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This page details the experiences I had in attempting to transfer some aged vinyls to CD for my parents. This started as a Christmas present for 2003, and is going to also be a Christmas present for 2004, as my final attempt was botched last year. As the real goal is to transfer a different vinyl altogether, I'll still have to do that at some point.

Hardware used

  • Athlon 1800+ XP, 512 MB ram, 80 GB IDE disk. Running Gentoo Linux, with the 2.6.9 kernel. NForce2 motherboard.
  • Turntable
  • Mixer

Having refined my hardware choices the last time I tried this, I decided to forgo the hassle of using the flasher sound card. It didn't really offer me a lot given the amount of mangling I am going to do to the recorded tracks. The only real concern is whether the audio on my motherboard is any good, and while I doubt it'll win any awards, it's "good enough" for recording crackly old vinyls.

Process

Recording

After setting up my turntable, mixer and PC, and getting the input levels right (which involved recording each side and paying attention, and every time it started clipping stopping the recording, dropping the gain, and starting again). After recording both tracks to disk, leaving plenty of lead-in and lead-out, I made a backup of the saved .wav files. Then I made another one.

Things to be wary of:

  • Mute any inputs that aren't being used.
  • Keep an eye out for extra sources of noise being added in. The Linux Audio-Quality HOWTO has a few suggestions for taking into consideration here. Worth a read.
  • Make lots of backups. Then make some more.
  • If your input starts clipping, you will find it very hard to smooth the sound out. I had better luck recording with low gain and running a software amplify across the track, then declicking/denoising, than I did recording at a higher gain and dealing with clipping audio. It seems the record "clicks" are easy to remove UNLESS they clip, at which point they are tedious to remove.

Noise reduction

Audacity and GnomeWaveCleaner both offer noise reduction tools. I didn't have a lot of luck with Audacity last time I tried it, but that was ages ago and it seems to have advanced a bit. I stuck with GWC however.

After going through each stage, it makes a lot of sense to back up your current work. It is really annoying to have to sit through another 15 minutes of declicking because you screwed up a decrackle phase and didn't keep your undo information / backups.

Removing clicks and pops

GWC has three tools for removing clicks and pops - the strong, weak and manual declick tools. I've seen[1] recommendations to use the strong declick tool several times in a row, and found this to have fairly good results. Depending on how bad your vinyls were, you may have to run this 3 or 4 times.

GWC outputs some statistics from its run:

115121 clicks repaired, 49 clicks marked, but remain unrepaired
DECLICK in 792.064 real seconds
27758 clicks repaired, 42 clicks marked, but remain unrepaired
DECLICK in 202.366 real seconds
3440 clicks repaired, 42 clicks marked, but remain unrepaired
DECLICK in  44.687 real seconds
532 clicks repaired, 42 clicks marked, but remain unrepaired
DECLICK in  31.677 real seconds

Removing crackle

Records have a lot of crackle. Can't get away from it. GWC has a handy tool to remove it. [1] says you should do this, Jeff Welty, a wiki visitor who commented on my previous pages, suggested skipping it.

Removing other noise.

GWC also has a denoise tool. This is reasonably configurable, with a selection of different algorithms and tunable parameters. Unless you're in a big hurry, you should really play around a bit.

DENOISE in 130.549 real seconds

Amplify and Normalise.

Optional, but amplifying and normalising your final tracks might be useful. It'll stop huge volume disparities when you switch between the latest Wu Tang CD and whatever you just recorded off vinyl, at least.

Writing out to CD.

GWC supports track tagging, which is based off waveform amplitude or something. If you get a silent patch, it marks it as a track boundary. I've had mixed success with this, but in my final run I just let it do whatever - I got about three times as many "tracks" as there actually are, but seeing as they are really only a convenience thing I wasn't fussed.

You can either split the file out and write to separate .wav files, or you can write out a cdrdao style TOC file for the .wav, which you can then use to burn to CD later on

Sites Referenced.

Comments from Paul Cleary:

Turntable sound output is down around 5mVolts compared to CD output at around 150mVolts. Also the signal needs something called frequency equalisation to restore the output to proper proportions. Disk Smith sells a turntable with inbuilt preamp for $100 that will do the job. --Paul Cleary

I use a cheap $60 Creative soundblaster card for this work and I get very good SNR. The thing to realise is that in all low to med cost soundcards, the audio input part that converts the analog signal to digital is virtually the same. The difference in the cost of the cards is paying for is all the fancy signal manipulation and sounds effects. A person recording from LP to a WAV file just needs the conversion part. I recommend you read Clive Backham's webpages on converting vinyl LPs to CDs (Google:Clive Backham convert lp cd). He discusses the whole process from start to finish, including equipment, soundcards and software. I use his Waverepair software for LP to CD conversions but it only works on Windows. --Paul Cleary