Reproduction of 78s: technical notes

Technical Notes Index

Introduction
Basic turntable
Styli
Stylus tracking
Speeds
Equalization
A preamplifier circuit for equalization
Using a computer for equalization
The reason for equalization
Surface noise
Demonstration of 78rpm transfers in mp3
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INTRODUCTION

        It is now forty years since 78 rpm records were discontinued and it is becoming increasingly difficult to find equipment to play them. Most hi-fi turntables don't even run at 78rpm, and few cartridges are obtainable with suitable styli. Even if you can get hold of a player, none of the readily available equipment addresses the four major difficulties: stylus size and shape, speed,equalization, and surface noise. This article gives brief notes on each aspect. I have provided some demonstration transfers in mp3.

BASIC TURNTABLE

       It is now quite difficult to find turntables capable of playing 78s at all, let alone the more specialized ones needed to do the job properly. If you just want one which will run at 78rpm without the speed variations a good bet would be the Pro-ject Debut, available from Henley Designs Ltd . The basic 33/45 turntable with arm and cartridge costs £215, and there is an optional additional kit for playing 78s costing £20 (the turntable is belt driven and the kit gives you an extra pulley). Rega also make a 78rpm turntable.

       An American correspondent tells me: 'Many DJ turntables have 78 on them - or at least they have an Add-Speed feature meaning if you push 33 and 45 together at the same time they add and become 78. Most Technics or Stanton DJ turntables of recent vintage will do the job. As far as cartridges, we use Stanton 500's on the studio lots here in Hollywood. They are the only readily available cartridge we know that has an equally-readily-available 78-RPM stylus (3 mil).'

 

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STYLI

        At the time the format disappeared the recommended stylus size was 2.5 thousandths of an inch conical tip. This would be satisfactory for records made in the final few years, but for the great majority of the time since the beginning of 78s in 1896 the grooves were wider than the 'standard', with the result that a 2.5 thou stylus skates about in the bottom of the groove, seriously increasing the surface noise.

        (I have written a separate note on stylus tracking with illustrations.)

        The simplest solution is a 3 thou. conical stylus. This will play older records quite well, although end-of-side distortion is quite apparent; but it doesn't cope well with latter-day pop records, particularly since these are usually recorded at a very high level.

       I have obtained the best results with a truncated elliptical tip having a major radius of 2.8 thou. The narrower minor radius enables the stylus to track the grooves with much less distortion, while the major radius allows the contact points to be well up the groove walls away from the muck in the bottom.

       In order to obtain one you will have to find a firm who can cement a specially made tip onto an existing cartridge. This can come a bit expensive, but since a modern cartridge tracks the records at an extremely light weight, the wear is almost non-existent and the stylus should last for a very long time.

       For readers in the U.K., I can recommend The Expert Stylus Company (who have also taken over re-tipping work from 'The Cartridge Man' who offer ready-made stereo cartridges but no longer do re-tipping):

The Expert Stylus Company
PO Box 3
Ashtead
Surrey
KT21 2QD
England
Telephone +44 (0) 13 7227 6604
Fax +44 (0) 13 7227 6147

       Musonic offer a large range of styli and cartridges, which they can equip with 78rpm stylus tips on request:

Musonic (UK) Limited
271B Wenta Business Centre
Colne Way
Watford
Hertsfordshire
WD24 7ND
 
Tel: 020 8950 5151
Fax: 020 8950 5391
E-mail: sales@musonic.co.uk
Web: http://www.musonic.co.uk

       Readers in the USA could try these addresses:

WEST TECH SERVICES
Box 130
Prospect, TN
USA 38477
Tel: 888-828-8455.
 
Yesterday Once Again.
Antique phonographs.
P.O Box 6773
Huntington Beach, CA
92615
Tel: 714-963-2474
 
KAB
P.O.Box 2922
Plainfield, NJ 07062-0922
Tel: 908-754-1479
Fax: 908-222-3442
Web: http://www.kabusa.com
 

Antipodeans (and indeed anyone else - they supply worldwide) could try:

Styli
P.O Box 90 439
A.M.S.C.
Auckland
New Zealand
Tel: +64 9 820 6525
Web: http://www.styli.co.nz/
Email: info@styli.co.nz
 

Also see Esoteric Sound - details at the bottom of this page.

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SPEEDS

        By no means all 78s were actually recorded at 78 rpm. Even in the late 1920s English Columbia was still using 80 rpm, and prior to about 1921 speeds were widely variable. Some of the audio tracks included in the Music hall section of this site were transferred at speeds as low as 74 rpm, and I have come across records where the speed was as low as 68 or as high as 84 rpm.

        To make matters worse, relatively few records state the speed (and when they do it's not always accurate). If the work is a classical piece such as an opera aria, it is possible to check the correct pitch against a score or a modern recording: but as occasionally singers would transpose, this isn't completely reliable. My best recommendation is to gradually reduce the speed of a record until it starts to sound sluggish, and then increase it slightly (in my experience the ear is much more sensitive to low speeds than high speeds). I'm afraid it's all rather rule of thumb: and the narrow bandwidth of old records doesn't make it any easier.

        As to a turntable capable of coping with these speeds, that is yet another problem. Few turntables have more than a tiny variation (usually 2 or 3 per cent, which is nowhere near enough); but electronically controlled turntables may be modifiable. You need a speed range of 72 to 82 to cover most records. I'm using a Goldring-Lenco turntable which has a mechanical system for continuously varying the speed from about 32 to about 84 rpm, but it's not available any more - indeed I have had mine since 1963!. (For anyone who needs Goldring -Lenco spares I have given an address on another page).

 

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EQUALIZATION

        (I have written a separate technical explanation of the reason for equalization)

        As with the styli, the 'standard' reproduction curve was set in the mid-1950s, and is wrong for most of the history of 78s! Using tone controls doesn't really get it right because they don't reach the middle of the frequency range. I list here the principal curves for 78s, and, since I have them available, those for early LPs before RIAA(CCIR) became the standard.

        The curves follow much the same pattern: a treble cut above a specified frequency; a bass boost below another frequency, and sometimes a flattening of the extreme bass. Early electrical 78s have a flat upper frequency response. Note that these are the reproduction curves: the recording curves would of course have been the inverse (allowing for losses in the head mechanism, etc.).

        I have provided a preamplifier circuit with the following curves:

COARSE GROOVE ('78 rpm')

SYSTEM

Treble turnover

Bass turnover

Lower bass t/o

Cut at 10 kHz

Boost at 50 hz

DECCA 78

3.4 kHz

150 Hz

-

9 dB

11 dB

ffrr 78

6.36 kHz

300 Hz*

40 Hz

5 dB

13 dB

WESTREX

flat

200 Hz**

-

-

15 db

BLUMLEIN

flat

250 Hz

50 Hz

-

12 dB

BSI 78

3.18 kHz

353 Hz

50 hz

10.5 dB

14 dB

MICROGROOVE (lps and 45 rpm)

SYSTEM

Treble turnover

Bass Turnover

Lower bass t/o

Cut at 10 kHz

Boost at 50 hz

RIAA (CCIR)

2.1215 kHz

500.5 Hz

50.5 Hz

13.6 dB

17 dB

ffrr LP

3 kHz

500 Hz

100 hz

10.5 dB

12.5 dB

EMI LP

2.5 kHz

500 Hz

70 Hz

12 dB

14.5 dB

NARTB

1.6 kHz

500 Hz`

-

16 dB

16 dB

COLUMBIA

1590 Hz

500 Hz

100 Hz

16 dB

12.5 dB


       *I originally had 250Hz here which I had understood to be correct: but information which has recently come to light suggest that 300 may be correct. In practical use the difference is fairly minimal, about 1dB.

       **200Hz was the original specification, but later recordings may have a higher value of 300Hz, or possibly even 500Hz.

        Jørgen Vad manufactures a preamplifier which provides equalization curves: details from his web site.

        Millennia Music and Media Systems make a preamplifier with the ability to configure many equalizations: their manual lists (on page 13) equalization details of many old labels.

        Not many people have suitable preamplifiers: it is possible to transfer 78s using the usual RIAA equalization for LPs and then convert. Equalizer by Brian Davies is free and will convert RIAA or flat (unequalized) to a number of other equalizations. If you have transferred a 78 at a lower speed and then speeded it up in an audio editor it will also adjust the equalization to suit. Prior to this being available I worked out some figures, and I have left them posted here in case anyone wants to experiment with them.

        RIAA (CCIR is identical) is the current standard for all microgroove records,ffrr LP for pre-1955 English Decca LPs, EMI LP for pre-1955 HMV and English Columbia LPs, COLUMBIA for older American Columbia LPs, NARTB for some early American labels.

        78s: WESTREX (English Western Electric) for HMV 78s with triangle matrix code and English Columbias with a matrix code. BLUMLEIN for HMVs with a square by the matrix number, and English Columbias with a , or in both cases with no code (post 1945) up to about 1953. BSI 78 for all post 1953 78s (in theory). HMVs withare American Victor recordings: use WESTREX.

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SURFACE NOISE

        So, you've got the right stylus, the right speed, and the right equalization, and you play the record. It should sound fine, but there is still one problem - surface noise, always the great bugbear of 78s. There are three principal causes:

Earlier records had an abrasive filler added to the shellac mix from which they were made, with the idea of grinding down the steel or fibre (cactus thorn) needles to fit the groove shape

Wear and damage - steel needles were very hard on the groove and a badly worn record could look quite grey. Add scratches or even splits to that and you can have a major problem.

Granulation: some makes of records - inter-war HMVs are particularly bad - are prone to bacterial attack from bacteria living in the cardboard sleeves (particularly if they get damp) which causes the shellac to harden in little granules and increase the noise, even on a mint record.

        What can you do about it? Firstly, try to get a good copy! - easier said than done. In the case of HMVs, you will get better results from Indian or Australian pressings than British ones. Some makes are markedly better - British Columbias are usually very good, using a finer filler to reduce the noise (or at least move it up in frequency where it is less of a problem). If you find an inter-war HMV which hasn't granulated, keep it dry, preferably in a polythene sleeve.

        After that, you have only three choices:

Ignore the surface noise. That is what I do - you get used to it if it isn't too horrendous, but I am aware that for many people this is difficult. Incidentally if you are dubbing to cassette, you have to reduce the surface noise, because the tape simply won't cope with the very high levels at high frequencies (another equalization problem).

Filter it - reduce the top, preferably with a fairly steep cut filter rather than an ordinary tone control. I use a filter circuit reverse-engineered from a Quad 33 preamplifier, which provides separate adjustment of turnover frequency and slope, and is very flexible. Something along these lines is very useful if you can find it. Most LP or CD issues of 78s, at least until recently, filter records heavily, thus removing a good deal of the life from the recording together with the surface noise; what is needed is a compromise. Ideally use as little filtering as you can stand.

Noise reduction: until recently this involved extremely expensive hardware or software, of which Cedar is the industry leader - costing some thousands of pounds. The older Packburn (still available) is an analogue device which in effect compares the two groove walls moment by moment and chooses the quieter. Subsequently digital processing systems became available. The Cedar system applies digital processing to the signal, analyzing it to decide which is signal and which is noise. Carefully set up it can produce quite stunning results - the noise almost disappears, even on alarmingly noisy originals.

Now, however, much cheaper software is available. I would particularly recommend ClickRepair ($40) and Denoise ($40) by Brian Davies: using these two in that order can produce very impressive results on noisy 78s (I've used it on most of the records on my podcast) and the price is very affordable. They both work on Macs and Windows.

        In the unlikely event that I have any rich readers, here is the contact addresses for Packburn, and for Cedar Audio, which produces standalone units and also computer programs running under Windows for the removal of crackle, clicks, hiss and azimuth errors.

Packburn Electronics, Inc.
P.O. Box 226
Syracuse
NY 13215
Email: Tom@PackburnElectronics.com

Cedar Audio Ltd.
9 Clifton Court
Cambridge
CB1 4BN, UK
Tel.: +44 1223 414117
Fax: +44 1223 414118
Email: sales@cedar-audio.com
WWW: http://www.cedar-audio.com
 
Cedar Audio USA
43 Deerfield Road
Portland, Maine
ME04101-1805, USA
Tel.: +1 207 828 0024
Fax: +1 207 773 2422
Email: cedar-audio@gwi.net

 

        KAB Electro-Acoustics produces their own noise reducer which is much cheaper than the Packburn and claims greater effectiveness, the KAB Souvenir USP+; they also sell a range of styli, turntables and audio enhancement products.

K-A-B
KAB Electro - Acoustics
P.O. Box 2922
Plainfield, NJ 07062, USA
+1 908 754-1479
E-mail info@kabusa.com

 

        The Windows program Adobe Audition has a noise reduction module which I have been told is good, but I have had no experience of it,

        There is more information on old records at the WOLVERINE ANTIQUE MUSIC SOCIETY, including addresses of some American manufacturers of variable speed turntables and other goodies.

The American firm Esoteric Sound sells turntables, cartridges and styli for 78rpm, electronics and software for dealing with archive recordings, and vintage records, and can do transfers and restoration of old recordings.

ESOTERIC SOUND
1608 Hemstock Avenue
Wheaton, Illinois 60189 (U.S.A.) 
Telephone & Fax: (630)-933-9801
http://www.esotericsound.com
Email EsotericTT@aol.com
 

If you need help in transferring 78s into your computer (for burning to CD for example) BlazeAudio have a tutorial which walks you through the stages. It is based round their own program (for Windows) but the general principles are applicable to any system.

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