Recording 78 rpm records

Introduction

Notes for section:

• Ideally use a TT with 78rpm and adjustable speed - though can use lower speed dunbbing.
• Use a proper 78 stylus - see below - may need a separate headshell/cartridge.
• Clean your records.
• Audacity setup - use the default 32-bit 44.1kHz
• Processing to remove noise - and review results.
• Export to WAV/MP3 in the normal way.

Use a special Stylus for 78rpm records

Note that you should not use a normal stylus (needle) to play 78's. The grooves on a 78 are significantly larger than the grooves on an LP and the normal stylus will bottom out in the grooves. This will result in noisier transfers and could potentially damage your stylus. 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".

78s may hiss if you use the wrong stylus. The hiss comes when the narrow "long play" 33-1/3 stylus will rest on the floor of the 78 groove. The wider 78 stylus will rest on the vibrations in the wall of the groove which is much quieter and more accurate. You can only get a very bad approximation of the 78 music by using the wrong stylus. On loud passages, a narrower stylus designed for vinyl will bounce around the groove like shaking a penny in a tin cup.

Not only will you get a bad recording if you use the wrong stylus - you are also likely to damage your stylus and possibly the cartridge.

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).

Equalization

When recording 78 rpm's, there is a problem in that the pre-amplification (built into your pre-amp or USB turntable) is 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 equalisation" to it. This equalisation is essential when playing records made from the 1950s or later, as it cancels out the high frequency biased "RIAA recording equalisation" that such records are cut with, and so makes them sound normal again. The problem is that as 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 equalisation.

So, to make a fully professional job of transferring your 78 rpm records, you would be advised after recording to use Effect > Equalization in Audacity and draw and apply the inverse of the RIAA playback curve. See below

This will cancel out the unwanted RIAA equalisation then you can apply one of the 78 rpm playback curve presets that are supplied with the Audacity Equaliser effect. Note that these curves are generic and in practice many different equalisations were used according to the record label or even the recording engineer.

Inverse RIAA curve

Peter 26Feb10:I do not know how to actually load such a curve into Audacity.

• Can someone else (Bill?) with actual experience of handling 78 transciptions please help out here and explain to the user just what to do with this curve.

• Is there any sign of either the Inverse RIAA curve being supplied in Audacity as one of the EQ presets - or the curve inversion feature being implemented? Both of which were discussed a while back on the dev lists.

The following is a listing of an inverse RIAA curve that you can load into Audacity's EQcurves.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>

Lower speed dubbing - 33 1/3 or 45rpm

If your tuntable does not have the facility to play records at 78rpm, you van use Audacity's ability to cjhange 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.

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 - see 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).

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).

Note on actual speeds<p> 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 thay 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.

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. Normalize to around -1 dB with DC offset correction.
3. Then run a high pass filter to remove subsonic rumble - set the cut off frequency to suit the vintage of the record. For recordings from the 1940s or later set the cutoff frequence at 9K Hz or 10K Hz; for electrical recordings (1926 to 1939) about 8K Hz, and acoustic recordings (before 1926) about 7 K Hz. Use at least 12 dB per octave, 24 dB per octave would probably be better.
4. Then deal with the low frequency noise (rumble above our previous cut off frequency) - take a "noise sample" from the current audio track and copy it to a new track - Use the "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.

An alternative 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.

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