The below is a extract from Lenco Heaven where the Individual who measures Intrinsic Properties for Materials, has shared info to an inquirer about the Polybentonite Resin Plinth Material.
As this is not commonly seen on the Gon, especially in the Analog Section, it is worthwhile showing.
Polyester resin/kitty litter (DF=0.618).
The resin used with Bentonite is Isophthalic Polyester,
Anybody interested in the Substance can get very good guidance on DIY Audio, where it is discussed to the point of tips offered by those who have used it for moulds that are made to produce a form.
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Individuals find their way, some through Trend being an influence and others through turnover of experiences.
I have Trend as a influence in earlier endeavours and more calculated choices as increased learning and experiences were sought to assist with making decisions.
When I spoke of a Plinth Structure requiring Cabinet Making Skills adding materials to manage transferred energies, I was referring to Mimick Plinths using Nantis Methodology.
As a result of experiencing Plinth born from Nantis Ideas, one individual chooses Slate as the alternative, where as another extends an investigation and ends with a Board Only Structure produced from a particular material.
There is no one path in anything Audio, choice of Source, methods for Amplifying a Source Signal, Cable Choices, Speaker Choices.
Much in depth discussion will not create systems that Mimick each other, 99% of systems built differ?
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Granite is one of those materials that ought to be good for plinth-making but which has been found by most to be disappointing, at least as regards the Lenco idler. I forgot to mention that prior to building the slate/PTP Lenco, I owned a Jean Nantais Lenco made of layered marine plywood and using Jean’s damping tricks. IMO, the slate/PTP is superior, but in fairness I added a massive after market bearing and also dampened the platter with special paint.
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Firstly, I don't need to do anything but I did.
Secondly, My first venture into Alternate Plinth Materials with a intention to make a New Improved Design for a Plinth, resulted in my ending up with 9 Stone in weight Monolith Granite Plinth. A real feat of One Mans expression of a Dominance over Nature. I'm Older and not so silly, well a little bit less, as the Back Screams at such ideas, where handling is still to follow.
Thirdly, Not too far on in following years of having the Granite Plinth. The Engineer I refer to who carries out Materials measurements was becoming a contributor on a forum, and was becoming more frequent in being vociferous for using Polybentonite Resin as the material to substitute other materials used for producing Mass Plinths for a TT. As the main market for Mass Plinths both DIY and Commercial was aimed at Idler Drive TT's, the alternate ideas for Plinth Types got my attention.
I would say it was at this time my interest in Plinth Materials took hold in a similar way mechanical interfaces on a TT Platter Bearing Assembly had become an established area of interest.. I would suggest I was beginning to recognise a TT / Plinth - TT / Chassis / Plinth as another mechanical Interface needing a careful condideration. This has evolved over numerous years and many demonstrations of Plinth Designs being used., as well as rethink on how a TT interfaces with a Plinth Design.
As a Mass Plinth alternative, I heavily rate Polybentonite Resin as a Plinth Material on a Idler Drive, there is something extra to the End Sound in comparison to a Mass Plinth.
I also know of Polybentonite Resin users who have now adopted Densified Wood as their alternative material of choice.
Additionally I have not too long ago strongly suggested a High Compression Bamboo Board used a Plinth on Garrard 401, when mounted on Densified Wood Sub plinths has been the best experience recollected of being in the company of a 401 being demo'd.
I ended up going down the Densified Wood route as a result of seeing the attractive measurements for Polybentonite Resin as a Plinth Material being Superseded with Densified Wood.
I also at a similar time was being able to be demo'd my own 401 by the New Owner, in a selection of New Wood Based Designs, using MM Cart's on SME 3009 Tonearm with removable Headshells.
All demon's using the non-Granite Plinths were more attractive as a end sound in the new owners system.
Similar was also done with GL 75 vs my PTP Solid Nine mounted on Corian. There were Saucepan Style GL75's mounted into a bedding Co. Pompound on a Timber Design Plinth that was seemingly inseparable to the PTP.
Hence Timber Materials become the main interest. Which led to Penultimately Compressed Boards and Ultimately Densified Wood Boards.
Moving over to a different DD TT Drive Type, a OEM Resin Type Plinth, possibly having a Similar Function to a Polybentonite Resin?, has been compared to Marine Plywood, MU25 and Phenolic Resin Impregnated Wood Board Densified Wood (Panzerholz}, using same TT >Tonearm > Cart' and Support Structure.
I've done my footwork made my choices, initially influenced by a individual who publishes information on Materials and have also had other material types used measured for my own learning.
The final choices made through a process of ilimination, where Traditional Mass Plinth Types, using Granite has been Superseded.
Having experienced Resin Plinths as a Mass Alternative and Wood as a Mass alternative and Wood as design to create a Structure with Cabinet Making Skills and adding materials to control energies, the use of Wood Superseded other option available.
In the use of Wood for demo's of Wood Types for a Plinth, the experiences had, showed a Wood Type claimed to have attractive properties for use as Plinth Structure proved the most attractive in use as a Board only serving the Purpose of a Plinth.
This Phenolic Resin Impregnated Wood Board has also been the best Sub plinth Material experienced in use under a broad range of Audio Devices.
Other experiments undertaken with this material has shown it's Value above other materials typically accepted to be used for the role.
It is no surprise Brands of Wood Board such as Panzerholz or Brands producing a Wood Board as a very similar product are finding these products encroaching into Audio Equipment use.
Linn are the latest I know of using this Board Type on their latest $60K TT.
My route adopted is much much cheaper as means to experience this material type.
I have no discussion left on this material, I am only willing to share my experience and impression made.
I am an advocate of Densified Wood Board Material. As a result of Trials undertaken and Experiencing the material in comparison to alternate options.
For myself in all things Audio Related, Math alone is not the convincing influence for my choices considered to be made or choice made and realized.
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Interesting. A few months ago I asked Pindac to define "damping factor" as he applies it to materials used for plinth construction, especially slate, which he dislikes for reasons obvious in the above 2022 post. In the recent exchange he declined to provide the information that he did provide above. Perhaps he did not recall quoting that paragraph describing experiments done by an engineer. I have a dog in the fight, because I own three turntables housed in slate or slate and hardwood plinths. First, I would not argue that panzerholz and the like materials may be superior to slate; I have no way to argue that point, because I do not own a Panzerholz plinth. Albert Porter does or did own an SP10 MK3, like mine, in Panzerholz, and he at least used to sell plinths to others for SP10 Mk2 and Mk3. I have high regard for Albert, so I don’t doubt that P’holz is good.
My thoughts on the experimental results described above are that this may be a classic example of over-interpreting data. Like you said, Noromance, we don’t know much about the slate tile that was used in the experiment. And both of us (apparently) are using very thick (50mm for Lenco and Denon DP80 and 65mm for SP10 Mk3) and very heavy pieces of slate. The engineer says his version of "damping factor" is independent of dimension, but he needs to do an additional experiment to prove that point; I find it hard to believe at face value. In addition, "slate" from different sources is different in density and hardness; Pensylvania slate used by OMA and us is different from slate sourced on the Euro continent; I don't know where the engineer did his work. Another point is that slate is a layered form of stone, so its "damping factor" is likely to be quite different if measured in the plane parallel to the layers vs a plane perpendicular to the layers; this factor is not investigated. In a typical plinth, the layers of a piece of slate are likely oriented in the plane of the TT bearing, where the capacity to absorb vibrational energy is maximal. And finally, who goes around striking a plinth while an LP is in play? I will add one observation: This is completely subjective, but I felt that the SQ from my SP10 Mk3 was slightly enhanced, when I added a base to the slate, composed of solid cherrywood and firmly bolted up into the slate itself, to provide some constrained layer damping. Also, I use the idea I got from Albert, damping the Mk3 bearing housing from below by a heavy metal block. Meantime, my Lenco and DP80 sound wonderful in just plain old slate, the Lenco mounted in the PTP top plate I bought from Peter Reinders.
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@pindac A slate tile is not the same as a 40kg 50mm slab of Pennsylvania state!
The trace below shows how a slate tile rings for about a second, when struck, (and they say it makes a good plinth material). Its damping factor is 0.017, very poor!
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I use a source of information that has been a reference point within the HiFi community for many years, it is used both by Professional and Amateurs to extract information.
I have used the resourcefulness of the producer of the information further and they have received materials I am using and New to them for testing.
I have made it one of my goals to become quite familiar with materials used for Plinths that are described as having optimum damping, and the result is that I have become very impressed, and have moved away from the Massey Plinth Designs as the mounting methods.
I am keen to maintain the experiences had from being demonstrated the materials with a obove optimum damping measurement, hence my having access to Densified Wood and acquiring a supply of Permali and Panzerholz which carries a considerable expense.
The Polybentonite Resin is in my view a Massey Plinth Design, when produced it has very high measurements compared to other Massey Materials, the Resin measures above optimal damping, but the sonic is different from Densified Wood.
To put a further perspective on the above Materials that are with High Intrinsic Damping, when compared to other regularly mentioned materials such as Slate 0.017 and Aluminium 0.004 it can be seen the divide in the measurements are quite vast and the stone and metal fall way short of optimum damping.
The following is the words of the technician who produces the testing and recording of a wide variety of materials:
When a sample of material is struck, it vibrates, the frequencies at which it vibrates is dependent on its dimensions, its stiffness (Young's modulus), density and how much it deforms when compressed (Poisson ratio).
How long it vibrates for is a function of its damping factor. Have a look at the trace below. My three axis accelerometer was taped to this material, and struck. The sound was captured on a computer, and recorded using Audacity software. You will notice the rate of decay is quite well defined, fast at first, and becoming asymptotic towards the end. The damping factor is calculated by looking at successive peaks, and measuring their heights from the zero line. This gives the 'log decrement', and from this the damping factor is calculated.
The damping factor, Greek letter eta, n , is a dimensionless number which represents the amount of intrinsic damping a material has. The property is like density, it is irrespective of other properties, including dimensions.
A material with a damping factor of 0.07, or above, is said to be damping, above 0.1 and it is a good damping material, and as the damping factor is twice the ratio of its damping compared to critical damping, a value of 2 represents critical damping. Most materials encountered in hifi products have a damping factor between 0.01 (or below) and about 0.2, so they are well below the critical damping figure.
The trace below shows how a slate tile rings for about a second, when struck, (and they say it makes a good plinth material). Its damping factor is 0.017, very poor! Amplitude up the y axis, time (seconds) on the x axis.
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Can you define "damping factor" as it applies to materials of which you might construct a plinth? I can't imagine there is any single value that would describe that quality except if it has specific reference to a single frequency or set of frequencies, and perhaps other elements of the definition as well.
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The SPH Bearing is a success for two reasons, one being simple Geometry, when the extended length option is chosen the spindle will be less off axis when it rotates due the extended Spindle Length.
The other reason is that the common designed Vertical Plain Thrust Bearing from a vintage era, does not have Hydrodynamic lubrication as part of the design, a Sintered Bronze Bush is usually the part selected as the Sacrificial Material within the bearing housing. I have not seen evidence that a Sintered Bronze Bush is able to release a impregnated lubrication at the heat a Spindle Rotation can produce, and the Bearing Housing is unlikely to have a design that has a Hydrodynamic Lubrication.
The outcome is that an original design for a vintage bearing will end up with Metal to Metal contact between the Bushing and Spindle, and the Steel Ball and Spindle Base will most likely be in contact with each other as well.
This will mean noise is produced and it will be quite easily detected with a Stethoscope, which I have been shown on a few occasions where various stages of bearing work is being carried out.
SPH is using Thermoplastic Bushes and Thrust Pads, with a Non Metal Ball, so there is no Metal to Metal contact, this is a great improvement and the Stethoscope will show the quieter condition, by creating a Hydrodynamic Lubrication, the overall environment within the Bearing Housing is further improved.
A Vintage Bearing Assembly with Metal Parts that are without excessive wear to the used parts and a Modern design where non metal parts are selected in place of the Metal, if both set up to have Hydrodynamic Lubrication should both be as quiet as each other, as the Oil is supporting the Parts and separating the parts from coming into contact.
This leaves three other factors at play for the impression the SPH Bearing has made, the Geometry due to the extended Spindle Length, the Composite Spindle removing a Metal to Metal contact between Platter and Spindle, and the other being the use of a non Thermoplastic Thrust Pad, which will have removed the material that has elasticity and be subjected to the effects of Vertical Compliance.
The question is as a subjective analysis, can these three factors really be the influences that made the use of the SPH Bearing stand out as improved over the other versions.
I have a bespoke produced Tonearm, that is a modern thought process applied to a Vintage Model, that has been rebuilt in the concealed areas with Modern materials used for the design and a very careful approach to the R&D carried out to select the machining tolerances for the new materials.
I have followed this Tonearm as it has evolved in stages of design, and have been invited to receive demonstrations of the work as it has evolved. I know of one occasion when a material with an improved property, was used in place of an earlier selected material, the Tonearm moved forward in a night and day noticeable improvement, so the method used for the assembly within the Bearing Housing ’could’ be a feasible explanation.
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@pindac Thanks for an enjoyable read. I have three refurbished 401s—two early and one later model units. One in 50mm Pennsylvania slate, one in 5x13 layer Baltic birch ply with a solid walnut top, and the other as a working skeletal project. I too have been impressed by the large improvement in sound quality when using the SPH bearing.
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@noromance I have been fortunate to share in a variety of demonstrations from Idler Drives, I have also heard Thorens Models and the Garrard 301, but these are too long ago in the past to make a recollection of.
In the earlier post, I should have added a Corian (owned) and Polybentonite Resin Plinth, to the list of Plinths I have been demonstrated in use on a Idler Drive.
There is at present, a move toward Densified Wood in certain communities, where the board is to be used as a Plinth Material for Idler Drives and the users of Plinths produced from Board such as the Brand Panzerholz or Permali are making very positive reports.
I own boards in both Densified Wood Brands but have these materials at present reserved for another Model of TT and Plinth Design.
My most recent experience of being demonstrated a Idler Drive is a Garrard 401 that has been mounted in a Plinth with a Top Plate produced from a Side and Top Pressure Compressed Bamboo Board. When Bamboo is produced using this method, the Damping Factor is 0.200.
The Damping Factor of Permali is 0.688, Panzerholz is 0.599 and Polybentonite Resin is 0.618, the resin is a common 'go to' material for a Idler Drive, it is Massey and as far as I know, it does not dissipate energy as efficiently as a Densified Wood or the lesser efficient Compressed Bamboo.
The Bamboo Top Plate Mounted 401 > Origin Live ' Illustrious ' Tonearm > Sumiko Pearwood Cart' has had Isoacoustic Footers and has been mounted on a Sub Plinth assembly produced from my owned Panzerholz Board and AT-666 Footers.
The demonstration proved to be quite attractive and memorable, the 401 had recently replaced a SME 20/12 > SME V, the group in attendance and the 401 owner were not missing the sold of SME equipment that were all quite familiar with.
Through a friend I have listened to various works undertaken on a standard Lenco GL 75 Bearing and their methods adopted to rigidly secure the Bearing Housing from flexion.
I have had my own PTP Solid Nine used a comparison to the friends undertaken works, with the outcome being assessed that a standard Lenco with selected methods adopted, can sound almost identical to a PTP, possibly only the Plinth Materials > Tonearm > Cart in use being the main influences on the differences detected.
Shortly before the Covid Lockdowns, I would have suggested it is impossible from my experiences to pick an absolute preferred TT, as their were too many variables in the demonstrations, i.e, Plinth Materials, Tonearm, Cart's and TT Mounting Methods.
This changed just prior to the Lock Down Period, the friend with the GL75's had received a Extended Length SPH Bearing, it was supplied as a Special Version, as my friend had encouraged the Bearing producer to have a Spindle made that was a Composite design, the Spindle has Metal within the housing and a Ebony Wood is the attached Part of the Spindle that is visible above the Bearing Housing.
I also know the Thrust Pad was changed and the Lubrication in use was said to be working as Hydrodynamic. Being very familiar with this persons work and different concepts, as well as having my own PTP with the PTP bearing used as a comparison to their earlier work undertaken, I was not expecting too much of a margin of change.
The version of SPH Bearing in use attached to a GL75 with a Speed Controller, was the most indelible memory I have from any experience in recent years, it was a very gathered and exact presentation, that was the most attractive of many recollections and was being perceived as being noticeably improved over prior experiences.
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My advice is to buy a table that is built to last and that is easy to set up (the latter applying primarily to the arm) because your biggest obstacle to accuracy is your cartridge, the cartridge set-up, and the spotty quality of pressings. So back to your question-see my profile if you wish-my answer is "YES!".
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I would just keep the Garrard.
I have a 301 in a Woodsong plinth with an upgraded pulley, idler wheel and a Shindo bearing and platter. Some modern turntables may do some things better, but it will be difficult to exceed the overall sound.
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@pindac What bearing did you prefer?
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I have heard Idler Drives in there original Plinths, modified original Plinths and Custom Plinths from Laminated Materials, such as MDF, Plywood, Granite, Slate to produce a Solid Block with rebates machined into to enable the required space only for positioning the under chassis parts.
I have heard some of these TT's with replacement bearings from Jolyon, SPH and the PTP Bearing, I was once to set up a Bake off for a selection on six bearings.
A few of the TT's I have heard as Stacked Platter assemblies.
Some have been purpose produced to offer the chassis a additional support to reduce flexion and the Bearing Housing has been rigidly encased in rebate as part of the Plinth Design.
From my experiences through demonstrations offered, a Massey Plinth is always the better method, there is a perception of improvement on the Bass Notes.
A Supported Chassis and Bearing Housing that is designed to reduce flexion has a much improved performance on the overall presentation, the idea of returning to a previous plinth design is a 'no no', I am not alone in this thought.
A selection of these TT''s have been demonstrated with the Nigel Speed Controller and another selection have been used with the NSC and the LDA quartz Locked Speed Controller as a Comparison.
In all cases the Speed Controller has a very positive impact on the Bass which makes for a better mid and high frequency, the LDA has improved on this best in my experiences.
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I do like Garrard, but I have now a Thorens 124 MKII with SME 12 inch : I adore !!
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I too have a slate plinthed rebuilt 401 with aftermarket idler (Artisan Fidelity), platter (PAC), and SPH bearing. I don’t have a power supply. One inexpensive tweak that really helped open up the mids/highs was to add 3 x Nobsound springs as feet. Another was to use a "rack" of concrete blocks. See my system under my profile.
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The shop I mentioned above that puts idler tables into ultra high end systems likes the Thorens 124 the most for sound quality. Their tech who refurbishes and sets up tables likes the Garrard for its simpler design that makes maintenance and adjustment easier. I like both brands from what I hear.
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Thorens TD-124 MKI or MKII
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The 301 was the late Art Dudley's favorite TT. He preferred it over his Linn Sondek!
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I owned and used a Garrard 401 which received a Martin Bastin Overhaul inclusive of his Modified Platter Bearing for many years, it was used with a SME IV for a proportion of its life and was mounted in a Substantial Monolith Granite Plinth weighing in at 9 Stone.
The Bass Authority you are referring to was dominatingly present in my set up, it was able to underwhelms the Mid's, Upper Mid's and Highs.
The Plinth and Tonearm were introduced to attempt to control the coherence across the frequency range, but in fairness even though there was an improvement, the Bass remained the Authority throughout most replays.
This changed though, but not as part of my ownership, but when it was with a friend and its new owner.
I bought in a Nigel Speed Controller that was designed able to work with Lenco's and Garrards. The NSC was used on my PTP Solid Nine and it cleaned up the Bass Authority on this one very well and the Bass become much less bloomed, with a tighter note and faster decay. This really allowed the upper frequencies to project.
The NSC was used on the Garrard owed by a friend and he was so impressed he built one for his Garrard and Lenco's
Over a period of time, a few other friends acquired Lenco based TT's to be second/third TT's and a opportunity became available to loan a Long Dog Audio Quartz Locked Speed Controller, this was used as a comparison to my NSC and My friends NSC design, at three different properties on Lenco's and Garrards, all with different Tonearm > Cartridges, the LDA was the most impressive in use by a large margin.
The use of this tightens the bass further and introduces a noticeable fast decay, where the Mid's and Highs are much further projected.
I heartily encourage a home trial of a Speed Controller on a Garrard or Lenco Idler Drive TT.
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so I guess what I'm asking is if that weighty full sound of the idler is a coloration. An over emphasis of a certain frequency that is perhaps not true to the record??
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If there were an agreed upon standard by which to compare something to, the concept of “accurate” might have some meaning, but there isn’t. On top of that, there are so many ways by which something could deviate from that ideal, there would be no way to decide which takes priority and how deviations in one measure should be weighed against deviations in another aspect of performance. In short, accuracy is meaningless. If the Garrard delivers musical insight and pleasure, it is performing well.
I like the punchy and weighty sound of idler tables like the Garrard 301 and 401. A local dealer puts these tables into six figure systems based on sound and only resorts to modern tables where customers are reluctant to go with vintage tables. I own a good modern table-Basis Debut with vacuum clamp and motor controller. It does a better job than idler tables at suppressing ticks and pops and other noise, but, I would not argue with someone who finds the table to sound “dead” compared to an idler table. In their particular way, the 301 and 401 are fully competitive with good modern tables.
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