Recording 78 rpm records

Ready for Proofreading

This tutorial outlines the steps that are needed to process the recording of 78rpm records with Audacity:

• Ideally use a turntable with 78rpm 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 thoroghly.
• Audacity setup - use the defaults: 32-bit floating bitrate and 44.1kHz Project Rate
• Processing to adjust equalization and remove noise - and review results.
• Export to WAV/MP3 in the normal way.

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:

• noisier, more hissy transfers
• far less accurate reproduction of the music
• damage to the stylus which will then impair its further use for LP's

Check the web site 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". If you can afford it, use a separate cartridge which will support tracking at the heavier 4 or 5 gram weights that most 78 rpm's need. Ideally you should consider more than one stylus width if you are playing really old shellac records, because there was no standardisation 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.

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 (placing the record on a piece of kitchen towel can absorb the majority of the distilled water if you are in a hurry, but avoid wiping).

Repair

Fairly obviously, do not record warped warped, cracked or badly chipped records. With a certain amount of patience, problems such as this can be repaired.

Equalization

When recording 78 rpm's, 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 Effect > Equalization 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 78rpm playback curves in the Audacity Wiki for a list of known equalizations used by different manufacturers of 78rpm records.

Inverting the RIAA curve

Audacity 1.3.12

Audacity 1.3.12 introduced an "Inverse RIAA" preset curve for the Equalization effect. Choose this curve from the "Select curve" drop-down menu, then click OK to apply the effect. Note: be sure to select the "Draw curves" radio button - in Graphic EQ mode, the drop-down menu will display a "custom" version of the curve adjusted to meet the needs of that mode. Alternatively, you can select the "RIAA" curve, then use the "Invert" button to invert it.

The Invert button provides other opportunities for correcting inappropriate equalization. For example, if you were recording an acoustic record on equipment that could only reproduce one of the listed "78" or "RCA" curves meant for electrical 78's, you could negate that curve, then apply the very different "acoustic" curve. The result would not be ideally accurate, but far better than not changing the equalization at all.

Earlier versions of Audacity Beta

The Inverse RIAA curve can be applied by modifying the "EQCurves.xml" file that is stored in the same location as your Preferences settings. Open the "EQCurves.xml" file with a plain text editor, then copy and paste the following code near the end of the file just before the line "</equalizationeffect>". Save the file, making sure that the file extension remains ".xml".

<curve name="Inverse RIAA">
     <point f="30.000000000000" d="-18.600000381470"/>
     <point f="31.000000000000" d="-18.500000000000"/>
     <point f="50.000000000000" d="-16.899999618530"/>
     <point f="63.000000000000" d="-15.899999618530"/>
     <point f="70.000000000000" d="-15.300000190735"/>
     <point f="100.000000000000" d="-13.100000381470"/>
     <point f="125.000000000000" d="-11.600000381470"/>
     <point f="200.000000000000" d="-8.199999809265"/>
     <point f="250.000000000000" d="-6.699999809265"/>
     <point f="300.000000000000" d="-5.500000000000"/>
     <point f="400.000000000000" d="-3.799999952316"/>
     <point f="500.000000000000" d="-2.599999904633"/>
     <point f="600.000000000000" d="-1.799999952316"/>
     <point f="700.000000000000" d="-1.200000047684"/>
     <point f="800.000000000000" d="-0.800000011921"/>
     <point f="900.000000000000" d="-0.300000011921"/>
     <point f="1000.000000000000" d="-0.000000000000"/>
     <point f="2000.000000000000" d="2.599999904633"/>
     <point f="3000.000000000000" d="4.699999809265"/>
     <point f="4000.000000000000" d="6.599999904633"/>
     <point f="5000.000000000000" d="8.199999809265"/>
     <point f="6000.000000000000" d="9.600000381470"/>
     <point f="7000.000000000000" d="10.800000190735"/>
     <point f="8000.000000000000" d="11.899999618530"/>
     <point f="9000.000000000000" d="12.899999618530"/>
     <point f="10000.000000000000" d="13.699999809265"/>
     <point f="15000.000000000000" d="17.200000762939"/>
     <point f="16000.000000000000" d="17.700000762939"/>
  </curve>

Pre-Beta versions of Audacity

With patience, the above points can be drawn on the Equalization graph in pre-Beta versions of Audacity, but not saved as a preset. If you are really in a hurry, draw something that looks like the green "Record" curve here.

Lower speed dubbing - 33 1/3 or 45rpm

If your turntable does not have the facility to play records at 78rpm, 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 disk slower than normal, tracking should not be an issue. The top frequency on a 78 will be around 8 kHz, and playing it slower will lower that to about 4.6 kHz.

If your turntable doesn't have a strobe or speed adjustment, you can measure the RPMs very accurately by recording the playout of the end groove and selecting the distance between the recorded clicks on the wave form on the waveform display. Measure the time for 10 consecutive revolutions which you can actually measure to 1/1000 of a second by zooming in on the waveform. Then it is simple mathematics to determine the actual rpm. Thanks to forum user L_Libza for this method.

Record the track into Audacity at your chosen speed and then simply select all the track by clicking in the Track Panel (where the mute/solo buttons are) and click Effect > Change Speed. In the "From" box choose the speed you played the record at (e.g. "33 1/3" or "45") and in the "To" box choose the speed you want to convert the recording to (i.e. the speed it should be played at according to the label).

Note that you should reverse the RIAA equalization before changing speed - now the transfer is "flat". Then change the speed. Then apply the "proper" 78 rpm equalization (whatever that may be). So the workflow seteps for this part of the process are:

1. Record the 78 at 45 or 33 1/3.
2. Apply the Inverse RIAA EQ (to make it like a 'flat' recording).
3. Change the speed to 78rpm.
4. Apply appropriate EQ for what the 78 was recorded with.

Note on actual speeds In the 1930's The United States had recordings that spun at the rate of 78.26 rpm. but the rotational speed of "78's" was rather approximate as clockwork mechanisms were widely used right up into the 1940's. Many disks that had the speed stamped on the label - and they weren't 78. They depended on the early players which had a speed control. so you may need to check carefully for accurate transcription/processing.

Stanton T-series USB turntables still offer 78rpm working, and helpfully they have a wide speed adjustment range. If you know exactly what speed your records should spin at you can print out a strobe disk with exactly the right spacing of bars. Thanks to forum user pdxrunner for this insight.

Filtering & noise removal

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 removal

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 removal - but there are better tools than Audacity for removing 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

Bill 26Feb10: This section needs expansion, I think, to make it more understandable for novices.

• Peter 27Feb10: possibly - but maybe it would be better to create a separate tutorial on filtering and noise removal. It is a fairly complex topic in its own right. Also note that this summary came from two posters on the forum responding to 78 xfrs (SteveTF and L_Libza - for which, thanks) and none of the OPs or readers posted back saying it was too complex or that they didn't understand.

1. Make sure you have set the Audacity bit depth to 32-bit floating (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 files.
2. Perform DC offset correction. You do this uing the Normalize Effect - but do not apply any Normalization at this stage, just the DC offest.
3. Then run a low pass filter to remove high frequency noise - set the cut off frequency to suit the vintage of the record. For recordings from the 1940s or later set the cutoff frequence at 9 kHz or 10 kHz; for electrical recordings (1926 to 1939) about 8 kHz, and acoustic recordings (before 1926) about 7 kHz. Use at least 12 dB per octave, 24 dB per octave could probably be better. Listen to the result to make sure the sudden cut-off of high-frequency noise does not sound too artificial.
4. 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 Analyze > Plot Spectrum to see the noise frequency content. Use a low pass filter on this noise sample to isolate the lower frequency noise, (for a very rough and ready setting, try 12dB per octave at 1000 Hz), then use the resulting sample for the "noise profile" for the Noise Reduction effect. Finally, select the original track and run the Noise Reduction effect.

An alternative, simpler, method for dealing with low frequency noise is to use the high pass filter 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.

Normalization & Compression

As a final step you may wish to adjust the loudnesss of you recording.

Normalize

You can use Effect > Normalize to bring the maximum volume of your recording to a specified level - we would suggest to around -1 dB. Audacity's Effect > Amplify can also be used for the same function.

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 Effect > Compressor to do this.

Alternatively an excellent free compressor that is often recommended is Chris's Compressor. This is a Nyquist plug-in that can be added to the Audacity plug-ins folder inside the Audacity installation folder. Restart Audacity, then the new plug-in will be underneath the divider in the Effect menu.

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/orMP3 etc.

Don't expect miracles with badly worn records. The process can be very frustrating and the results can be disappointing. Avoid aggressive denoise. The artifacts are usually worse than the noise. Some users like to leave a little surface noise in my transfers (they are 78s after all!). Declick and equalization are the most important steps in the process. Learn to read the waveform. Sometimes an equalization can increase the amplitude of some frequencies to a clipping level, so consider reducing the amplitude slightly before equalization.

Summary - workflow overview

1. Clean the records
2. Recording capture with Audacity
3. Export a WAV as a raw master backup
4. Remove any DC offset that may be present
5. Reverse the RIAA equalization
6. Correct the speed via the Change Speed effect
7. Apply the correct equalization (whatever that may be)
8. Filtering to remove high and low frequency noise
9. Cleanup clicks etc.
10. Volume adjustments - normalization and compression
11. Review
12. Export as WAV, MP3 or whatever
13. Backup (you don't want to lose all this valuable work)

Brian Davies suggests a different method for capturing 78s at 45, and has a free "Equalization" program that that simultaneously applies the proper reverse-RIAA curve (corrected for the different playback speed) and a chosen 78 rpm EQ curve. http://www.clickrepair.net/

Links

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