Sample workflow for LP digitization

This tutorial outlines a set of example steps that can be used to digitize LPs with Audacity, ready for CD creation or loading into a digital jukebox or portable music player.

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 Default Sample Format of 32-bit float (the Audacity defaults). You can 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.

Wash the vinyl with water and little washing-up detergent, wipe the surfaces in the solution with a clean washcloth or a piece of velvet - try not to get the label wet. The detergent will float away all the greasy fingerprints and gentle scrubbing helps. 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 while recording: place your cursor at the approximate point required and click CTRL+B – alternatively you can mark the current recording point, while recording, between tracks 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

You may need to apply a DC-offset correction if you equipment is adding a DC offset (the visual indication of this is that the waveform is not centred on the zero line). Use the Normalize effect but ensure that you do not apply any normalization at this stage, only check the tick box that is labellled "Remove any DC offset ..." and make sure that the "Normalize maximum amplitude ..." tickbox is un-checked.

Remove subsonic rumble and low frequency noise

Apply Audacity's High Pass Filter (available from the Effect menu), using a setting of 24 db/octave roll-off, and a cut-off frequency of 20 - 30 Hz to rid of sub-sonic garbage frequencies. It's amazing that the waveform can show these sub-sonic frequencies, usually deficiencies in the cutting lathe during the original recording session.

Whether you need to or not will depend on the quality and alignment of your 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. You can use this either on selected portions of your audio or you can select the whole project for the effect to work on. You may need to experiment with the settings to get the best results.

The following methods are only really useful of you have a relatively small number of clicks and pops to repair as otherwise the approah will be far too labour-intensive and time-consuming:

• For stubborn (large) clicks you can use Audacity's Repair effect. This effect will repair a dameged waveform of up to a maximum of 128 samples by interpolating from the neighbouring waveforms. You will need to zoom in to see the individual samples to be able to use this effectively.

• For larger noise events, bigger than 128 samples, you can try to use the Draw Tool. You also need to be zoomed in to see the individual sample points to use this tool. Beware: this tool is not for use by the faint-hearted - it is tricky to use and get right.

• Also for large clicks the the Click Removal won't work on you can try the Hard Limiter effect. It is a spot removal tool, effectively extreme compression. The advantage is you don't have to zoom in to sample level

to use it as you do with Draw Tool and it will work on a larger sample size than the Repair tool.

Remove hiss and high frequency noise

Get a noise sample from the lead-in groove before the music starts. 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, 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 lower settings on the "Noise Reduction (dB)" slider until you get the best compromise.

Whether you need to or not will depend on the quality of your LPs and your stylus and cartridge.

Clean the inter-track gaps

These are rarely truly silent so replace them with silence by selecting the gap and using CTRL+L. Shorten the inter-track gap 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 if you do this you should ensure when later burning your CD that the CD burner software does not add an extra 2-second gap, you should set it to "gapless" burning.

GA: why 2 seconds - if burning to CD 2 seconds will usually be added.

• Peter 19Mar10: that's because I much prefer to control the intertrack gaps myself - sometimes shorter sometimes longer and sometimes no gap. I don't want my CD burning s/w "helpfully" adding a 2-second gap - even if that is the Red Book standard. I don't think George Martin worried about the Red Book gap with Sgt Pepper, nor Pink Floyd with their concept albums :-)>
• Peter: also I import a lot of the WAVs into iTunes for conversion into AAC - for this I need to control the run-out and run-in lengths.
• Gale - We definitely need to suggest adjusting the gap, I just thought this needed a line to say "why" choose a particular gap. Many novices are confused that the gaps are extended by 2 seconds on their CD, and they can sound poor too because the gap is half noise and half silence.

Adjust label positions

If you are using a 2-second gap, leave a silent tail of say 1.5 seconds and a run-in on the next track of 0.5 seconds.

Fade-ins/outs

You may wish to more cleanly fade out the track ends and fade in the track beginnings (normally fadeouts 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 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 1.3.12 a new feature has been added which will automatically prefix named tracks with 01, 02 etc. In the Export Multiple dialog box there is a bax called Name files: - check the radio button for Numbering before Label/Track Name.

Amplitude adjustment

Adjust the amplitude of the recording. Use Effect > Amplify 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.

It effectively makes the loud parts quieter and the quiet parts louder - so it is often used by people who say want to listen 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 will be applied by default to cover any clicky noise that may result from the sample size conversion from 32-bit to 16-bit down-sampling.

GA: Is Dither or different types of it an issue given the LP noise floor or USB hum (unless you really did a great job with Noise Removal)?

• Peter 19Mar10: actually this is really at the very boundary my technology. I merely have mine set this way after a long forum/email discussion with SteveTheFiddle - it was the setting he advised for the way I was working. BTW: What is the Audacity default? I can't remember as it a long time since I've had a clean install.
• Gale - As you can see I edited the above to state that shaped dither is the default. I'm just wondering if adjusting dither is an advanced step and there is enough detail already here for a novice. I'll grant it just possibly may be an issue for a tape, but this isn't about tapes.

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 you may wish to consider using

• GoldWave: though nominally about $US 25 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 Brain Davies' ClickRepair. Some novice users report that it is 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, it currently costs $40 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 get's much favourable mention on the Audacity Forum.

Links

|< Tutorial - Copying tapes, LPs or minidiscs to CD

>  See also tutorial on: Recording 78rpm records