Audacity, and a couple of filters, that's exactly what we're going to do. The powerful, open-source editor is going to help us take those old recordings, clean them up, and make them fit for digital consumption.
RecordingAudacity 1.3 Beta, which includes some new tricks and features that are perfect for this project.
Before we begin, you'll want to make sure all your hardware checks out. A decent sound card is a must here, as cheaper or integrated models can pick up interference from CD-ROM and hard drives. You don't need an expensive card, but it's worth doing a quick check for interference to make sure you won't run into problems.
As for connections and cabling, we'll leave all that up to you. Connecting that old VCR or cassette deck to your sound card is a pretty simple process, and usually involves RCA or 1/4" jacks you already have lying around the house. Just remember, record players need to be wired through a receiver, which handles the important task of amplifying and equalizing the vinyl record into a usable signal. Once all that's done, you'll be good to go.
ensure "Software playthrough" is checked; this is what will allow us to hear the audio as it's recorded. Now, with everything set up, record a short test. You want to record the signal as cleanly as possible, so play through both a quiet and loud portion of the source material and adjust your levels within Audacity to ensure there's no clipping. If all goes well, you should end up with something like this: Download Audio Sample 1.
For our example, we've ripped a vinyl recording of Paul McCartney and Wings' "Live and Let Die" from the 1976 live album ' Wings Over America'. Immediately, you'll notice there's a few things wrong here. There's a very audible hum at the beginning of the track, that continues on throughout the recording, while the age and condition of the vinyl are responsible for many of the pops and clicks you hear. Also, the levels here are way off — there's far too much bass — and it's hard to hear the mid and high frequency sections very clearly. As bad as these issues sound, this is the perfect candidate for our clean-up process.
High Pass FilterHigh Pass filter is going to help us tackle two problems at once — both the audible hum throughout our recording, and the heavy bass that distorts the majority of the song. The filter works by weakening or reducing frequencies below a certain cut-off point, allowing us to hear more of the mid-to-high levels instead. To start, select the filter from Audacity's effects menu, and try running it over your recording with the default settings.
If there's a lot of bass, as with our recording, you'll find the defaults do a decent job. However, you may want to further increase the cutoff frequency, as well as the rolloff value too. This will filter the audio a little more aggressively — though push too much, and you could end up distorting the audio a bit more than you'd like. Move the sliders back in the opposite direction and you can filter out less, which can keep the end result from sounding too tinny. The key here is playing with the cutoff frequency, rolloff value and filter quality until you find something that works.
Noise removalNoise Removal filter was designed for, and should remove most of the noise that's left behind. To work its magic, Audacity needs to sample a few seconds of this noise in order to build a profile for removal; if possible, try to select a few seconds of "silent" audio before or after your recording, and tell the filter to "Get noise profile."
Download Audio Sample 2 (before)
Download Audio Sample 3 (after, less noticeable in full mix)
Once completed, you can then adjust and apply the effect to the entire track. The noise reduction setting determines how much of the frequency should be reduced, whereas frequency smoothing determines how aggressive the removal should be. Be warned, however, that too much removal doesn't sound pretty, and could actually make your recording sound more like a poorly compressed MP3 than a noise-free classic. Once again, be smart with how much effect you apply, and don't be afraid to experiment until you get it right.
Pops and Clicks
Download Audio Sample 4 (before)
Download Audio Sample 5 (after)
Click removal tool is dead simple to operate. The higher the spike width, the more aggressively the filter will look for anomalous pops and clicks. But go too high, and the filter can begin to remove other features from the audio as well, reducing the overall quality — something we don't wont. Luckily, we have a visual guide as well, in the form of our recording's waveform. If our settings are too aggressive, then we can see the entire waveform begins to shrink, ever so slightly. But if our settings are just right, than only the small blips in the waveform will vanish instead.
While the tool works well for pops and clicks, other imperfections may not be so lucky. Warped vinyls or dirty cassette heads can produce irregular, inconsistent noises that are difficult for Audacity's algorithms to remove. In these cases, there's nothing to do but accept the limitations of the old analog copy, and try to improve other areas where possible.
Equalizationequalization. This is a concept many music lovers are probably familiar with, but it's worth covering briefly here too. It's possible that, after all of our editing, certain sections of the audio can still sound wrong. Trumpets may appear too muffled, or the bass may not be as clear as you remember it. If this is the case, we can run our audio through Audacity's graphic equalizer. Here, you're given a number of sliders that correspond to various audio frequencies. Lower values indicate low, bass-filled frequencies, whereas higher values denote higher frequencies. By altering the position of each slider, you can enhance the amount of low, mid or high frequencies for a more authentic sounding recording — perfect for quick adjustments to treble or bass.
When everything's been completed, you can finally export the finished product into your music collection for future enjoyment. FLAC is obviously the best format for preserving your analog recordings, though MP3 is obviously more suitable for portable players and other devices. Below, you can hear how we've improved upon the clip we started with: Download Audio Sample 6.
If you have any great recordings or obscure bootlegs you've digitized and shared, be sure to tell us how and where.
Lead images via Flickr users streetpreacher83, Mac Users Guide.