Dynavector DV-505 Tone arm Instruction
Manual
INDEX
Dynavector DV-505 tone arm has an
entirely new concept in tone arm design.
The DV-505 is a high performance tone
arm with various new functions that
make the cartridge in use work the best
way it can. The DV-505 user is requested
to please read through this brochure to
enjoy its niceties fully.
1. Foreword
2. Parts illustration
3. Pre use check points
4. Application(1)
5. Application(2)
6. Arm resonance
7. Two dampers
8. Specifications
1. Foreword
As is commonly known, a pickup cartridge generates electricity by cantilever motion relative to motion
of cartridge proper. While cantilever stylus precisely traces signals recorded in groove of disk, cartridge
proper receives those signals faithfully provided that it is held motionless (free of vibration). Hence, the
great role of a tone arm.
How should cartridge be held motionless without adverse effects on signal trackability? The DV-505
has solved this problem by adopting the unique (vertical/horizontal) Bi-axis system. The horizontally
movable main arm is of sufficient weight for vibration-free operation, and the adverse effect of weight
on signal trackability is nullified by use of an angular-radial compound bearing design. Conversely, the
vertically movable sub-arm is made so light that it never lets the stylus jump the groove of even a disk
with warp(s) previously unnegotiable.
Also, the DV-505 employs a double damper method -- inertia controlled dynamic damping type plus
electro-magnetic damping type -- to introduce an ideal solution to the problem of tone arm resonance in
low frequency range. This has generally been neglected about audio equipment that absolutely
requires a flat frequency characteristic.
2. Parts illustration
3. Pre use check points
The DV-505 leaves factory only after fine adjustment and meticulous check. But unexpectable
incidents in transit can possibly change its condition.
To use the DV-505 in its best condition, the user is requested to check the following points prior to
application:
Isn't damper plate in contact with magnet?
z
Pick up main arm and gently reciprocate it sideways.
If damper plate is free from bent (or distortion) and
clear of magnet, main arm can be thus moved
smoothly. Otherwise, metallic frictional sound occurs
and, as this motion is forced, it encounters growing
resistance. In such a case, confirm direction in which
damper plate is bent and apply finger pressure to put
it into right and straight shape. (This copper plate
can be deformed with ease. After its adjustment, it
must not be touched by hand or hit by foreign
object.)
Is inertia controlled dynamic damper
z
functioning?
Pick up main arm gently and look in from below.
Normally, damper weight is seen vibrating finely. If it
is in contact with arm's inner surface and is not so
vibrating, Loosen stopper and, with light downward
pull, refasten it, and/or straighten springboard.
4. Application (1)
Output cord fixing
As illustrated connect output cord connector (accessory
attachment) securely to output terminal plug below arm.
Even when this is complete, connector leaves plug
stem uncovered for 5mm, which is so designed to be
compatible also with other output cords sold generally
on the market.
Headshell/cartridge fixing
Fix cartridge to shell (for temporary purpose), insert
template between arm and shell, and lock shell. Then
where stylus points exactly at special mark on
template, fix cartridge securely to shell.
Do not remove template yet because it will also be
used, the way it is, for positioning arm.
(Stylus position so determined allows for template
thickness. When template is removed and shell finally
locked completely, stylus finds itself in right position.)
Base fixing to player board
The DV-505 can be fixed to player board simply by
nailing its unit base plate with four wood screws
provided to each unit.
Relax slide stopper and turn slide knob to lift main arm
to a height where cartridge stylus won't scratch
turntable. Then move arm base to where turntable
spindle smoothly fits in with spindle hole in template.
When spindle and hole so fit, and at the same time
main arm is situated right above arm rest, part of base
plate not overshadowed (overlapped) by turntable (see
illustration) is available for screw drive-through.
Base position so determined, drill convenient screw
holes in player board and fix base plate onto it with
wood screws (supplied).
* In case that player board has not insulator, or if the
user wants to set the DV-505 without fixing to player
board. Put the rubber sheet (supplied) under the base
plate. (At usual conditions of use, this is not
necessary.)
Arm height adjusting
With slide stopper relaxed, height of arm can be
adjusted by turning slide knob. But as arm slowly sinks
by itself when slide stopper is loosened, an easy way to
adjust arm height is, first lift arm to maximum height,
then let arm sink while holding stopper between fingers,
and finally fasten stopper just when arm comes down to
right place.
Arm must be just so high that sub arm may precisely
parallel record disk surface.
Arm balancing
Horizontal balancing
z
Main arm is designed to maintain itself always
level. But horizontal balancing is still necessary
to distribute bearing load evenly and thereby
realize best trackability. To achieve this balance,
shell and sub weight alone normally suffice. First
position sub weight A closest to the fore, or sub
weight B at white-color balancing point mark, and
then slide sub weight on scaled bar by one notch
backward per every 5g added to cartridge
weight. (In using any shell other than one
supplied, add to or deduct from cartridge weight
the difference in weight between these two
shells.)
Lateral balancing
z
If arm flows laterally to either side while inside
force canceller weight is suspended from zero
point or is removed from cartridge, slide lateral
balancer to either side to prevent arm from
flowing so. (Make sure beforehand that arm base
is set level.)
Tracking force adjusting
First set tracking force adjuster to zero point and
balance sub arm precisely level by sliding sub-weight to
right position. Sub arm so balanced, turn adjuster finger
screw to obtain necessary tracking force. Adjuster
scale is graduated by 0.25g and between graduation
marks, too, adjustment is done progressively in
proportion to adjuster screw advance.
Choose sub weight A or B according to guide table to
the left. Protruding in hole in sub weight is a pin to stop
sub weight from pivoting on scaled bar. Mount subÂweight onto bar with this pin pressed with screwdriver,
etc.
Inside force canceller
To suspend inside force canceller weight from weight
scale bar, do it exactly from graduation mark equal to
tracking force selected.
When the DV-505 tone arm is moved up (and down)
before and after record playing, main arm as a whole is
designed to be elevated. But user is requested not to
lift it excessively or with abrupt force.
5. Application (2)
Player equipped with cover
Player may have its cover. Because the DV-505 output service
cord is not led out through player board, cover won't close
neatly.
In such a case, make a hole (21mm - 25mm in diameter) at a
convenient place in player board, fit accessory bushing to hole
so made, and run output cord through it.
Arm base posture adjusting
In case that player board fails to provide sufficient space for
arm base, loosen screws on backside of base and change
direction of arm stand.
To carry DV-505 around
Stand top cover is screwed into stand. Replace it with
accessory carrying handle.
The DV-505 unit can then be carried around as illustrated.
To replace output terminal
Cord connector can be removed in the following manner,
either for replacement with another kind of connector or for
complete removal to eliminate needless contact resistance:
1. Link connector of accessory output service cord to
output plug;
2. Remove fastener screw (with screwdriver);
3. Pull cord gently, and output terminal is removed from
cord ;
4. Wiring colors mean:
red -Right channel hot
white -Left channel hot
green -Right channel ground
blue -Left channel ground
(Fastener screw also serves as unit connection to
earth.)
6. Arm resonance in low frequency range
Illustration shows spring in suspension from overhang
and weight slung from it. When pulled down and then
released, spring weight combination will reciprocate
longitudinally at a certain frequency. This is generally
called spring mass oscillation system. Oscillation of
two units of mass at a common fixed frequency is
called resonance. This frequency ('f') Is mathematically
expressed
Where 'c' is system compliance in cm/dyne and 'm'
stands for mass of system.
Similar phenomenon is observed in arm-cartridge
assembly as it reproduces sound from record disk.
Graphically, cartridge compliance may be likened to
spring, and arm pivot to weight.
This is what is called arm resonance in low frequency
area, and there are as many resonance sources as
there are pivoting gadgets in tone arm.
At such a frequency of resonance arm becomes very
sensitive to vibration and, even when frequencies of
'flat' characteristics are reproduced from record, arm
resonance causes larger output than true to record or
'peak' phases (See diagram 3). At frequencies higher
than arm resonance, arm does not so vibrate at all,
and cantilever oscillation alone translates into output.
But at frequencies lower than that, cantilever and arm
oscillate together and fail to generate electricity. This is
why arm resonance frequency 'fo' is called low sound
reproduction margin.
With conventional type tone arms vertical and horizontal pivots are placed in close proximity. This
causes these two resonance sources to vibrate at the same frequency, as if vibrating as a unit. Peaks
then become larger and so much harder to damp.
The Bi-axis type DV-505 separates one pivot remotely
from the other. It thus encounters two peaks
simultaneously, but each peak is smaller than the two
put together, and horizontal resonance peak is
effectively cut by a couple of unique dampers (See
diagram 4), for the following reason :
So-called '45-45' record groove cutting method which is presently in use, does horizontal cutting at
same phases of input signal and vertical cutting at inverse phases. Because sub-100Hz wave lengths
elongate for more than several meters, stereo recording of low sounds produces, almost
comprehensively, same phase signals for both right- and left-hand side channels and, naturally,
signals for horizontal cutting come excessively to the fore. Then considering disk structure, it Is not
possible to impress on it deep-going low frequency signals.
The DV-505 has solved just that. By reducing peaks over all, it adds to low frequency area stability.
Also, it faithfully tracks surfaces so warped that no other tone arms could negotiate well, and thereby
limits effect of such warped disks on sound reproduction. The DV-505 an out performer.
7. Two dampers
As explained in part 7, DV-505 employs two kinds of damper- - electro magnetic and inertia-controlled
type.
electro magnetic damper
z
This damper applies effect of eddy current, which is generated when conductor moves in
magnetic field, and which obstructs conductor in motion. It has almost no damping effect on
motion of non-vibrating tone arm, but is highly effective to vibration of arm, such as arm
resonance.
Inertia controlled dynamic damper
z
This damper, incorporated into main arm, consists of a pair of spring and mass, each of these
constituents having a carefully selected constant. This spring mass oscillation system oscillates
only horizontally as main arm resonance occurs, and causes resonance peak to dip.
Phase lag in one oscillation system relative to another is effectively applied in this damper,
which functions only in response to arm resonance.
8. Specifications
System Bi-axls inertia controlled dynamic balance type tone arm
Total length 335mm (including shell)
Effective length 241 mm
Overhang 15mm
Offset angle 21.5 degree
Height 72mm (liftable to max. 94mm )
Height adjustability 37-70mm (at sub arm center)
Optimum cartridge weight 0 - 23grams (or up to 35g including headshell)
Tracklng force adjustability 0 - 3grams by 0.25grams step
Lateral tracking angle error -1.1 degree to +2.2 degree
(0 degree at inner band of record disk, 2.2 degree at outside)
Motion sensitivity Lateral -- less than 50mgrams
Vertical -- less than 50mgrams
Net weight 1,250 grams
Output connector 5P connector with low resistance cord 0.025ohms/m , 37pF/m
Head connector: EIA standards
Head shell Aluminum headshell
Copyright (C) 2001 Dynavector Systems, Ltd. All Rights Reserved.
(December/3/2001)
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