Turntables
Design, Materials, & Construction.

  
**** New developments  for 2018/19****

A new small thing that matters.....the iota Prima

 In addition to the existing Phase III iota turntables !

  • iota iota QT
  • iota  jot S-P
  • iota QT Ultra
  • iota QT Ultra SP

Our current  range of turntable products represent our third phase of product development, they offer an ascending level of engineering complexity, cost, and  performance.

Since the beginning of 1990's we have produced a number of turntable models bearing the name of QT. These have varied in design, materials, and the performance levels. The original QT designs were conventional in appearance, with hardwood plinths and solid top plate.  ** See About US **

Around 1999/2000 the QT Evolution range was launched with a hardwood support frame, or with aircraft grade aluminium tensioned side rails,  removable arm plates, and a granite base board.

The phase three range  are very different in both appearance and materials from the original, but the design goals remain the same, we aim to provide the maximum musical enjoyment from vinyl records with an accurate and honest portrayal of what was actually recorded.

See also our Turntable page

Chassis, & motor/bearing module of our turntables.

To achieve our basic design goals it is desirable that the chassis of a turntable be a stiff, strong, resilient structure that offers excellent control of resonance and ringing. We have chosen to use both die cast aluminium, and  anodised extruded aluminium structures in our designs as these are both immensely strong and stable under all normal conditions.

The complex external shape of the extrusion, as well as its internal stiffening ribs, increases the rigidity of the beam rails that makes up the main chassis components of our current range. This provides a structure that has enormous strength and stiffness when compared to a solid material while at the same time offering a lower mass, thus reducing the storage and release of unwanted vibrations.
















To house the motor & main bearing we have created a module for which we have used a high quality rugged, die cast aluminium alloy box, this offers an enclosure that is both exceptionally rigid and strong and it also provides for improved EMI/RFI shielding, and its material structure is extremely consistent in all other respects.

The main bearing of the turntable is made from a bronze sleeve, this is surrounded by an Acetyl bush and this whole assembly is  rigidly mounted into the module, and it is then heavily damped and braced with a number of different damping materials and compounds used.

The centre record spindle of the turntable is also made from a bronze gunmetal, while the shaft of the bearing is polished stainless steel, this runs on a Grade 5, Silicon Nitride (Si3N4) ceramic ball, which in turn is in contact with a bottom thrust pad made from the ultra high performance PEEK polymer (Polyether ether ketone.) . Lubrication for the bearing is provided by an advanced synthetic lubricant, ensuring a long and noise free life for the bearing.

The sub platter of the turntable is constructed from a combination of a moulded ABS resin structure, bonded damping material, and polymer resin, and the top face has a constrained layer of carbon fibre. All of these materials were carefully chosen to control vibration and unwanted energy storage at this critical location directly below the platter.

In a separate section of the module the high quality AC synchronous motor is resiliently mounted and enclosed by damping materials and fitted with a thrust bearing to reduce "end play" & noise. The whole module is fitted to the chassis with decoupling gaskets and then mechanically fixed to the rear and front chassis beams to form the basic  shape of the turntable.

The arm board module on our QT & QT Ultra turntables are again constructed from a similar high quality die cast aluminium alloy enclosure, this is mechanically secured to form a cantilever to the rear chassis beam of the turntable.

The aluminium extrusion beams that make up the turntable chassis have “T” slots and the fixing mounts that hold the arm board module are located within this “T slot”, this allows arms of different effective lengths to be easily accommodated by simply loosing the arm board mount and then sliding the whole assembly along the chassis rail to the desired position, thus achieving the correct tonearm geometry, and then simply locking the arm board in place.

The  QT turntable is supported on a baseboard with height adjustable feet, these are made from Solid Beech hardwood faced with anti slip & furniture protecting material. This combination provides a stable support with excellent acoustic properties, and the turntable can be easily levelled if the surface upon which is to be used is not level.

Selection of Platter material


Over the years numerous different materials have been used by countless different turntable manufactures for the production of the platter that supports the vinyl record. The platter on a turntable not only acts as a suitable flat and even support for the vinyl record itself, it also has the body and tip of the main bearing in the form of the centre spindle embedded in the middle of the platter. As a result even with the finest main bearings there must inevitably be vibrations as a result of rotation of the platter and bearing, and these must pass into the body of the platter and therefore into the vinyl itself in addition there is also the noise of motor breakthrough transmitted to the platter through the belt or simply the structure of the turntable.

There is also acoustic feed back from the musical noise produced from the speakers that is also acting upon the turntable. Therefore the cartridge which is by design a device to produce electrical signals as a result of vibration will reproduce all these extraneous signals in the form of low level noise. Therefore a platter material that could offer good damping, and is to a greater or lesser extent an “inert” material may therefore be considered desirable.

Another factor often used to select the substance from which a platter may be fabricated is the mass of the material. Dense heavy platters although initially slow to get to accurate speed may be pitch stable as a result of inertia once up to speed. Unfortunately high mass also produces more strain on the main bearing, and hence more noise when compared to lower mass materials, and once noise has been induced in a high mass material it is released for a longer duration.


Our previous platter solutions.

Previously our turntables like many others used either acrylic or similar materials for the platters, with the aim that by using a material that closely emulates the mechanical properties of vinyl itself, should offer a close to neutral support to the record surface.

A platter made purely from vinyl is impractical for many reasons. Vinyl itself lacks structural integrity and therefore many designers try to achieve a close match to vinyl, whilst avoiding the limitations of vinyl itself, and acrylic is a very good compromise material for the purpose.

However when the platter is made from a singular and uniform material (like acrylic) its response when excited by vibration will be uniform, and this will occur specifically at the materials fundamental resonant frequency. Simply making a platter of a greater thickness, and therefore higher mass, but still from a single uniform material will not change that characteristic, only the amount of energy stored. As vibration can only be dissipated in the form of motion or heat, and acrylic no matter how great its dimensions will still therefore be subject to resonance and unwanted vibration.

In the case of a metal platter this will produce a “bell like” ringing mode, and any manufacturer using such a material must add some additional damping to try to avoid this. Rubber mats were often used in the past for this purpose. However the many detrimental affects on the vinyl record of rubber and similar materials were found to be undesirable. The same is true for felt mats, felt is also attracted and sticks to the vinyl record due to the static charge in many records, and felt is not particularly effective material for damping a ringing metal object like a metal platter.

The MLM Platter

During development of these latest turntable designs we experimented extensively with alternative platter designs and materials, one of the solutions we have implemented here is the MLM platter. This is a combination of an external shell of an extruded synthetic polymer that is very close to the material properties of vinyl, and on the circumference of the platter shell are bonded two resonance control damping bands, to further enhance resonance limitation the internal structural core is made up of different materials bonded in the form of multi laminated materials (MLM), hence the name MLM Platter.

The structural core provides the dimensional stability and mass, whilst the multiple layers of different materials are bonded in such a way that resonance from the main bearing and acoustic feedback are controlled. As a standard accessory we supply a natural cork mat as the final interface between vinyl and MLM platter, as we believe when combined with the MLM platter it will produce a neutral combination of damping characteristics, however as the mat is not fixed the final choice of the most suitable combination is open to user preferences. The addition of peripheral mass weights to the base of the MLM platter aids rotational stability, as it adds mass where it will make the greatest difference, rather than simply uniformly adding mass to the platter, however the weights are fixed to the platter in a well damped & decoupled manner.

The top of the main bearing and its spindle on our turntables is manufactured from gunmetal alloy, and we supply a record clap to flatten the vinyl record onto the surface of the cork mat, this clamp grips the gunmetal spindle and does not damage the vinyl in any way.



An example of the fundamentals of vibration control with singular and laminated materials:-

A speaker cabinet is subject to large amounts of vibration within the cabinet from the music produced, this can result in colouration of the sound we hear. In an attempt to reduce these cabinet colourations in the music reproduction, designers often resort to using thick cabinet walls or heavy damping to try to control or reduce these cabinet vibrations. If two cabinets of identical external dimensions and 18mm section are assessed, one of MDF/ particle board, and the other made from cross-lapped birch Ply, when the results for panel vibration are compared, the cabinet panel made from cross-lapped birch ply will outperform the MDF enclosure, so much so you would need to increase the section of the MDF from 18mm to 50mm to get the same degree of vibration control, or alternative additional damping materials or techniques must be applied.

Why is this? The cross-lapped Birch ply is made with an uneven number of layers of thin Birch hardwood that are laminated using resin bonding, with each layer applied at 90 degrees to the next, and with no additional damping. Whilst MDF or Particle board, is a uniform and consistent wood board made from wood dust or powder that is produced by bonding the dust into a totally uniform panel under great pressure. When energy attempts to excite and vibrate each of these panels, in the case of the Birch Ply as each layer of the laminated panel is so dissimilar to the next in its material make up i.e. Birch layer / resin bonding / Birch layer at 90 degrees and so on, as to offer a shift in frequency transition at each different layer boundary through the panel. On the other hand the MDF is totally uniform in its material content and make up, as a result it will uniformly vibrate at a singular resonate frequency, therefore allowing more energy and vibrations to pass straight through the panel.


iota Prima platter

During the development of our new iota Prima turntable we experimented with other platter materials in order to achieve a result close to that of the MLM platter, but using  less complex and involved manufacturing procedure, as the iota Prima is a lower priced turntable. MDF was chosen as a suitable option for its consistent performance, when we applied additional materials to this base structure.

To enhance the control and damping of vibration within the vinyl record, the high density MDF Prima platter is faced with a bonded mat of cork/ Nitrile composite, and around the circumference of the platter with a ribbed vibration control band, as well as underside "spot" dampers. The result is a compromise of both cost and performance, but we believe a very acceptable one.


External Turntable power supplies.   See also ***Power supplies***



iota MFP 1

As all our turntables use a high quality, inherently low noise, 24 pole AC synchronous motor, therefore to ensure motor performance is not compromised by poor mains or noise, all iota turntables are supplied as standard with our MFP 1 mains filter power unit, this is designed to protect the turntable from any extraneous noise that may be carried or picked up on your home electrical supply that could ultimately affect the motor.

The MFP 1 is constructed in an extruded aluminium housing, this contains a multi stage filter network using high quality components, it is double shielded and uses star earthing in its construction, it is also separately fuse protected. The unit is fitted with the front mounted illuminated rocker switch, and has on the rear a standard IEC mains input as well as dedicated socket for the turntable. The unit is generously rated at 250 watts so offers considerable “headroom” with regard to supplying the load of a turntable.

The down side ? To change the speed of the standard turntable you must manually move the round section belt on the easily accessible motor pulley, we believe this a small price worth paying! However if this is a compromise too far, or you simply wish for more performance without the loss of convenience please see the iota T/T-2 psu details below.



iota T/T-2 speed

turntable power supply is based upon a design that has been available & in service for many years, the original commercially available versions of this power supply were sold at the beginning of 1997, the prototypes having been developed by us and used for some years before that (1992)!

The power supply was developed in response to the large number of major manufactures T/T power supplies that were proving to be unreliable. Therefore reliability was a major factor that we considered when developing this product. Not only did we want maximum performance but did not want to sacrifice reliability, and this has proved to be the case. We invested in good quality components and the results and longevity of the product speak for them selves.

The unit acts as a mains regenerator and affectively isolates the turntable from variations in mains frequency, and voltage. Frequency stability is now crystal locked to +/- 30 parts per million. In fact in order to provide both 33 and 45 RPM for this two-speed model we commissioned specific crystals, these were ground to our exact specification, as we found the standard commercially available items (often used by a number of other manufactures) do not actually provide true 45 RPM! Speed change is now of course achieved by the "flick" of a switch.

The sine wave to drive the motor is generated by direct digital synthesis, and the output is defined for both source impedance and voltage. The unit has been designed to offer excellent "headroom" with regard to the applied turntable motor load. The output from this unit offers five times the maximum load on a continuous basis. With more than eight times the maximum load available short term. This of course ensures that the power supply can be used with a large number of other suitable turntables on the market. The unit is also available for all other international mains supplies. None UK/ EEC voltages P.O.A.

iota QT Ultra-SP

The Spindle Platter & more!


There are two different versions of the QT Ultra one uses a baseboard manufactured from high quality birch  plywood, and on this version is also the MLM platter. While the SP version has a 10kg diamond polished granite baseboard as well as our Spindle Platter, and a number of other options, including upgraded PSU & bearing, and many custom finish options....

The Spindle Platter was developed as an alternative improved platter design, and as such is substituted for the MLM platter. The Spindle Platter is made up from 126 individual components,  including eight centrifugal high mass weights in polished 316 stainless steel fitted onto eight internally damped 12mm polished support arms. The mass weights are fitted with silicon rubber outer “O”rings.

The central hub sits on top of a mass loaded and damped sub platter. Manufactured in aircraft grade aluminium and stainless steel, this has the central 100mm filled with a combination of constrained layer damping materials and is faced with sealed cork. The centre spindle fitted to the main bearing is machined from 20mm  gunmetal. This platter and its extra long gunmetal spindle allows the user to experiment with a variety of different platter mats.

The Spindle Platter was developed to extend further our ideas of reducing the impact of platter colourisations & the negative affects on the playback of vinyl. This Spindle Platter and its  126 individual components include a combination of highly polished stainless steel (type 316) high mass peripheral weights, and aluminium alloy components as well as natural cork, Acetal turned components and advanced polymer resin bonding agents.

Our aim was to create a structure that offers high rotational mass, but to position the majority of the mass at its extreme outer edge, therefore to gain the maximum benefit of centrifugal force. In addition whilst the structure is designed so that it supports the vinyl record where it is most required, at its outer edge, but also at the centre around the turntable bearing spindle. The result is this configuration also helps to control any influence or noise from the turntable main bearing.























The addition of a effective clamp then holds the vinyl flat to this damped area at the centre of the Spindle Platter. However the area of the vinyl that contains the groove from which all the musical information is extracted will be devoid of any platter reflections or interactions. The interface mat is left to do its job, and nothing else, and again as its not fixed, alternatives can be exchanged to the preferences of the owner if desired.

The design uses the high mass peripheral weights mounted at the extreme end of turned and damped support spindles, each weight is effectively decoupled as much as possible from its support mount, and wrapped around the weights are damping rings that are the only outer edge contact with the natural cork interface mat. The position of the eight high mass weights allows the full positive affect of centrifugal force to be applied to the Spindle Platter; this helps to maintain rotational speed stability, whilst at the same time reducing to a minimum the deleterious effects that would have resulted had we simply applied mass uniformly to the whole platter. The eight separate weight/supports ensure the vinyl is not allowed to deflect at its edge whilst the central record label area has total support and damping applied to the gunmetal centre spindle, this is further enhanced by the use of a suitable record clamp.

The iota QT Ultra and the Spindle Platter were also part of our development programme to produce our own somewhat unique Satori Tonearm . This uses bearing and support techniques as well as materials not previously applied or used in other tonearm designs, so we believe a new and fresh approach to a set of very old and familiar problems?