How to Convert Cassette Tapes to CDs or MP3 Files
By Gabriel Torres on June 20, 2012


Introduction

So, you have a bunch of old cassette tapes that have some sentimental value to you – maybe a recording of your kid when he or she was young or a recording of Nana who is no longer with us. Perhaps you want to start your own business of converting cassette tapes to digital format to make some money. In this tutorial, we will teach you how to convert old cassette tapes to CDs or MP3 files. Read on.

The first thing you need to know is that cassette tapes have low audio fidelity (low signal-to-noise ratio), meaning that it is not worth the time it takes to convert contents that are already available in digital format. You can convert your old Rolling Stones cassette collection; however, the audio quality will be far inferior to the CD version already available. In other words, you should buy the CDs or MP3s instead of wasting time converting the tapes. But if the recordings are either personal or unique, it is well worth converting them.

Here is what you will need:

Tape deck
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Figure 1: Tape deck

Cable
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Figure 2: Cable

As you can see, we recommend a motherboard or sound card with at least 100 dB signal-to-noise ratio for its analog input (the higher, the better) if you intend to offer this conversion service professionally. (This specification is also known as “input SNR” or “ADC SNR.”) This specification means that the motherboard integrated audio circuit won’t be adding noise to your work. If you are not paranoid about audio quality, you can get away with using an audio codec with lower signal-to-noise ratio. To know the signal-to-noise ratio of your motherboard, consult our “Audio Codec Comparison Table” tutorial and look at the “Input SNR” column. 

Before connecting the tape deck to your computer, you will need to clean it and, optionally, fine-tune it. Read our “How to Clean and Fine-Tune a Tape Deck” tutorial to learn how.

Connecting the Tape Deck to the PC

Connecting a tape deck to the PC is very easy. Basically, you will connect its two outputs to the computer’s “line in” input, which is a blue jack available at the rear panel of the PC. Below, we show the step-by-step process.

Note: You can’t use the “mic in” (pink) jack.

First, locate the connectors labeled “line out” at the rear of your tape deck. You will see two female RCA connectors, one red (right channel) and another white or black (left channel). In our case (Figure 3), the connectors were the ones located at the right-hand side.

Tape deck connectors
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Figure 3: Tape deck connectors

Then, install the two male RCA connectors from the cable to the corresponding female connectors. On some older tape decks, the left channel connector may be painted black instead of white. This is not a problem; simply install the white connector on it.

Cable installed on the tape deck
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Figure 4: Cable installed on the tape deck

Now look at the rear panel of your computer, and locate the “line in” connector. This is a light blue jack. See Figure 5.

The “line in” connector on a typical PC
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Figure 5: The “line in” connector on a typical PC

The final step is to connect the male 3.5 mm connector from the cable into the “line in” jack from the computer.

Cable installed on the computer
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Figure 6: Cable installed on the computer

That’s it. Now your tape deck is connected to your computer and you will be able to transfer the audio present in your cassette tapes to the PC.

Setting Up the PC

First, download and install Audacity. After the installation of Audacity is completed, close Audacity (if it was automatically opened) and download and install LAME, so you can export your work as an MP3 file if you wish.

Launch Audacity. The first thing you need to do is select the proper audio source, which is done by selecting “Line In” on the drop-down menu available near the microphone icon. Make sure that the output device is set to “Speakers” (unless you are using headphones connected to the computer’s front panel; in this case, you should set the output device to “Headphones”). See Figure 7.

Selecting the audio source
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Figure 7: Selecting the audio source

Click on the little triangle pointing down near the microphone icon on the upper part of the program, and select “Start Monitoring.” See Figure 8.

Start monitoring
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Figure 8: Start monitoring

Now we need to adjust the “line in” input level so that the sound won’t be so high that it will be distorted or so low that it will be inaudible. For that, go to Control Panel, Hardware and Sound, and Manage audio devices. On the window that will appear, click on the “Recording” tab. Select “Line In” and click on the “Properties” button. A new window will show up. Make sure that “Device usage” is set to “Use this device (enable).” Click on the “Levels” tab. You will see the screen shown in Figure 9. This is where you will adjust the tape deck’s input level. We will show you how in a little while. Leave this window open. (We were using Windows 7. On other versions of Windows, the path to access this window may be different.)

Input level adjustment
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Figure 9: Input level adjustment

Setting Up the PC (Cont’d)

Connect the tape deck to an AC outlet and turn it on. Press “play” on the tape deck. (You should start hearing the tape playing through your computer’s speakers. If not, you should double check all the steps that you have performed thus far.) Press “forward” or “rewind” on the tape deck until you hear the part of the audio program that you want to record. Make sure to play a part where you think the audio is at its highest level.

Now, start paying attention to the Audacity’s record level indicator, which is comprised of two moving red bars above the microphone icon on the top of the screen. You should adjust the input level (screen shown in Figure 9) up and down until you have the sound touching, at its maximum peak, the 0 dB line. Audacity assists you by adding dark red vertical lines where the sound level peaked for the past few seconds.

In our case, the default configuration of “50” made the sound level too high, so the sound was distorted. See Figure 10. In Figure 11, you can see when the input level is configured too low. And in Figure 12, you can see the input level correctly configured, which was achieved with the input level at “17.” Note that on your computer the correct level may be at a different value. The difference between Figures 10 and 12 is that in Figure 10, the two bars were always filling the boxes (i.e., they didn’t move with the audio program), while in Figure 12, the bars were moving and touching the 0 dB level only during peaks. If you are not 100% sure where to set the input level, set it on the low-level side, as you can always electronically increase the level/volume later inside the program, but if audio level is recorded too high, the sound will be distorted and you won’t be able to fix it.

Input level is configured too high
Figure 10: Input level is configured too high

Input level is configured too low
Figure 11: Input level is configured too low

Input level correctly configured
Figure 12: Input level correctly configured

The final adjustment is to enable Dolby Noise Reduction (“Dolby NR”) if your tape deck has this function and if your tape was recorded with this function enabled. Enable Dolby Noise Reduction and listen to the audio program to see if the audio quality got better without a background white noise (a sound similar to an old TV set to a channel without any image being broadcasted). However, if the recorded sound got “muffled,” it means that the audio was not recorded with Dolby NR enabled, and it should be left disabled, as it will decrease audio fidelity.

Now that you set up your system, let’s transfer the audio from your cassette tape to the PC.

Transferring the Audio to the PC

Now you are ready to go. Rewind the tape or place the audio program a little before the part that you wish to transfer to the PC. (You can always cut out what you don’t want later.)

This is not supposed to be a full tutorial on Audacity, so we will cover only the basic functions that you must know. You can try playing with other options available by yourself. We also recommend that you read a tutorial or book on Audacity if you really want to explore all of its potential.

Click on the “record” button on Audacity (the red circle icon). Press “play” on your tape deck. Now Audacity should be recording, in digital format, the contents of your tape. Wait until the tape finishes or the part that you want to convert is concluded, and then click on the “stop” icon on Audacity.

Now you have a digital file of your tape. You can save it right away in digital format, using the File, Export function. For now, we recommend that you save it as an Audacity project.

Cassette tapes have a typical noise (called white noise) when they are playing parts that are “silent,” frequently before or after the audio program. We want to capture this noise, as we can “teach” Audacity what noise sounds like, so it can remove noise automatically. We always recommend that you start recording a few seconds before and a few seconds after the part that you want to transfer.

Now that you have your audio file in front of you, select a few seconds of “tape noise” with the mouse; then go to Effect, Noise Removal, and click on the “Get Noise Profile” box. This will “teach” Audacity what noise sounds like. The window will close. Unselect the noise by clicking anywhere on the screen or by hitting Control+Shift+A. Again, go to Effect, Noise Removal. This time, click on the “Ok” box. Listen to your file by clicking on the “play” icon, and see if you like the end result. If not, simply undo (hit Control Z).

Another useful tool is found under Effect, Normalize. This will fix any volume issues you may have on your file.

After you are done editing your audio file, go to File, Export and either save it as an MP3 file or a WAV file. If you want to create an audio CD, we recommend that you export your file as WAV in order to get the best audio quality. If you want to create a CD with several tracks, (i.e., you want to separate parts of your original file on separate tracks on the CD), you will have to export each part that you want to save as a separate track as a different WAV file.

To create an audio CD, you will need an audio CD burning program, such as Nero, where you must select the project to be an “audio CD” and select the WAV files you want to add. As previously mentioned, each WAV file will be a different track on the CD, so pay attention to the order of the files on the CD, as this will be the track order. Do not select the project as a “CD-ROM” or “data CD.” Otherwise, the CD won’t be playable on conventional CD players.

Originally at http://www.hardwaresecrets.com/article/How-to-Convert-Cassette-Tapes-to-CDs-or-MP3-Files/1579


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