Recording a Cassette Tape into a Computer

Transcription

1 Recording a Cassette Tape into a Computer The copyright law of the United States (Title 17, United States Code) governs the reproduction of copyrighted material. The person using the equipment on our campus, and in the University Library, and associated software is liable for any infringement You may need to digitize an analog cassette tape for any number of reasons. One of the most popular in academic settings is to convert analog recordings to digital for research purposes and to convert the recordings into a format that is not currently obsolete. Connecting a cassette tape player to a computer is not particularly difficult. However, there are many different options and a wide selection of components from which you may have to choose. This document tries to address many of the issues you will have to confront and assist you with the decisions you will need to make. It is not possible to answer every single question that could come up when digitizing tapes, but this document should help you overcome the majority of obstacles. New products have recently come on the market that will convert your cassette audio tapes to digital formats for you. Some are self-contained machines that do everything in a box, others are special tape players that connect directly to a computer by a USB port. Depending on your circumstances, these machines may be perfectly suited to your application. However, there are any number of reasons why you may wish to use your currently available equipment. In fact, specialized machines are rarely necessary if you already have a tape player. All you really need are the appropriate cables and plugs. Making a High Quality Recording One of the key factors that affect the quality of the digitized recording is the cassette machine that will be playing the tape. A good hi fi stereo cassette deck will provide better playback than an inexpensive mono table top or Walkmantype player. The image on the right is a typical two-bay cassette deck that was a very popular part of home stereo systems. Connection to a computer is easiest using a simple Y stereo cable. A pair of matched right/left RCA connectors (one red and one white) combines to a stereo jack. It is best if the jack is 1/8 male stereo as this is the standard size for a line in port on a computer. 1

2 Such a cable is illustrated on the right. The 1/8 make stereo jack at the end of the cable is shown on the right. Note that this cable has a 90 o turn. Some versions of this type of cable have straight ends. The photograph on the right is of a 1/8 male stereo jack of the straight type. 2

3 Somewhere on the rear of the cassette deck will be two pairs of RCA output connectors. They will be labeled either input and output or record and playback. The labeling will depend on the manufacturer and age of the equipment. These are line-out connections. Their signal is line level. Connect the Y cable to the output/playback connectors. Make sure that white goes to white and red goes to red. Misconnecting red to white will not damage the equipment, but it will cause the left and right channels to be reversed. Most desktop computers and some laptop machines will have a line-in port. Connect the 1/8 male stereo jack to the line-in port. The photograph in the right shows such a connection. NOTE: If your computer does not have a line-in port you may have to use the mic input. We will discuss that option below. Typical line-in port with cable plugged in circled here. Yours may look different. On most modern computers the line-in port is color coded in light blue and will have an arrow-in type of symbol that resembles the illustration on the right. Connecting the line-out output/playback RCA connections on the player to the line-in provides a line level signal. This is a standard specification analog signal that is identical from device to device. Using line-out to line-in prevents problems such as damaging the device doing the recording by overpowering the signal. 3

4 Some computers have a joint linein/microphone port. This is usually identified by a two-color coding system. Pink denotes mic and blue is for line-in. Note that in the photo on the right there are also icons for mic and line-in. Some computer manufacturers will include the words in and mic in very small font. Microphone in ports have different signal characteristics that line-in ports. Computers with dual ports, as shown above, have sensors that detect whether the signal is line or mic. The diagram below shows the typical connection scheme when using a tape deck, computer and Y cable. Red connector Tape deck White connector Y cable Computer Using Alternative Tape Players Not all tape cassette tape players are created equally. Hi fi tape decks are generally the best. However, it is also possible to use Walkman-type players, high-end recorder/playback portable machines, or simple table top recorders. In this next section we will discuss some of the alternatives to hi fi tape decks. 4

5 High-end cassette tape recorder/playback portable machines were used in the field by reporters, researchers, and musicians. Similar to the one shown on the right, these types of machines were usually constructed fairly ruggedly and often came with leather or vinyl cases. The better grade devices had microphone inputes, line-in, and telephone connections. Outputs on these machine almost always had line-out using RCA jacks. Some even had ¼ sockets. Many of the devices, such as the one illustrated, were stereo, others were mono only. Because these cassette machines have the same ports and jacks as a hi fi deck the methods used to connect to a computer are identical to those for Table top recorders include the two styles shown on the right. Most of these cassette devices are mono only, not stereo, and very few had line-out. Connection to a computer is done using the earphone jack in the cassette recorder/player. We will explain how that is done next. 5

6 Connecting a table top recorder/player to a computer is simple, but it may require more parts than connecting a hi fi deck. Those parts are very inexpensive, however, so if you need to purchase them the cost is usually not great. The main challenge that you will encounter is that these tape machines are mono and you will be connecting them to a stereo input on the computer. Because of the way that the various cables are constructed, this may or may not be a problem. In many instances the recorded audio file will come out with the right and left channels combined to create a mono recording. However, it is also likely that one side or the other will not be properly recorded and that when you listen to the finished recording the left or right side will be silent. Under normal conditions it is possible to play stereo tapes on a mono cassette player and have them sound perfectly acceptable with no channel drop outs. But, when you play a stereo tape on a mono machine that is connected to a stereo computer (all computers are stereo) using the wrong cables may cause you to lose half of the recording! The solution is to always use a set of adapters when making the connections. You have several choices and the following information will help you make the right selections. Understanding the connection goal is key to choosing the right parts. You are seeking to connect a mono output on the tape machine to stereo input on the computer. In a sense you are splitting the mono signal into a stereo signal. There are a wide range of adapters on the market. Some connect mono to stereo, some connect stereo to mono. This may sound complicated, but it is not really hard to figure out. Let s start with your cable. On the right is a photograph of the two ends of a stereo cable. Notice that these ends have two black rings and three metallic segments. The metal segments are the conductors and the black rings separate them. This type of connection allows the left and right channels of a stereo signal to be transmitted. 6

7 The cable ends illustrated on the right are mono. Notice that they each have a single black ring and two metallic segments. Some cable ends are silver, others are gold. The gold plated connectors are supposed to be higher quality because gold conducts electricity better. However, in most applications this makes little difference. If you use stereo cables to need an adapter at the tape machine. If you use mono cables you need an adapter at the computer. As with cables, there are two basic types of adapters. The adapter illustrated on the right has a female mono input and a male stereo output jack. Note the number of black rings and metallic segments. The photograph on the right shows an adapter with a female stereo input and a male mono output jack. Again, you can tell that the male end is mono because it has one ring and two metal segments. How can you tell if the female end of the adapter is mono or stereo? This can be a bit of a trick. Most modern adapters will have a small S for stereo or M for mono engraved or molded into the housing. Look closely to see it. The original packaging will always have this information printed on it, and in cases where the type of adapter is not obvious you can mark it with a little paint or permanent marker pen. 7

8 Following are diagrams showing how we use these various parts. This drawing illustrates the parts and connections necessary if you are using a stereo cable: Table top player/recorder Adapter Mono male to stereo female Stereo cable Computer In the diagram above the adapter is connected to the cassette player/recorder s earphone jack. Specifying the play level settings with this setup is discussed later. The cable is connected to the computer s line-in port. 8

9 This drawing illustrated the parts and connections necessary if you are using a mono cable: Table top player/recorder Mono cable Adapter Mono female to stereo male Computer In the diagram above the cable is connected to the cassette player/recorder s earphone jack. Specifying the play level settings with this setup is discussed later. The adapter is connected to the computer s line-in port. 9

10 You can also use a personal tape player. Although it is a brand name, a device such as this is often called a Walkman. Two classic examples are shown on the right. Personal tape players rarely have line-out connections. If you elect to use one of these devices it is necessary to connect the cable or adapter to the earphone socket. Use the diagrams shown on the previous pages to determine which parts to use and how to make the connection. NOTE: In the illustrations presented so far we have shown 1/8 jacks and plugs. In some cases, especially older table top player/recorders, the sockets are ¼ in size. These larger dimensions require you to use adapters to match. Adapters are available in all configurations and include models that not only adapt from between mono and stereo but also adapt between sized. All you have to do is choose the adapters you need and buy or borrow the right parts. Specialty Adapters and Connections Unfortunately, not all computers have line-in ports. Most will have a microphone port, but you may not want to use that port when you make your connections. You may, as an example, already have a microphone connected to it! In situations such as this you may wish to use an audio USB adapter. An example is shown on the right. The example displayed here has one microphone input and a headphone input. The output is standard USB and plugs into a port on your computer. There are several models on the market from various manufacturers, so the main task is finding the right adapter to do the job. 10

11 Software, Settings and Configuration Once you have made the various machines, adapters and cables connected in the proper order your next task will be to actually make the digital recordings. You will need recording software. There are several programs available. One of the most popular is Audacity. Because it is Open Source, you can download Audacity for free. We have several handouts available at tutav.htm that will help you set up and run the program. If you are using connections from the cassette player s line-out jack to the computer s line in port you will not have to adjust the player s volume controls. You may have to adjust the input settings in the recording program, but that is not the same as manipulating the knobs and dials on the player. However, if you are using the player s earphone jack to the computer s line-in port or microphone input you will have to be very careful. If you play the tape too loud you could damage the computer. At the very least the overloading might cause distortion. To prevent problems such as these, lower the volume level on the cassette player BEFORE you turn it on to play. If you are connecting the player to the computer s mic in port you should turn down the computer s microphone setting using the machine s mixer panel. Once you are sure that the settings are down all the way you can start to play the tape. Raise the tape machine s volume slowly until you see a wave form in the recording program. If you are connected to the computer s mic in port you will have to slowly raise the mic levels, too. The key is to achieve a balance that provides enough input signal for good sound without causing overpowering or distortion. The following diagrams will help you understand the various adjustments and settings. Line-out Line-in Tape recorder/player When the connections are lineout to line-in you will probably have to ONLY adjust settings in the recording software. Computer 11

12 Earphone-out Line-in Tape recorder/player When the connections are earphone-out to line-in you should lower the tape player volume and adjust settings in the recording software. Computer Earphone-out Mic-in Tape recorder/player When the connections are earphone-out to mic-in you should lower the tape player volume and the microphone settings. Increase them carefully and monitor the software. Adjust as necessary to achieve a good quality recording. Computer Check your computer s documentation to find out how to adjust the sound mixer and microphone level settings. 12

13 The appearance of the recording s wavefrom in the recording software (such as Audacity) will help you determine if the various levels are too high. The image below shows a wave form where the input from the cassette machine s earphone jack was overpowering the computer s line in. Notice that the peaks of the wave from top out as high as possible. This will cause distortion. The image below shows proper settings. The peaks and valleys of the wave from are obvious and none of the peaks top out. There should not be any distortion with this setting. 13