Many people have collections of vinyl recordings which they would like to transfer to digital format. At the March 2, 2009 meeting of the Multimedia SIG Bob White presented suggestions for how to enhance the quality of these transfers by removing extraneous noise ("pops" and "clicks") from these recordings.
Before you begin, Read tutorials for LP transfer on the audacity wiki:
There is some really good information here, especially about equalization curves on older records, which probably isn't available any other way, let alone so convenient!
The wiki also has suggestions for pop and click removal:
If you're going to digitize some old records, start by cleaning up the record(s) as best you can. I use an audioquest anti-static record cleaner: Go to http://www.audioquest.com/ then go to the Accessories tab, select "Vital Vinyl" and scroll down to “Record Brush” (A list of dealers carrying this brush can be found under the "Dealer Locator" tab)
- After setting your record on the rotating turntable, apply the brush gently to the record with the long axis radial and the inner end covering the lead out groove. Bristles should be perpendicular to the record surface and just barely deflected by the record's rotation. Let the record spin about 3 turns.
- Next pivot the brush about 45 degrees to the radius by moving the inner end “forward”, i.e. towards the oncoming grooves (over about 1 turn). Then sweep the brush forward (perpendicular to it's long axis) and off the record, over about 5 turns. This should sweep any collected dust off the record.
- Move the brush away from the record and turn its handle (bail) under the bristles to shake loose the accumulated dust. (A short version of these instructions appears on the back of the brush's package.)
I have not used any of the liquid “washers”, but they may be very effective. If you use one, DON'T use tap water with it. This will leave residue, such as precipitated calcium, which will add surface noise to the groove and which you will never be able to remove. Ensure your liquid washer removes ALL of the liquid (and dirt, of course!) and leaves NO residue! Consult with someone who has experience with such a washer.
Store your newly cleaned record in a poly lined paper sleeve, for example as found at:
If the original cardboard jacket has disappeared or disintegrated, the same website offers new clean ones. You want a jacket for mechanical protection and the original one usually is good enough. The original jacket is a significant part of the record's historical (and monetary!) value and should NEVER be discarded.
Having spent several more hours removing pops & clicks (these weren't my first transfers) I have a few observations about the process:
- Using the Zoom controls, set a time scale with tick marks every second and time labels every 5 seconds. I've found this works pretty well for locating pops and clicks. Fit the tracks vertically (View -> Fit Vertically) to give yourself plenty of room to work. You should get something like:
- Your ear is by far the best instrument to find pops and clicks. (Note the spike just before 32 seconds in the nearby image.) As audacity plays, lead the playback time line slightly with the mouse cursor, and click on a noise to set a mark. Then quickly stop playback. With experience you will be able to visually spot and "camp out" on noise candidates, which can be clicked on if they correspond to actual noise.
- Your eye is the best instrument to zero-in on a suspect click or pop. Mouse clicks, or Ctl+1 keep zoom centered on your marker. (See note below.) Re-target the time marker as needed, for example after about 6 clicks of “zoom”, to keep it on the central zero-crossing of the noise spike. If the spike isn't fairly narrow (200 - 500 microseconds) it's probably not a pop or click. Time scale tick marks are now 100 microseconds apart and you'll see something like:
- Choose the draw tool (looks like a pencil).
- Re-draw the waveforms as needed to eliminate spikes. Set the draw tool on the dot left of the first one you wish to change, then drag the tool through the disturbance to correct the waveform. You can go back and modify individual dots if you wish. Usually the spike is much more prominent in one channel than the other, but consider redrawing the less affected channel as well. Do the best you can with shaping the waveform, and don't worry about it. You're dealing with a VERY small time slice, and just getting the spike cut down will be a MAJOR improvement! Result should look like the following:
- Choose the selection tool (to prevent accidents!).
- Zoom back out, should be 13 clicks (Ctl+3).
- Back up a few seconds and re-play the section. Pop or click will be gone.
- With experience you'll realize how short pops and clicks are compared to desired sounds. This will guide you in determining what to try removing.
- Think cosine-squared.
Pops and clicks approximate this shape, which means there may be small deflections before and after the main peak which go in the opposite direction. Plan to remove these as well if you see them.
- 90% of pulses will need the first 10% of your time to remove. Always be aware of when your work is good enough! Do you want to take a LOT more time to chase the last 10%? MAYBE you do, but make it a conscious, informed decision!
- Inter-band gaps: At about 5:11 to 5:19 the example recording has a gap between bands. Typically there is surface noise here which you might want to suppress. In the example recording the original tape had a paper leader in the gap so is known to have been completely silent. Zoom to this region using Stan's method, which is superior for this purpose. Then select exactly the region you want to silence and use Edit -> Silence (Ctl+L) to remove the noise. This may seem redundant (see Recording strategy) but it makes band gaps easier to identify later.
Note on zoom:
Stan suggests making a selection over the click or pop by dragging the marker, then use Ctl+E to zoom to the selection. Typically this will need 2 “select and zooms” to get to an editable expansion. The resulting scale may not be what you'd like to work with. You may prefer this to the “13 click” method. I recommend trying both methods and use what works best for you.
Record an entire side at a time into a single Audacity project. Remove tone-arm drop & lift noise by selecting each region and deleting (Edit -> Delete or Ctl+K). Keep each side as a single project during clean-up. After clean-up, use selection (Edit -> Selection Save) to separate bands into individual files for burning to CD. In the save step you can determine file type (.wav, .mp3, etc.). In the CD burner setup you can insert inter-band silences.