The History and Evolution of Audio Recording

Sound recording originated with Thomas Edison around 1892. The process is simple. Air pressure moves a large, light weight, flat object. Think of the blades in windmill that get struck by wind (airpressure). They are tilted slightly so as the air moves by the big flat surface (propeller blade of the wind mill) it causes it to move as the air pushes past it and tries to go around the blade. That’s the concept of the microphone (and loudspeaker) except instead of being designed to turn around a hub the flat surface of the microphone undulates or pulsates forward and backwards (to and fro). We then connect this to some mechanical process for recording.

Originally the recording process was simply a strong steel needle placed into a cylinder made of smooth wax.

You can do this yourself. Mount a big candle on a crank spindle. Take a paper Dixie cup and stick a sewing needle into the bottom rim so it touches the bottom of the cup. Then stick that needle into the wax, turn the crank and shout into the Dixie cup! Your voice (fluctuating air pressure waves) will move the flat bottom of the cup, which moves the needle, which vibrates and cuts grooves into the wax. You need to move the cup along the length of the wax to create a cork screw like path for this groove (Edison used a rack and pinion gear to move the needle in tandem with the circular motion and at a consistent rate of spacing).

After a few years the Edison cylinder process was replaced by the more efficient phono disk. This was a flat pancake with the grooves cut into both the top and bottom surface. The wax medium was replaced with a metal plated coated with lacquer. The cutting needle of the recording device etches grooves into the lacquer.

The process of direct recording from a paper cone, which makes up the essential elements of the RCA “His Master’s Voice” logo where the dog is listening to an old phono record on a turntable using a cone for playback instead of electronics, because no electronics existed until 1912, some twenty years after Edison first made the phonograph!

When Lee DeForrest invented the electronic tube around 1915 this made electronic amplification of signals possible, improving the telephone, radio and record player. To record records they now used electronics rather than direct diaphragm to recording medium method as pictured above.

Instead of a needle embedded into the back of the cup (which is the diaphragm – a flat, circular material) a magnet is placed there inside a coil of wire. As the diaphragm moves back and forth the magnet moves back and forth through the coil of wire creating electricity. A microphone is a mini electric generator. The electronic tubes of DeForrest makes this small electrical current larger and larger (amplification). This current then moves a magnet connected to a needle mounted over turntable with the lacquer covered metal disk. Records were made this way since around 1920 and they are still made this way today, although the Compact Disk (CD) has replaced 99% of the phono records out there in the world starting around 1990.

Phono disks are cut on what is called a lathe. The lacquer on metal disk is called the master. This lacquer disk is then placed into a metallic solution and plated with metal by making an electrical contact between the outside of the solution and the metal inside the disk (see our story on gold from July, which shows how electroplating is done, this process is virtually identical, except a lot more metal will be ‘grown’ on the laequer disk).

This metal that is grown over the soft lacquer (which is the compound that covers your guitar or furniture – that clear surface coating you paint on with a brush like varnish, which hardens – that’s a lacquer compound) can be removed. This metal “part” has protrusions (it is male) that represent the grooves of the lacquer master (the female part). You can stamp records from this metal part, but it will lose its clarity after a few thousands disks are made. So, instead of stamping records for this part (called a “one step process” in the record making industry) we stamp some new female parts (mothers) from which children (stampers) can be made (called a “three step process”). It is now possible to make about 1000 mothers and from each of these about 3000 records – or about a million vinyl records.

Originally all recordings were made using a single microphone with the musicians and singers placed around the microphone in such a manner to make one sound source louder than another (to MIX or BLEND the sounds).

Then someone decided to start using multiple microphones and mix these by hand using electronic devices called volume controls (we call them “faders” today) so that you didn’t have to move people around so much!

Records we made by direct to disk recording until around then 1940 when wire and tape recorders for audio sounds came into being. Then sound was recorded on magnetic tape, which could be erased and reused if a mistake happens (not so with lacquer, the master lacquers must be discarded). But, it was also discovered that some sounds (most notably the acoustic piano) didn’t record very well on tape, hence some jazz and classical performers record direct to lacquer disk (right up to today).

Disks were made out of lacquer until the 1950s when vinyl plastics were substituted. The speed of the disk was also much faster – 78 RPMs (revolutions per minute) which was an effective speed of 25 to 50 inches per second of tape record speed, or the professional speed.

When vinyl records were introduced the concept of the “long play” record also came into being. With new recording techniques it was possible to extend playing time beyond 5 or 6 minutes, but there was a loss of fidelity. To combat this a method of encoding records was devised. This changed the mix or blend of the music by increasing some tones (the high end) and decrease others (the low end). Then during playback these encoded records were expanded to full fidelity by increasing the low end and decreasing the high end. This was called the RIAA (Record Industry Association of America) equalization curve. It allowed them to slow down record speeds (from 78 to 33 and 1/3 RPMS), change groove cutting depths and get about as much (if not more) fidelity than a 78 RPM single.

Smaller 45 RPM records made of vinyl using the RIAA curve were also created but at a smaller size (7” instead of 12” for the long play 33 RPM records). These 45 RPM records were adopted by juke boxes and radio stations and were made with a very large center hole so they were easier to load on automatic turntables!

It was in the 1950s that the concept of “stereo” was dreamed up, but like color television it took a long time to catch on with the record buying public (especially since “stereo” records cost about $1 more for long play records than the monophonic).

What stereo allowed was spectral sound – 7 distinct locations from which sounds could emanate (Far left, mostly left, left of center, center, right of center, mostly right and full right) which let the listener get the feel of true concert performances (often called binaural, because we have two ears, one favoring the left side and the other favoring the right side) with the strings on the left and the brass horn section on the right, with the singer in the middle and the background chorus off centered to one side.

By and large most commercial music has been recorded on multiple tracks since the 1950s with the advent of stereo and the tape recorder. You could record all the music, for example on one side and then record different singers (English, French, German) on the other side to be released around the world in their natural language! This made music suddenly a tailor made item for the audience.


The original concept of this actually started with guitarist Les Paul just prior to the creation of stereo. He used several tape recorders to bounce recordings from one to another while adding new music over the existing recording (call sound with sound). Buddy Holly also recorded this way. Then when stereo equipment can into operation creative people would record different elements on the stereo tracks one at a time. Say a rock or jazz band on the left channel. Then you can take that recording from Los Angeles, go to New York and add an orchestral score to the right channel. Now you have rock or jazz fusion. Then if you copied this to another tape recorder adding a singer doing sound over sound you had three separate tracks, but you also picked up some noise as tape recorders make noise and recording this nose to another tape recorder compounds the process!

So some clever company came up with a 3 track tape recorder. This allowed people like Buddy Holly to record his band on one, the orchestra on another track the vocals on a third track. After this came the 4 track with larger tape (1/4” tape was used for stereo recording at 30 inches per second – IPS – for 4 track record ½” tape was used, giving 1/8” of an inch of tape width for each track, which is considered optimal).

Three and four track recording was in wide use starting around 1958 and one of the premier wizards of this recording process was George Martin of EMI’s AIR studios in England. Martin had several 4 track machines and he put them to good use recording both classical, pop music and comedy records such as those for the wacky group the Goonies who did production records, much like Cheech and Chong did in the 1970s in the US.

Martin started working with the Beatles in the early 1960s and in the beginning he used the typical method of recording the band in stereo or one track and then adding other voices and instruments to the other tracks. Starting with Rubber Soul and then Revolver the Beatles started getting involved in the production process bringing in tape loops they recorded at home on a high quality tape recorder from Grundig. Lennon was among the first to bring in these tapes and have Martin incorporate them into the 4 track recordings they were doing to create songs like “She Said” and “Tomorrow Never Knows” with backwards guitar tracks and snippets recorded off TV or radio ("samples" – made in 1963, long before computers and digital electronics or rap musicians).

One of the first complex uses of recording came when they were working on their next album, which would eventually become Sgt. Pepper’s Lonely Hearts Clubs Band. That time Paul McCartney and George Martin were working on a blending of the Beatles band with classical instruments like horns for a song called “Penny Lane.” Lennon and Martin had just finished a Beatles recording of one his songs “Strawberry Fields.” Lennon asked if they could re-do the song orchestral and George Martin arranged the music for horns (which required change the key by a half-step). After they finished this track, Lennon asked if Martin could put both recordings together. Of course, they were on separate tapes and a half tone different in key!. Martin tried his best, by turning the knobs of the speed control and fading from one machine to another he put both the Beatles rock track and the orchestral arrangement together into a single recording using three separate four track tape recorders and copying from one to another. This was the first use of synchronization I have ever heard of, done in real time without any electronic coupling. Martin and his assistants just did take after take and used their ears and fingers to adjust the speed of each take deck, while fading in and out from one machine to the other and making copy of this on a third machine (the master tape).

Around 1968 the tape width was increased to 1” so they could put eight total tracks on the tape. It took a while for producers like George Martin to catch on to the differences between 8 and 4 track (they would still record the band in mono or stereo and just add tracks like violins). After a while however the concept of recording bands instruments on separate tracks caught on. This allowed them to record the drums on 2 of the tracks, guitar and bass each on a separate track and they still had 4 tracks left for keyboards, harmony vocals and a lead guitar solo.

As multitrack recording caught on they expanded this concept to 2” 16 track around 1971 and then 2” 24 track using a slightly smaller track width (which results in a loss of low end, but does give you another 8 tracks of audio). Starting around 1974 the 2” 24 track has been the industry standard and is still used today by a lot of artists, because analog audio tape is warm and offer a differ set of characteristics (just like there was between direct to disk and tape in the 1940s).

Around this same time the consumer home recordist was coveted by Teac Tascam with the introduction of a 1/4" four track recorer priced around $1,500 US (Ebony Eyes by Fleetwood Mac alumni Peter Greene was started on a 1/4" four track and transferred over to a 2" machine and turned into a major radio hit). After a while a even lower costing four track was made with a slower speed (7 1/2 against 15 IPS used by the Tascam) by Dokorder. Eventually Fostex also started producing home recordist multi-track machines. Eventually larger format and track configurations came in to being starting with the Tascam 1/2" 8 track and later the 1" Fostex 16 track (used by Steve Via to record his solo album which got considerable radio airplay).

Digital recording started to come into existences in the 1980s and I was one of the first people working with Sony 2 track processors which masters on video tape in the mid-1980s. At that we were recording the multi tracks on analog and mixing to Sony PCM digital. There is a big different the dynamic range (which is the difference between the threshold of hearing and the loudest noise you can record, expressed in a logarithmic range called decibles or db for short) – analog tape had about 50 dbs of dynamic range and the Sony 16 bit PCM digital had more than twice as much, over 110 dbs of range. But, it also made instruments like the guitar louder (brighter) and harder. To my ears, for example, it made a Gibson Les Paul guitar sound more like a Fender Stratocaster!

Again, Tascam entered the home recordist market with the DA-88 R-DAT and eventually Alesis introudced the A-DAT for the home market. These were lower cost, multi-track digital recorders. Today, some computer sound cards and software can directly support DA-88, R-DAT and A-DAT formats to the computer.

The next leap in technology came with the linking of two tape decks, originally done during the Fleetwood Mac Rumors album. The master tape had lost some of its brightness during repeated playback and they had to run a copy they made of the master along with the original to restore the brightness. But, there was no means of linking the two tapes together so like George Martin they used the speed control and listened for the drum hits to flam (hit at slightly different times, a chorusing effect).

After this point in time they started using video time code on one track of the 24 track machines so they could link up two 24 track recorders (giving you 46 tracks of audio and 2 tracks of synch code). Experiments were tried with 36 track 3” tape but these never caught on. Digital 24 track recorders were also perfected using 1” tape.

Then in the late 1980s a company developed a system of recording directly to computer in multiple tracks and mixing on the computer. This was a very professional system using the 3 wire XLR connectors at the professional standard of +3 dbv (about two times more power than home stereo line inputs which have a –7 dbm input 1.3 volts and .77 volts respectively) This was known as Pro Tools and it was designed for the Apple Macintosh computer which has a faster processor than the IBM PC. The price of this system with 8 track hardware, computer card and software was about $6,000+

By the late 1980s the makers of Pro Tools also designed a system for the PC called the Session 8. This allowed you to record 8 tracks at one time and mix up to 64 or 128 audio elements into two tracks on the computer. This system used the more semi-professional RCA and ¼” inputs having a –7 db input. The price of this system was more affordable for the home musician -- around $2,000, plus computer.

There were also several other software systems introduced for the home market, such as those from Data Becker in Germany, Cakewalk and Cube Based in the U.S. These packages allowed you to organize your stereo recordings into groups of 48, 64 or 128 combined audio and MIDI tracks for processing and mixing. This way you can record two tracks (stereo) at a time on your computer (much like George Martin did in the 1960s) and then keep adding fresh stereo pairs up to the limit of your system or the software. At a cost from between $50 and $1500 you had up to 128 playback tracks, sound effects (echo, chorus, reverb), equalization and mixing. Dedicated machines offering this amount of playback tracks were still over $50,000 so the cost factor was very enticing!

It’s still quite expensive to get 16 tracks worth of simultaneous recording hardware and software (still over $2,000) but if you can work with 2 tracks at a time you can do far more on your computer than you can do in a $500 4 track analog or even a $1,200 8 track dedicated digital machine.

As for the rest of the technology, the microphones made and used up to the early 1970s are the best and most popular mics, such as the Telefunken U-47 tube mic, which can cost as much as $15,000 used! These are the same mics used since the 1930 and 40s and discontinued in favor of transistor electronics (like the Sennheiser U-89 FET which while sounding close to the U-47 is still not of the same quality as the older tube mic).

Compressors and limiters using tubes like the LA 2 and 4 were also more popular than the transistor circuits of similar units like the Urie 1178.

Earl R. Dingman has done live sound and studio recording since 1975. He engineered and worked at several studios, including Hit City West, Rusk and L.A. He produced or engineered a variety of artists, some of whom got on radio and made the ASCAP 'Current Performance' listing.

Our Music Special continues with these other articles:
Learning Music | Promo Pictures | Booking Agents| Managers | Producers | Pressing CDs
Record Companies | Copyrights | Recording Software | Sound Cards | Guitar and Bass
Multi-Track Recorders | Live Sound Gear | Microphones | Recording Engineer | Bands in Texas
Teen Band: Y@nK | Gigs and Clubs | Music Theory | Radio Airplay

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