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Purpose
and Function of the Turntable Mat
1.
The mat has to provide a firm grip to both the platter and the record,
so the mat does not slip, nor does the record.
To improve the contact between platter and mat a record weight (stabilizer)
or clamp can be used. The record can also firmly coupled to the mat/platter
by means of a vacuum pump as in the sophisticated vintage turntables
of Micro Seiki where this system is integrated. Audio-Technica produced
the special Disc Stabilizer (AT666EX) which could be used on a variety
of turntables and is a so called vacuum mat. Another very effective
accessory is a record
stabilizing ring.
The firm grip diminishes distortion of mechanical origin. That is
distortion caused by heavy modulations which make the mat/record move/vibrate.
A weight/stabilizer is best used with a rubber mat. An acrylic turntable
mat is best served with a clamp.
However a stabilizer weight can very well be used on an acrylic mat
if at the same time a stabilizer ring is used.
To improve the stability of any mat, gluing the mat at at least three
points with very thin two sided tape gives excellents results.

2.
The mat should support the entire (grooved) surface of the record.
In example A only
contact with the mat is made by the groove guard (edge of the record)
and the lable. This is because the mat's diameter exeeds the actual
diameter of the engraved surface of the record.
In B the mat has the appropriate size and perfect contact is possible.
If the mat you use is too large it should be trimmed down to 28.7
cm. Support is improved when the mat is slightly concave (as is the
case with the Goldmund mat) or convex (as in the case of the Oracle)
in conjuction with a clamp. The center part should be a little receding
to accomodate the label.

If the mat does
not support the record at the periphery, the easiest thing to do is
to cut a small circle from 200 grs. cardboard (the thickness of an
audio magazine) and put this at the rim of the platter under the mat.

If that does not
improve the support, you can use The Universal Record Stabilizing
Ring which not only improves the contact of record and platter/mat,
but also improves the reproduction significantly: larger image, more
depth, precise harmonics and details.

The
Universal Record Stabilizing
Ring on one of the modified
and optimized Garrard 401 turntables by expert Martin Bastin.
(See the review by Stewart Wennen in
the April 2005 issue of HiFi
World.)
3.
The mat should protect the record's surface in order to avoid damage.
Nevertheles
the mat has to be cleaned from time to time. It should be kept clean
and dustfree in order to avoid particles settling in the record groove.
A rubber mat can be washed with lukewarm water and a few drops of
soap. An acrylic mat can be cleaned the same way or by using a paper
tissue wetted in blue spirited alcohol.
Note: If your turntable does not have a dustcover just use a carton
disc (the size of the record) that you put on the mat when the table
is not in use.
4. The mat's
material should have good sound characteristics.
Although a mat
does not generate sound by itself, it should have an even frequency
characteristic. No part of the audioband should be accentuated.
Here again the use of a record clamp, weight or stabilizing ring will
improve the sound. The lower frequencies will be tighter, the midband
firmer and the high frequencies will be neater and more precise because
the needletip and cantilever of the cartridge will not transmit false
high frequencies caused by minute vibrations of mat (and record),
but will track the grooves in a more controlled and precise way since
the record itself cannot move.
Remember: we are talking about analog recordings which may have up
to 700 bits (not 16), or even more. One or two micrometers of movement
that do not come from the groove itself will distort the sound. The
mat should not give cause to vibrations. That is why it is not advised
to use flimsy and light mats of felt.
5. The nature
of the mat's material should be close to that of the vinyl.
Another important
feature which adds to the sound characteristic of the mat is that
the mat is relatively hard. In that way it is as if the record is
heavier, only of course if a clamp is used and the fundamental resonance
of the mat (and record) is damped (attenuated) by several dBs.
As said: fixing the mat to the platter at least at three points, with
a very thin two sided adhesive, improves the signal reading.
If a clamp or a stabilizer
is being used the material which the devices are made of also plays
a significant role.
When a stabilizing ring
is used the characteristics of the mat itself are better controled
and therefore somewhat less interfering, although mats made of light
materials (rubber, felt, paper, cork) easily cause a slight phase
shift in the lower-mid region which is translated in a slight smeared
out attack and coloration which is always caused by one or two peaks
in the mid frequency region and shows in the high frequencies. At
first hearing it may result in more details, but soon you will discover
that these are make believe refinements. Peaks in the frequency curve
should be avoided at all times.A hard mat is the best option: acrylic
(Goldmund type), hard rubber (the Technics SP-10mk2 type). Supple
mats like soft rubber, fluffy felt and very soft sorbothane are all
just fantasy. It is like eating cake with too much cream. After a
while you get sick of it. And if the sound is not detailed enough
you should check if your phonocable is the restricting factor or the
preamplifier does not deliver or maybe it is the cartridge?
If a heavy clamp is used which has to be screwed on the spindle and
the sound characterictic is too dull, a small aluminium disc of 8
cm in diamter and 2 mm thick can be inserted between a heavy clamp
and the label (not on the Oracle of course!). This can dimished the
effect of the clamp's original material. The final result has to be
evaluated on points of (a) clean transient, (b) linearity of frequency
curve and (c) absence of distortion.
History
In the early days
of the record era the gramophones which played the 78 RPM shellac
discs generally had their platters covered with a velvet fabric in
nice green, black, red, brown or blue.
After the Lp had arrived the rubber mat was introduced. At first it
was just a very thin rubber sheet with a circular pattern to cover
the platter. Rubber was used because it was a practical material.
It kept the grooves relatively free of dust, could be removed and
easily cleaned whereas velvet could contain dust and leave this behind
in the micro grooves of the vinyl.
In time thicker
rubber mats were used and audiophiles and manufacturers discovered
the differences in sound depending on the sort of rubber and the difference
related to a good contact between record and mat.
Technics,
Thorens, Nakamichi
In the nineteen
seventies designers of turntables started to listen even more carefully
to their products and many not only came up with a heavier platter
but also with specific turntablemats.
In Japan Technics used a not too thick mat on their SL-series direct
drive machines.
On the SP10Mk2 a thicker mat
made of hard rubber was used which contributed to the straightforward
and uncolored soundquality.
From Japan were
also the specifically shaped mats from Nakamichi. One made from extremely
hard and heavy rubber (it contained a relatively high percentage of
metal). And there was also a thin mat from red copper, specifically
shaped for maximum support and close contact with the record. But
such a mat was easily bent. Initially the mats on Thorens turntables
were not too good. The later versions of TD160 and TD126, at the end
of the nineteen seventies, had mats which supported the record in
a better way and on top of it they were made of a harder rubber which
contributed to a far more dynamic and precise performance.
Spectra,
Audioref, Dumpa
In France the
Spectra turntable mat was introduced. It consisted of 3 layers of
different
kinds of polymer, each with specific properties. The surface povided
a firm grip on the record because it was sort of 'sticky'. A record
was not easily lifted up. This mat provided a remarkable transient
response which was more situated in the upper regions as with a felt
mat than in the fundamental frequencies as in harder rubber mats or
the acrylic mats. The diameter of the Spectra was too large, 300 mm
instead of about 280 mm. Records with a thick groove guard were not
always optimally supported.
The Spectra was
superseded by the Audioref (marketed by Jean-Claude Fourière
in the 1970's in France) and a later edtion which he devised was the
Dumpa mat. It was made of harder rubber and made it less tricky to
remove the record.
It also had more neutral properties which translated in less colouration.
Measurements showed that rumble was less prominent as in conventional
mats.

Not only the
rumble spectrum was many dBs lower but now the curve also had a regular
pattern in the lower register which is the fundament for a faithful
reproduction of the many harmonics.
(Note: One could say that Jean Claude Fourrière knew what he
was doing. He was the designer of the incredible loudspeaker systems
named Audio Reference 800 which could boast on four 38 cm Audax woofers
(from the PR38 series) per channel and yet the sound was as light
and fast that the most refined details and subtleties in the recording
were heard. Later he designed the Toltèque cold plasma loudspeakers
which would promise an even more transparant sound devoid of matter.)
Mission,
Ariston, Linn, Hiraoka, Oracle
In the UK Farad
Azima of Mission Electronics proposed a mat made of sorbothane which
was said to have excellent damping properties. (Mission used sorbothane
also in the 3 feet of their turntable. But there it was apparent that
the isolation of rack or other support was insufficient.) The properties
gave an airy sound with a clear upper midband but the attaque still
could be improved.
Mission's mat prompted Ariston of England to produce a mat with a
more amorfous structure and different damping properties.
When Linn originally started the production of the Linn Sondek LP12
a rubber mat was used for several years. It was a mat with a striped
profile. Later Linn discovered that the LP12 would project a more
tasteful image with a felt mat, first relatively thin and soft and
later somewhat thicker and "harder" if that is the word
to describe the feel.
From Japan came the Hiraoka mat which was a very heavy and thick mat
consisting of rubber with a high content of metal. This mat promised
to give a better stereo image, a cleaner sound, and improve speed
constancy. The mat is not supple but stiff and very hard. This resulted
also in a much better transient.
Another interesting design was the mat which adorned the Oracle turntable.
It was used in conjuction with a clamp that had to be screwed on the
threaded spindle. The shape of the mat was slightly convex and the
record was clamped down in order to make a firm contact between the
surface of the record and the mat. This led to a more precise signal
and an improved transient response.
Micro
Seiki Copper Mat
Micro Seiki proposed
a mat turned from copper, the CU-180, which could be used on different
turntables.
This mat could be covered with an additional mat of felt and this
would result in more or less the same sound pattern as was given by
the Linn LP12 turntable: detailed high frequencies, smooth and fast
mid section and transparant bass.
The CU-180 could
also be used with no additional mat and in that case it would not
only add weight to the existing platter, but also would give a clear,
no nonsense transient without any phase shift. In that case more attention
would have to be paid to the choice of cartridge and arm combination
and choice of phono cable.
The CU-180
was marketed for several years and was a gadget which was appreciated
by many a high end audio adept.
Goldmund,
Acrylic, Marantz, Nagaoka Glass Mat
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A
DIY acrylic mat 28.8 cm in diameter. The center hole is larger
than the spindle to keep the spindle free. The rings in the middle
give room to the label of the record. For practical purposes the
diameters of 10" and 7" records have been marked. There
is also a marking at the periphery of the label.
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When the Goldmund
engineers designed their turntables (Studio, Studiette, Reference)
an acrylic platter was used in conjunction with a specially designed
clamp which consisted of different materials. They also made a seperate
mat plus clamp available for audiophiles who wanted to imitate more
or less the 'Goldmund sound quality' with their existing turntables.
Also imitation
Goldmund mats with clamps where made by hobbyists and a few other
manufacturers. They did not succeed in obtaining the same effect for
100% because the materials used by Goldmund (specifically in the clamp)
could not be imitated entirely. Nevertheless these imitations were
not too bad. Important is that an acrylic mat is glued to the turntable's
platter using a very thin double sided adhesive sheet in order to
obtain the clean sound.
The drawback of
course is that a glued mat an not be removed in case a new turntable
is bought, hence many audiophiles glue the mat only at three points
with the extremely thin double sided tape.
Here I give the measurements for having a
simple and a more sophisticated acrylic mat turned by a machinist
in a workshop. The maximum diameter should not exceed 290 mm and should
be preferably less: 285 mm..

Marantz proposed
a mat of glass on their TT4000 top of the line turntable. Nagaoka
marketed a seperate glass mat, the Crystal. Rega gave their turntables
a glass platter to be covered with felt in order to counteract 'the
sound of glass' (which also can be heard in designer audioracks with
glass shelves). With the revival of the long playing record other
mats have been proposed in the last decade: cork and suede leather,
a.o. It seems however that many people are trying to reinvent the
wheel as if all these years from 1950 on of designing, of research
and development (and of marketing) were useless. Especially the praises
for carton, a thin sheet of foam or bithumous sheet should not be
believed.
Firmness of the material, good damping characteristics (not collecting
the energy but transmitting the energy so it can gradually die out)
and the optimum diameter for support of the entire Lp (and not just
the groove guard and the center) make a good mat.
Well
Tempered, Fulton, Sota, Townshend
There are more
mats (according to Greg Stewart from Minneapolis) which were maybe
not so prominent because they were not available seperately or did
not get a vast prolifiration. Well-Tempered Labs used for a time on
their Well-Tempered Table a moderately-soft damping mat like the Audioquest/Mission
and the Oracle, but much thinner. The idea was to damp while but increase
the firmness of bass and impact which was lost in the thicker sorbotane
mats. The Well-Tempered mat was fairly effective, but didn't catch
on and could not establish itself due to the introduction of acrylic
platters and acrylic mats. So Well-Tempered started to use a better-damped
acrylic-like platter.
Another thick
flexible mat that appeared about the time of the Dumpa/Spectra was
the one by Robert Fulton. Then there are the acrylic varieties. Sota
had an acrylic mat on top of a flexible Sorbothane-like material to
try and get the best of both. Nowadays, you see a lot of turntables
with an acrylic or similar plastic platter, but no mat at all. These
can work pretty well, but unless they are damped like the Goldmund
platter in the 1980's, they can be lively and procure a less balanced
sound. There was also the Townshend Elite Rock with the plaster-filled
aluminum-shelled platter with a flexible, but rigid plastic mat on
top of it which was quite effective, but the plaster had a tendency
to separate from the aluminum. The Warren Gehl mat is a favorite of
certain audiophiles. It is a multi-layer, heavy plastic composite
that does a great job of damping the record on the topside and damping
the platter on the bottom side while providing a rigid surface for
good impact, slam, and bass. The mat was extremely expensive and rarely
seen, but is by far the most detailed, accurate, neutral, and revealing
mat.
What
is the Right Combination?
Of course there
is a relation between your turntable and the mat, and also between
the nature of the arm and the mat. And there is a relation between
your loudspeakersystem and the turntable. Because of the very fine
structure of acrylic, the sound and its characteristic is accordingly.
The sound is somewhat rounded in the midband and the result can give
the impression of a slightly retracted midband (if compared to most
ordinary rubber mats) and providing more space but less straightforwardness
depending on the clamp or turntable weight which is used. In the top
the frequencies are refined. Because of the well controlled lower
register and the lower-mids, transients are less exhuberant and do
not get the distortion as with rubber mats. So that is a good thing
too. Acrylic mats are precise and sound natural because of the correct
phase (the harmonics are established at the same time as the fundamentals),
especially when using a screw-on clamp.
Glass accentuates the top frequencies but lacks in transparancy and
structure of the low and mid-low registers. I would never advise the
use of glass because of its amorphous nature. Yes, go for a hard mat.
But than preferably an acrylic mat.
There are various
kinds of rubber which all sound differently. Rubber is in general
more blatant, but has speed and can add to realism, and often sounds
also more 'ordinary', less sophisticated.
The Spectra mat has a more airy sound but seems to shift everything
one octave higher in the spectrum.
The Mission sorbothane sounds also a bit lighter with less firmness
and weight in the lower-mid band, but is also speedier (which is good
for transients) than acrylic mats and most rubber mats.
The Ariston mat was in my view not in accordance with the harmonics
of the music and sounds a bit amorfous.
The best mat delivers
sound with good transients, an even characteristic, deep bass which
is well controlled, and gives clear and detailed high frequencies
with the least distortion. The best mat provides the best signal reading
in order to give a sound reproduction as if the music is performed
live. Do not forget that. By all means do dare to change an acrylic
mat for a rubber one if it gives more realism in your system. Or leave
the felt mat in the cupboard and change it for a rubber one. In other
words: do not follow trends but find the best solution for your sound
system. But above all: follow your own ears and not your eyes! And
if you do that you probably will opt for the acrylic mat. A commercial
one or the poor man's home made acrylic mat.
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