Okay, this is going to be a long post. Bear with me...
Converting cassettes to CDs can be a time-consuming affair that requires a lot of effort and a keen ear.
You will need:
A) High quality cassette deck with line-out
B) Computer (PC/Mac) with CD writer, studio-quality sound card
C) Audio editing & CD burning software
D) Stereo Interconnects
E) Blank Audio CD media
Let's start with the Computer: you will need a fairly recent computer setup, a PC running Windows XP SP2 is the most common so we will consider that. You will have poor results with onboard sound or low-end sound cards. The recommended and also the cheapest of the "pro-sumer" cards is the ESI Juli@ available at Rs. 8,500-9,000. It features 24-bit 192Khz recording/playback capability. However it lacks both mic pre-amp and headphone amp but those are not needed for this operation.
You can connect your cassette deck to the sound card just as you would your amp to the cd player - with a high quality RCA stereo interconnect such as the QED, etc. You can get superior results with PC noise filtering software so you may wish to disengage any noise reduction filters (Dolby B-C, etc.) on your deck.
There is a wide variety of PC sound editing software. The best free software is
Audacity. However if you have access to commercial software, Adobe Audition will be a better solution. Now, industry professionals may frown as ProTools and Nuendo tend to be their weapons of choice but Audition has a slightly more intuitive interface.
Before you begin the recording process, it is a good idea to check levels. In Audition, the levels are visible at the bottom of your screen. Once you have setup your audio mixer to have line-level input as your recording source, begin playback and press "F10" (in case of Audition, others will vary) to see meter levels. You are not recording at this stage, simply determine the ideal level for playback.
Once you have set the volume, we will now begin recording. Create a new waveform - choose 88200 (or 96000) Hz as the sample rate, Stereo channels and 24-bit or 32-bit float resolution. The reason for recording at 96/24 is the larger dynamic range available - less distortion at high levels, greater headroom. Rewind the cassette and begin the recording process after you press Play on the deck. Record the entire side at once. (Warning: make sure you have large amounts of hard drive space available. At least 50GB would be a good start).
At the end of the recording process you have the entire waveform on your PC. You should save the waveform at this point in WAV/PCM format (or AIFF on a Mac). Be sure not to choose a lossy format such as MP3, MP4, RealAudio, etc. You can now tweak the sound if you wish. Noise reduction is a good start. A wide array of 3rd party noise reduction plugins are available for Audition and other editors and there is also a fair native system. I prefer the X-Noise filter available from
Waves. The basic theory is the same - use the plugin to "sample" less than a second of pure noise (usually at the beginning of the track). Then subtract this sample from the actual recording using various parameters - this is best learned through trial and error as writing about it would be an entirely new post. A word of caution - do not overdo noise reduction and make sure to leave some in. Excessive noise reduction leads to your audio sound "metallic" and errors such as temporal aliasing (occasional "ricochet" like sounds) creep in. You can tweak other aspects of the sound such as the overall tone, bias adjustment, etc. You can "finalize" the waveform by using off-the-shelf solutions such as the L1/L2/L3 Ultramaximiser mastering plugins from Waves -- make sure you do not fall into the trap of boosting the levels too high leading to clipping and distortion. Purists may frown on this step and point to it as the cause of the recent trend towards harsh, radio-friendly mastering that is becoming all too common but if used with great care this is a good finishing touch to your recording. It is not a bad idea to save different versions of your recording separately so you can go back if you do not like how an effect sounds.
Finally we come to the CD burning part. You can use software such as Nero Burning ROM though freeware alternatives do exist. Again, Nero like Audition makes life easier so that is recommended. The most important element here is the CD media rather than the software. You will
not get good results with standard CD-Rs that are meant for data storage. Special media for CD Audio recording is available from companies such as TDK, Verbatim and Maxell among others - just check to make sure the media is stated as being for "professional digital audio". Using a Data CD will lead to a severe degradation of quality and a waste of all your engineering efforts. Back to the PC - once you are satisfied with your recording, it is time to save it in a CD-friendly format. First we will downsample it to the appropriate standard. In Audition, press "F11" (in others, convert sample type) to convert the waveform. Select: 44100 sample rate, Stereo channels (unchanged), 16-bit depth. Audition has extra settings - tick the Pre/Post Filter box and drag the quality slider to the extreme right (999). Press OK and wait while conversion is carried out. You can now split the waveform into separate files so that you have separate CD tracks.
First, right-click on the timeline, select "Display Time format", set it to "Compact Disc 75fps". Set "Snapping" to "Snap to Frames". Now we insert the track markers. Go to the very beginning of the file and press alt-F8 to open the Markers window. Select the range for the first track and select "Add" in the Markers panel. Do the same until you have created ranges for all tracks. Now select all the Markers in the Marker Panel and click on "Batch Process Marker Regions" (last icon) and select "Save to files". Select a prefix such as "Track" and the destination folder where you wish to save. Ensure that format select is "Windows PCM (*.wav)". Click "OK" and the folder will then contain all your tracks saved as "Track001.wav", "Track002.wav", etc. Ignore the Peak waveform ".pk" files, you do not need them unless editing these individual tracks.
Final step - run Nero and choose to create a New Compilation. Select "CD" and "Audio CD" at the left. Do not change the default options, especially do not choose to normalize tracks. Then click "New". In the window at the left you will see the track list. At the right, a file browser. Browse to and select all the tracks for the CD (that you generated in the last step above). Drag and drop them to the window on the left and ensure that the order is correct! Click play to preview the CD. Finally, insert your media and click the "Burn" button - make sure "finalize disc" is ticked and disc-at-once write method is selected. That's all. Click OK and your CD is ready.
There may of course be easier ways but this is mine. Hope it was useful to you and others who wish to carry out this task.