Purpose and Function of the Turntable Mat

1. The mat has to provide a firm grip to both the platter and the record, so that 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 by 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), but only in conjuction with a clamp!

Custom mats should have a center area which is somewhat receeding in order 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 gr. cardboard (the thickness of the cover of an audio magazine) and about the diameter of the mat. Put this circle at the rim of the platter under the mat.

3. The mat should protect the record's surface in order to avoid damage.

In order to comply with this criteria 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 by using a paper tissue wetted in blue methylated spirit.
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. Generally the characteristics of the mat itself are better controled by a clamp or weight and therefore somewhat less interfering. Nevertheless mats made of light and softmaterials (rubber, felt, paper, cork) can easily cause a slight phase shift in the lower-mid region which is translated in a slightly smeared out attaque. At first hearing a rubber mat will allow more detail, but you may discover after a while 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). The choice of mat should always be made in relation to the turntavle itself and the arm and cartridge combination. 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 or even the relation between ampolifier and loudspeaker system.

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 from rack or other support was not sufficient.) The properties gave an airy sound with a clear upper midband but the attaque still could be improved, specifically in the mid band. Sorbothane is also used today by Audioquest.
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.

Mikro 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.

 

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.

Goldmund, Acrylic, Marantz, Nagaoka
Glass Mat

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 can 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 bituminous 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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