out. This noise is of course filtered. The engineers devise a method of connecting this noise to the audio frequency band containing the music. If the level is carefully adjusted, the sound of the cymbal, the cello, the violin, etc. is reproduced with uncanny naturalness. If the level is too high, the sound is no longer recognized as being natural. Click on the picture at left to view a larger image.

Denon Alpha Processing is first incorporated in a high end playerm
Denon: Alpha Processing
The Denon engineers follow a completely different path. After analyzing the complex algorithms of the CD they find a way to extract and use data from the lower, least significant bit, well before the actual conversion takes place. These data represent pulses of sounds with high dynamics occurring mostly at the beginning of a sound. These data are processed in such a way that they are added to the actual converted wave form. In popular terms, the steep filtering around 20.000 Hz. is disabled for a few milliseconds every time the data give a specific value. The disabling can be just once in a while or can occur repeatedly. During these instances the width of the frequency band is not limited by the conventional process of conversion and its brick wall filter. No, it extends beyond 20.000 Hz. In this way upper harmonics can be generated. The result is that all acoustic instruments do sound more natural, have an analog quality. The Denon engineers call it "Alpha Processing" and introduce this conversion type in 1993. In designing their flagship DP-S1/DA-S1, they also pay the utmost attention to the construction and functioning of the CD-turntable.
Low Bit and Multi Bit compared

The benefits of Alpha Processing are not only heard, but can also be measured. Look at the four wave forms at the left:

a = An original 1 kHz. sinus wave.

b = The sound is digitally recorded at minus 90 dB and after being treated by a multi bit D/A converter, the sinus is more like a small number of stairs. The level of -90 dB is of course an extreme low recording level, chosen to demonstrate the workings and benefits of Alpha processing.

c = The signal is converted by means of a low bit or single bit D/A converter. The sinus looks like a woolen thread still showing the rudiment of the steps of a staircase. The oversampling of 256 times also multiplies the smallest inaccuracy and distortion 256 times, hence the thicknes of the sinus wave. The multiplied noise is audible in a low bit CD converter and in the SACD (Direct Stream Digital) conversion. This distortion has to be filtered out by means of a noise shaping filter.

d = If the signal in the Pulse Code Modulation used in the Compact Disc format and is retrieved and converted using alpha processing, the sinus is as the original.

  Accuphase
Despite the introduction of low bit converters, which are cheaper to produce, there are manufacturers who stick to the precise adjustment of every bit. They are the adepts of the multi bit conversion and use high quality Burr Brown converters. To arrive at a very precise and analog like sound, the engineers of Accuphase take 4 converters for every bit. The result is that the dynamic steps are more refined. But not only that. The distortion is decreased by a factor 4 which is important for lower levels where common DA-Converters show the original high levels of distortion.
It's Only A Paper Moon
Also hobbyists take part in the discussion and many a recipe they come up with to remedy a specific problem, often turns out to be just snake oil. Or the solutions are valid for the audio set of that individual only. And many times the differences are just too subtle for one aspect while neglecting another.
The best CD Player uses multi bit converters which are precisely adjusted. The best CD Player has a regulated power supply, and has a well constructed and carefully dimensioned, damped cabinet, in order to produce a wide and deep sound stage. Yes, despite the bits and bites, here on earth we are still living in a material world! First attention has to be paid to the cabinet and resonating moving parts. Only then... yes, only then high grade capacitors to filter the signal and specific resistors can be changed. Only then sophisticated operational amplifiers can be fully effective and only then they will contribute to the naturalness of the sound! Even without replacing the original (ordinary) components, the player can deliver an audio signal of quality if the cabinet has been treated carefully and selectively while listening to the effect of every mechanical modification made in specific places

 

Practice Makes Perfect
In the early days of the CD most recording technicians and sound balance engineers need to get to grips with the new medium. They discover that the microphone placement used for analog recording is not valid any longer. Instruments and instrument groups need closer miking. Otherwise the less than perfect resolution at low recording levels will be noticed. If the clarinet in Gershwin's "Rhapsody in Blue" is positioned in the back of the orchestra, far away from a microphone, it is possible that the shifting from one dynamic level to another (from one bit to another) can be heard. The addition of dither (a low level of digital noise) brings the sound a few bits higher and it can be recorded more precisely.

Close Miking
Using more than three microphones (as in Robert C. Fine's Mercury Living Presence recordings) and position these close to the instruments or groups of instruments (multi-miking) will easily result in differences in phase (time) and harmonics can be canceled out. Not only the harmonic build up of sounds but also the stereo image will suffer. Attributing to each microphone (or group of microphones) a separate AD-converter which allows phase correction, is the solution.

Denon demonstration record at 45 RPM

Denon Demonstrates PCM at 45 RPM
In order to emphasize their important part in the development of digital audio and the upcoming revolution, Denon releases another demonstration disc in 1980 with on the cover their range of moving coil cartridges. Maybe there was some concern that the CD would decrease sales severely so they had to stop producing them. For some cartridge manufacturers that became a reality. Not for Denon. Their cartridges are still choices for many audiophiles who do not want to drown themselves in the above $5000 category. The disc had several tracks with all kinds of music plus two tracks for channel check and balance check respectively.

Early Digital recording on LP produced by German HiFi Institute
DHFI, German HiFi Institute
In the acceptance of the Compact Disc magazines played an important role. With the large numbers of subscribers they became the most important platform for promoting the new digital audio format. It was engineer Karl Breh, once chief editor of HiFi Stereophonie and a leading figure in the German audio world, who had the idea to ask Albrecht Gasteiner to produce a long playing record with digital recordings. For instruments and ensembles the microphone technique differed. For the piano recording of Beethoven's Piano Sonata No. 23, "Appassionata" (performed by Peter Efler, the MS configuration was used. For the recordings of "Junges Blechbläserensemble Baden-Würtemberg" and the Swiss Chamber Orchestra, Jürg Jecklin was asked to join. These ensembles were recorded using the Jecklin disc microphone (Scheibenmikrofon). The LP was released in 1980.

 

 

 

COMPACT disc DIGITAL AUDIO - logo

 

 

 

vinyl LP record

 

New Approach
In 1986 a recording engineer/producer tells me that the Compact Disc needs a completely different approach. The already mentioned recording of Mussorgsky's Pictures with the Concertgebouw Orchestra and Sir Colin Davis is the audible proof that in the early days of digital, the technicians are still "thinking analog" which results in a less chiseled sound character of this (nevertheless) very well recorded performance.

Blessings
It is more and more recognized that the restricted format of the CD is also a blessing. Now the format is more or less prescribing what the outcome will be: 44.1 kHz. is 44.1 kHz. and 16 bit is 16 bit. The CD-Player incorporated in the playback system is more or less definite. There is no worry about the necessary exchange of the cartridge's needle in the turntable. The CD-Player just performs the same, time after time. That can also be regarded as its drawback. To improve not a needle or a new cartridge has to be bought, but now an entire player or Digital to Anaalog Converter has to be bought.

Evolution
Gradually the converters are being improved upon. And further understanding of the algorithms result in software which is getting better and better. And then there is the benefit of breaking the codes for all sorts of editing purposes. The signal can be copied, pasted, repeated and it can be changed (cleaned). The re-recording and editing of historical performances is possible.
And last but not least, by incorporating the CD in the personal computer as a recordable disc, the CD has become the most democratic medium in history.
However there is no medium for sound recording which took so much work and development over such a long period as the Compact Disc because of its computer format which is unchangeable. The introduction of PCM recorders like the Tascam DVRA1000HD High-Resolution Audio/DSD Master Recorder with Hard Drive, which can make recordings at up to 192 kHz/24 bit PCM resolution, is one step to reinstating the term "high fidelity" in the vocabulary of technician and music lover. There may be exciting times ahead. And because of the vinyl Long Playing Record stgill can play an important role, not just because of the new pressings that keep appearing on the market.

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The Versatile LP


Diagram representing the most important steps and components involved when recording and reproducing sound with the use of a digital or an analog format.
LP and Digital formats compared


Someone wrote on the internet:

"Today everything is recorded digitally and edited digitally. So there is no point putting it on vinyl. Once it's been recorded in a digital format, the fullness and depth of the recording is gone."

If the recording is made in a format which uses, let's say, 32 bit, that recording cannot be played on a SACD Player nor on a stationary CD Player. Instead of designing and manufacturing a new digital player that would accept the 32 bit format, the LP can be used as the sound carrier.

More so, many LP record collectors have noticed that a vinyl record containing music which originally was digitally recorded can sound better than the CD equivalent. This is mainly because of three reasons.

1. The digital information was converted to analog by the record company with high quality converters that are not present in common CD Players, and the signal was equalized according to the RIAA curve with the least deviation. A difference of less than 0.2 dB is acceptable.

2. The playback of the record profits from the wide frequency band of the RIAA stage and is filtered above 20.000 Hz. with a 6 dB filter (coherent phase). So there is no brickwall filter, as was already proven by Mr. Guisto from Paris when he had designed the specific interface.

3. The interaction between diamond tip and record groove results in a high rise time without delay and generates upper harmonics that are not present in the CD and give a superior transient response.

The Codes

AAD
CDs with original analog material can have the indication AAD which means that the recording was an analog recording edited in the analog domain and then converted to the digital format.

ADD
Or the original analog tape recording can be converted to a digital format, subequently edited in that digital domain, and then be transferred to CD. That CD has the code ADD.

ADA
Old vinyl records generally do not have a code printed on label or sleeve. If these should have a code that code would be AAA. If it concerns a modern reissue, the old analog material can have been transferred to a digital format and then, after editing in that format, the signal is converted back to analog again and from that signal a lacquer is cut. That would mean ADA but I did not come accross a cover or label that mentioned this code.

DDA
If it concerns an original digital recording which is tranferred to LP, the appropriate code is DDA, because after recording and editing the signal would be converted to analog. The final medium is the analog LP.

DDD
This code is only valid for CDs and can never be used for vinyl records. The recording was done digitally, and the editing was in the digital domein also. And since it is a CD, the medium is a digital sound carrier.

The medium is the message.

The last Sony LP

Expensive
The analog direct-to-disc recordings are the most expensive and the most ideal when judging on quality of sound alone. The drawback of the vinyl long playing record is however that only a restricted number of copies shall be pressed. A number of 1500 per matrix is the maximum if a relatively high level of quality is to be guaranteed.
Less attractive is also that the vinyl disc is easily damaged.
On top of that, the gramophone record asks for a high quality playback system: the optimum turntable-arm-cartridge-amplifier combination. In principle the Compact Disc does not have these drawbacks. The signal can be copied with a minimum of loss or alteration.

Limited Frequency Band
The restriction of the CD is the chosen sampling frequency which sets the width of the frequency spectrum of the format. The chosen number of bits determines the dynamic detail and the depth and harmonic build up of the sound. The 16 bit and the clock frequency of 7 MHz. of 1982 look rather poor if compared to the 64 bit and 4 Giga Herz. processors with which modern computers are operating.
It is clear that a digital format with a higher sampling frequency and a greater number of bits will come closer to the analog sound recording. However to play back such a format, consumers will have to buy a new player for the new digital disc.

Philips Digital Classics LP Sampler

Analog LP Record and UDF
The gramophone Long Playing record - despite its physical shortcomings - can again demonstrate its versatility. Sound which is originally recorded in a high resolution digital format can be engraved in the analog disc. No need to manufacture a player for that format, unless the UDF-Players of the future can accept extra boards with the appropriate converters.

At left the covers of The Last Sony-CBS LP pressed in the Netherlands in March of 1998. The factory was sold and is still pressing some 6 million records a year.

The other cover is of digital Philips LP 6570 994 from 1981 including a catalog of the first Philips digital recordings of classical music.

The link at left should lead you to a CBS Sunday Morning report of BROOKLYN PHONO on YouTube.
It's a turntable... Vinyl LP records - still spinning after 60 years!

But CBS deleted this instructional clip. We regret this immensely as the report compiled by clever journalist Thalia Assuras (and her crew) was so well done.

So it is replaced by the first of a series of videos originating from forwardbound's channel on YouTube explaning: How Vinyl Records Are Made.

Enjoy!

If you want scientific proof of the difference between the frequency range of LP and CD you may want to view The VWestlife Experience on YouTube.

Click on the image at left or click on the link bedlow:

And you may also visit this page later:
Audio frequency range of LP vs. CD.

At the Remington LP pressing plant

"In the old ages..."

Visit http://www.soundfountain.org/rem/websterplant.html

and see how records were pressed in the early 1950s.

Modern Vinyl Recorder T 560

Cut your own records? If you are technical and musical and you have a few dimes to spare, you can do that today.

Visit http://www.vinylrecorder.com/order.html
for prices and technique of the VINYLRECORDER T560 from Germany.

© Rudolf A. Bruil. Page first published on August 17, 2007 and expanded since.
This is the translation and adaptation of an original article,
written in Dutch and published in the Spring of 1993.


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RESPONSIBILITY: Every so often you will find a link to the website of this or that manufacturer, to a shop, a designer. These links are there for you to inform yourself about interesting facts, products, views, etc. It is up to you to contact manufacturers. It is not my responsibility.