Given that your phono cartridge has an overwhelming
influence on the fidelity of the reproduction quality of your hi-fi rig, would
the bits that make the first contact on the vinyl disc – the stylus and the
cantilever have the most influence on sound quality?
By: Ringo Bones
For more than a decade and a half into the 21st
Century, it seems that the vinyl record had managed to hold its own as the
playback medium that is better than Redbook CD – or those downloadable digital
music on the internet – by a significantly wide margin in terms of sound
quality. Despite being introduced a few years ago, three popular entry-level
turntables: the Project Carbon Debut DC, the Pioneer PL-30-K and the Onkyo
CP-1050 Direct Drive Turntable are still selling strong. But what about phono
cartridges – has there technological progress being made since the early 1990s
vinyl record revival?
Any phono cartridge faces a major problem: how to cover the
full three-decade-wide bandwidth (20Hz to 20,000Hz) needed for high fidelity
audio playback. High frequency resonances seems pretty well inevitable and
mid-band “glitches” are difficult to avoid, too, as the frequency-response and
vertical / lateral crosstalk sweeps with the use of test records showed. Not
surprisingly, the success with which these are controlled is very closely
linked to the cartridge’s overall sound quality.
Phono cartridge stylus and cantilever construction have
significantly – even radically - improved since those osmium phonograph needles
used during the introduction of electrically / electronically recorded records
to the market back in November 1925. During the post World War II period that
lead to the Golden Age of Stereo, stylus dimensions got smaller and smaller to
better track the microscopic grooves of the vinyl long-paying record introduced
by Peter Goldmark. First it was made of sapphire – a gem quality form of corundum
with a hardness of 9 on the Mohs’ scale which was later replaced by micro-profiled
elliptical diamond stylus for better sound quality reproduction. While during
the Golden Age of Stereo – the material of choice for high quality phono
cartridge cantilevers is the most rigid alloy of aluminum that is commercially
available, which during the 1950s is typically aircraft / aerospace grade
aluminum.
Then and now, the moving coil phono cartridge – despite of
its low signal output - has been considered as the best when compared to its
moving magnet counterparts due to its lack of frequency response problems in
the upper midband and high frequencies. Traditionally, moving coil phono cartridges
have had relatively incompliant cantilever hinges in comparison to its moving
magnet counterpart which resulted in poor low frequency tracking. Anyone
looking to preserve their record collection find this alarming. Remember those
early Decca London phono cartridges with their tip resonances that are
notorious for doing damage to vinyl records? So tip resonance control is also a
factor in choice of materials in stylus and cantilever construction.
Ideally, the stylus should be constructed from the same materials
to consistently control the inevitable resulting resonances. Given that the
microscopic-dimensioned stylus is barely visible to the unaided naked eye and a
modern phono cartridge stylus measures around 7.5-mm long or 5/16 of an inch
long and 0.5 –mm thick or 1/32 of an inch thick constructing one from a single artificial
produced diamond should not carry a prohibitive price premium. Dynavector’s 17D2
Mk. II diamond cantilever MC cartridge is one such beast. With a hardness of 10
on the Mohs’s Scale, solid diamond is the hardest possible material and supreme
for cantilever use. And given that diamond is a good heat conductor, any heat
friction generated during vinyl playback can easily be dissipated by the stylus
and cantilever assembly because they are made of the same material. But since
its introduction in the early 1990s, many competing phono cartridge makers have
managed to create better sounding cartridges using both more exotic and tried and
true materials.
Solid-boron-rod cantilevers constructed from the crystalline
allotrope of the element boron that has a hardness of 9.5 on the Mohs’s Scale
has been extensively used for moving coil phono cartridge construction during
the latter half of the 1990s due to its subjectively better sound quality when
compared to diamond. Used on the Van Den Hul Frog with a specially shaped Type
1S diamond stylus, this cartridge has the highest cantilever compliance and the
lowest recommended tracking weight of all the commercially available cartridges
and is notable for its ability to ignore vinyl scratches which is very
important if you frequently purchase vinyl LPs and 45 RPM singles from used
record shops. While the Clearaudio Signature uses a hollow boron cantilever
variant.
Cantilevers made of sapphire or corundum – which has a
hardness of 9 on the Mohs’s Scale - was also tried as far back as the late
1970s. The most famous example of these is the Bang & Olufsen MMC 20CL
phono cartridge – which a diamond stylus is attached to a sapphire crystal
cantilever that resulted in the elimination of audible tip resonance and thus eliminating
distortion in music reproduction and it also means it won’t be destroying your
precious vinyl records every time you play them. Enthusiasts back in 1981
praised its life-like ability to reproduce choral recordings like never before
and it is probably the first cartridge that started the exotic materials
construction wars.
As a go to material for phono cartridge cantilever
construction, aluminum has held its own since the Golden Age of Stereo. The mid
1990s era Ortofon Rohman uses a tapered aluminum cantilever and still manages to
gain converts unimpressed by the newfangled solid-boron-rod cantilever
construction of competing cartridges. While the Lyra Parnassus DCt uses a more
exotic diamond-coated, ceramic-reinforced aluminum cantilever said to be
stiffer than ordinary aluminum alloys previously used in cantilever
construction.
Sound quality wise, audiophiles weaned on the “dreaded” compact
disc tend to gravitate towards boron cantilevered phono cartridges largely due
to its wider perceived bandwidth in comparison to ones using aluminum alloy as
a cantilever. While those Iron Maiden and Judas Priest fans who extensively
listen to vinyl during the early part of the 1980s say that aluminum
cantilevered phono cartridges are more neutral sounding in comparison to their boron,
diamond or sapphire / corundum counterparts.
