Recording 78 rpm records
- Ideally use a turntable with 78 rpm and adjustable speed - though you can use lower speed dubbing.
- Use a proper 78 stylus - you may want a separate headshell/cartridge.
- Clean your records thoroughly.
- Audacity setup - use the defaults: 32-bit float sample format and 44100 Hz Project Rate
- Processing to adjust equalization and reduce noise - and review results.
- Export to WAV/MP3 in the normal way.
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Use a special stylus or cartridge:
You should not use a normal stylus (needle) to play 78's. The grooves on a 78 are significantly wider and deeper than the grooves on an LP, so a normal stylus will bottom out in the grooves and also bounce from side to side in louder passages. This will result in:
Check the website or manual for your turntable to see if the manufacturer supplies a special 78 rpm stylus or cartridge. If not, search the web for "78 rpm stylus". A typical good starter sapphire stylus size is 3 mil or 0.0762 millimeters, but watch how many sides you play as the stylus does not last as long as a diamond one. Typical groove widths on 78's prior to the 1940's range from 2.5 mil to 4 mil. There is wider variation with recordings from the 1920's and older. Use a separate cartridge: If you can afford it, use a separate cartridge from the one you use for your LPs. You need one which will support tracking at the heavier 4 or 5 gram weights that most 78 rpm recordings need. Ideally you should consider more than one stylus width if you are playing really old shellac records, because there was no standardization of groove dimensions until late in the 78 rpm era. Again, search on the internet for advice. Use a spare headshell: The safest way to swap between stylus types (if you are doing this often) is to use a separate headshell and cartridge. This way you will not be continually swapping the stylus on your cartridge - a risky procedure. |
Workflow overview
- Clean the records
- Recording capture with Audacity
- Export a WAV as a raw master backup
- Remove any DC offset that may be present
- Apply the correct equalization (whatever that may be)
- Invert the RIAA equalization
- Correct the speed via the Change Speed effect
- Filtering to reduce high and low frequency noise
- Clean up clicks and other random noise
- Fade in/out the track beginning/end
- Volume adjustments - normalization and compression
- Review and Export as WAV, MP3 or whatever
- Backup (you do not want to lose all this valuable work)
Workflow
1. Cleaning the records
Try to clean the 78s as thoroughly as possible before recording. This will save you time later as cleaning clicks/pops is hard work if you do it manually.
Do not use alcohol-based solvents on the shellac, use only water or water-based cleaners. You can use a bit of washing up liquid on a piece of velvet and warm water. Give them all a wash, in cool not hot water, and place them in the dish rack - then change the water and rinse thoroughly - finally rinse off with distilled (de-ionized) water, then drain and dry off with a dry piece of velvet.
Avoid wiping with kitchen paper or similar, as these are both abrasive, and can leave fibres stuck in the grooves. If you are in a hurry, placing the record on a piece of kitchen towel can absorb the majority of the distilled water, but avoid wiping the record.
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You should never attempt to play a shellac disc when it is wet. |
2. Capture
Record both sides of the 78 into the project prior to doing the processing. You can either Stop the recording after the first side using the 
button or and then use (or use the shortcut R) to restart recording when you are ready. Alternatively you can pause by pressing the 
button (or use ) at the end of the first side and then press the button again once you are ready to record the second side. After recording you may find it helpful to zoom out to display the entire recording in the Audacity window.
You may prefer to work with a single side at a time as the noise levels may vary from side to side.
3. Export a WAV as a raw master backup
Export a single WAV for this recording at 32-bit float (not 16-bit).
Retain this WAV file as a maximum quality "raw capture" file that you can import back into Audacity later to start over (if you damage the project while working on it).
4. 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. If this is the case with your recordings, see the Normalize page for how to use Normalize to remove DC offset and how to check if your Windows sound device can perform this correction automatically.
5. Equalization
When recording 78 rpm records, there is a problem that the pre-amplification built into any consumer-level pre-amplifier or USB turntable will be designed for vinyl records made from the 1950s onwards. This is because the pre-amplification not only provides the necessary amplification for the cartridge signal that is sent to Audacity, but applies what is known as "RIAA playback equalization" to it. This equalization is essential when playing records made from the 1950s or later, as it cancels out the high frequency biased "RIAA recording equalization" that such records are cut with, making them sound normal again. The problem is that most 78 rpm records were not cut with such a strong high frequency bias. They therefore sound dull if played through modern equipment that applies RIAA playback equalization.
So, to make a fully professional job of transferring your 78 rpm records, you should open or in Audacity immediately after recording, and apply the inverse of the RIAA playback curve (see the next section). This will cancel out the unwanted RIAA equalization, after which you can apply one of the 78 rpm playback curve presets supplied with the effect. Note that the 78 rpm curves are generic. In practice, many different equalizations were used according to the record label or even the recording engineer. See Playback equalization for 78 rpm shellacs and early 33⅓ LPs in the Audacity Wiki for a list of known equalizations used by different manufacturers of 78 rpm records.
6. Inverting the RIAA curve
You can select the "RIAA" curve, then use the button to invert it. Then apply the appropriate equalization to the recording.
7. Lower speed dubbing - 33 1/3 or 45 rpm
If your turntable does not have the facility to play records at 78 rpm, you can use Audacity's ability to change the speed of recordings to record your 78 rpm records at either 33 1/3 rpm or 45 rpm. Since you are playing the disc slower than normal, tracking should not be an issue. The top frequency on a 78 will be around 8000 Hz, and playing it slower will lower that to about 4600 Hz.
- Record the leadout of the final groove and select the distance between the recorded clicks in the Audacity waveform
- Measure the time taken for 10 consecutive revolutions (you can measure to 1/1000 of a second by zooming in on the waveform)
- Divide that time by 10 (for example, if you measured 8 seconds, dividing that by 10 gives you a resultant value of 0.8)
- Divide the resultant value into 60 (in our example, 60/0.8 gives us the answer that the record was playing at 75 rpm)
Record the track into Audacity at your chosen speed then select all the track by clicking in the Track Control Panel and click . In the From box choose the speed you played the record at (for example, "33 1/3" or "45") and in the To box choose 78 rpm if that is the speed you want to convert the recording to (that is, the speed it should be played at according to the label).
If some other speed is required, use the Speed Multiplier box to set the speed to be converted to. Divide the actual speed of the record by 33.3333 (or by whatever speed you were playing it at) then enter the result in Speed Multiplier. For example, if you were playing an 80 rpm record at 45 rpm, the calculation is (80/45) = 1.777778. Enter that result rounded to three decimal places (1.778) in Speed Multiplier.
Note that you should reverse the RIAA equalization to make the transfer "flat" before changing speed, and then set the appropriate EQ for the record. So the workflow steps for this part of the process are:
- Record the 78 at 45 or 33 1/3 rpm
- Apply the Inverse RIAA EQ
- Change Speed to the actual speed of the record
- Apply appropriate EQ according to the make of the record.
Note on actual speeds: With the early clockwork turntable mechanisms the rotational speed was rather approximate and manufacturers produced records in the 70 to 90 rpm range with 78 being the most commonly accepted “standard”. Many discs had the speed stamped on the label and they depended on the early players which had a speed control. With the introduction of the synchronous AC motor, for detailed technical reasons, the standard was changed to 78.26 rpm. See this website for details: http://www.videointerchange.com/vintage_78s.htm.
Note on actual EQ used: See 78 rpm playback curves on our Wiki for an extensive list of 78 rpm playback equalization curves and a Nyquist plug-in that can generate XML files from these curves for use in Audacity's Fileter Curve effect.
8. Filtering and noise reduction
Noise on 78's is complex, and relatively high in level. You will need to try to reduce some of the different types of noise in separate passes.
Noise reduction: Over the years your 78s will undoubtedly have received scratches and wear, which will result in clicks, pops and crackle. Audacity does have tools for click removal and noise reduction - but there are better tools than Audacity for dealing with these, although "Effect > Repair" works extremely well for removing single clicks.
Some of these tools do cost some money but most have free-trial periods. Goldwave is often recommended by Audacity users, as are Brian Davies' ClickRepair and DeNoise packages.
Filtering:
- Make sure you have set the Audacity Default Sample Format in the Quality Preferences to 32-bit float (the default) because you are probably going to do a fair bit of processing, and some of the filters appear to work better with 32-bit input.
- Then run to reduce high frequency noise. Set the cutoff frequency to suit the vintage of the record as follows:
- 9000 Hz or 10000 Hz for recordings from the 1940s or later
- 8000 Hz for electrical recordings (1926 to 1939)
- 7000 Hz for acoustic recordings (before 1926).
Use a roll-off of at least 12 dB per octave or even 24 dB per octave. Listen to the result to make sure the sudden cutoff of high-frequency noise does not sound too artificial.
- Then deal with the low frequency noise - select a "noise sample" from the current audio track (that is, a section of the recording that is surface noise only) and copy it to a new track. Use to see the frequency content of the noise. Use the Low-Pass Filter effect on this noise sample to isolate the lower frequency noise, (for a very rough and ready setting, try a roll-off of 12 dB per octave at a cutoff frequency of 1000 Hz). Then open , select the low-passed noise sample and choose "Get Noise Profile". Finally, select the original track, open Noise Reduction again, choose the slider settings and run the effect.
An alternative, simpler, method for dealing with low frequency noise is to use to filter out frequencies below 20 Hz. It's amazing that the waveform can display these sub-sonic frequencies, usually deficiencies in the cutting lathe during the original recording session.
9. Click Removal
Remove any clicks and pops from the recording using
10. Fade In/Out
You may wish to more cleanly the track end and the track beginning. Normally the fade out should be longer (typically a few seconds), and the fade in, if required, quite short (typically a fraction of a second).
Consider using instead of the linear Fade Out. It applies a more musical fade out to the selected audio, giving a more pleasing (more "professional studio") sounding result.
You may also get a more musical fade-in by applying multiple times to the selcted audio; three times is a good guideline. This will produce a shaped, curved, fade rather than a linear one.
11. Normalization & Compression
As a final step you may wish to adjust the loudness of you recording.
Normalize: You can use to bring the maximum volume of your recording to a specified level - we would suggest to around -3.0 dB. Audacity's can also be used for the same function. Normalize has the advantage that it can be optionally set to adjust for channel imbalance.
Compression: As a final step, to increase the perceived loudness and density of the recording, more advanced users can perform compression on the recording. You can use Audacity's to do this.
There are also some alternative free compressors available as separate downloads which work well with Audacity.
12. Review & Export
Then review the track to decide if any further treatment is required, or if you need to restart from scratch. If you are happy with your work than your project is ready for Export to WAV and/or MP3 and similar.
13. Backup
Don't forget to backup your finished audio files as you will not want to lose all that hard work; ideally at least two separate copies on separate media. You may wish to consider also backing up your original capture masters as WAV files, then you can always come back to the raw recording later and re-process it if you need or want to.
Links
|< Tutorial - Copying tapes, LPs or MiniDiscs to CD
> See also tutorial on: Sample workflow for LP digitization
- Brian Davies offers a free Equalizer application that simultaneously applies the proper Inverse RIAA curve, corrected for the different playback speed, and a choice of 78 rpm EQ curve.
