dk nkf - Nordisk Konservatorforbund Danmark

Pickups (and cutterheads) are very delicate
electromechanical mechanisms that need the care of
delicate scientific instruments. They have moving
parts and supports and dampers made in rubberlike
compounds that originally had very specific
mechanical and rheological qualities.
Machines (i.e. gramophones) are clockwork driven
(wind-up) (1897-1960) or with an electromotor
(in most cases a universal AC/DC motor) (1921-
1950), both types using a centrifugal governor.
From ca.1950 an asynchronous motor or transistorcontrolled
low-voltage motor was used. All machines
must be correctly lubricated to run. Modern motors
have sintered bronze bearings with permanent
lubrication (however, I recommend a minute drop of
molybdenum disulphide suspension). Drive belts and
rubber idler wheels are prone to deterioration[5,11].
The clockwork uses just one spring in a barrel
or several barrels in series. Each spring is tightly
compressed inside its barrel (danger!) and lubricated
with graphite-loaded grease. A gear train increases
the speed to the ca. 78 rpm needed for the record
and the ca. 1000 rpm needed for the governor. The
whole gear train must be well lubricated as must the
leather pad for the adjustable centrifugal governor.
All weights for the governor must be present and
the carrying springs must not be broken[10].
The universal electromotor uses a helical gear to
obtain the gear ratio, and the adjustable centrifugal
governor is fitted to the main motor shaft, because
it already has a sufficient rpm. Everything has to be
well lubricated, and the carbon brushes have to fit
and not be worn down. The voltage for the motor
must be correct. Humidity may have corroded
bearings and broken down the insulation (danger!).
Reflections on the record as
document and it place in the
system.
Modern users of the records have to take several
aspects into consideration: one is the physical
restoration of original record and original equipment
in order that the two may meet to generate a
sound that is close to the sound at the time these
industrial items were modern. Will this generate an
authentic sound? What will it be used for? Several
sophisticated modern methods of reproduction
exist, and they all break the system and they give
different sounds. Should the characteristics of the
original reproducing equipment be simulated in the
modern equipment?[14]
Author
George Brock-Nannestad
Patent Tactics
Resedavej 40
DK-2820 Gentofte
pattac@image.dk
Notes and references:
[1] Henry Seymour: The Reproduction Of
Sound. Being a description of the Mechanical
Appliances and Technical Processes employed
in the art, London: W.B. Tattersall Ltd. n.d.
[1918]
(this was the semi-professonal handbook of the
first, acoustic period, dealing with everything
regarding recording, including cylinders)
[2] H. Courtney-Bryson: The Gramophone
Record, London: Ernest Benn Limited 1935
(this was the industry handbook of the
1930s, dealing with everything concerned
with records, but not the mechanics of
gramophones)
[3] P.G.A.H. Voigt: Getting the Best from
Records. Part IV: The Record Has the Last
Word, Wireless World, Vol. 46, No. 7, pp. 242-
245 (May 1940)
(a very thoughtful discussion - in the words
of a shellac record - relating to a number
of record manufacturing and reproduction
fundamentals)
[4] Emil R. Riegel: Chemical Machinery. An
elementary treatise on equipment for the
process industries, New York: Reinhold
Publishing Corporation 1944
(a very good introduction to the type of
equipment that was used in the period of
interest)
[5] Harry Mileaf: Servicing Record Changers,
Slough: Foulsham-Tab Limited 1973
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