Sample workflow for LP digitization
From Audacity Manual
It is not the only way of working - there are many alternatives. Like any recipe it can be adapted to suit your personal needs. Most of the clean-up steps are optional and need only be applied if your particular recording requires them.
You can work in AIFF rather than WAV if required.
Note that this workflow does not at any stage necessitate the saving of an Audacity project (though you may wish to do that if you need to interrupt your work). It relies on the export of WAV files.
All of the processing in this tutorial is carried out with Audacity. Some users may prefer to use alternative software for specific sub-tasks like noise removal and the removal of clicks and pops (current Audacity Click Removal may not give as good results as other software).
Workflow
Audacity settings
Work with Audacity set to a project rate of 44100 Hz and 32-bit sample format (these are the default quality settings). Use 16-bit if you prefer; it will give smaller working file-sizes but you may lose a little quality in some of the processes. Export WAV files at 44100 Hz 16-bit PCM stereo. That is the standard required for burning CDs and it will produce WAVs that are accepted for import by iTunes (and other music player software).
Clean the LP
Cleaning the LP carefully and thoroughly before recording it will reduce the number of clicks and pops and will improve the quality of your recording.
Prepare a solution of water mixed with a little washing-up detergent. Use a clean washcloth or a piece of velvet to carefully wipe the LP surfaces - try not to get the label wet. The detergent will float away all the greasy fingerprints - a gentle scrubbing motion will help. Rinse in luke warm water until all the detergent is gone and then finally rinse in distilled water which drys and leaves nothing behind. Ensure your record is thoroughly dry before playing - do not be tempted to play the record "wet" as this may damage the LP and possibly your stylus.
There are a number of commercially available cleaning fluids and cleaning machines that you may wish to consider:
- KAB EV-1 Record Cleaner & KAB cleaning solution
- Disco Antistat
- Discwasher
Recording levels
Check the levels: play portions of the LP, or even the whole side of the LP, to check the recording levels so that you avoid any clipping during the recording. Try to aim for a maximum peak of around –6 dB (or 0.5 if you have your meters set to linear rather than dB}. Tip: enlarging the Meter Toolbar by clicking and dragging helps with this task.
Capture
Record both sides into the project prior to doing the processing. You may find it helpful to zoom out so as to show the whole side of the LP in the Audacity window. You can if you wish work with single sides of an LP as it gives a smaller working set.
Place-holders for song labels
Mark the approximate label points: click in the waveform at the approximate point between the tracks on the album, then click CTRL+B. Alternatively you can mark a label point while recording by using CTRL+M.
Raw master backup
Export a single WAV for this side of the LP at 32-bit float (not 16-bit). Retain this WAV file as a maximum quality "raw-capture" file that you can import back in to Audacity later for any future re-editing (or to start over with editing if you damage the project while working on it).
Remove DC offset
DC offset can occur at the recording stage so that the recorded waveform is not centered on the horizontal line at 0.0 amplitude. Use the Normalize effect to remove any DC offset. Put a check mark in "Remove any DC offset..." but leave "Normalize maximum amplitude..." unchecked.
Remove subsonic rumble and low frequency noise
Use with a setting of 24 dB per octave rolloff, and a cutoff frequency of 20 - 30 Hz to remove unwanted subsonic frequencies which can cause clicks when editing. If your record is warped, this will definitely generate unwanted subsonics, in which case consider a lower cutoff frequency.
This step can probably be omitted given a flat record and high quality turntable, arm and cartridge.
Remove clicks and pops
There are a number of ways you can use Audacity to remove clicks and pops from your recording.
Use the Click Removal effect on either selected regions of audio or on the whole project. Preview the effect with different settings to get the best results.
Clicks which did not get removed with Click Removal can be treated individually with other methods. These are only really useful if you have a relatively small number of clicks and pops to deal with, otherwise the approach may be too labour-intensive and time-consuming:
- Try Audacity's Repair effect. This repairs a very short length of up to 128 samples by interpolating from the neighbouring samples. You will need to zoom in to see the individual samples to use this effect.
- For somewhat longer regions of audio, try:
- Draw Tool. You also need to be zoomed in to the individual samples to use this. Some patience may be needed with this tool, but the principle is to put samples back into line with their neighbours so that a smooth contour is presented.
- This is an extreme compressor effect, but can be effective used on an individual click. There is no need to zoom right in to sample level to use this.
Remove hiss and high frequency noise
Get a noise sample from either the lead-in grooves immediately before the music starts, or from a lead-in between tracks. Apply the Noise Removal effect with Noise Reduction set to no more than 12 dB (9 dB is a good guideline), Frequency smoothing 300 Hz and Attack/decay time 0.25 seconds.
Noise reduction is always a compromise, because on the one hand you can have all the music and a lot of noise, and on the other hand, no noise and only some of the music. Try different settings on the "Noise Reduction (dB)" slider until you get the best compromise.
Whether you need to use Noise Removal will depend on the quality of your LPs and your stylus and cartridge.
Clean the inter-track gaps
These are rarely truly silent so you may want to replace them with silence by selecting the gap and using CTRL+L. Reduce the inter-track gap as desired to around a maximum of 2 seconds, though you may wish to use a shorter gap or even no gap at all for some recordings.
Note that CD burning software almost always adds a 2-second gap between tracks by default. Check for any options to turn this off, or for "gapless burning" or "Disc-at-once (DAO)" options that you can enable.
Adjust label positions
If you are using a 2-second gap, adjust the label position as desired to be 0.5 seconds before the start of the next track. To move the label, drag by its center circle.
Fade Ins/Outs
You may wish to more cleanly the track ends and the track beginnings. Normally fade outs should be longer, and fade ins, if required, quite short.
As an alternative: you may find it easier to do: fade-out, silence gap, fade-in, shorten gap, adjust label position – in that order, one track at a time.
Track names
Edit the labels for the song names: we suggest using 01 <song-name_1>, 02 <song-name_2>, and so on as this helps keep them in the right order for CD production or loading into iTunes. You may find that changing the zoom level will help you with this task - or you can advance to the next label by ensuring that the focus is in the current label then using the <Tab> key.
In Audacity 1.3.12 a new feature has been added which will automatically prefix named tracks with a sequential two-digit number. In the "Name files" section of the Export Multiple dialog, select the "Numbering before Label/Track Name" radio button.
Amplitude adjustment
Adjust the amplitude of the recording. Use as the last editing step to bring the amplitude up to around -1 dB. Use Amplify rather than Normalize as Audacity’s Normalize effect operates on each stereo channel independently and can thus change the stereo balance. If your equipment is not balanced you may prefer to use the Normalize effect.
Compression
The Compressor effect reduces the dynamic range of audio. One of the main purposes of reducing dynamic range is to permit the audio to be amplified further (without clipping) than would be otherwise possible.
Compressor makes the loud parts quieter and (optionally) the quiet parts louder. It can be very useful for listening to classical music in a car. Such music normally has a wide dynamic range and can thus be difficult to listen to in a car without constant volume re-adjustment.
Export a set of WAVs
Use Export Multiple to produce a set of WAVs for each track on the LP at 44.1kHz 16-bit PCM stereo. Audacity will down-sample on export from 32-bit to 16-bit. Shaped dither noise will be applied by default to cover any clicky noise that may result from the conversion from 32-bit to 16-bit. Advanced users can change the type of dither, or turn it off, in the Quality Preferences.
Place all the files for a particular album in a specific named folder for that album to facilitate later retrieval and use.
Export Labels
Some users advise a final step of exporting a file containing the labels. Use This produces a text file that you can later re-import using , should you wish to re-edit from the raw capture file that you backed up earlier in the workflow.
Backup
Backup your WAV files: you don't want to lose all that valuable work and do it all over again, do you? Use two separate external 1 TB USB disks to hold the WAVs - each LP can be stored in its own named folder by artist (or composer for classical) to make retrieval easier.
Alternative software
- GoldWave: though nominally not free, it is effectively a top class, free click remover as well as an excellent alternative audio editor (its click removal is an effect, just like in Audacity). The trial version limits you to a hundred or so commands per session, and a total number of several thousand commands before it expires, but if you export from Audacity as 32 bit WAV and just do Click Removal in it, you should be able to do several hundred records for free. Note that Audacity's Noise Removal is probably superior to Goldwave noise removal on the whole.
- Gnome Wave Cleaner: - for Linux users
Clicks & pops
- ClickRepair: A good tool for removing Clicks and Pops is Brian Davies' ClickRepair. Some new users may find it a bit intimidating as an entry level tool, but once you have understood the settings you want to use it is effectively an automated tool. It is not free, but many users report that its saves a lot of time and produces good results.
Hiss & noise removal
- SoundSoap: - reckoned to be better for broadband noise reduction than for click removal. Note that this software is not free.
Compression
- Chris's dynamic compressor: this tool gets much favourable mention on the Audacity Forum.
