an extended popular music
confirmed requirement for a
more economically fulfilled
version have been under consideration.
desk to the original specification may
by a model from the new Radio series.
A
be
300mm Diameter Drive Unit (LS2/l)
Work continues
Department to
forming the
and tested on
on producing the mandrels, jigs and moulds for Equipment
commence
quantity
production.
The
vacuum
moulds for
bextrene cones and p.v.c. surrounds have been adapted to,
the new vacuum forming machine at Avenue House.
In order to achieve higher temperature voice coil working, and hence a
higher power drive unit, new former materials and new adhesives have
been assessed.
General Loudspeaker Production
The maintenance of current loudspeaker designs in production, whether at
Equipment Department or, in the case of the miniature O.B. loudspeaker,
at licensees, continues to form a sizable part of the Section's work on
loudspeakers. The variability of drive units and the uncertain supply
of construction materials cause frequent liaison and investigative work.
Noise Measurement to Recommendation 468 (ME8/l)
New international recommendations on noise measurement specify the use
of a wider-band weighting network and different characteristics for the
measuring device. Both aim to provide more satisfactory agreement with
subjective assessments. The new weighting network was introduced into
general BBC use in January 1977 and all the A.C. Test Sets in use are
suitably equipped.
Because of
Test Sets
circuit
suitable
response
the continuity discussions on measuring characteristics, the
have been issued without the specific noise measurement
although
the traditional
T.P.M.
method
is
included.
A
measurement circuit which conforms to the recommended impulse
characteristic is now ready for trials.
Telephone Effects Generator for Television Studios (UN4/5P)
The revised generator which meets
requirements arising from the more
extensive use of post-production
editing is undergoing field trials
and manufacture of a pre-production
batch has started.
Regional Radio Continuities
With the proposed expansion of the
national regional network operation,
including much local origination,
work has started in conjunction with
SCPD to design production continuity
suites for installation at Glasgow,
Cardiff
and
Belfast.
The
design
will also be used to increase the number of suites in Broadcasting
House, London. Installation of the first suite is planned for 1979.
- 10 -
Po~tabZe TeZephone Effects
cJene~ato~ fo~ use in TV Studios

18