Satori Tonearm

So what's different about the iota-audio-design Satori tonearm? &  **See also our other Tonearm page **

This is something of a hybrid in that it combines some aspects of two different construction principles. Therefore we would describe the tonearm as a “suspended control point” tonearm, in that the tonearm is suspended from an overhead “suspension bridge” by a pair of mono filament cords, these are attached above the tonearms centre of gravity to a pair of stability outriggers fixed above and at either side at 90 degrees to the main arm tube. At the same time the tonearms excursions are constrained by the action of the upward facing control point spike, this is located below the tonearm and is located in a control cup. This bronze control cup locates on the cone of the upward facing hardened stainless steel spike rather than the tip of the spike, which actually makes no contact with the arm at all.

As a result the arm has controlled low friction movement in both horizontal as well as vertical planes, and from the users point of view when cuing the arm it has the feel and convenience of a totally conventional tonearm, and consequently doesn't “flop around” in all directions as the uncontrolled variants of the unipivot designs have a rather disconcerting habit of doing, that is before making contact with the vinyl surface.

Not only do the suspension cords ensure the free movement of the tonearm; but they also have another role, when you apply a twist to the cords the amount of twist applied provides anti skate or bias. This the opposition force that is essential to overcome the pull force towards the centre of the record, which is exerted by the cartridge tracking the diminishing diameter of the spiral groove of a vinyl record when using any pivoted tonearm.

Another advantage of our bearing design is that because the Satori is located on the cone rather than the point of the control spike, and the position of the suspension cords are able to be easily adjusted, and our counterweight is able to swing to find its correct vertical position after any adjustment. The result is the Satori tonearm also allows for micro adjustment and compensation of Azimuth or left to right tilt of the cartridge body and tip. Normally in a conventional tonearm such as a Gimbal bearing arm this can only be achieved if the head shell can be independently rotated and re-fixed, and most designs don't allow this or for that matter any other form of Azimuth adjustment.

What is the Satori made from?

After a great deal of testing and development we concluded that carbon fibre for the majority of the arm construction gave us the best results. This material choice in its self is nothing new, many designs use this material. However most designs use round“roll wrapped” carbon fibre tubes, made up by wrapping carbon fibres around a former in a combination of unidirectional and bi-directional weave. This produces a strong, light, and stiff structure, these “roll wrapped” tubes were developed for applications that require enhanced strength in multiple axes. For example the tubes that make up the frame of high performance  road racing or mountain bikes, or fishing rods etc. In such applications these tubes will be subject to significant twisting and torsional forces, as well as occasional massive shock forces. As a result manufacturers of such items are prepared to forgo some of the maximum stiffness and longitudinal strength to increase resilience for such applications.

However we have chosen to use an alternative type of carbon fibre, Pultruded carbon fibre. There are other designs on the market that use this material in their products,but we are not aware of any other design that employs Pultruded tubes for a tonearm with a square profile. Think of it as round tube with four additional “stiffening nodes” running along its outside length.

Tube manufacturers quote:

Carbon fibre square tubes are Pultruded resulting in very straight fibres cured at high temperature yielding in high fibre to resin ratios and very stiff parts. Square carbon tubes contain no fillers - ONLY continuous fibres.

Compared to other materials and processes, carbon fibre square tubes are twice as stiff as aluminium of the same cross section. Carbon shapes are 350% stronger in tension and 550% stronger in compression than the traditional wet lay-up with carbon fibre room temperature resin systems.

Unlike roll wrapped carbon fibre, Pultruded tubes are made by a machine pulling continuous strands of carbon fibre through a “die” to form its shape, in our case a round central core with a square outer former with rounded corners; as the fibres are pulled through they are automatically coated in epoxy resin, and as they come out of the “die” the epoxy resin is cured at high speed. Tubes made in this way are exceptionally consistent and have all of their fibre running length-ways down the tube, this means that they are exceptionally strong along their length, and also very stiff,and light, therefore offering excellent resistance to bending forces, much more so than similar roll wrapped constructed tubes.

However Pultruded tubes are not as able to resist twisting forces, we believe a tonearm is not going to be subject to any significant twisting forces what so ever, therefore this is not an issue. The only other slight concern with a Pultruded tube is a requirement to take account of any significant crushing forces that may be applied to the tube. Once again this will not be a problem in any respect with a tonearm. Obviously we have taken full account of this fact in our construction and mechanical bonding techniques used in the design.

So why if as we suggest we believe this is a superior material for a tonearm application, you may ask why doesn't every other tonearm using carbon fibre us Pultruded tubes rather than roll wrapped? Whilst we are very happy with the appearance and finish of our material and delighted with the performance it provides. We can only conclude that perhaps the appearance of roll wrapped tube may be a factor. Our Pultruded tube is uniform and smooth in external appearance, but does not bear the “hallmark” carbon fibre chequer pattern that most people seem to expect to see and associate with carbon fibre material.

This look has become so ubiquitous in so many areas of modern life that “fake carbon fibre look” material is now used for many other consumer commodities, and for most people this appearance alone will be enough to satisfy them in the belief that something that simply has this characteristic, is in fact the real high tech material, even when in reality its simply a photographic image sandwiched inside some very ordinary plastic!

We are not for one moment suggesting any tonearm purporting to be carbon fibre is in fact simply a plastic fake, its just that many designers may feel its vital to comply with the average persons expectations of a carbon fibre products appearance, even if an alternative material make up could perhaps offer some potential performance advantages.

The other reason we have used Pultruded carbon fibre tube for the Satori and Satori "B" tonearms,  is we believe as the fibres are all aligned along its length any unwanted energy has a more direct path to the effective “grounding point” which in our case would be the stainless steel control point below the arm. Our design overcomes the unwanted energy which might, for example, be produced by a moving coil cartridge. We have eliminated any standing waves being generated up and down the length of the tonearm. 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 mistracking

Our bearing design, and the rigidity of the tube material used in the construction of the tonearm, help to control any vibration within the arm structure, and this is also why we have filled the main arm tube with a granulated damping material, this surrounds the Cardas cartridge wires that are run inside the arm tube in a PTFE protective tube sleeve.

The tonearm is constructed using a structural adhesive bonding agent, and is also mechanically fixed where this is required to form the structure.

We add a clamp plate on the top of the head-shell, this avoids any physical damage to the composite head-shell by the cartridge fixing bolts, as well as evenly loading this area with the applied fixing load of the cartridge mounting hardware, by doing so this also helps to damp unwanted energy that may be generated by the cartridge.

Similar items added on many tonearms are sometimes used when a low mass cartridge is being used with a heavy counterweight, and under these circumstances can be viewed as undesirable, as the load plate could be seen to add unwanted mass to the structure at a critical point, this is because on a conventional arm a standard metal head-shell can easily add up to 12 grams or more in weight, our head-shell is a fraction of this, therefore the load plate does not adversely influence the total overall mass of our tonearm.

The effective mass of our tonearm is at what we consider an ideal of 11 grams, and is therefore considered to be medium mass, and as such ensuring our arm is a perfect match for a significant number of modern and classic cartridges of all types.

Why is the effective mass of a tonearm important?

This is a subject upon which much has much has been written, discussed, and opinions expressed, if you are unsure of how the relationship works I would suggest consulting some of the numerous sources of information within easy access of your preferred search engine, but by way of a quick step guide, see below.

The correct effective mass of a tonearm is vital to produce the best results from any arm and cartridge combination. All cartridge designs have a degree of “springiness” built into their mechanism, this is to act as a suspension, this “springiness” is defined by a set of manufacturer defined numbers, this is the compliance of the cartridge.

The effective mass of the tonearm(inertia), is often expressed as the amount of mass as seen by the cartridge styli under dynamic conditions, this is not to be confused with the down force, that  force is applied by the counterweight, this is a static figure unaffected by changes in dynamic conditions, suspension, and any internal damping. So think of it as the cartridge is a spring and the tonearm is the mass acting upon it, any effective mass figures quoted are calculated without the tonearm counterweight in place.

To achieve the “ideal combination” we suggest a low or medium compliance cartridge (e.g. moving coil) with our medium mass arm, as a high compliance cartridge requires a low effective mass tonearm. We would recommend using an optimising range of 8Hz to 11 Hz as the resonance figure, although some latitude outside the upper range is considered to be acceptable by some sources of information.

If this is ignored and a cartridge is fitted to a tonearm, and the resulting combination exhibit specific resonant frequencies that occur at a critical point, for example somewhere above 20Hz or even at a much lower frequency, this could coincide with the frequency of record warps or rumble, this “boosted” frequency output can be 3db or even 6db or more, and a 6 dB increase represents a doubling of output when related to noise! The result is bloated or very uneven bass response or even mistracking.

Satori Swingweight

For the Satori we have chosen to develop 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.

As with the stainless steel iota Swingweight II, 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!

The tonearm has a rest position that holds the arm when not in use. In order for the tonearm not be accidentally knocked and moved from this armrest, a magnetic lock assembly holds the tonearm so as to avoid accidental damage to the cartridge.

To aid the fitting of cartridges the whole tonearm tube assembly can be simply unplugged from the socket on the top of the arm board and removed, and upon replacement very easily adjusted with the supplied Allen key,to ensure the correct length and tension of the suspension cords. The arm is supplied as standard with the correct control point and arm board spacers so as to easily accommodate a wide variety of cartridges. Inevitably there may be some cartridges of more extreme height dimensions. For these non standard items we are able to supply the addition hardware required to provide a match for any other cartridge on the market.

The tonearm is internally wired with Cardas cable especially designed for this role. This cable was selected as it provided us with the most outstanding results from all the cables we assessed for the Satori. The headshell is fitted with short cartridge leads that are easily replaced to allow for different cartridge pin dimensions or simply for service replacement purposes. We strongly feel that this is the best option rather than the tonearm being wired in one piece.

Cartridge leads offer the best solution as internal tonearm wires are not robust enough to withstand potentially frequent changes of cartridge, and we concluded the potential very small improvement in performance is simply not worth the loss of convenience and long term reliability that cartridge leads provide.

For connection to your phono stage the tonearm is fitted with a captive output cable fixed to the underside of the arm board top plate. The standard length of cable is 1.5 mtrs, other lengths can be specified. We offer termination of this cable with either XLR balanced plugs or RCA phono plugs at no extra charge.

For customers wishing to experiment with output cables we offer a version of the tonearm where the captive cable is replaced with a termination box, allowing any alternative cable to be connected, the terminator box is fitted to the arm board top plate.

Dimensions and specifications

Tonearm length styli tip to pivot point..................240mm

Tonearm pivot point to centre spindle...................225mm

Overhang ….....................15mm

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

Effective mass.................11.2 grams

Standard mounting plate ..100 x 120mm

Headshell Fixed std ½” mount.

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

Materials used in construction

Stainless steel 316.“suspension bridge”, arm lift pod, & misc other components.

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

Glass reinforced Ny66....”suspension bridge” lock nuts.

LG-3.... counterweight.

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

Pultruded carbon fibre.....Tonearm tube.

PVDF (polyvinylidene flouride) Mono filaments.

Die cast aluminium....Arm mounting plate.

PTFE protection sleeving.

Various....Granular damping.