How does tape recorders work

Problem number two. If you have recorded a live session using two machines, one stereo and one two-track, and you wish to edit between the tapes then because the track width changes abruptly at the edit point you will get a jump in level when playing on the stereo machine. My advice, ideally, would be to use a machine with a stereo record head then there will never be a problem with a tape you send out to someone and a two-track playback head then there will never be a problem with an incoming tape.

Incidentally, you can tell the difference between the two head types just by looking. Take a peek at Figure 4. Just to complicate things further, there has been a recent return to the old two-track format in order to accommodate a timecode synchronisation track that is recorded down the centre of the tape. Not to be confused with the old American three-track format. Who's confused? I'm not confused!

This format is a disaster area. If you ever see one of these machines I would advise you to dial and ask for the quarter-track tape recorder disposal squad! The quarter-track format is a bit like two-track except that when you come to the end of the reel of tape you can turn it over and use it the other way just like a cassette.

I shall leave you to imagine the horrendous problems that this might cause. Be warned! Back to saner territory, though there are still a variety of formats here which fall into three groups - professional, semi-professional and obsolete. Professional formats: 4-track on half-inch tape 8-track on one inch tape track on two inch tape Semi-professional formats: 4-track on quarter-inch tape 8-track on quarter-inch tape 8-track on half-inch tape track on half-inch tape track on one inch tape Obsolete formats: 4-track on one inch tape track on two inch tape I think it is fair to describe the track on two inch tape format as obsolete, although it has been popular until recently.

It is possible to play old 4-track one inch tapes on modern 8-track machines by selecting alternate tracks for replay eg. I am told you can play track tapes on track machines in a similar way but I have never seen it done.

What all these multitrack machines do for you is allow you to play back tracks already recorded and to record new material synchronised with the old, keeping each track physically separate on the tape. Where would we be without them?

What good is a tape recorder without the tape? You might not know it but there is quite a variety available. Some people have got the distinct impression that there is only one sort of tape these days - Ampex - but there is more to life than that.

Tape comes in a range of thicknesses, which simply means that the thinner the tape, the more you get on the reel. The normal tape in daily professional use is termed 'standard play'. Portable recorders, and other machines such as the Fostex A8, which only take small size spools may use 'long play' tape which lasts one and a half times as long for a given spool size.

There are trade-offs, of course - the recording quality is not quite as good and the tape is not as robust. Tape also comes in different coatings, the normal variety not being given any special name, the more expensive type being labelled 'high output'. The first professional high output tape was Ampex The idea is that you can put more level on the tape, improve the dynamic range, and so get a better performance as regards noise and distortion.

The problem is that this only applies at low and mid frequencies, so if you take advantage of a high output tape's good points, you may have slight difficulties in other areas. The moral is to shop around and find what is best for you. The back of the tape also deserves attention. Nearly all tape now has a matt finished back coating. The idea of this is to reduce static and also to help air escape from between the layers of tape as it is fast wound onto the spool.

Not all back coatings are equally efficient and you will find that some tapes wind more evenly than others. Obviously, if a tape is unevenly wound it stands a greater risk of edge damage. Where would we be without a few problems to keep us interested?

Although tape recorders are an awful lot better than they were, they are not perfect and one or two small gremlins can still leap out and surprise you on occasion. Let's look at the potential problem areas.

Noise Because the size of the magnetic particles on tape is not infinitely small, there is bound to be a certain granularity in the recorded sound which manifests itself as noise. The larger the number, the better.

Most modern tape recorders have a signal-to-noise ratio approaching the theoretical maximum, but one point to bear in mind is that the wider the tape, the lower the noise level. A track recording on half-inch tape will have a signal-to-noise ratio only half as good as track on two inch tape. Yer dunna get owt fer nowt, as we say in Woking. The earliest magnetic recording device was built in by Danish engineer Valdemar Poulsen. His telegraphone was capable of magnetically recording sound on a steel piano wire, but never achieved widespread use.

A few decades later, a device for recording audio signals via magnetized tape, similar to what we know today, was invented, making its debut in By the late s, magnetic tape cassettes and cartridges with pre-recorded music were common in American households, largely supplanting phonograph records. A key advantage of magnetic tape is its ability to be easily erased, recorded on, and instantly played back, all processes that require a single device generally known as a tape recorder, pictured in the tutorial below.

Located inside of a tape recorder are multiple heads. Each head is a small electromagnet consisting of a ring of ferromagnetic material around which a coil of wire is wound.

At the base of each ring is a small gap positioned directly over the tape, a plastic film coated with minuscule magnetic particles. The head in the center is the record and playback head containing the two tiny electromagnets. On the right are the capstan and the pinch roller , as seen below:. The capstan revolves at a very precise rate to pull the tape across the head at exactly the right speed. The standard speed is 1.

The roller simply applies pressure so that the tape is tight against the capstan. Most higher-end tape decks have controls like those below for different tape formulations and bias. Most higher-quality tapes tell you their formulation by stating a type. There are four types of tape in common use today:. Sound quality improves as you go from one type to the next, with metal tapes having the best sound quality. A normal tape deck cannot record onto a metal tape -- the deck must have a setting for metal tapes in order to record onto them.

Any tape player can play a metal tape, however. The controls on the tape deck let you match the recording bias and signal strength to the type of tape you are using so that you get the best sound possible. Bias is a special signal that is applied during recording. The first tape recorders simply applied the raw audio signal to the electromagnet in the head. This works, but produces a lot of distortion on low-frequency sounds.

A bias signal is a kilohertz signal that is added to the audio signal. The bias moves the signal being recorded up into the "linear portion" of the tape's magnetization curve. This movement means that the tape reproduces the sound recorded on it more faithfully. Several of the links on the next page go into this topic in detail, and also cover Dolby noise-reduction systems. For more information on tape recorders, cassettes, magnetic recording and related topics, check out the links on the next page.

Sign up for our Newsletter! Mobile Newsletter banner close. Mobile Newsletter chat close. Although a handful of smaller manufacturers, including Stephens, Aces, and a few others also entered the fray, Ampex, Studer, 3M, MCI later owned by Sony , and Otari became the dominant brands. Each of these manufacturers' different models became loved or despised for their mechanical attributes and characteristic sound.

In the day, a recording studio's model of multitrack tape recorder was considered as intrinsic to its sound as their acoustics, console or microphone collection. A multitude of factors influence each machine's characteristic sound, beginning with the tape heads, amplifiers, and other electronics.

Beyond that, other factors have a bearing on the sound of an analog recording, some of which are unique to each particular machine. Variations in the machine's speed stability wow and flutter , alignment of the tape heads and the angle of the tape, condition of the heads cleanliness, magnetization, etc , tape tension, and other physical factors are just a few things that can affects the sound of a recording. Besides the machine itself, other factors can affect the particular sound of an analog recording, including the brand of tape used.

Back in the heyday of analog, the major brands of tape each had their supporters and detractors. Ampex tape was one of the leading brands, with their formula being the most prominent. Each tape formulation imparted its own subtle sound to a recording, and each machine had to be realigned each time a brand was changed. Some studios made a policy of sticking to one brand of tape, but it was not uncommon for variations to occur even within different batches of the same brand of tape. Tape speed is another major factor.

Faster tape speeds tend to deliver cleaner sound quality, since the signal is spread over a larger area and the signal-to-noise ratio is increased. The most commonly used speeds with two-inch tape are 15 and 30 IPS inches per second. Indeed, in the modern era, when tape is most often being used for its sonic effect, slower speeds prevail.