Series V


The fruit of many years of creative research, the handmade prototype V was shown to prospective distributors at the American and German shows in 1984, but it took a long time to get into production. Components were continually tried from prospective suppliers until the quality was right. When first shown , the price was targeted at what was then a very high level. Some expressed doubts concerning its credibility at that price, indeed of any similarly-priced tonearm.

The available competition included the Sumiko and the Breuer, but these were seen as high-end exotics. SME had traditionally operated in what had become the middle ground, the Series II arms, of which the non-detachable headshell version became the most popular, being very competitively priced. They were joined by the Series III tonearms, these again also competitively-priced, low-mass, designs. However, when the original SME Series I arm was introduced in 1959, it was simultaneously the best and the most costly arm available.

SME have suffered some criticism for failing to recognise that the hi-fi market has changed, particularly in the US and the UK. The moving coil cartridge has become dominant in the quality end of that market. While a few high trackability, high-compliance moving-coils are produced, notably from Audio-Technica (the AT100) and Denon (the DL1000), most have followed the example set by Ortofon and Supex in producing models of moderate compliance.

With one compliance unit (lcu) equivalent to l x l0-6 cm.dyne, a low-to-moderate compliance design has a relatively stiff stylus cantilever suspension in the 8-15cu range. The medium compliance range runs approximately from 15 to 25cu, while very softly suspended cantilevers fit in the high compliance range, from 25 to 50cu. In the bad old days when low frequency trackability was just about the only well-regarded performance parameter, cartridge compliances over 60cu were achieved, the Empire ZX1000, for example.

In an ideal world, tonearms would be well-matched to specific ranges of pickup compliance, assuring the customer of optimum performance from both. SME chased the high trackability dragon with their ultra low mass Series III, which employed nitrogen hardened titanium and carbon fibre technology. While it was expensive to tool up, the arm sold in large numbers, due to its affordable pricing.

Depending on the precise set up, the Series III offered an effective mass in the 5-7g range, optimum for cartridges in the 25-50cu region. When cartridges offering a better subjective performance emerged, cartridges with a lower compliance, SME offered a ballast weight to increase the arm's effective mass, but this was tantamount to shutting the stable door after the horse had bolted. An arm must be totally engineered for the target effective mass, if the performance is to be maximised. Lower compliance cartridges feed more vibrational energy into the arm, and this can only be dealt with using a structure of superior rigidity and resonance control. Simply adding mass to the headshell of a lightweight arm could make things worse. If a higher mass is required, the designer must exploit this engineering resource to give the best possible structure.

Some readers may be wondering why the arm mass needs to be matched to the cartridge compliance. It's a long story, but was thoroughly researched by Shure. Briefly, the total moving mass, made up of the cartridge and that of the arm seen by the cartridge - the effective mass' or moment of inertia - in combination with the spring of the cartridge cantilever suspension results in a mechanical resonance, capable of oscillating or vibrating as the groove is dragged past the stylus. Such a resonance will result in an undesirable, non-musical low frequency output from the cartridge, and worse still, it can impair the stability and the tracking behaviour of the pickup. The worst effects can be ameliorated by some form of arm damping, perhaps by means of a viscous fluid filled dashpot, which reduces the amplitude of the rise in output at resonance, but the alternative, of applying damping to the cartridge suspension, results in even worse tracking on difficult recorded passages.

If the arm/cartridge resonance is on the high side, above 15Hz, say, it will begin to affect sound quality in the bass. Conversely, the tracking is secure and recovers quickly from vibration or shock. If this resonance is too low, lower than 8Hz, the cartridge wobbles alarmingly and is unduly excited by minor warps - Shure's work showed that this has a maximum content around 6Hz. Close examination at such a condition will show the pickup perpetually vibrating at its resonance frequency. A further problem arises with the best-sounding turntables, which generally employ a floating, spring-suspended subchassis. These chassis systems have their own resonances in the 2.5Hz to 5Hz region. For arm/cartridge resonances below 8Hz, the proximity is too great and unwanted energy coupling often occurs, worsening stability and increasing the overall turntable flutter, an unpleasant rapid variation in musical pitch.

Thus 10-12Hz is the ideal region in which to place the arm/cartridge resonance, requiring matching of the arm mass with the cartridge compliance; arm damping will help to extend the range of compatibility, but only so far. Arm damping should be used at a sensibly low level, just enough to take the edge off the resonance magnification factor or 'Q', reducing it from 15 to 4-8, say. Excessive damping adds additional loading to the stylus tip, unbalancing the left and right groove contact forces and disturbing the channel balance as the damping attempts to prevent the cartridge from following minor warps and related disc eccentricities

So we come to the SME Series V - better late than never - potentially a statement of the arm designer's art and a tonearm designed for the finest modern cartridges, virtually hand-built, moderate-compliance, moving-coils. The selling price has risen above the initial target, the 'V' sells for more than £1200 - without any doubt a fantastic price for a tonearm. However, its stake on SME's traditional claim, 'The best tonearm in the world', is supported by an exceptional standard of design - technology, engineering and aesthetics directed towards versatility, compatibility, but above all, sheer performance.

A medium-to-high mass arm, with a 10-11g effective mass, its use of materials has been optimised to provide maximum structural resonance control and rigidity. The latter is essential to hold the cartridge firmly so that as much musical groove information as possible is transformed to its electrical equivalent and fed to the preamplifier. Satisfying this requirement for rigidity and simultaneously allowing for the cartridge to move freely in two axes is a major problem which all arm designers have to solve. Their in finding a solution which remains consistent in production, largely determines how well the arm will perform subjectively in the real world.

To quote SME in their excellent instruction manual for the 'V': 'in theoretical terms an ideal pickup arm is supposed to be perfectly unyielding in four out of six possible degrees of freedom. That is, all except the two linear dimensions in which the music signal is generated by groove modulation. In those two linear dimensions, an ideal arm is supposed to act as a pure mass'.

SME do not claim to have achieved this; rather, they believe that they have approached closer to this paradigm than before. 'Pure Mass' implies that no compliance or potential for flexure exists. If realised, such an arm would be totally non-resonant, except at subsonic frequencies, and would be devoid of frequency imbalance or coloration.

Arms typically exhibit flexure in several parts of the structure, sometimes at surprisingly low frequencies. Detachable headshell models generally 'sing' between 200Hz and 300Hz, due to the headshell/arm joint. Arms with decoupled counterweights can run into trouble at frequencies as low as 50Hz. Poorly designed main beams, or for that matter bearing assemblies, can introduce a series of resonances from a few hundred Hertz upwards. The Linn Ittok LVII is an early classic design which has stood the test of time. It avoids most pitfalls, and has been the model for later designs. The Swiss Breuer predated the Ittok, but was always regarded as too costly - little would we have guessed that the ultimate SME would cost very much more!

The new SME arm aims to solve a major headache in one bold stroke, one already partially addressed by Roy Gandy in his Rega RB300. This is to remove all the usual bonds between headshell and armtube, tube and pivot assembly, assembly and counterweight. By doing this, a number of potential weaknesses are eliminated. The SME designer chose to make the main beam a massive-looking affair of heavily-tapered, relatively thin-wall, magnesium alloy, cast in one piece with the substantial cartridge mounting platform, bearing assembly and the rear gantry and track for the counterweight. The large diameter of the cast beam maximises the torsional stiffness, while the strong taper to the headshell exerts a firm grip on any possible bending vibration modes.

Following various reports obtained during prototype testing, it was decided that the counterweight be clamped tightly in position after alignment, eschewing the rubber coupling often employed to try to lower the amplitude of midband resonances. In the event, such compromised damping was not required. Ideally, the counterweight material should be of high density, allowing its mass to be concentrated physically to allow placement close to the pivot/bearing position. This minimises self resonance and lowers its contribution to the effective mass, allowing more mass to be used to reinforce the main arm beam. To help realise this goal, SME chose to employ a tungsten block, optimally dimensioned. (Rega also use tungsten for their RB300 counterweight.)

In their previous designs, SME aimed at providing very low bearing friction in the two required planes of motion, employing a small precision ballrace for the horizontal motion and a gravity loaded knife-edge bearing for the vertical. Recognising that lower compliance cartridges impart significant acceleration to the arm, SME resolved to use ballrace bearings for both planes. In the case of inexpensive designs, these are generally left on the slack side to ensure low friction. Any trace of play, however, can have dire subjective consequences, the general effect being a grainy imprecision in the treble, an additional degree of sibilance on vocals, and in some cases a brittle brightness at high frequencies.

The new SME, as with other great tonearms, had to be devoid of any play. However, strong bearings require a degree of pre-load tension to take up any slackness and stiffen the operating assembly.

To sustain these forces without any brinelling, or indentation, of the bearing surfaces, high-load, large-size, stainless steel ballrace assemblies are used.

In harmony with these strong bearings, the whole pivot assembly, yoke and pillar, are substantial in size so as not to prejudice the overall rigidity. An ingenious lathe-like double-jaw clamp locks the pillar into a pair of guides which run between the main mounting bars of the bedplate. Once the arm has been positioned after lateral stylus overhang and height alignment, the whole assembly is locked together with a ball-head socket wrench. A rack and pinion drive allows precise overhang adjustment.

This rigid construction, as with the lttok, Breuer, Sumiko, Zeta and a few other models, means that a substantial degree of audio range energy from the cartridge is communicated to the arm baseplate and hence to the turntable chassis, an important point which will be considered later. As we shall see, it may strongly affect the ideal choice of turntable.

Nominally compatible with the earlier SME arm baseplates, the fixing centres for the four screws and the familiar oval armboard cutout are the same. Thereafter, some differences emerge. Unlike its predecessors, which used a compliant rubber grommet mounting, the 'V' is rigidly bolted to the turntable, and the through bolts need clearance below the chassis. Care must be taken with the Linn, for example. Another minor difficulty concerns the current LP12's corner plinth reinforcements: that nearest the arm fouls the 'V's leadout assembly and needs careful paring away.

At this point it would be appropriate to discuss the basic specification of the arm. Intended to be compatible dimensionally with earlier SME models, the 'V' is a rigidly-pivoted tonearm with a 233.15mm stylus-to-pivot distance, and a 23.6350 offset angle. Fixed locating centres are provided for the cartridge, overhang or lateral alignment being accomplished by moving the arm on its bedplate. While the 'V' is massively constructed, it is relatively compact and will fit turntables with normal internal lid clearances.

The line drawings give a good idea of the mechanical construction. Note the right-angle exit for the leadout socket, a viscously damped joint which will rotate itself to a convenient point determined by the cable. This simplifies cable dressing with subchassis turntables.

No provision is made for headshell rotation or azimuth adjustment, the cartridge mounting plate being set parallel with the record surface. As a consequence of the offset angle, a slight degree of vertical rotation may be applied by altering the height adjustment.

This can be done once the clamps are slackened, either by hand or with a threaded bar. With this aid, the arm may be raised precisely during play to determine the optimum combination of height and vertical alignment. With care, lateral adjustment can also be done during play. The arm is then locked in the correct position.

While the majority of top-class arms suffer from the inconvenience of uncalibrated dials, the 'V', as befits a precision instrument, uses resonance-controlled internal springs to set downforce and bias. Balancing of the arm is attained by means of a fine motion thumbscrew on the counterweight guide; once balanced, the counterweight is locked with a lever.

All subsidiary attached parts, the support gantry, and the lift/lower assembly have been designed to minimise resonances. Such attention to detail has resulted in giving the user the choice whether or not to fit the fingerlift on the headshell. In theory, its omission will give the lowest level of coloration.

The final feature is the optional damping facility. This is a built in well of silicone fluid, capped when the arm is at rest to prevent the ingress of dust. It applies overall damping by controlling motion in the horizontal arc. Once the well is charged, the degree of damping may be adjusted via a scale or disengaged altogether.

The electrical details are also worthy of mention. The headshell wires are replaceable in case of damage, or to give the user a choice. The clips are gold-plated, and the wiring is silver Litz. Silver is also used for the internal wiring, this a flexible grade to avoid unwanted torque fracture. SME have designed their own low-profile version of the semi-standardised 5-pin arm connector, and this is fitted with a special high performance van den Hul stereo cable of selected audio quality. Gold-plated, SME-manufactured, phone plugs terminate the cable. The arm is properly grounded for a high signal/noise ratio, and uses the 5-wire, triple earth system. Alternative arm cables may be fitted if required.

Taken overall, the SME Series V is an example of superb precision craftsmanship, excellent finish, and eminently intelligent, well balanced engineering design. As a result, it is a joy to set up and use, should remain adequately aligned for long periods, and will endure for years to come - and so it should at the price!

Lab results

In earlier tonearm reviews, I employed a swept-lone test record to assess the arm resonant behaviour. A micro-accelerometer, placed on the side of the cartridge, was used to sense the complex pattern of resonances in the arm and cartridge as it was excited by the mechanical energy from the stylus tracing a 20Hz-2OkHz swept signal. This method was complicated by difficulties of calibration, by the variation in mechanical impedance of the stylus, the second differential of displacement recorded, itself modified by the doubleslope equalisation of the test record.

A new and more reliable method has been tried for this review. A cartridge is fitted in order to mass-load the assembly correctly, while the sensing accelerometer is attached to the headshell, its position offset so as to measure both torsional and bending vibration modes. An energy pulse is applied to the headshell via a small calibrated mass impacting at a reproducible velocity. This may be sensed directly, the decaying resonances appearing in the impulse response of the arm, which in turn can be transformed by Fourier analysis to a resonance spectrum in the familiar frequency domain.

In the case of the 'V', the result is of particular interest: fig.1 shows the result on a linear frequency scaling, which emphasises the remarkable result - an almost total lack of break-up beyond the first division, which represents 2kHz. Related tests reinforce this result. All previous tonearms I have measured have shown a range of fine structural resonances beyond 20kHz, often with a considerable subjective influence. Very good structural control is shown here by the 'V'.


A conventional logarithmic frequency scaling has been adopted for fig.2 to show up the low frequency behaviour more clearly. The arm was tested on an Oracle Delphi, and it must be noted that some of the measured effects are due to the Oracle's chassis and armboard resonances. That at 1 kHz, for example is suspected to be due to the Oracle. The lowest frequency mode is probably due to the counterweight and is quite moderate. The main arm modes occur at approximately 1.3kHz and 1,6kHz, indicating a very rigid, well damped structure. (The best arms tested so far have shown torsional modes below 1kHz, sometimes as low as less than 500Hz.)

The effective mass was estimated at around 10.5gm, somewhat dependent on the mass of the cartridge counterbalanced and the choice of mounting hardware. Stainless steel socket-head bolts are preferred for mounting the cartridge, but add 1-I.5g of mass. The geometric alignment was rated highly, while the arm's dynamic stability and lack of structural resonance resulted in superior pickup tracking. With the signal excellently screened, hum levels were low with test cartridge (a van den Hul MC1 0).

Bearing friction was moderate, at 40mg lateral. This was not the lowest I have measured but accorded with the alignment required for zero play. In the vertical plane it was 10mg or less. Given a sensible playing downforce of 1.25g or more, these friction values are negligible. Set to 1.5g, bias compensation at the innermost grooves was appropriate for an elliptical or similar stylus (the range allowed covers 180-225mg). At the rim the force was marginally low, but should not result in any noticeable ill effects.

The downforce dial proved to be correctly calibrated, while the cue operated well with negligible lateral drift and sensible descent and ascent rates. A generous range of subsonic damping was available; on audition its use at the first calibration was thought sufficient.

Sound quality

We had the opportunity to sample the 'V' in three great turntables, a current Linn LP12, the latest, and in my view, much-refined Oracle Delphi, and the massive West German Audiolabor Konstant. Cartridges used included the vdH MC1 B and MC10 and the Koetsu Red. A wide range of amplification was available during the test period, including the Audio Research SP-11/M-100 and the conrad-johnson Premier 3/4. Earlier listening had taken place with the Cyrus Two; while on the face of things this modest amplifier seems an inappropriate companion, the superior quality of the 'V' was more than obvious.

Perhaps I should admit straight away that the SME Series V was very much my kind of tonearm. I have used and respected the lttok for years, dabbled with Alphasons and Zetas, but have felt the need for something capable of truly great performance. Yet another model with a differently shaded view of the truth was not enough.

The 'V' redefines the art of pivoted tonearm sonic performance. It is possible to extemporise on various specific aspects of quality relative to other models, but one simple test will readily reveal its greatest strength. A well-recorded, wide-range singing voice will suffice: one experiences an almost revelatory exposition of articulation and clarity, notable for its uniform texture over the vocal range, freedom from 'edge', sibilance or unnatural emphasis, and superb placement in the central stereo stage. This fine vocal neutrality is its key attribute, and only later do the fine details of its overall performance make their presence known. Slowly the listener has a dawning awareness of the coherent musical control exerted by this arm.. This control was contiguous over the entire frequency range, from low bass to high treble, All areas seem to be given fair weight and balance, which was held both in terms of tonal quality and in the stability and coherence of the stereo image.

Images were reproduced with exceptional width and depth, with fine perspective layering and little spatial distortion, ambience and space lying around and beyond the frontal stage. Coloration was as low as expected, an aspect which supports the recognition of its relaxed transparency, again this well maintained over the entire frequency range.

While the above comments represent a distillation of its 'absolute' performance, it is affected by the choice of motor unit. Of those tried, each showed specific effects. On the Oracle, the bass was very fine and the clamp/mat system exploited the arm's transparency and low coloration to the full. Some clouding of information was apparent in the midrange, perhaps due to the outrigger type arm mounting platform. On the Audiolabor, the low bass was excellent, strong but dry, while the upper bass was not differentiated to the same standard. In the upper mid and lower treble. the arm sound hinted at excess brightness with a loss of stereo depth. This turntable uses a massive, heavy metal subchassis, and energy reflections at the mounting were felt to be responsible. Nevertheless, the standard was very good.

Perhaps it was logical that the Linn should have turned out to be the best all rounder. In a sense optimised for the lttok, the LP12 handled the SME, which is relatively similar mechanically, very well. On the Linn, the 'V' appeared optimally terminated with the standard, composite fibre, mounting board, While the upper bass was marginally bumpy, low frequencies were tuneful and well extended. The midrange was at its most even, and balanced well with the treble. Ultimately, this was the most satisfying combination. Other players need to be tried and hopefully the industry will build up some experience here.

Conclusion

Upon first hearing, the arm's accurate control may appear to impose too much restraint on the reproduction of the music. However, once properly experienced, the SME Series V has the ability to make many other tonearms sound forced, ragged and untidy, both in terms of coloration and of stereo imaging. Many arms are brilliant in specific areas, but in my opinion, none so far have comprised a superb midband with such excellent control and uniformity over the rest of the audible range.

It is a tonearm which is unlikely to be replaced.
An impressively engineered design, its powerful looks well reflect its strong subjective and objective performance. The attention to finish and detail extends to all aspects, including alignment, packing and instructions. A new standard has been set, perhaps the last great flowering of the tonearm designer's art. Those who can afford it will have much to appreciate.

See more of SME'S products: http://www.linkhouse.co.uk/hifi