Recording 78rpm records - Audacity Manual

# Recording 78rpm records

### From Audacity Manual

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 thoroughly.
- Audacity setup - use the defaults: 32-bit float sample format and 44100 Hz 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. 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.

You should never attempt to play a shellac disc when it is wet.

### Repair

Fairly obviously, do not record 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 invert 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.

## 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 playback speed in revolutions per minute (RPM) very accurately thus:

1. Record the leadout of the final groove and select the distance between the recorded clicks in the Audacity waveform
2. Measure the time taken for 10 consecutive revolutions (you can measure to 1/1000 of a second by zooming in on the waveform)
3. Divide that time by 10 (for example, if you measured 8 seconds, dividing that by 10 gives you a resultant value of 0.8)
4. 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 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 (for example, "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 steps 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: With the early clockwork turntable mechanisms the rotational speed was rather approximate and manufacturers produced records in the 70 to 90rpm range with 78 being the most commonly accepted “standard”. Many disks 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

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 find a strobe disk on the Internet and print one out with exactly the right spacing of bars. One example site is: http://www.78rpm.com/rescat/strobe_info.htm.

## 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

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.

### Click Removal

Remove any clicks and pops from the recording using Effect > Click Removal - or using alternative third party software as discussed above.

## 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/or MP3 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 their 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. Invert 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. Clean up clicks and other random noise
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)

## Links

|< Tutorial - Copying tapes, LPs or minidiscs to CD

> See also tutorial on: Sample workflow for LP digitization

The following website: http://www.videointerchange.com/vintage_78s.htm gives a very detailed purist approach to capturing good quality transfers from 78s - well worth a read if you are serious about this subject.

Brian Davies offers a free "Equalization" program that that simultaneously applies the proper Inverse RIAA curve, corrected for the different playback speed, and a choice of 78 rpm EQ curve. See: http://www.clickrepair.net/

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