SOTA Cosmos Turntable

Manufacturer's Specifications:

Speeds: 33 1/3 and 45 rpm.

Speed Stability: 0.1%.

Wow and Flutter: 0.1%, DIN wtd.

Rumble: Unweighted, -60 dB; weighted, 75 dB.

Dimensions: 20 1/4 in. W x 16 in. D x 7 1/2 in. H (51.4 cm x 40.6 cm x 19.1 cm).

Weight: Turntable, approximately 60 lbs. (27.2 kg); vacuum pump, 15 lbs. (6.8 kg).

Price: $4,000 in black matrix finish; $4,500 in high-gloss acrylic.

Company Address: 954 86th Ave., Oakland Cal. 94621

"The turntable is not dead! Long live the turntable!" This seems to be what SOTA is saying with their introduction of the Cosmos turntable. In fact, the Cosmos is not just a statement in favor of the turntable as a viable source of pleasure to those of us who enjoy listening to our record collections; it seems to be SOTA's way of saying, "There are subtle nuances and details on your favorite records that you haven't yet enjoyed; we want you to be able to hear them." How well they have succeeded is the subject of this report.

In the June 1986 issue of Audio, I reported on the SOTA Star Sapphire turntable, which featured a vacuum system to hold the record firmly against the turntable platter; SOTA has applied a further refined version of this system to the Cosmos turntable. The purpose of this uncommon feature is to increase the transfer of mechanical energy from within the plastic record material to the platter surface, where it can be dissipated harmlessly and not re-enter the playback system as delayed energy. This energy, which is generated by the interaction between the stylus and the record groove, can smear and obscure subtle details in the recording.

The Cosmos is a completed design. In most turntables, there is still something that can be improved; sometimes, these improvements appear in later designs. The Cosmos is different in that, given SOTA's design philosophy over the years, it seems that nothing can be significantly improved. For example, when trying to adjust the vertical tracking angle of the cartridge stylus, the record should be down flat against the turntable platter. The fact is that without the vacuum system operating to pull it down against the platter, the record would be sitting up on the soft rubber vacuum-sealing lip around the periphery of the turntable platter.

But if you turn on the power so that the vacuum system will operate, the turntable will rotate, making the VTA adjustment very difficult. SOTA has the answer to the problem: The power cord from the power-supply/vacuum-pump box is unplugged from the turntable and terminated in a female DIN plug (supplied). This fools the system into supplying vacuum even though the turntable is not rotating. These little details add up to a well thought-out total design. It is almost embarrassing to see a product like this because one of the reasons for this type of report is to point out failings as well as good points. Here, failings were hard to find.

From the standpoint of engineering and construction the Cosmos is impressive; the smooth, glossy, salt-and pepper finish, the rounded surfaces, the black record mat with its integral soft rubber lip that seals the record to the platter, and the small half-round a.c. power and speed change buttons are unlike any I have ever seen before.

They are unmarked, as on previous SOTA turntables, and have the same salt-and-pepper finish as the turntable base. So, while the Cosmos is obviously related to the previous SOTA offerings--the Sapphire and the Star Sapphire turntables--it differs in significant ways. I try very hard not to be swayed by appearances when I evaluate products, but I must admit that products that look as good as the SOTA Cosmos turntable make keeping one's head a bit difficult.

The Cosmos has a vacuum system like the Star Sapphire's but with some added refinements. The Star Sapphire vacuum system relies on a timing circuit to apply two levels of vacuum to the turntable platter and record interface. The first is applied to purge the air line and to achieve a good seal between the record and the turntable platter; the second is at a lower level, just enough to maintain the vacuum seal. This allows the motor of the vacuum pump to operate at a much reduced level of vibration, thus lowering the noise level.

The Cosmos' vacuum system is more refined than that of the Star Sapphire turntable. It incorporates a sensor that monitors the amount of vacuum in the line connected to the turntable platter; this sensor provides a signal to an electronic circuit which, in turn, controls the vacuum pump. The first level of vacuum is high enough to cause a good seal between the record and the turntable platter. As soon as the sensor determines that a good seal has been made, the vacuum is reduced to about 2 inches of mercury. If for any reason the vacuum is reduced, the sensor causes the vacuum pump to increase the vacuum and try to pull the record tightly against the platter surface. The vacuum hose and the fittings are also much better on the Cosmos turntable; the ends of the hose have solid, twist-lock connectors that mate with the fittings on the turntable and auxiliary control box. If your listening environment is extremely quiet, it is possible that you might hear the vacuum pump running, even though it produces very little vibration in its normal operating mode.

Just in case, SOTA supplies a generous amount of vacuum hose, allowing you to locate the auxiliary box containing the vacuum pump away from your listening environment.

The Cosmos is supplied with the SOTA Reflex Clamp, which also holds the record down against the platter at the center and helps to maintain the integrity of the vacuum seal. The Electronic Flywheel power supply, which stabilizes the rotational speed of the turntable during a.c. power-line voltage fluctuations, is no longer an option as it was with the Star Sapphire but has been upgraded and combined with the Cosmos vacuum system in one auxiliary box. The Electronic Flywheel power supply for the turntable motor and the power supply for the vacuum pump have separate power transformers, so the different functions are well isolated from each other.

As I mentioned previously, there are two buttons on the left, forward portion of the turntable base-one for power, the other for speed change. (The Cosmos can operate at either 33 1/3 or 45 rpm.) A knob on the rear of the turntable allows the speed to be adjusted to obtain exact pitch for records that might be slightly off. The exact speed can be reset at any time by adjusting this knob while looking at the appropriate pattern on the strobe disc that comes with the turntable. This speed-adjusting pot is a high quality Mil Spec type.

The turntable platter is not removable and is locked by two transit screws to protect the main bearing during shipping. These screws must be removed before you can operate the turntable, but I suggest that you tape them to the underside of the turntable base because you should reinstall them if you need to move or ship the turntable any appreciable distance.

The Cosmos turntable, like previous SOTA turntables, uses four springs to suspend the main platform. The weight is equally distributed, with the tonearm being part of this weight-distribution system. When you order the Cosmos, you should decide which tonearm you will be using so the dealer can set it up for you and add the proper amount of extra weight. SOTA provides a bag of lead shot to balance the system. The heaviest combination of tonearm and tone arm mounting board is the SME V and the Cosmos laminated tonearm board. If you order the Cosmos with this combination, you will not need any additional weight because the Cosmos tonearm board is designed to be balanced with this combination installed.

I tested the Cosmos turntable with the SME tonearm and the Cosmos tonearm board, which is constructed as a six layer lamination. The top layer is 0.1 inch of polished black acrylic, followed by a 1/8-inch layer of clear acrylic, a 1/8-inch layer of black acrylic, a 1/16-inch layer of lead, another 1/8 inch of black acrylic, and finally, at the bottom, 1/8 inch of aluminum.

This sandwich of different materials dissipates a. great deal of unwanted mechanical energy that might otherwise be reflected back to the phono stylus and blur musical detail. Such blurring is a result of the delay caused by the transit time of the energy from the stylus down the tonearm tube to the base and back up the tube and to the stylus.

The bottom of the tonearm board is machined out and it can be ordered for the SME type base and the Eminent Technology linear tracking tonearm. SOTA "Composite" arm boards are available for all other tonearms, many of which are pre-drilled. The Cosmos tonearm board has three countersunk mounting holes and the aluminum subchassis of the turntable is threaded to accept the screws that are provided. These screws are 2 1/2 inches long, which gives some indication of the thickness of the tonearm board and subassembly.

The turntable base is an integral part of the system, not an afterthought. It measures 20 1/4 inches wide, 16 1/4 inches deep, and 4 inches high including the three adjustable feet.

These feet allow you to balance the turntable while using the bubble level supplied. The bottoms of the feet are recessed to allow special conical isolators, also supplied, to be inserted if you want to use them.

The subchassis, which is suspended by four counter wound springs, is a carbon-fiber honeycomb. The rear of the turntable base has an elongated opening (3 5/6 x 1 1/8 inch) for a plate on which are mounted the five-pin DIN power connector, the vacuum connection, the speed adjustment knob, and a knurled grounding post. This ground is connected to the main subchassis and although I did not need to connect it to my system ground to reduce hum, I found that it was necessary for draining the static charge that builds up when playing vinyl records.

The motor is a Pabst servo type specially modified by SOTA for the Cosmos. The control electronics supplies 400 mA of current to bring the motor up to speed quickly, then switches to 30 mA for normal running. This lowers the vibration and allows the motor to be mounted directly to the subchassis. Because of this arrangement, the main bearing and the drive motor are at a constant fixed distance from each other and are unaffected by any motion of the sub chassis caused by vibration of the springs. This means that the belt is always under a constant tension and remains unaffected by outside vibration, making the speed very stable even during earthquakes (very important here in California where we like to hear exciting music during our movies and earthquakes).

The Cosmos turntable mat is also unusual; it is a multi layered casting that takes 10 days to make because of the curing times involved in its fabrication. The top layer is a proprietary material chosen because its mechanical impedance is close to that of the type of vinyl used to make records; this allows a much greater transfer of mechanical energy from the record into the mat than if the impedance were different. The next layer is a damping layer in which the energy is dissipated; the last layer is chosen to interface with the turntable platter and act as a barrier. An optional dust cover is available, and threaded inserts are already at the rear of the base to accept its hinges. The one-piece, thermo-formed, smokey brown cover provided with the Star Sapphire was exceptionally good at reducing and absorbing airborne vibrations, but apparently dealers and customers are enamored by the solid, clear-acrylic, multi-piece covers of other turntables, and SOTA has followed suit.

Measurements and Listening Tests

I used the SME V tonearm and Talisman Virtuoso Boron cartridge for the technical measurements and listening evaluations. I made all of the setup adjustments and technical measurements before the listening evaluations so that I could be certain that everything was functioning correctly.

The absolute polarities of the reference system and the SOTA Cosmos system were determined and all of the recorded selections were marked for correct absolute polarity. Some people might think that worrying about the absolute polarity of a system and the program material is carrying things a bit far but, believe me, when you are evaluating such high-quality systems, capable of revealing every tiny and subtle detail, then I assure you that absolute polarity is a definite factor in determining how you will perceive the system's reproducing qualities. Each of the listening panel members was given a form allowing them to rate the reference system and the SOTA Cosmos turntable from 0 to -5 for each musical selection. If a system were perfect, it would receive a 0 rating, while a really poor system would receive a rating of-5. Without being told which system was which, the panel members are asked to judge system "A" versus system "B" and rate them; written comments about the perceived quality of the sound were encouraged but panelists were asked not to talk or make any outward sign during the playing of any selection. If a panel member asked to hear something again (which can happen when the two systems being tested are very close in reproducing quality) I replayed the selection.

---MEASURED DATA---

Fig. 1--Wow and flutter spectrum, from 0 to 100 Hz. Most of the output is at 9.5 Hz, the tonearm/ cartridge resonance, and is not due directly to the turntable itself.

Fig. 2--Speed drift over 42-S period.

Fig. 3--Speed stability, referenced to 3,150-Hz tone on B & K 2010 test record. The cursor is at 3,155.4 Hz, the center of the speed variation; see text.

Fig. 4--Rumble spectrum. Most of the output is at the tonearm/cartridge resonance; the rumble is very low above and below this frequency.

Fig. 5--Output vs. time for a mechanical shock applied to edge of a stationary record, with stylus resting in groove near the middle of the disc.

Fig. 6--Spectrum to 5 kHz of output from a series of 16 mechanical impulses (averaged) applied to edge of a stationary record, with stylus resting in groove. The smoothness of the spectrum indicates that the platter's energy absorption is uniform and will not color the sound.

Fig. 7--Output vs. time for a mechanical shock applied to the platform on which the turntable base rested, with the stylus resting in a stationary groove. Note the difference between output with the standard feet (top trace) and with the pointed feet added (bottom trace).

Fig. 8--Averaged spectrum to 5 kHz of vibrations caused by 16 mechanical impulses applied to turntable platform with stylus resting in a stationary groove. Again, note the difference made by addition of the pointed feet.

Since the quality of sustained tones is affected by the speed stability of a turntable, a very low amount of wow and flutter is quite important. Figure 1 shows the wow and flutter spectrum of the SOTA Cosmos. I have always felt that this spectrum reveals much more about wow and flutter than a simple number does. Since the resonance of the tonearm and cartridge can have a great influence on that number, seeing its contribution is very enlightening. If this resonance is great, it can give a higher wow and flutter value than the turntable deserves. The output of the SME Series V tonearm and Talisman Virtuoso Boron combination is very low at their combined resonant frequency of 9.5 Hz. It therefore contributes very little to the wow and flutter meter readings in my "Measured Data" chart. When reproducing piano (one of the most revealing instruments with respect to wow and flutter), both the reference system and the Cosmos were given very high ratings by the panel members.

Figure 2 shows the drift in speed of the turntable over a 42-S period. This excellent performance shows that the Cosmos is capable of sustaining the musical pitch of a piece of music over a long period. The speed stability is presented another way in Fig. 3, which is a graph of the variation in the frequency of the 3,150-Hz wow and flutter test tone of the B & K 2010 record averaged over sixteen samples. The deviation is ±8 Hz, representing a variation of only ±0.254%, which is excellent. No adverse comments were made by any panel members that would correlate to speed variation in either the Cosmos or the reference system. I did find a correlation between the peaks of the variation curve and the tonearm resonances. Although it isn't shown in Fig. 3, when I changed to another tonearm and cartridge combination, which has a higher O at resonance, the plus and minus points, rather than being flat as shown in Fig. 3, actually peaked up in a very pronounced manner. When I listened to this other tonearm and cartridge combination, the variation in pitch for a steady test tone was more obvious than with the SME V and Talisman Virtuoso Boron. This tells me that when testing or listening to a really high-quality turntable, the choice of tonearm and cartridge has a much greater effect on the wow and flutter than one might assume.

The spectrum of the rumble for the SOTA turntable is in Fig. 4. The rumble is most pronounced at the tonearm and cartridge resonance; this shows that the choice of tonearm and cartridge also plays a major role in the measured and perceived rumble of a turntable like the Cosmos. Some panel members commented that the rumble from the Cosmos was slightly less than that from the reference system.

Figure 5 shows the output versus time for a mechanical impulse applied to the edge of a stationary record with the stylus of the cartridge resting in a groove near the middle of the record. The mechanical energy is well damped and dissipates quickly. The spectrum produced by a series of 16 mechanical impulses, applied to the edge of the record and averaged, is shown in Fig. 6. The importance of this graph is not in the absolute level of the output, but in the shape of the spectrum: It is very smooth, without any peaks or dips. The presence of peaks and dips would tend to color the perceived sound. The turntable's three-layer, laminated mat is not only very effective in removing mechanical energy from the record but it does it in a very uniform way without favoring any particular band of frequencies. This is not a trivial engineering task, as anyone who read the report I did on turntable mats in the April 1988 Audio should realize. I commend SOTA for solving the problem. But how does this relate to the perceived sound ? Well, the acid test is how well a rapid series of musical notes, particularly a piano arpeggio, is delineated. Can each note be distinguished clearly, or does one note tend to blur into the next? When such a musical selection was presented to the listening panel, their rating of the SOTA Cosmos was the highest they had ever given to a turntable exceeding the reference system, which has always been given high marks in this regard. If you are looking for clarity of detail, you will find it in the SOTA Cosmos.

The graph of the output from the Talisman Virtuoso Boron cartridge with its stylus resting in a stationary groove near the middle of the record, when a mechanical shock was applied to the solid platform upon which the turntable was resting, is in Fig. 7. I conducted this test both with and without the pointed insert feet which come with the SOTA Cosmos. The top trace shows the output without the pointed feet and the bottom trace is with them inserted between the normal turntable and the platform upon which the turntable rested. As I mentioned before, the normal flat turntable feet have recesses which accept the pointed inserts, and it appears from this test that these pointed feet are very effective in reducing the amount of mechanical energy that can reach the turntable. The spectrum of this output, for 16 shocks, applied and averaged, is shown in Fig. 8. There is a decrease in energy transfer across most of the range except for a few frequencies, particularly 162.5 Hz. The SOTA Cosmos is immune to outside mechanical vibration with or without the pointed inserts. Electing to use them may be more dependent on whether you want to risk scratching the surface where you would place the turntable.

The panel members rated the Cosmos slightly better than the reference system for voice, strings, acoustic guitar, double bass, drums, and piano. The sound of violin was perceived to be a bit smoother and more detailed with the Cosmos, and the sounds of the strings being plucked on an acoustic guitar were more precise. The sound of the double bass was full and yet very tight and well defined. The drums were reproduced with just a bit more realism. The Cosmos and the reference were rated equal for brass, full orchestra, and the ability to reproduce a sense of openness and space. Both systems were rated equal in presenting a stereo image that allowed panel members to point at the location of specific instruments. (I should mention that the loudspeakers are hidden from view behind light colored, acoustically transparent drapes, which allows panel members to concentrate on the stereo presentation without being distracted by the physical location of the loudspeakers.)

Conclusions

Here we are at the point of this report to which everyone, including me, looks first! As anyone who has ever written a report of any kind knows, the opening and the closing are always the hardest. In the case of the SOTA Cosmos turntable it is particularly hard because I am tempted to use a "boiler plate" ending--you know, the kind that says, "This is a wonderful (type of product). The (name of product) is the best I have ever heard. You owe it to yourself to rush out and hear it." The trouble with cliché endings is that they don't really tell you anything, and the SOTA Cosmos doesn't deserve that. It is really a super turntable and I admire all the work that must have gone into its development. I might however, question the sanity of David Fletcher and Robert Becker, who obviously have placed a quest for phonographic perfection above economic reality. I don't mean that the Cosmos isn't worth its price, because it certainly is to anyone who is looking for the best turntable he can find.

There are turntables that are more expensive but I think that the SOTA Cosmos is as good as they get. I only wish that more people could enjoy the pleasure of hearing their favorite records with a turntable like this.

-Edward M. Long

SME 309 Arm & Signet OC9 Cartridge

Manufacturer's Specifications

Tonearm:

Type: Tapered aluminum tube with detachable, clamped headshell.

Pivot-to-Stylus Distance: 232.32 mm (9.15 in.).

Pivot-to-Spindle Distance: 215.35 mm (8.48 in.).

Offset Angle: 23.204°.

Overhang: 16.98 mm. (0.67 in.).

Linear Offset: 91.54 mm (3.6 in.).

Tracking Error: 0.013°/mm max.; 0° at 63.62 mm and 119.46 mm from record center.

Vertical Tracking Force: 0 to 2.5 grams, at minimum cartridge weight.

Cartridge Weight Range: 6 to 17 g rams.

Effective Mass: 9.5 grams.

Wiring Characteristics: Internal wiring, 15 pF/channel, 0.54 ohms/ conductor; external audio lead, 140 pF/channel, 0.15 ohms/ conductor.

Weight: 717 grams (1 lb., 9.3 oz.).

Price: $995.

Company Address: c/o Sumiko, P.O. Box 5046, Berkeley, Cal. 94705.

Cartridge:

Type: Moving coil.

Stylus Assembly: Elliptically polished, nude, miniature diamond on gold-plated beryllium cantilever.

Tip Dimensions: 0.2 x 0.7 mil.

Frequency Response: 15 Hz to 50 kHz.

Tracking Force: 1.25 to 1.75 grams.

Charnel Balance: Within 1.0 dB. Output Level: 0.4 mV at 1 kHz.

Recommended Load Impedance: 20 ohms.

Mounting: 1/2-inch centers.

Weight: 7.8 grams.

Price: $395.

Company Address: 4701 Hudson Dr., Stow, Ohio 44224.

The range of SME tonearms has expanded once again. In the June 1986 Audio, I reported on the SME V tone arm, which remains the flagship of its maker's range of tonearms. After the Model V reestablished SME as the preeminent maker of precision tonearms in the world, and a subsequent, cost reduced version (the Model IV) was introduced, SME turned its attention to the redesign of the famous 3009 III tonearm. This arm had been refined over the years to a point where it had become the most popular and versatile universal tonearm of all time. It was universal in that it was designed to accept an extremely wide range of high-compliance, low-mass cartridges and bring out their best performance capabilities. The 309 tonearm has many features that result from the experience gained during the design of the Models V and IV. The 309 tonearm is designed to appeal to a greater range of users and to be more affordable than the Models V and IV. (If you want to see how the 309 compares with the original 3009 III, my test report on that arm appeared in the May 1981 Audio.) If you would like a little more background on SME, there is also a videotape featuring Alastair Robertson-Aikman, the managing director of SME, which was made by Sumiko, Inc., the importers of this British-made tonearm. If you are interested in seeing the tape, you can contact Sumiko and they will let you know more about it.

Signet was started about 12 years ago, offering high quality cartridges through specialist audio dealers. It is a completely separate division of Audio-Technica U.S., Inc. I mention this affiliation because although the OC9 moving coil cartridge is a Signet product, it is made for them by Audio-Technica in Japan and has Audio-Technica markings. At this point in time, Signet has decided to make the

0C9 available in limited quantities and with the Audio-Technica markings and packaging, as this will allow them to keep the price reasonable. The original price for this cartridge was to be $700, but since its introduction it has sold well enough around the world that the increased production has allowed economies of scale; this has allowed Signet to offer the OC9 at a more reasonable $395.

Audio-Technica U.S., Inc. was begun in 1972 by Jon R. Kelly, who had been the phono-cartridge and microphone product manager for Electro-Voice, Inc. in Buchanan, Mich.

At that time, the Japanese Audio-Technica company had been working with JVC on the CD-4 discrete four-channel phono system. This system used a very high frequency carrier (about 50 kHz), which was modulated with the rear channel information. The requirements of this now-defunct system had a great effect on phono cartridge and stylus research. The first of the new generation of high-performance cartridges was the direct result of the requirement that they be able to trace high frequencies well above the normal 20-kHz limit of the audio band. We are still enjoying the benefits of the extended-bandwidth techniques applied to the cartridge designs and the elliptical and fine line contact stylus shapes that were developed in this era.

Although Audio-Technica of Japan is a very diversified company that makes laser pickups, bar-code readers, microphones, and headphones, it is interesting that they not only continue to produce phono cartridges but are still engaged in advanced research on cartridges and styli.

The tapered tonearm tube of the 309 is a single piece of drawn aluminum similar in appearance to the magnesium tonearm tube of the Model V; aluminum is less expensive and easier to work than magnesium, which helps to reduce the cost while still providing excellent characteristics. When I performed the tap test on the tonearm tube, which features the same internal, constrained-mode damping as the model V, I found that it had very little sound of its own and that the character of this sound was very difficult to describe. Near the headshell the sound was like "tuck;" in the middle it sounded like "tick," and near the tonearm pillar the sound was like "tug." The sound was difficult to characterize because there seemed to be more sound coming from the metal tapping tool I use than from the tonearm tube. What all this means is that any resonances in the tonearm tube are very well damped and should contribute very little coloration to the reproduced sound.

When I grasped the tonearm tube in one hand while holding the arm pillar firmly in the other hand, and tried to push, pull, and twist the tonearm tube, found absolutely no looseness or play in the bearings, which is a good sign; loose bearings can cause much coloration in the sound.

The SME 309 is finished in matte black and satin aluminum and appears to be designed and manufactured with great care and attention to detail. The base mounting requires the famous SME elongated slot, which allows the necessary stylus overhang to be adjusted very precisely using a rack-and-pinion system in the base.

I looked for a serial number on the body of the Signet 009 cartridge but I couldn't find any. The sample that I received for evaluation did not have an amplitude-frequency response graph, although the listing for the 009 in the October 1989 Audio magazine directory indicates that one is normally supplied. The stylus is not user-replaceable so the cartridge must be returned to Signet should the stylus need to be replaced. I am not certain what this costs but, since the cartridge is reasonably priced, I assume that it will be of commensurately low cost. A snug-fitting stylus guard may seem like a minor thing, but I appreciated that it did not fall off easily. Many of the more expensive cartridges seem to lack this little refinement and offer loose-fitting stylus guards that seem more like afterthoughts than planned designs.

Features As a replacement for the venerable 3009 tonearm, the 309 is more than an improved version; it is a complete redesign. One of the main features of the 309 is its removable headshell. Most modern tonearm designs have eschewed removable headshells because they tend to cause sonic coloration due to the poor mechanical connections to the armtube. Such connections can cause energy to reflect back to the stylus, where the delayed energy is reproduced as a blurring to the sound. The SME 309's headshell is firmly locked to the armtube by a bolt and captive nut which seems to be very effective in solving this problem. Changing cartridges mounted in different headshells is not a quick process, as you'll see from the following description. The armtube has a slot that lines up with the bolt, which must be removed from the headshell and then reinserted when the headshell is pushed against the spring-loaded gold pins at the end of the armtube. This assures that the headshell is firmly in place and that good contact is made both electrically and mechanically. There is a slight amount of rotation available so that the exact stylus azimuth can be adjusted. The SME booklet suggests using a mirror to set the stylus azimuth.

The SME booklet, a model for all other product set-up booklets, contains step-by-step instructions with 40 close-up photos detailing every aspect of installing and adjusting the 309 tonearm. It begins with specific information on the use of the supplied templates for drilling and creating the slot in the mounting board. If you are interested in buying an SME 309 tonearm, this booklet might persuade you that the people at SME really know what they are doing; ask the dealer to let you see it.

The SME tonearms provide a unique way to adjust the stylus overhang. Overhang is necessary to compensate for the tracking error introduced by playing records made by a straight-line cutting lathe with a pivoted tonearm. The over hang refers to the fact that, if you swing the tonearm so that the cartridge is placed directly above the turntable spindle, you will notice that the stylus "over-hangs" the spindle by a small amount, usually about 15 mm. Most tonearms feature a pair of slots in the headshell to allow the cartridge to be slid back and forth until this overhang is set correctly. SME uses, instead, a rack-and-pinion system as an integral part of the arm base mounting; a special tool is provided to allow you to slide the whole tonearm back and forth until the correct overhang has been achieved. A template is included with all SME tonearms so you can make this adjustment easily. When the correct position has been found, the tone arm pillar can be locked securely by tightening two clamp bolts on either side of the tracks. A finger-lift can be installed on the headshell, but I opted to rely on the damped lever, located near the tonearm pillar, to raise and lower the arm.

A swivel-mounted output socket at the bottom of the pillar accepts the five-pin DIN mating plug on the output leads that are terminated, at the other end, with gold-plated phono plugs. Three separate grounding wires are provided; one is attached to the body of the tonearm while the other two are connected to the separate cable shields. The shell of the phono plug is not connected to the ground wire, thus providing a balanced output for the signal. The internal tonearm wiring and the external cable use oxygen-free copper.

A special, calibrated tool is provided to set the tracking force. It has a ball-shaped hexagonal end that can be inserted into a screw on which the counterweight is mount ed; turning this screw moves the counterweight and allows the tracking force to be set. After the desired tracking force is set, the counterweight should be locked firmly to the rear of the armtube by tightening another screw. A sidethrust or "anti-skating" adjustment is provided by a calibrated knob mounted on the same assembly supporting the damped tonearm-lifting system.

It seems that the relatively low cost of the Signet 009 moving-coil cartridge is the result of applying some of the mass production techniques commonly used during the manufacturing of moving-magnet cartridges. While I realize that the assembly of moving-coil cartridges is a bit more complicated than the assembly of moving-magnet cartridges, I have often wondered why they couldn't be produced at a more reasonable cost than we are used to seeing. I also know that smaller quantities usually cause greater manufacturing costs, but I have often wished that the benefits of wide-band design could be enjoyed by a greater number of people. Since the requirements of moving-coil cartridge design result in a relatively low coil inductance and source impedance, this type of cartridge seems ideal for wide-band design. This doesn't mean that moving magnet cartridges cannot provide wide-band response, but since they do not require small, light coils, they are usually designed to provide high output. This means that the coil inductance, which limits the high-frequency response, is higher because the coils have more turns of wire. The coils of the Signet 009 MC cartridge have very low inductance and resistance. Their inductance is so low that I found it impossible to make a measurement that I considered reliable; this was partly due to the very low resistance of the coils, which lowered the Q and swamped the inductance.

Normally, coil resistance as low as the 009's would mean the cartridge's output would be very low because there were few turns on the generating coil. If ordinary magnets had been used, this would be true; however, since the 009 uses samarium-cobalt magnets, which produce a very strong magnetic field, its output is relatively high. Still, the output of the 009 is lower than that of some high-output moving-coil cartridges, and Signet therefore recommends the use of a step-up transformer or pre-preamp between the cartridge and the phono input of a preamplifier or receiver. I found the output acceptably high without the use of either device; all of the technical measurements and the listening evaluations were conducted with no step-up device.

Measurements and Listening Tests

The measurements were made before the listening panel members were assembled to audition the SME 309 tonearm and Signet 009 cartridge. I always make the technical measurements and calibrate the system before the listening sessions because too many things can cause problems in a phono playback system if it isn't set up and adjusted correctly. The listening evaluations were conducted by comparing the sound of the Signet 009 cartridge with the sound of a reference system most of the panel members have listened to in past evaluations. While it is of exceptionally high quality, this system is used merely as a reference, to which panel members may compare the sound of the device being evaluated. Sometimes, as you will see later, a panel member will make a written comment that although the sound of "A" may be in some respects superior to "B," he or she still would prefer the sound of "B" for certain types of program material. By the way, all comments are written and no discussion is allowed during the listening evaluations. Discussions take place after the listening sessions have been concluded.

Fig. 1--Frequency response and interchannel crosstalk of the SME arm and Signet cartridge. The crosstalk increase at low frequencies is an artifact of the B & K 2010 test record.

Fig. 2--Low-frequency arm-cartridge resonance is at 7.0 Hz with a Q of 2.6.

Fig. 3--Response to a slow sweep from 2 to 100 Hz to check for lateral and vertical modulation.

Fig. 4--Slow sweep from 20 Hz to 1 kHz to check for system resonances; see text.

Fig. 5-Output vs. time of arm/cartridge when mechanical impulse was applied to armtube. Ringing is apparent, but the higher frequencies are damped quickly.

Fig. 6--Spectral output (average) of arm/cartridge due to 16 mechanical impulses applied to armtube.

Fig. 7--Interchannel phase difference, using pink noise from B & K 2011, band 7.

Fig. 8--Interchannel phase difference vs. frequency for same track as Fig. 7. Phase difference at 20 kHz is -72.6° (10.1 µS).

Fig. 9--Tracking of arm and cartridge with 1-kHz test tones at 19.2 cm/S (top) and at 25 cm/S (highest level on B & K 2010, bottom). Signs of mistracking are apparent at the higher signal level; see text.

Fig. 10--Spectrum of cartridge output when reproducing the 19.2-cm/S and 25-cm/S signals of Fig. 9. The third harmonic is -39.8 dB (1.0%) for the 19.2-cm/S signal and -22.3 dB (7.7%) for 25-cm/S. Note the increase in the even harmonics at the higher signal level.

Figure 1 shows the amplitude versus frequency response and the interchannel crosstalk for the Signet 009 cartridge mounted in an SME 309 tonearm. The response holds up well above 20 kHz, and the slope is mainly that inherent in the B & K 2010 test record. There is a definite indication that the high-frequency resonance is at 28.5 kHz, which I verified by using another measurement technique. One of the characteristics that made moving-coil cartridges so well liked by audiophiles was their lack of the swaybacked response, in the range from about 2 to 5 kHz, which many moving-magnet cartridges exhibited; this smoother response made the sound more forward and realistic. The better moving-magnet cartridges of the present era have also eliminated this swayback response and are very smooth through this range, but I think that the acceptance of the moving-coil cartridge had much to do with making this a design goal for moving-magnet cartridge designers. If anything, the SME/Signet combination has a more pronounced output in this range than the reference system, which also features a moving-coil cartridge. Comments such as "more up front" and "sharper images" made by listening panel members correlate well with the response characteristic shown in Fig 1. The crosstalk of the SME/Signet combination is excellent; the rise in the lower frequency range is an artifact of the B & K test record. (By the way, for those who might wonder, crosstalk means leakage of signal from one channel into the other, not that the channels are mad at each other.)

Fig. 11--Output from 15and 30-cm/S, 10.8-kHz pulse test, Shure TTR-103 test record.

Fig. 12--Spectral analysis of distortion products from signals shown in Fig. 11. This is excellent performance.

Fig. 13--Output from 1-kHz square wave, using CBS STR-112 test record. The ringing is at 28.5 kHz.

Fig. 14--Spectral analysis of the 1-kHz square waves shown in Fig. 13.

The response to a complex signal is excellent.

The low-frequency resonance due to the compliance of the Signet 009 cartridge and the effective mass of the SME 309 tonearm is shown in Fig. 2. It occurs at 7.0 Hz but the relatively low rise in response at this frequency is due to the desirably low Q of 2.6. Comments by some of the panel members about the sound of double bass and kick drum rated the OC9 as being "slightly less rounded" and "less full" than the reference system, while other comments were "very close" and "hard to choose between A and B." Figure 3 shows the low-frequency resonance in the vertical and lateral planes for the Signet 009 cartridge mounted in the SME 309 tonearm. They are very similar, which indicates that the compliance of the 009 and the mass of the SME 309 are fairly evenly distributed between the vertical and lateral modes; they make an excellent combination from this perspective.

The combination of the SME 309 tonearm and Signet 009 exhibits a very smooth response for the slow sweep of frequencies between 20 Hz and 1 kHz (Fig. 4). There are no glitches that would indicate structural discontinuities. This is exceptional for a tonearm with a detachable headshell.

The output of the SME/Signet combination for a mechanical impulse applied to the armtube is shown in Fig. 5. The gain of my digital storage oscilloscope had to be set quite high to obtain this graph as the actual output is really very low. The fact that the constrained mode-damping within the SME 309 tonearm does an excellent job is apparent from the low output as well as the rapidity of the decay in energy, especially at the higher frequencies.

Figure 6 shows the spectral components due to a series of mechanical impulses applied to the arm tube. While there are peaks at 1,750, 2,850, and 6,650 Hz, they are at a very low level. It is possible that these frequency components could add a slight brightness and enhance the forward quality of the sound.

Figure 7 is the output of the left versus the right channel for wide-band pink noise. If the channels were perfectly identical, the result would be a straight line at a 45° angle.

Figure 8 is a graph of the interchannel phase-transfer function, which indicates a slight phase difference between the left and right channels. The time difference between the channels is 10.1 uS at 20 kHz. The panel member comments that might correlate with this phenomenon concerned image stability and the sound of bells and cymbals. They were "slightly less precise images" and "cymbal sounded bigger." Figure 9 indicates that the OC9 has very good and consistent tracking capability. It shows signs of mistracking at the 25-cm/S velocity but showed no signs of groove-jumping at this extremely high level. The 009 cartridge was rated as being "slightly more gritty" during high-level drum and cymbal passages than the reference, but "more mellow" and "more refined" on moderate-level passages of string, brass, and acoustic guitars. In fact, for the brass ensemble passages one panel member commented, "B [SME/Signet] was a bit muffled compared with A [reference system] but B was more pleasing to me." Figure 10, the spectrum of the output of the 009 for the 19.2- and 25-cm/S levels of the B & K 2010 test record, also indicates that the distortion increases rapidly at the higher level but that the increase is greater for the even harmonics. An increase in even-order harmonics like this usually causes a perception of mellowness and body in the sound. One panel member's comments were right on target for the louder guitar passages; this listener found the passages to be "full-bodied" and "mellow." Figure 11 shows the output of Signet OC9 cartridge for the 10.8-kHz shaped tone burst of the Shure TTR-103 test record. The symmetry is excellent and Fig. 12, which shows the spectrum due to the output shown in Fig. 11, reveals little change between the 15- and 30-cm/S bands of the test record. This can be correlated to comments by various panel members, such as "the bells and triangle sound very real." The performance of the Signet 009 in this area is excellent.

The square-wave output of the Signet OC9 is shown in Fig. 13, while the spectrum of this output is shown in Fig. 14.

The overshoot and slight ringing indicate that some phase shift is occurring at higher frequencies. Panel-member comments such as "less spaciousness" and "less depth" may be related to this because the reference system has less phase delay in this range; I would still rate the 009 cartridge very highly, regardless of these comments, because the reference system the listening panel was comparing it to j is excellent in this regard.

Conclusions

The SME 309 is a good value and provides many of the features of the more expensive SME tonearms. It is an especially good choice for anyone who has more than one phono cartridge, because it has interchangeable head shells. I think that the Signet 009 cartridge is an excellent value. Both the 309 and the 009 have their strong points and their weak points as this report has shown.

If you went out right now and bought the SME 309 tone arm and the Signet 009 moving-coil cartridge, I don't think you would be disappointed; each is offered by a company that has been specializing in its particular products for many years and each has earned its excellent reputation by producing excellent products. Make certain, however, that your preamplifier or receiver phono input has enough gain, or you will have to buy a step-up transformer or pre-preamp.

All of my testing and the listening evaluations were done without a step-up device, because I think that "less is better" and the normal 47-kilohm phono input worked just fine with the Signet 009. If you have been using a run-of-the-mill moving-magnet cartridge, the Signet 009 will introduce you to the wonderful world of moving-coil cartridges without breaking the bank.

-Edward M. Long

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MEASURED DATA

SME 309 Tonearm

Pivot-to-Stylus Distance: 9.14 in. (232 mm).

Pivot-to-Rear-of-Arm Distance: 2.375 in. (60.3 mm).

Tracking-Force Adjustment: 0 to 2.5 grams.

Tracking-Force Calibration: None (use calibrated tool provided).

Cartridge Weight Range: 6 to 17 grams.

Counterweights: One (154.2 grams).

Counterweight Mounting: Locked to rear of tonearm after adjustment.

Sidethrust Correction: Knob on extension from arm pillar.

Pivot Damping: None.

Lifting Device: Damped lever near pillar.

Headshell Offset: 23.5°.

Overhang Adjustment: Sliding base.

Bearing Alignment: Excellent.

Bearing Friction: Less than 40 mg, vertical and lateral.

Bearing Type: Ball and race, vertical and horizontal.

Lead Torque: Very low.

Arm-Lead Capacity: 10 pF, each channel.

Arm-Lead Resistance: 0.12 ohms, each channel.

External-Lead Length: 3.9 feet (1.2 meters).

External-Lead Resistance: 0.9 ohms, each channel.

External-Lead Capacity: 90 pF, each channel.

Mounting: SME rack and pinion.

Signet OC9 Cartridge

Coil Inductance: Less than 100 H.

Coil Resistance: Left, 11.6 ohms; right, 11.7 ohms.

Output Voltage: Left, 0.10 mV/cm; right, 0.093 mV/cm.

Tracking Force: 1.75 grams.

Cartridge Mass: 8.0 grams.

Microphony: Very Low.

Hum Rejection: Excellent.

High-Frequency Resonance: 28.5 kHz.

Rise-Time: 11 S.

Low-Frequency Resonance: 7.0 Hz.

Low-Frequency Q: 2.6.

Recommended Load Resistance: 20 ohms or greater.

Recommended Load Capacitance: Unaffected by up to 500 pF.

( Audio magazine, Sept. 1990)

Also see:

SOTA Star Sapphire Turntable (Jun. 1986)

SME V Tonearm and Talisman Virtuoso DTi Cartridge (Jun. 1986)

Revolver Turntable, Standard Arm, and Bullet Cartridge (Apr. 1989)

Thorens TD 320 Turntable and TP 16 MK III Tonearm (Mar. 1987)

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