Nad 5120 Owners Manual 3

Page 1

5120
DVA TUNING DATA FOR POPULAR CARTRIDGES

The table (page 2! lists many at the phone pickup cartridges on the world market.
wiln telerence data tor tuning the DVA (dynamic vibration absorber) in the llexible
MAD tonearm. This table will be updated periodically as more inlormstion is obtained
lot existing cartridge models. and as manuiactures introduce new pickup cartridges.

For each cartridge the table provides suggested settings oi the resonance frequency
(Fr) and the damping (0) ol the dynamic vibration absorber These have been
computed using the nominal values at pickup body weight (Mp) and stylus
compliance (Cs) listed in the table.

it your cartridge is listed in the table. the suggested DVA settings will provide very
nearly optimum penormance with the unique llexible NAD toneartnlt is not necessary
to be very exacting when making the adjustments: a variation oi 32 Hz in resonance
irequency (Fr) or :1 in the damping value to) will yield only a smell dilierence in
system perlormance

The suggested values in the table are only approximate. because various samples or
the same cartridge model may dilrer slightly in compliance For this reason the
resonance lrequoncy may vary by one or two Hz lrem sample to sample. It you wish to
obtain exactly optimum DVA tuning tor your particular cartridge. you may use the
NAD test record to determine the resonance irequency by direct experiment as
described in Appendix a pimp instruction manual tor the NAD 5120 turntable.

If your cartridge is not listed in the table. you may try any or the lollowing
approaches ior tuning the DVA'

(1) Adopt median settings lFr=10 Hz and 0er Even il these are not optimum, they
will provide better perlorrnance than a lonoarrn that lacks the DVA feature.

12) Contact your NAD dealer to discover whether there may be an updated version
oi this table that contains suggested DVA settings lor your cartridge.

(3) Use the graphs below to determine approximate settings oi lhe resonance
lrequency and damping

(4) Obtain the NAD test record and determine the optimum DVA settings by direct
experiment.

USING THE GRAPHS

ii the cartridge weight (Mp) and the stylus compliance (Cs) are known. the resonant
lreguency (Fr) can be Computed, This relutionahip ll lhown in the first graph. To use
the graph. first locat! the net weight 01 the cartridge body on the horizontal lxia. From
thlt point draw a vertical lino upward until I! intersects the curve that represents 111.
compliance (Cs) 011719 stylus assembly. From there. draw I horizontal line in the left
until it internects the resonance lrdlzuellcy (Fr) scale along the lett edge or the graph.
The graph illustrates this process lot a cartridge having a weight or 5.7 grams and a
compliance or 20; the resulting resonlnce lrequency is 9.5 Hz.

You need to know Mp and CI in order to use this grlph. The weight at the cartridge
body usually is included among the specifications at lhl pickup cartridge. or it can be

measured directly. The dynamic complldnce usullly is not specified (ll lt is specified. '

it may have been measured at mld-lrequencies; the compliance at infrasohic
lrequencies may only be two-thirds at the specified value ) The low

trequency compliunce is sometlmes given in ltst reports. not-bly in Hi-Fl Choice"
(England) and Hi-Fl Sleraoohonie" (Germlny).

In any case, the VTF provides an approximate guide to the compliance It the
Optimum VTF is Over 2 grlml the compliance ii likely to be relatively low (araund 12)
it the correct VTF is approxima ly l.6 grants. the cartridge probably has a medium
compliance (Around 20). H the VTF is only 12 grams, the compliance is hlgh (above

RESONANCE FREQUENCY (Fr)

us Go PLIANCE

L FR 0U VS

14
13
12
11
10 (Fr=9
9

8
7
G

RESONANCE FREQUENCY F,[Hl]

F ,5. I)

23456159101112

0 1
PHONO CARTRIDGE MASS up (GRAMS)

30]. Using these estlmntes you can use the graph to compute Fr, Though only
approximate. the resull will be accurate enough (within tZHz) to obtain must 01 the
benelli ol the DVA.

Damping. The second graph provides a means oi estimlting the optimum setting at
the damping rod. To uselt.ll'§1fl015 your cartridge weight. Subtract the VTF that you
are using. and locate the relulting number on the horlxontgl alt-a oi the graph. Draw a
vertical line upwlrd lrorn there until it intersects the curve thll represent: the
resonance lrequency that you hove tuned the DVA to. From thlt point. drnw a
horizontal line to the Ialt until it intersects the damping scale along the Ielt edge of the
graph

The graph illustrates the process tor a cartridge thlt weighs 5.7 grams and is used
with I VTF 01 2.0 gums. The vertical lino ts drawn It 3.7 grunts. The rcmnlnce
lraquency was determined (in the lust graph, or by direct m auremant using the NAB
lest record) to be 9.5 Hz. so We draw the line up to the 10 H1 curve In the quph.
Looking to the lelt. this corresponds to a damping vulne(0l013.

As mentlondd earlier, the calculated Value at Q is the tot-l dlmping desired tor the
entire Vibrating system. Some damping may be provided in the cartridge. so you will
alien tlnd that the best setting at Q on the DVA is about and grade lower thln the
computed value.

CONTENTS OF THE TABLE

MODEL Llsted In alphabetical order by manulucluror

TYPE MM = moving magnet (and rel-led types, such as induced magnet. moving iron,
or variable relucinncu).
MCH : moving CDII with high output. intended tor Connectlon to I conventlonal
MM phone input.
MCL : moving coil with low output voltage. to be used with a step-up tranalormer.
ore-preamp. or high-gain MC nhono input
ELEC = electret

9 The axial distance item the stylus tip to the mounting screws. in mtllimeters it no
value is listed. you may measure it yoursell 11 P ls equal to 9 5mm. the cartridge
should be mounted with the screws located midway In the slots is: indicated by
the while dotsl

vrr vertical Tracking Force. in grams. (For milliNewtons. multiply by to. l 5 g = l5mN l
A nominal. or med-an setting ol the Mr is given a slightly higher value may be
required for secure tracking oi the highest modulation levels in recordings

Up The mass. or net weight or the cartridge. in grams

CI The dynlmtc compllance 01 the stylus assembly, measured II ihiruaonlc
irequencies [around to H1)
F! The resonant trouncncy 01 the arm/cartridge system. computed "cm the listed

values or Mp and Cs ll the value is lower than 7 Hz you may remove the white
tuning screw entirely

a The damping grade. on a scale train a (no viscous dampingito 3v (mlxlmum
damping. with the damping rod inserted iully into the tluid), The listed value is the
recommended total d mping tor the vibrating system including any damping
provided within the clrtrldge, Many cartridges have some internal cantilever
damping (and Shure models are equipped with a damping brushl. so you may rind
that optimum perlormance is obtained by using a lower value or 0 than that listed

DAMPING (0)

01234507891011
Mp-VTF (GRAMS)