The restoration procedure - part 1
There are two main points to remember. The first is the need for patience. Much better results are likely to occur from several small restoration steps than from one very large one, especially when reducing noise or crackle and when applying band filtration or equalisation. The second and certainly the most important point is to work with a record in the best possible condition!
The first part of the process is the actual recording and that is covered on this page. The second step is the digital restoration which will be explained on the next page.
If you have the choice, check that a suitable stylus is being used. For most pre-war records the 2.8 mil (0.0035 inch) truncated elliptical will be best, but for older records a stylus of 3.5 mil may be better. Records in excellent condition, and those dating from the 1950s or later may be best if played with a 2.5 mil conical stylus. Some early small format records such as 8 inch discs with a full length performance may produce a descending vibrato whistle over their latter part of the recording and a smaller stylus, as low as 2 mil, may reduce this.
For most records a sample rate of 22050 in stereo is adequate. An exception is likely to be recordings made in the second half of the century, which may need a sample rate of 44100. Recommendations made by the audio software prodcuders must also be followed. The maximum frequency is usually taken to be half the sample rate, just over 10kHz for the recommended setting. Until the late 1930s the upper frequency limit of recording was generally little more than 6-8 kHz, although transients and higher overtones of some instruments such as trumpets and violins could be recorded nearer to the 10 kHz ceiling. However, after a record has been played only a couple of times with a steel needle, the higher musical frequencies could be flattened and swamped by surface noise or obliterated by needle wear.
Check that the turntable is revolving at the required speed. This may not necessarily be 78 rpm; early Columbia records were recorded at "Speed 80", for example. A stroboscope is the easiest means of checking this. See http://www.78rpm.com/rescat/strobe_info.htm for details of a tailor-made stroboscope for any speed which can be printed easily.
Check that recording level (on Options-Properties-Recording-"line in" in the Windows Volume Control) is adjusted until there is no clipping of signals, but that the maximum level is less than 3 dB from the peak. Use the Recording option on the Volume Control panel for access to the recording level slider. If you can't see your volume control, go to Start-Settings-Control Panel-Sounds and Multimedia and check the box to show the Volume Control on the Taskbar.
Decide whether you want to use an equalisation curve on your preamplifier, if you have this luxury. If in doubt, record it flat and you can later experiment with various equalisation settings. If you only have a preamplifier which is optimised for LPs and vinyl, you will have to apply quite a lot of equalisation adjustment during digital processing.
Include a section of the run-in and, if possible, the run-out during recording. These can be used to identify and eliminate noise surface noise and electronic noise in the preamp and sound card.
Record and save the audio file, preferably in Windows PCM .wav format.
You may decide that you will want to keep this original recording. The advantage of this is that as your experience increases, and your restoration technique improves, you may want to go back to some of your earlier attempts and have another go at them. Duplicating on to a CD or DVD recordable disc can save hard disc space when you have finished with your original recording and may provide a reasonable archive lifetime.
Start with some of your less cherished records and move on to your favourites when you are an expert.