- Effective length: 233.15 mm
- Overhang: 17.8 mm
- Effective mass: 10.0 g / 11.0 g
- Weight: 720 g
- Unique one-piece pressure die-cast tone-arm utilising the
advantages of magnesium, replace conventional fabricated construction.
- Internal constrained layer damps minute residual vibration
leaving the tone-arm acoustically inert.
- Fine machined cartridge platform, enamel free to avoid interface
resonance.
- A Stainless steel cross shaft, ground and thread ground. Carried
in massive yoke on 10mm ABEC 7 ball races. Axis at record mean level to minimise
warp-wow.
- Dynamic balance graduated vertical tracking force (VTF) control
applies 0-3g x 0.125g through resonance controlled spring.
- Unique assembly gives high rigidity and allows bearings to be
critically adjusted before tone-arm is fitted.
- Stainless steel vertical shaft, ground and thread ground, with
integral 16mm diameter flange to couple shaft and yoke.
- 23mm diameter steel pillar, heat treated, ground and honed,
carries two 17mm ABEC 7 ball races, widely spaced to resist tilt.
- Anti-skate control operates through tension spring and filament.
Dial corresponds with VTF and has positive OFF position.
- Lowering/raising control gives smooth positive action. Height of
lift can be adjusted.
- Subsonic lateral mode fluid damper can be instantly adjusted or
cancelled.
- Dual-lock base provides movement control with high rigidity.
- Tungsten-alloy balance weight carried on damped two-point
suspension. Extra-low inertia design assists warp riding.
- Underslung weight housing corrects centre of gravity and
provides non-reflective tone-arm termination. Adjustment leadscrew journalled in
twin ball races with lever clamping.
- Swivelling damped output socket minimises vibration transmission
in sub-chassis use.
- Fine adjustment of arm height (VTA).
- Reference lines on tone-arm facilitate VTA setting.
- Fine adjustment of horizontal tracking angle (HTA).
- New design alignment protractor sets HTA with greater accuracy.
- Advanced jig/template system guarantees correct positioning.
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SME engineers, recognising the potential of the latest complementary equipment,
accepted the challenge to design and build a pick-up arm which unlike others in
existence would make no detectable sound contribution of its own. The work took
almost four years and the measure of its success is the acceptance of the Series
V precision pick-up arm by technical experts and users as one of the world's
truly great audio products.Series V sound has an almost startling dynamic range
and neutrality enabling high levels to be enjoyed. It escapes the 'LP' sound and
demonstrates that structural resonances in pick-up arms are responsible for much
that makes vinyl records readily discernible from master tapes.
The functioning of a pick-up arm appears simple but is in fact very complex. All
cartridges employ relative motion between armature and stator portions of a
generating system to produce the signal output. Reproduction can only be true
therefore when all movement representing groove modulation is made by the
armature to which the stylus cantilever is attached and none by the stator
represented by the cartridge body. Unless the pick-up arm holds the latter
against even the minutest movement at audio frequencies the signal will be
modified in some way. The result is a subtle loss of clarity, dynamic range and
transient attack that can make the sound from even the best system tiring to
listen to.
The following notes will help a better understanding of the problems and how
they were resolved in this radically new design.
In common with any mechanical device the behaviour of a pick-up arm is governed
by three properties of matter that also define the laws of motion. The first
property is mass which opposes any change in motion. The effective mass of an
arm and cartridge resists motion least at low frequencies but increasingly as
frequency rises. It is this resisting force which makes the operation of a
cartridge possible. At subsonic frequencies the armature and stator move as one
allowing the slow movements needed to negotiate the record surface without
generating a signal. At audio frequencies however the increased resisting force
causes the armature to move relative to the stator and a signal is produced. The
transition point between these two conditions is important for a clean low
frequency response and is established by the compliance of the cartridge and the
total effective mass of the arm and cartridge body. The second property is
stiffness which resists bending or flexing. It is a restoring force,
proportional to position or deflection.
The third property is damping or resistance to motion. Here motion means
velocity and without it there is no damping. The total equation of force acting
on a pick-up arm is therefore the sum of three parts: acceleration acting on the
mass, velocity acting on the internal or applied damping, and bending or
deflection acting on the stiffness.
Mass and stiffness determine how much a pick-up arm will flex and vibrate and
damping determines how long it will vibrate. Damping alone cannot prevent
flexing or vibration, it can only lessen its effect. The stiffer the arm the
less it will flex and vibrate; the more massive the less it will vibrate.
Very high tone arm mass would therefore be ideal to control the cartridge had it
not to be strictly limited to preserve the required relationship of compliance
and mass already referred to. Stiffness, the second part of the equation of
force, must therefore be used also. Infinite stiffness would be ideal but we
have to be more realistic. In a beam of given length stiffness is dependent on
the material used, its cross-sectional area and in the case of a cylindrical
beam increases as the cube of its diameter. Doubling the diameter will make it
eight times as stiff.
Although the proportions of the Series V tone-arm reflect these facts, tests
showed that the required stiffness was still unattainable using conventional
fabricated construction. A one-piece die-casting in magnesium alloy was
therefore adopted comprising the shell, tube and balance weight cantilever. 36%
lighter but only 25% less stiff than commonly used aluminium, a magnesium arm of
the same mass could be as much as 25% stiffer. In addition die-casting would
allow the numerous changes of section required to optimise effective mass and
control standing wave effects. Finally magnesium's high self-damping factor was
augmented with an internal constrained layer to damp the tubes’ high frequency
resonance.
The Series V's excellent vibration analysis results owe much to the high
stiffness and damping of its tone-arm, but stiffness to be of value must refer
to something rigid. Tests disclosed the many points at which rigidity could be
lost so all other principal parts were pressure die-cast allowing each to be
tailored precisely for its purpose and utilising the high mass of zinc-based
alloy to damp out vibration. Ultra-high quality 10mm and 17mm ABEC 7 radial
shielded bearings were selected to provide low friction vertical and lateral
movements, while holding the tone-arm motionless against front/back and
torsional forces. The support afforded by these large, wide contact angle
bearings, excludes the possibility of chatter and wear or damage in normal use.
The horizontal axis bearings carry the tone-arm in a substantial yoke also
housing a spring tracking force mechanism. The bearing axis is at record mean
level to minimise warp-wow effect and the spring, a possible source of
coloration, is resonance controlled.
The main pillar is 23mm diameter, machined from steel, heat treated, ground and
honed. It houses the vertical shaft and bearings, and carries the control
bracket incorporating the anti-skate mechanism, lowering/raising control and
motion damper.
The base is highly original. The pillar moves vertically between two jaws and
horizontally between two slideways. Locking is effected by transverse clamp
bolts, spring loaded to maintain settings when released. The design ensures
extremely positive clamping maintaining the rigidity of the assembly which is
then secured to the mounting surface of the deck with four cap-head screws.
The weight housing is undersung to correct its centre of gravity and provide a
vibrationally non-reflective termination of the tone-arm. A damped two-point
suspension carries the tungsten-alloy balance weight . Its unique shape enables
it to be positioned close to the fulcrum reducing inertia to minimise the
effects of record warp and eccentricity. Movement is made along mitre-ways by
rotating a thumb wheel and leadscrew carried in twin ball races. Only l9mm of
travel is required to cover the whole balance range and a lever effects clamping
in any position.
Electrical aspects received no less attention. The internal wiring is of
specially developed silver litz, each conductor having five insulated strands.
The damped output-socket swivels allowing it to take up its own position for
installation and to minimise vibration transmission when used on a sub-chassis.
The high quality linear crystal oxygen-free copper audio lead selected for its
electrical and mechanical characteristics is terminated at one end with SME
right-angle 5-pole DIN contra-plug and gold-plated phono plugs at the other.
The magnesium tone-arm is finished in satin black enamel, other major parts in
black chrome with details in bright chrome and polished stainless steel. Each
unit is complete with tools, accessories, and an advanced drill jig/template and
alignment system simplifying mounting and exact placing.
Structurally inert the Series V embodies every worthwhile feature in a pick-up
arm. As part of a complete system working in concert with a comparable turntable
and cartridge it will provide wide range transparent reproduction of vinyl
L.P's, bringing the listener audibly closer to the clarity and dynamics of the
original performance. |
