RECORDS & TURNTABLES
The rotational direction of a turntable platter coupled with the playing angle of
the Tonearm causes the stylus, and subsequently the entire tonearm, to drift
toward the center of the record. This drift tends to increase as the tonearm gets
closer to the end of the last recording. There is an adjustment at the base of the
tonearm to counteract this force and allow the stylus to travel in the center of the
Not all turntables have an anti-skate adjustment. On those turntables, the anti-
skate adjustment is fixed. Some turntables use a balance weight connected to a
piece of thread. The thread is then connected to the tonearm which, is also a
fixed adjustment. Misalignment of the anti-skate adjustment can cause the stylus
to apply more pressure to one side of the groove wall which can adversely affect
record wear and in extreme situations, affect the fidelity of playback.
Cartridge, in this case, refers to a Phono Cartridge which, is that thing attached
to the record playing end of the Tonearm. The cartridge holds the stylus and
converts the mechanical vibrations of the stylus to the electrical energy that is
amplified by the phono preamp. There are two predominant types of phono
cartridges: Moving Coil and Moving Magnet.
cartridges are built using tiny coils of very fine wire that are
modulated by the stylus. These coils are centered in the field of stationary
permanent magnets. Electrical energy is induced into the stationary magnet by
the modulating coils. The stationary magnet also has several turns of very fine
wire around it forming the coil that connects to the phono preamp. When first
introduced, Moving Coil cartridges were known for their high fidelity. However
with advances in technology there is now little, if any, noticeable difference in
fidelity between Moving Coil and Moving Magnet designs.
Cartridge is built just the opposite of a Moving Coil Cartridge
in that permanent magnets are modulated by the stylus and electrical energy is
induced into stationary coils which, in turn, are connected to the phono preamp.
Moving Magnet cartridges typically have a higher (louder) output than a Moving
Coil cartridge and are generally cheaper to produce.
There is a third type of Cartridge known as ‘
.’ This type consists of a
piezoelectric crystal that is modulated directly by the stylus. The rapidly changing
pressure on the crystal causes a tiny electrical current to be generated which is
then amplified by the phono preamp. Ceramic cartridges, while less expensive to
produce, suffered form fidelity problems as the output of the crystal is typically
non-linear. Produced from the 1950’s through the 1970’s, Ceramic cartridges
were found in many of the lower cost systems.
This refers to the stylus and is a representation of it’s springiness. Actually, it
refers to the assembly that holds the stylus known as a ‘Stylus Bar.’
The compliance, along with the mass of the Tonearm, will determine the low
frequency resonance of your cartridge and eventually your system while playing
a record. The compliance of your cartridge can be observed in real time if you
ever play a record that is warped.
This is the area of a record that lies between the last groove of recorded sound
and the label. It is the area where the Tie-off groove is and is also where the
Matrix number and any other information is placed.
In the audio realm (particularly professional audio), equalization refers to the
deviation of certain frequencies or certain groups of frequencies from their
original relationship to each other. The tone controls on your home stereo can be
referred to as the ‘equalizer’ section. Adding or subtracting Treble or Bass is the
process of equalizing the audio signal that is passing through your audio system.
With respect to records, it was determined early on that reducing a certain
amount of the bass frequencies allowed for more time to be recorded on the
disk. This is because the bass frequencies require a wider groove width to be
accurately reproduced and there is a finite amount of space on the side of a
given record. Thus, there is a built in base boost in your phono preamp to
compensate for this. Likewise, it was discovered that increasing the treble
frequencies when cutting a disk had the effect of eliminating some of the surface
noise when played back using the opposite emphasis or ‘equalization’. So,
depending on the type of record being played, there is a specific equalization
curve being applied by your phono preamp to compensate for the ‘pre-emphasis’
applied during the disc cutting process.
Basically, it is any album jacket that has a hinged cover to house multiple
records. I’ve seen as many as three in a set. That is called; ‘Triple Gatefold.’
A single record can also have a hinged cover. The purpose being to allow extra
space for more text, artwork or both. Double albums are gatefold by design in
order to house both discs. The term started in the early 1950’s with some
45RPM releases and evolved with the LP era.
The headshell is that hood-like shaped device at the record end of the tonearm
that holds the phono cartridge. Many headshell designs are removable allowing
for an easy change of the cartridge-stylus combination to accommodate the
varying types of record grooves.
This refers to the record groove being ‘side-to-side’ with respect to the disk.
Lateral groove records are
or Mono. The vast majority of records
made since the beginning of record production are lateral groove.
Stereo records look like they have a lateral cut groove but the information for
each channel is cut into the groove walls where the outside part of the groove
contains the Right channel information and the inner groove wall contains the
Left channel. A stereo stylus differs from a mono stylus in that it can track both
horizontally and vertically because it is reacting to the individual channel
information on each groove wall. Here is a link to an excellent representation of
how the various styli track a record groove:
This is the groove on the outer edge of a record that guides the stylus into the
first recording or track. Lead-in grooves are usually silent. Some records don’t
have a lead-in groove.
This is a unique design of a turntable whereby the tonearm tracks straight across
the record as opposed to the usual arc of a tonearm that is fixed at one end.
Linear tracking turntables work by using a feed screw mechanism that causes
the tonearm to move straight across the record surface at a predetermined
speed. The idea behind a linear tracking turntable is to track a record in the
same manner as a record cutting lathe which uses a linear mechanism to create
the lacquer coated master disc.
This is a number, or combination of numbers and letters, that is inscribed (often
stamped) into the Dead Wax area of a record. Think of it as a catalog number.
This number is usually assigned by the record company to keep track of the
masters used to press records. It can also be assigned by the pressing plant for
the same purpose. Also, in the dead wax area, can be found the inscription by
the Mastering Engineer. Collectors will often use both the Matrix number and the
inscription to determine how collectible the disc may be.
Introduced in 1948 by Columbia Records, the Microgroove record boasted a
groove width about one third that of the conventional 78 RPM records produced
prior to that date. This also heralded the ‘re-introduction’ of the 33-1/3 RPM disk
for consumer use which was manufactured using a vinyl compound. This format
boasted better fidelity, longer playing times (almost 4 times longer) and was
touted as unbreakable compared to its 78 RPM predecessor.
The format became known as the LP. 45 RPM records introduced by the RCA
Victor Company in 1949 also incorporated the microgroove format.
The Platter is the round platform that the record rests on while being played.
The Platter is the driven element in a turntable. The methods for rotating the
platter vary from direct drive where the platter is part of the motor, to belt drive,
to rim drive where a small motor-driven rubber wheel turns the platter from inside
Plinth is actually an architectural term that refers to the base of a column.
However, in record turntable parlance, it refers to that part of the base to which
the Platter and Tonearm are attached. The plinth is usually isolated from the
main turntable base by some sort of suspension system.
Often referred to as ‘Quad’ or ‘Quadrasonic’, actually started in the late 1960’s
as a four channel audio tape format. Today, it is usually referred to as 4.0.
The configuration is; Front Left, Front Right, Rear Left and Rear Right.
In the early 1970’s it was adapted to LP’s and the three most popular formats
were; QS, SQ and CD-4. The formats were incompatible and may have led to it’s
RIAA is an acronym for Record Industry Association of America. The RIAA Curve
refers to a record and playback EQ or ‘Equalization’ that was standardized for
the production of microgroove records in about 1954.
It is also known as RIAA Equalization.
Rumble is in an induced low frequency vibration in the turntable platter that can
be caused by anything from the platter drive system, to worn bearings, to one of
the kids running across the living room floor. Since rumble is an induced
vibration in the turntable platter, it gets directly coupled to the stylus when a
record is played and subsequently amplified by your stereo system. Rumble is
measured by playing a record with a noiseless groove (no modulation) and
monitoring the output of the cartridge. Measured Rumble is generally expressed
in decibels as a minus number.
The Stylus is that ‘needle point’ part of the phono cartridge which makes contact
with the record. The small shaft sticking out from the phono cartridge with the
stylus at the very end is called the ‘stylus Bar.’ The stylus itself is a shaped jewel.
The jewel is most often a diamond or sapphire and it is finely ground to a conical
or elliptical shape which, are the most common. There are actually several
shapes available for stylus tips and which shape is best for a given application is
often the subject of a discussion.
The Tie-off groove is that groove at the end of the last recording on either side of
a record. It consists of two parts; The
groove guides the stylus to the
groove. The locked grove is a continuous circle designed to keep the
stylus from wandering into the label area. The locked groove part of the tie-off
groove also serves to trigger the mechanism of automatic record changers by
virtue of its small diameter. The lead-out groove and the circular locked groove
are usually silent however, some inventive artists have used this groove to
create a loop of audio.
The Tonearm is easily identified as that pivoted arm or lever that holds the phono
cartridge over the record being played. The Tonearm has two important
adjustments available; A counterweight that allows for adjustment of the
of the stylus and an Anti-skate adjustment to keep the stylus centered in
the groove as the record plays closer to the end of the record.
Tracking force is the downward pressure applied to the stylus to keep it in the
groove of the record. Tracking force is calibrated in grams and is adjustable by
virtue of a weighted counter-balance at the opposite end of the tonearm from the
stylus. This is a very important adjustment. Too little tracking force and the stylus
will slip out of the record groove, possibly damaging the record. Too much
tracking force can damage the record, the stylus or both. Tracking force is
measured using a specially designed and constructed balance beam scale that
is placed under the stylus with the platter at rest. There are also some specially
constructed electronic scales for this purpose.
Transcription discs were direct-to-disc recordings made from radio broadcasts.
The discs were usually 16 inches in diameter and were 33-1/3 RPM. While these
discs were typically made at the same speed as vinyl LP's produced later on,
the groove width was similar to 78 RPM discs. Quite often, these recordings
served as masters for short runs of disks to distribute syndicated programming to
individual radio stations.
The turnover frequency (or frequencies) is that part of the audio spectrum not
affected by the
curve being applied. If you look at the pre-
emphasis curve on a graph, the turnover frequency would be in the mid-point of
the graph or at zero. When record masters are cut on a recording lathe, a certain
amount of pre-emphasis
is applied to the audio being inscribed in the disc.
This pre-emphasis amounts to reducing the low frequencies and increasing the
high frequencies. The amount of pre-emphasis and the specific frequencies
involved, depends on the type of record being produced.
33-1/3 and 78 RPM records, for example, have different amounts of pre-
emphasis applied at different frequencies.
Vertical Grove or, Hill and Dale
The predominant method for record grooves starting from the very beginning of
record production was lateral grove or ‘side-to-side.’ There were however, a few
discs whereby the grove was cut vertically. This type of record groove is also
known as ‘Hill and Dale.’ Some of the early recordings that were produced with
vertical cut grooves were Phonograph Cylinders, Edison Disc Records, Pathé
Disc Records, and a few Transcription discs. One cannot play a vertical cut
record with a stylus designed for lateral groove records. It is possible however, to
modify the wiring scheme of a stereo stylus to play a vertical grove because a
stereo stylus can move vertically as well as laterally.
Howard M. Tremane, “Audio Cyclopeia” Second Edition, Howard W. Sams, 1973
Rudolph F. Graf, “Dictionary of Electronics” Howard W. Sams, 1974
Glenn D. White, “The Audio Dictionary” University of Washington Press, 1987
© Corey Bailey Audio Engineering