To make the DV 507 MKII compatible with a wide variety of
turntables, the overall length and height of the arm have both
been reduced compared to the earlier versions. The DV505 and
DV501 have enjoyed an excellent reputation in the European
audio market since being awarded the
Design and Engineering Award at C.E.S. Chicago in 1977,1982
and 1985.

The DV507MKII has important sonic improvements as well as being
easier to install and use. It includes all of the technology
of our tonearm design developed since the DV505 and 501.

"Bi-axis inertia separation" may
sound complex but it simply refers to a tone arm having two
arms which operate independently in the horizontal and vertical
planes. In contrast, a conventional tonearm has only one
arm which moves both horizontally and vertically. This is
called a gimbal type tonearm and the inertia for both planes
is the same.

The DV507 bi-axis tone arm has a large inertia
for horizontal movement and a very small inertia for vertical
movement. We shall now explain the reasons why this is advantageous.

It is well known that a cartridge generates
an audio signal by the differential motion between the cantilever
and the cartridge body. Consequently, if the supporting point
of the cartridge (the tonearm) vibrates, the tonearm motion
affects the audio signal.

In these conditions, the signal, which causes
the tonearm to vibrate is of low frequency and large amplitude.

In the currently used 45-45 stereo record cutting
procedure, low frequency signals are almost entirely recorded
in a horizontal direction. This means that the low frequency
signal, which can cause vibration in the tone arm, exists only
as a horizontal force.

The tonearm therefore must have sufficient effective
mass and rigidity in the horizontal plane in order to provide
a stable platform for the cartridge.

On the other hand, for the mid to high frequencies,
the effective mass of the tonearm should not be too large since
the combined mass of the cartridge and the head shell need
to be taken into account as well. In particular, where records
have a warped surface, the vertical effective mass needs to
be small enough to ensure a good tracking ability on such surfaces.

To summarise, the
tone arm should have a large effective mass and enough damping
in the horizontal plane and at the same time a small effective
mass in the vertical plane.

These conditions are almost impossible to achieve
with a tone arm of conventional design using a simple gimbal
pivoting system. To solve the problem,
Dynavector designed a bi-axis, inertia controlled tonearm where
the shorter and lightweight vertical sub arm is placed at the
end of the horizontal main arm. This is the special feature
of our design.

To illustrate how the system works in practice,
the following measurements will be of interest:

Cartridge behaviour with two different two different
types of tone arm was analysed when tracing warped discs. Fig.
1 is with a conventional tone arm and Fig. 2 with the DV507.

In these figures line A refers to the displacement
of the record surface and line B the behaviour of the cartridge
body. With a conventional tonearm, the displacement of the
cartridge is much larger than the actual warp on the disc.
At times the cantilever does not touch the record surface.

However, the DV507 shows a much better tracking
ability because of its low vertical inertia.

A non-contact, electro-magnetic damping mechanism
has been been designed to prevent sound distortion and poor
tracking performance arising from arm resonances induced by
low frequencies.

Neodymium magnet for eddy current dynamic damping

In this system, a curved rod attached to the
rear of the arm is mounted in a magnetic field supplied by
two powerful neodymium magnets. Any minute movement of the
rod, due to an undamped arm resonance, causes an eddy current
to be induced in the rod, which in turn interacts with the
magnetic field to return the system to its rest state.

As already demonstrated in our DV505 and
DV501 arms, this damping system is highly reliable as there
is no performance loss with extended use. Expensive Neodymium
magnets are employed because of their superior properties
and the thicker copper damping plate used gives a much better
damping action.

The tracking
force is applied by a precision spiral spring device.
This dynamic balance system maintains an unvarying tracking
force regardless of any record warp. Tracking force is
easily adjusted by turning a calibrated dial.

Dynamic Balance Tracking Force Mechanism

High precision, stainless steel bearings are
used in the sub arm. By having a long span bearing support,
the dynamic sensitivity has been further improved. The vertical
shaft to which the sub arm is attached has a smooth bearing
action, an important factor for the arm’s operation and sound
reproduction quality. Thus tracking ability has been significantly
improved and the bearing mechanism performance enhanced.

Dynamic Damper in the sub arm” src=”http://www.dynavector.com/products/images/507mk2_subarm.jpg” height=”188″ border=”0″ width=”250″ /> Dynamic Damper in the sub arm

Most tonearms have some frequency response
irregularity in the mid-low range at about 100-150Hz. This
is called multi-resonance or anti-resonance. To eliminate such
unwanted resonances, a dynamic damper has been installed in
the bottom of the sub arm. This solution was developed after
much theoretical consideration and experimentation.

A larger arm lift has been
provided to ensure ease of operation so that cartridges can
be raised and lowered without stress.The arm lift has also
been improved to provide long-term stability of performance.

To adjust the VTA (Vertical Tracking Angle of
the stylus to the record surface) more easily, a height adjusting
lever is provided. The height can be adjusted more precisely
than with other systems, within a range of 0 to 7mm.

The anti-skating force is set using a dial indicator.
The anti-skating force can be adjusted even while playing a
record.

a height adjusting lever is provided

the anti-skating force is set using a dial indicator