For best performance, the tonearm and cartridge must be
matched. All cartridges will not work with all tonearms,
and vice versa. To insure a proper match, one must be aware
of the mechanical specifications of both the arm and phono
cartridge. To see how these characteristics interact and
determine compatibility, we must first understand the dynamics
of the relationship.
Any cartridge/tonearm combination will exhibit resonance
at a specific frequency (or frequencies). This resonance
is due to the interaction of the cartridge (acting as a
spring), and the weight of the arm (acting as a mass). The
"springiness" of the phono cartridge is described
as compliance, the weight of the arm is specified
in mass. As an example, a heavy weight on a light
spring would obviously over-flex the spring, conversely,
a light weight on a strong spring would not allow sufficient
At resonance, the arm/cartridge combination produces a
dramatic rise in output. An increase of 3 to 6dB or more
is common. This tremendous boost can cause severe problems
if it occurs in the region of recorded music (above 2OHz),
or in the area where record warps and rumble are problematic
(below 5Hz). A cartridge/arm whose resonance occurs in the
region above 2OHz can be influenced by music on the record.
At this frequency a significant jump in output (resulting
in a "bloated" or "tubby" sound) will
be experienced. In extreme cases, the stylus may actually
jump out of the groove. Similarly, a cartridge/arm combination
that exhibits a resonance below the desired range will exaggerate
the effects of record warps, or rumble produced by the turntable.
The goal in matching a specific cartridge and arm is to
achieve a resonance in the 10 to 14Hz range. Some feel that
limiting this range even further, to 9 to 11hZ, is best.
I've seen the following formula for calculating the
resonant frequency of an arm/cartridge:
Resonant Frequency = 1000/[6.28*square root (M*C)]. Where M
is the mass of the arm and cartridge and C is the compliance
of the cartridge. As an example, if we had an arm/cartridge
with a combined mass of 14g, and a cartridge with a
compliance of 20, the resonant frequency would be 9.535.
This simple equation doesn't take into account all
factors, including tonearm damping and, internal cartridge
damping, but it will give you general idea of compatibility.
A decade ago, high-compliance cartridges were the rage and
these needed to mate with very low mass tonearms. However,
today’s heavier, lower-compliance phono cartridges
(especially moving coils) have required tonearm designers/manufacturers to
reorient themselves in the direction of medium to high-mass arms.
Further, some of the currently available MC cartridges put
back a tremendous amount of energy into the arm. This
reflected energy takes the form of standing waves, which
travel up and down the length of the tonearm, potentially
creating mis-tracking problems and/or frequency dependent
cancellation. A well designed
tonearm will dissipate this energy, rather than reflecting
it back to the cartridge. The ability of the arm to accomplish
this will be dependent upon bearing design, internal damping
In a situation where a higher compliance cartridge is
employed in a medium to high mass tonearm, the ill-effects
of the match can be mitigated to some degree if the tonearm offers fluid
damping. Here, a small paddle connected to the arm rests
in a reservoir filled with viscous silicone fluid. This
design feature restricts small, rapid motions of the arm
(like the small undulations that would occur in a high-compliance
cartridge), while providing unrestricted progress to the
arm as it slowly traces across the record. This system also
may improve the sound of some phono cartridges that offer
little internal damping of their own.
The only way to accurately measure system resonance is
with a calibrated low frequency test record and a chart
recorder, or other sophisticated test equipment. Since most
of us do not possess this capability, it is wise to do some
preliminary homework in assessing the compatibility of any
potential arm/cartridge combination. There are a few general
"rules of thumb" that we need to consider:
* A tonearm whose effective mass is rated at 10 grams
or below is considered low mass (e.g. early SMEs,
Grace 747 etc.). A tonearm whose effective mass is rated
between 11 and 25 grams is considered moderate mass (e.g.
SME 309, IV, IV-Vi, V, Triplanar, Graham). Arms above 25
grams of mass are high mass in nature (Eminent Technology,
* A phono cartridge whose compliance is rated at 12 x l0ˉ6
or below, is considered low compliance. A cartridge whose
compliance is rated between 13 x l0ˉ6 and 25 x l0ˉ6 is considered
high to very high. Note: Another way of expressing compliance
is um/mN. Here a rating of 5 to 10 is considered very low,
10 to 20 is moderate and above 35 is very high.
* Low mass arms mate well with both moderately high and
very high compliance phono cartridges.
* Moderate mass tonearms are good companions for moderate
to low compliance cartridges.
* If a low compliance cartridge is used with a low mass
tonearm, undesirable resonances can occur in the audible
range. Mistracking may also be a problem.
* When a high compliance cartridge is mated with a moderate
mass tonearm, resonances in the infrasonic range may occur
in addition to some unwanted high frequency damping.
It may not be possible in every case to accurately determine
whether a particular cartridge is suited to a given tonearm
by a simple glance at the specifications. This is especially
true in border-line situations. However, poor combinations
can be easily identified and avoided.
Several variables can influence our ability to accurately
predict a match using the manufacturers supplied specifications.
Some of these are: 1) The manufacturers
specifications themselves can vary in accuracy due to differences
in measurement techniques. 2) Sample to sample variation
of the cartridge. 3) Differing amounts of internal
damping of the cartridge or tonearm and 4) the age
of the cartridge. The situation is further complicated by
the fact that we should calculate both vertical and horizontal
Happily, most of the popular, modem-day moving coil (and
many moving magnet) cartridges
and the current crop of medium mass tonearms represent a
fairly good match. Exceptions do exist however, and we should
be aware of the sonic pitfalls. An improperly matched cartridge
and tonearm will not only sound poorly, it may even cause
irreparable damage to records and stylus. So, it is well
worth the effort in preliminary comparisons to determine
the compatibility of the proposed cartridge and tonearm.
For further help in determining whether a particular
cartridge is a good match for a given arm, consult the graph
below (courtesy Ortofon).
Total (tonearm system) mass can be calculated by using
M = 10⁶ : (f˛ x (2π)˛ x C where:
Cartridge resonance frequency in Hz
π - 3.14159265359...
Cartridge compliance in µm/mN
NB: Total (tonearm system) mass M is a sum
of Mass of cartridge, Mass of headshell and screws and
Effective mass of tone arm (all values in gram)