Tonearms

The iota-audio-design “Satori”







































Design and development of the Satori range of tonearms....


The iota-audio-design Satori tonearms are the culmination of many years of design, development, and testing, which comes after more than thirty years direct involvement in the design and development of Hifi products. During this time I have been very fortunate to have had an opportunity to both own and  evaluate many of the finest tonearms available.

Throughout this exposure to these many different tonearms I have been able to assess what properties I would like to see in my own designs. The Satori therefore incorporates what basic principles I believe represent the biggest influence to the sound and tonal characteristics of a tonearm.

Many designers eulogize about the virtue of ultimate rigidity and therefore apply it to all aspects of tonearm design, and when they do so I believe they can miss a salient feature of vinyl record sound reproduction. The sound we hear is as a result of vibration, and I believe absolute rigidity at the expense of all else does not always provide the best solution when you are searching for tonal neutrality and information retrieval. I believe vibration control and the channelling of unwanted energy are actually the key elements to consider in tonearm design.


  










































During the design and developed of our turntables we use  a wide variety of tonearms, as a result when it comes to your preferred choice of tonearm  you are the final arbiter as to what principles, appearance or price you feel is best suited to your needs.

Whatever you choose you can be sure that due to the design principals employed in our turntables your chosen tonearm will easily be accommodated and allow you to get the best from your music.

Obviously we now have our own range of  tonearms in the form of The iota-audio-design Satori, The Satori II, & The Satori B, but we appreciate these  may be out of reach for some customers and we therefore offer our turntables with a number of different arm boards, so that we are able to offer more affordable products as well.

Probably from the most successful tonearm range of all time are the products from Rega, these offer a starting point with our turntables especially if our own offerings are not within your initial budget. Then at a later date the standard Rega arm can be replaced by either the Satori B or Satori II as these are both compatable with standard Rega arm geometry on our turntable products.  The iota  Swingweight II the original version of which has been available since 1998 is incorperated in all our tonearm designs.


















The iota Satori B uni-pivot tonearm.

This is the starting point of our tonearm range, and is designated as the Satori “B” as this is our “base” design in the Satori series, as such it is our essential foundation or starting point, forming part of the essence of all our other designs . However its performance is anything but basic!

Our other models share some materials, techniques, and design features with the Satori “B” , but this is not simply a stripped down or basic version of our other designs,its merely a different implementation to achieve the same goals, that of accurately holding a cartridge and extracting as much detail and musical information as is achievable, while adding as little as possible of its own character to the sound reproduced.
 
Key features of the Satori “B” tonearm.

The main body and structure of the tonearm is made from a combination of machined Acrylic/ Delrin, and carbon fibre . The arm wand has a resin composite fixed headshell that uses our “load plate” clamping arrangement for cartridge fixing. The wand itself is manufactured in square section Pultruded carbon fibre, this material is square on the outside and the internal is round in section, thus providing additional structural rigidity. This wand is supported on a hardened single point of stainless steel held in a brass base, the point of the bearing is in contact with stainless steel bearing cup in a uni-pivot configuration. A pair of lateral side pods or weights enclosures are attached on each side of the wand, & above the bearing point on the wand, these pods can be loaded with different mass weights internally to ensure the correct lateral balance of the tonearm.

As with our other tonearms The Satori Swingweight is  again used and bias is applied by attaching a bias weight to the rear stem of the tonearm by mono filament line, this weight is supported on a stainless steel wire support hook attached to the base of the arm.

As with our other tonearms the internal arm wire is once again from Cardas and this exits the top of the arm and terminates at the rear of the turntable in a plug and socket arrangement, as used with our other tonearms, once again with a choice of either XLR or RCA phono connections on the output cable. This ensures ease of cartridge fitting as the tonearm can be simply lifted off its bearing point and unplugged from the output cable.

The arm is fully height adjustable by simply slackening a grub screw in the arm base that acts upon the locking groove machined into the side of bearing support stem.

The tonearm wand and structure is grounded from the base of the bearing support stem to ensure an appropriate grounded connection to a phono stage earthing point.

The tonearm has a fully height adjustable arm lift, and when not in use the arm wand is held in its support cup to prevent accidental damage to the arm wand and cartridge.


To understand the development of the Satori range it may be helpful to establish the first principles as they apply to tonearms.


What does a tonearm do…….?

The basic purpose of the tonearm is simply to hold the cartridge, of whatever type, moving coil, moving magnet, just above the surface of the vinyl record in order that the tip of the stylus is in full contact with the spiral groove that is pressed into the surface of the vinyl record, thus allowing the cartridge to “read” the groove modulations. The subsequent movements of the styli are used to generate electrical energy; this signal is then sent to a suitable phono stage in order to pass through an RIAA equalisation network to reproduce the original sound.

In order to achieve this the tonearm must be able to maintain a suitable pressure or down-force thus ensuring the stylus contact with the vinyl record groove, whilst also accommodating any warps in the record, and to accurately follow the spiral groove on the vinyl as its size diminishes as the record rotates and the groove approaches the centre of the vinyl record.

What's the “conventional” approach to tonearm design?

  • The majority of tonearms on the market whilst varying in materials, dimensions, and appearance, still follow one of three or four basic design fundamentals when it comes to how the arm is manufactured. Most tonearms but by no means all are usually made from metal, often aluminium, magnesium or similar. The most common type of tonearm irrespective of other factors normally have conventional roller bearings arranged to provide movement in both horizontal as well as vertical planes, in a Gimbal bearing arrangement.

  • A smaller number of designs use an alternative construction, these are arranged as a Unipivot where the arm is again commonly manufactured in metal and sits on a single point or spike and pivots in both vertical and lateral planes, in order to limit the maximum excursion of the arm some designs also include some form of control pins or dowels at the side of the pivot point.

  • A small number of other tonearm designs use some form of suspension, often a single cord and then usually employ some additional form of controlling force, for example magnetic attraction or floating the tonearm in a bath of damping fluid etc. once again to limit the excursion of the arm.

  • A fourth and far smaller number of designs are the more rarefied group of parallel tracking tonearms, operating on a fundamental different principal from all the other designs listed above. These allow the cartridge to track the record in a parallel manner as opposed to all other types that are pivoted from a single position and then traverse the vinyl in an arc.


The Satori II uni-pivot tonearm.

This new tonearm is of a different design and structure to our original Satori suspended control point tonearm, the Satori II is a little more conventional uni-pivot type of tonearm design & uses the same geometry and mounting hole size as any standard Rega pattern arm, with a three point fixing base and single 25mm mounting hole, and can therefore also be used as a “drop in” replacement on any other turntables that accepts this form.

The tonearm is made from a combination of stainless steel for the bearing point and fixings, & POM (Polyoxymethylene), precision turned components, and a fully damped roll wrapped carbon fibre arm wand tube, and composite headshell. The internal arm wiring is Cardas and this terminates in a plug/socket assembly mounted on the rear of the turntable chassis. From this point we offer a choice of tonearm cables terminated in either standard phono connections or three pin balanced XLR plugs suitable for our balanced phono stages. The tonearm counterweight is of our “swingweight” type to maintain dynamic balance under all conditions.

The Satori II uni-pivot tonearm uses a precision ground point and bearing cup that are manufactured in stainless steel. The bearing point and the arm is height adjustable by slackening a 30mm diameter knurled locknut by hand, on the tonearm base, while inserting an Allen key into the arm mount from below. The arm base, arm lift, anti skate bias assembly and the main “top hat” shaped sections of the tonearm are all manufactured from solid extruded Polyoxymethylene (POM) also known as Acetal or Delrin. The “top hat” has a pair of stabiliser weights cross-bored into its bottom section at 90 degrees to the arm wand. These side weights consist of a combination of brass and stainless steel weights, and stainless steel knurled hand adjusters, this allows the weight to be varied to ensure the arm can maintain lateral dynamic balance with any weight of cartridge.

The silicon damped arm lift is fully height adjustable to accommodate different cartridges, and at the back of the arm is the anti skate bias assembly. This consists of a Acetal top cap on a carbon fibre tube that is mounted on a base section, that is in turn attached to the arm mount base. Inside the carbon fibre tube, protected from any strong current of air or drafts is a tungsten weight suspended on a monofilament line. This passes through the top cap and is then looped at the end, this goes around the end of the arm wand at the back of the arm, just before the counter weight. The loop is held in position by a pair of Nitrile “O” rings and their position on the arm wand stem determines the amount of bias applied, with the greatest bias effect being set with the bias monofilament line closest to the the counterweight. The ideal position of the bias line is best determined by trial using different musical material. We do not recommend the use of blank bias test tracks on test records as they tend to provide generally unrealistic results when compared to real vinyl recorded music.

The arm wand is constructed from roll wrapped carbon fibre tube that is internally damped, this offers exceptional rigidity. Our bearing design, combined with the tube material used in the construction of the tonearm help to control any vibration within the arm structure, and we have filled the main arm tube with a granular damping material, this surrounds the Cardas cartridge wires that are run inside the arm in a PTFE protective sleeve. The internal tonearm Cardas cable is especially designed for this role, and this cable was selected as it provided us with the most outstanding results from all the cables we assessed during both of our the Satori, Satori II, & Satori "B" tonearm developments.

Our design takes account of the unwanted energy which might, for example, be produced by a moving coil cartridge & we control the generation of standing waves up and down the length of the tonearm by the use of internal damping. If these waves are not dissipated appropriately it can result in potentially out of phase frequency affects, or even loss of certain frequencies due to cancellation or possibly induced mis-tracking in the cartridge.

Satori Swingweight

For the Satori we have  developed the "Swingweight" that we first introduced as a modification offered for Rega arms some years ago (1998). However we have used the opportunity to build the weight assembly  from gunmetal and the counterweight has a non resonant centre core section made from Acetyl, this material is used as an interference fit within the counterweight to act as additional damping.

The counterweight stem is  manufactured in brass with a lock nut assembly of the same material. The threaded counterweight stem actually passes into the arm tube when the position of the counterweight is adjusted. As a result small changes in the effective mass of the tonearm take place as the position of mass behind the pivot point of the arm changes, however these are very small and consequently do not significantly affect the quoted figure of 11 grams.

The gunmetal counterweight is mounted below the centre line of the arm, on the threaded counterweight rear stem, this allows for very fine and accurate weight adjustment. The weight is mounted on an independent bearing assembly and is decoupled from the rear stem, this allows a controlled amount of free movement of the weight. The result is high levels of decoupling from the arm structure, whilst the low mounting point for the counterweight, below the arms centre of gravity produces greater dynamic stability, particularly when encountering record warps.

The sonic improvements offered by the counterweight include greater tracking ability & dynamic stability, more low level detail retrieval, as well as much more precise and solid presentation of the stereo image. In short, more information less colouration!


Dimensions and specifications

Tonearm length styli tip to pivot point..................237mm

Tonearm pivot point to centre spindle...................222mm

Overhang ….....................15mm

Offset …..........................22 degrees

Effective mass.................10.80 grams

Standard mounting plate ..100 x 120mm

Headshell Fixed std ½” mount.

Cartridge weights.............4>11 grams



Materials used in construction

Stainless steel  components.

Acetyl.... arm board spacers and other turned components.

LG-3.... counterweight.

CZ121.....lock nut & misc components.

Pultruded carbon fibre Satori "B"&  Roll Wrapped  Satori II.....Tonearm tube.

PVDF (polyvinylidene flouride) Bias weight  filaments.

Die cast aluminium....Arm mounting plate.

PTFE protection sleeving.

Various....Granular damping.