Denon dp-80 (and other vintage direct drives) vs modern turntables

When a Individual Adopts the intention to have a Bearing created being as  Optimised as they can create as a performer.

Even if this is a discipline restricted to having a look within the Bearing Housing at the lubrication Condition/ Exchange Lubrication on a Yearly - One and Half Yearly - Two Yearly task to be carried out, the Thrust Pad can be inspected at these times.

There is little info to be seen where Thrust Pad Wear has been witnessed, to suggest even a Thrust Pad with a much increased point loading will be subject to excessive wear at this timeline. There is only a very small cost to be incurred, if periodically a Thrust Pad is exchanged, even if a Thrust Pad in use, is showing no evidence of wear that is a detriment to the performance.  

I do suggest that a Sapphire Selected as Material will create a condition within the Bearing Housing that pretty much needs the set up to not undergo a transportation. A Trust Pad could receive an impact from the Spindle through being in transit, which could lead to a Sapphire Part fracturing. I put Sapphire on the materials option as there is not better to create the lowest coefficient of friction and least drag. Look at the modern TT's, Sapphire is on their materials used list. 

More robust parts selected to be in use, are not a concern to be selected, only downside being a lesser low friction and drag will be the outcome.

Assuming the average TT owner, especially TT owners with TT;s in use with multiple of years of usage and potentially never having received an investigation/service of a Platter Spindle Bearing, has the outcome where the owner is likely to to consider / adopt such methods, as to use new materials and change interface tolerances with intent to change the design for the TT’s Bearing Assembly is wishful thinking.

Over multiple years, I have as a guestimate had a dialogue with 50ish People through forum activity, where like minded individuals have expressed a keenness of of interest when it comes to Bearing Servicing.

Tighten that down to between 15 - 25 like minded individuals when it comes to expressing a keenness to learn more about Bearing redesign concepts and achieving a design.

Tighten that down to a handful+ when it comes to the actual work being carried out, and not all individuals expressing the interest are intending on carrying out any of the work. The most valuable work undertaken in this area, is done by the hand of a few only.

In recent times it has been learnt, especially within the past few years, due conditions of a Vintage TT when in use, there is different conditions discovered to the wear witnessed on a Vintage TT’s.

Not one TT can be the model to produce a Pattern Part for all sibling models.

The learning shows, each TT is needing to be dimension checked and Bespoke Parts are likely to be required to produce the tolerances wanted to be used, when it comes to the Bush/Spindle Interface. This means to get the interface with precision, a Bearing Housing and Spindle needs to be with the Machinist for their producing and fitting the parts. This does make the option more limiting if the wanted success is to be the outcome.     

There is not too much of a concern for the Thrust Pad Interface, choices made are transferrable without complication if another wants to adopt the method.

For the Thrust Pad, I have seen Bowling Balls machined down to be the Parts, which turns out Parts in use are Lignum Vitae Wood. 

For the Base of the Bearing Housing I have seen new Sump Caps produced, that allow for the Base of the Bearing Housing to be rigidly anchored through additional fastening options being used with the design for the new sump cap.

The anchoring has also be seen to work like a drain, where energies are transferred through a tie rod into a hefty brass foot and oil compacted sand. 

Once the concepts start flowing some ideas go for the controlling any flexion of the Bearing Housing prior to concerning one self about the internals of the bearing housing.

To date I would strongly suggest the most rigidly secured bearing housings where flexion is potentially not present are belonging to those seen on Kaneta Design SP 10 Mk II and a Yamaha GT Model. My own assessments suggest all typical designs for a Bearing Housing, especially on a JVEDDTT, where a Stator Bowl is in use, are all potentially showing a flexion. Some Stator Bowls are pressed from Metal less than 1mm (1/32").  

The Kaneta design I have in use, has advantages as the new produced Panzerholz Plinth/ Chassis is designed to have the Stator Bowl and Projection of the Bearing Housing couple together as an interference fit. A notion is on the table to produce a new design sump cap and have a tie rod drain option, but as the design lends itself to a whole new design for the bearing parts and assembly, the focus is on a new bearing design.   

I am a full ’heart on sleeve’ advocate of giving Vintage TT’s a new lick of life, this has been with me for the best part of 30 Years. I started out with Garrard ID's superseding used BD TT's and then moved fro Garrard ID's to Lenco ID's, where I still own the PTP Solin Nine to date. This then extended to Japanese Vintage Era DD TT's 

I have a few reasons for the intent to refurbish/modernise, but strictly relating to audio, when undertaken where modern design is fully adopted, a substantial performing TT, is to be encountered and no one else is owning one unless they commit to the similar venture.   

To get confidence the Speed Control on the owned DP 80 is not affected will come with a small cost, as a Standalone Speed Strobe Light will be the most accurate way to do a on the fly Speed Rotation Investigation.

Owning a Strobe Light is a useful tool to have for anybody using a TT, built in strobes are not accurate, and I have been demo’s this too many times.

If the DP 80 is with a speed stability fault and it is suspected to be a damage to the Magnetic Coating, there is a further option to be considered.

1, Using available Info, set up the magnetic sensor to the correct spacing to the magnetic coating to become assured, the sensor is not able to scratch the coating.

2, Look to source a second DP 80 as a Donor Model or First Model, adverts on the sale site in the link usually show the TT’s Built in Strobes are locking onto required speeds.   

The Model in the Link has undergone a proportion of an Electronics Overhaul and has Strobe Images Shown.

https://www.fromjapan.co.jp/japan/en/auction/yahoo/input/g1196538096/

Note: These Designs Have Their Fragilities, so once functioning need very special attention to be preventative against creating further unwanted damages to critical interfaces.

The Platter Bearing will substantially benefit from a investigation and service.

Applying light pressure from the fingers to the Bearing Spindle might detect an amount of movement.

If movement is felt by touch, the Standalone Speed Strobe Light should have detected an instability of Speed as well,  as eccentric rotation of the Platter Spindle will be detected as erratic speed control, the Wow/ Flutter will be askew.  

The Likelihood when extending the investigation to the Internal of the Bearing Housing, is that the condition of Lubrication is one that is Arid Dry.

The parts on the Spindle that Interface and the Parts that are Sacrificial and expected to show wear can be discovered with quite concerning conditions, when a Dry Bearing has been in use for ??? ??? ??? Rotations.

The Spindle Sidewalls will need checking for surface damage at the Bush contact points and the Base of the Bearing will need checking for damages, the Interference Fit Ball may have a scribing on the surface.

The Thrust Pad when used in an arid environment will also be expected to show some type of Damage.

The Seal used in the Base will most likely enable a liquid lubricant to leach out!!!.

A Thorough clean of the Inner Housing and Parts removed will be very beneficial.

As the minimum prior to a lubrication being added, consider that the Original Seal can be exchanged for an ’ O ’ Ring or ’ X ’ Ring. This is proven successful on other Japanese Vintage TT’s. 

A low level lubricant fill can be done and monitored over a period of One Week, if no leach occurs then there is the Eureka moment. This will be useful to learn as containing lubrication is a high priority.  

An Interference Fit Ball could be swapped out for a Sapphire or a Ceramic Ball.

A Thrust Pad could become a Sapphire Disc.

If wear is discovered in the inner wall of the Bushes, this is a more difficult to correct. Discussion on a correction would need to be a follow up topic.    

The Top Bush could be recessed into the housing by pushing it down a few extra mm’s (1/4") would be too much. Use the Top of the Bush as the fill level for the lubrication. A Felt Pad could be used to Cap the Top of the Bearing Housing.

If bushes were reproduced using a very stable Thermoplastic and interfaced with the Spindle using small microns as the dimensional spacing, this would be in keeping with some of the best journal bearing designs that are being offered to purchase.

The Mod’s above are found in after market Bearing designs commanding up to £2K.

The DP 80 when working with no Speed Control Issues and produced to a certain standard mechanically. When housed in a Plinth which uses a material that assists with the Optimisation of the Mechanical Interfaces between TT > Cart’ > Tonearm being moved towards optimisation for Damping and Dissipation as the overall design for the TT. There will be a real time challenge produced for other designs from the modern era to better.

I am familiar with a selection of TT’s taken to the above design suggested or close variants oof this design type and know how they compare to an original design for the TT model. Where the outcome is the New Design is not going to be undone in any ways, and the older design is not given any extended time in being used as a comparison demo’, it is proven as being a TT that is truly bettered.

Even though not having heard a DP 80 taken to this design stage as of yet, but owning a selection the models and having this intention for one model, past experiences and the knowledge attained about the effect of other design changes on other TT’s, gives confidence for myself to suggest, modern TT’s of £20Kish is where it might be discovered that the DP 80 has a weakness if encountering these TTT types for comparisons. 

There is plenty known about what to look for when investigation the of the Bearing Housing Parts are being exposed.

Always best to keep a keen eye for discovering minute gold coloured dust, this is the softer material from the Sintered Bronze Bush having been separated from Spindle Metal in contact with the Bush, it is the occurrence, that substantially contributes to eccentric rotation, speed stability issues and an amplified platter run out at the rim.   .  

The Sump Seal will be under suspicion for not being able to retain a Low Viscosity Lubricant, having a alternate ' O ' or ' X ' Ring to be the replacement Part will assist with creating a seal that works. I like the ' X ' Seal, as it supplies two lines of contact for what is a low pressure seal. 

My engineering friend has informed me, that a correctly designed Journal Bearing with all metal parts will be as quiet in operation as one with non metal parts used in the same design Journal Bearing.

The challenge is creating a design that is able to have non contact between metal parts. The slow rotation and non pressurised design used typically on a TT Bearing makes this very very difficult to achieve.

A Lubricant Filled Bearing Housing will remain subjected to Boundary Effect issue, where when Metal on Metal is to occur, this becomes the cause of Friction and Drag and in certain cases a sticking of the Parts. The use of a design that removed Metal on Metal is known throughout industries for the benefits on offer.

This is where certain designs of Thermoplastics have proven their value in all areas of industry, even in the low speed rotation Journal Bearing, as the Thermoplastic when produced to a particular compound and hardness, does not generate the same effect as a Metal when the rotating spindle makes a contact with the non metal part.

Well before I was showing an interest in separating Metal on Metal in an audio related interest, another Interest I was involved in during my late teen' years was using Teflon to separate Metal on Metal and substantially reduce drag and improve the user interface.

Over a few years of the success at a competitive level the designs were having, not many of the items being produced for competitive level activity were without Teflon or some other equivalent used for separation, the cat was well and truly out of the bag. 

More importantly, an alternate lubricating method to negate the use of a Separation was or has been discovered, but such designs are superseded to day for a completely different mechanical design. 

With such a background, I have made it known before, I was Instrumental in encouraging a friend quite into the Lenco TT, to have produced a Bespoke Platter Spindle Design to go with a replacement Bearing Design that was incorporating no Metal on Metal as the fundamental design.

The Spindle Design for the Bearing was suggested to be in keeping with the overall Bearing Design. The Spindle Design was Bespoke in itself for a few reasons.

The Spindle was increased in overall length to the typical extended length option, with the intention to minimise the effects of Runout at the Platters Rim.

The Spindle was a design which was offering the option for using Two Different Materials. Where the lower Spindle was a metal section that was within the Bearing Housing. The Upper Spindle Section was able to have different material used that are in contact with the Platter.

This option of choosing the material to be in contact with the Platter was proven to be quite beneficial through trialling a selection of materials to come into contact with the Platter. Change to the levels of noise detected using a Stethoscope has occurred, where it is clearly understood which materials used were influential on reducing the noise being transferred into the TT's structure.

Non Metal Interfaces used at the Spindle / Patter interface were showing superior influences on noise transfer over metal.

My take on it was to extend the use of Wood Type to a Panzerholz type wood, as it is engineered as a design and will be more stable in use than an African Blackwood.

Panzerholz would have properties that assist with it to be closer to the stability on offer from a Metal Part.