The DP75 Story
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The 70mm Newsletter
|Written by: Colin
image from the DP75 brochure, when it was launched during Photokina 1966
in Cologne, Germany.
DP70 the DP75 projector was a travesty''. This sentiment
has been widely held by many in the past and is maybe understandable
given the striking difference in appearance of the two machines, it is
however a view made perhaps without fully appreciating the design
process and engineering that makes a projector mechanism and why
economic considerations are taken into account when producing what is
essentially a specialised piece of equipment.
When a term such as 'specialised' is used to describe a piece of
equipment the cost of production becomes important if looking to produce
that item in numbers. The use of alternative materials and simplifying
of a design is the ongoing story of the industrial revolution and it
takes a company with vision to successfully achieve both - Philips was
More in 70mm reading:
Brand new complete DP75
70MM Projector for sale
Visiting 70MM Cinemas of
London's West End, September 1990
PDF: DP75 brochure
DP70 / Universal 70-35 / Norelco AAII -
The Todd-AO Projector
A Brief History of Philips
projecting "Hamlet" in 70mm at Kronborg Castle, Denmark 2013. Image by
The Dutch electronics company Philips was in the 1950s made up of
various manufacturing disciplines not all in the field of electronics -
for it should be remembered that until the latter part of the 20th
century most electronic devices required probably as many mechanical
parts as electronic components and where therefore electro-mechanical
The philosophy of the company had from its inception had been to
innovate in design and manufacture and was probably at this time the
foremost company in Europe if not the World in this field of research
and design, something they where to later to impress upon the world with
their consumer electronics products sold under the slogan of ''Simply
The history of the development of the World famous Philips DP70
projector is well documented elsewhere on this website but with the
foregoing statement it should be of no surprise that a design as radical
as the DP75 could also have been produced by the same company. Whilst
the DP70 is undisputedly the Rolls Royce of projectors, a masterpiece of
projection engineering, the design of the DP75 is probably more in line
with the radical spirit and philosophy of the Philips company generally,
but this is not to say it is better than its predecessor, only a
development there upon.
Placing its development in a broader context it is reasonable to imagine
that given the philosophy of the Philips company and its interest in the
development of cinema technology at that time, it for-saw a day when
reduced labour and costs in the projection room would be the norm and
designed its equipment with that future very much mind. Whilst their
short lived experiment in the use of pulse-lamps did not significantly
change cinema, the concept of using discharge lamps (Xenons),
transistorised modular amplifiers, platters (cake-stands) and automation
(Cinemation?) most certainly did, many of these ideas Philips where the
first to seriously exploit.
projecting Ultra Panavision 70 at the Schauburg, 2006. Projectionist
Vincent Koch checking the gate and the rubber bands. Image by Thomas
Undoubtedly the DP75 is a direct descendant of the Philips FP20
projector first designed in 1955 further developing ideas started with
this model to make it dual gauge and mechanically more compact. The FP20
was the first of the Philips designs to seriously look to reduce mass
and weight in its construction by using a fabricated welded steel box
cabinet and lamphouse beam so doing away with 80% of the heavy metal
castings used in traditional designs. At this stage however use was
still being made of individual precision units such as sprocket drives
and gate components - the gate being a 35mm derivative of the gate used
on the DP70 - mounted on the main body of the cabinet, units that
comprised several smaller individual parts that where costly to
produce. The sound head assembly whilst being opposite 'handed' on the
FP20 was a more 'standardised piece of design that was later used on the
DP75 with only slight re-working. Interestingly the whole of the rear
gear train of the FP20 was run open within the main cabinet without
continuous lubrication, use being made of a combination of OILING POINTS
and self lubricating materials such as nylon to reduce wear.
Whilst initially not sold in large numbers in England the FP20 was used
mainly in specialist applications, 'Circlorama' 1962-65 whilst strictly
speaking a 'roadshow' presentation used 15 X FP20s owing to their
relatively compact size, suitability to accommodate Xenon lamps and
ability to be easily adapted to run synchronised to one another.
70mm The Requirement
DP75 advert, October
By the early 1960s the Philips company where no-doubt aware that 70mm
was still the best card that cinema had to play when competing with
other forms of entertainment specifically television, and that Hollywood
still intended to invest in 70mm production.
Perhaps as importantly the emergence of the Italian
Cinemeccanica Victoria X dual 35/70mm projector in the late 1950s meant Philips now
had a rival to their flagship machine the DP70.
Having by this time proven that a 35mm projector could be successfully
designed along simpler lines and no doubt conscious of how costly the
DP70 was to produce, Philips management may have felt that if a dual
gauge machine could be produced for similar cost to a conventional
machine (and less than its Cinemeccanica rival) then cinema chains
around the world maybe interested in purchasing such a machine.
Presented as a 'cost-effective' solution to re-equipping it could be
marketed on the basis that 4 track stereo and 70mm big screen films could
now become available to a wider 'out-of town' audience and away from the
major city centre theatres, and being constructed to the new 'compact'
design would it was hoped lead to streamlining of future maintenance and
reduce costs in the long term.
DP75 The Design
ready for open-air "Hamlet" in 70mm at Kronborg Castle, Denmark 2013.
Image by Thomas Hauerslev
The DP70 is a machine engineered in the traditional manner, so for the
same design team to undertake design of a machine as radical as the DP75
would be to ask a world class classical composer to write a best selling
album for Iron Maiden!
In the DP75 then far from being a design to criticise let the observer
acknowledge the clear open minded thinking (today's blue sky thinking)
that must have backed the teams ability to fulfil its design brief,
knowing what could be re-worked, reshaped and generally pared down, free
thinking that was probably unmatched by any contemporary at the time.
In describing in more detail the design of this projector I impress upon
the reader that the same skill and engineering genius that made the DP70
projector what it was, was at work in the simplicity of design of the
DP75, for it is not crude but engineered with an elegant simplicity.
One might imagine therefore the production brief from which the design
team had to work, to read something like ''to design a dual gauge
35/70mm projector following the lines of the FP20, but more cost
effective to manufacture and maintain''
The genius of the resultant design lay in the fact that the whole of the
mechanism that formed the film path was re-assessed for what it did and
more importantly how it did it. Where multiple parts once made up
individual precision units independently attached, the whole mechanism
(excepting the soundheads) became contained within one easily detachable
semi-cylindrical oil filled compact main casting measuring little more
than 35cm x 7cm and attached by 6 caphead screws to the main steel
and DP70 side by side at the Plaza, London, around 1990. Image by Thomas
The reduced though robust gear train driving the main shafts still
maintained the reputation of Philips projectors for their excellent
smoothness of operation. As if on a mission to reduce or remove as many
machining operations during manufacture mating surfaces of components
were simplified and 'O' ring oil seals used extensively throughout.
Probably the piece-de-resistance was the hugely simplified method by
which 'Rack' adjustment is affected, by the use of a sliding bush to
change the relative position of one shaft - to which the intermittent
sprocket is attached - to the other, the driven shaft of the
This one idea is typical of how something previously complex was
radically rethought saving several machining operations in manufacture
and in this particular instance, the use of multiple precision gears.
The normally large solid gate block that one would have thought beyond
change was ruthlessly and completely re-designed taking away much
precision machining in metal to be replaced by lightweight alloys and
injection moulded plastics, everything it would seem that could be
pared-down but still retain its function was looked at and re-designed.
Where once many metal precision parts formed guides pads and other parts
of the gate assembly, use was made of ceramics and high impact plastics
to achieve the same result.
As with so much of the design, the cost of manufacture was in the
initial R & D and tooling to make each component, the resultant
component itself costing very little.
DP75 in Cinemas
The hope of interesting a cinema chain was realised in England with the
ABC chain of cinemas who backed by Associated British - Pathe' where by
the mid 1960s looking to replace their existing Ross projectors. The
opportunity presented by Philips with the DP75 model would be too good
to miss, for here would be an chance to re-equip many ABC cinemas with
new projectors with improved specification (i.e. 35mm stereo 4 track mag
as standard) AND have the bonus of being ready and capable of showing
70mm films for less than Ranks where re-equipping their theatres with
the dual gauge (though not fully spec'd) Cinemeccanica machines - see
With new transistorised amplifier racks to be supplied by Westrex
augmenting the package would give ABC cinemas a technological lead on
Rank, for again the concept of using modular units would (it was
believed ) mean less time lost due to break-downs and reduce time spent
on service call-outs. To complete the whole cost effective package it
was probably also envisaged that each theatre would change from using
carbon arc lamps to Xenons - why this eventually did not happen en-mass
may be that in this Philips underestimated the size of lamp that would
be required to fill a 70mm screen in the large halls that then existed (3,000 or 4,000 watt Xenon lamps where not then readily available),
alternatively this may have been one area where the management of ABC
felt they could save money by retaining their excellent and widely used
Peerless Magarcs arc lamphouses.
Note 1 - Whilst many Rank theatres where re-equipped with the dual gauge
Cinemechanica machines, many did not have the 70mm gates, lenses or
additional amplifiers required.
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