Manufacturer's Specifications:
Tonearm
Type: Straight-line, air-bearing arm with fixed headshell and inter changeable, tapered armtube.
Pivot-to-Stylus Distance: 7 3/8 in. (18.7 cm).
Tracking Error: 0°.
Effective Mass: Vertical, 7 grams; horizontal. 25 to 35 grams.
Height Adjustment: 3/8 in. (19 mm).
Vertical-Tracking-Angle Adjustment: Accurate, ±2° from center of range.
Overhang Adjustment: 1/2 in. (12.7 mm).
Cueing: Adjustable-height, eccentric-bar mechanism.
Azimuth Adjustment: ±2° from vertical.
Tracking-Force Range: 0 to 7 grams.
Pivot Damping: Vertical, none; horizontal, motion damped at counter weight assembly.
Bearing Surface Area: 6.8 square in.
Overall Arm Weight: 14.25 oz. (405 grams)
Lead Wire: Van den Hul linear-crystal silver; oxygen-free litz wire optional.
Capacitance: 40 pF.
Resistance: 0.9 ohm.
Materials: Hard-anodized aluminum armtube and bearing spindle; high-modulus carbon-fiber composite armtube joint; glass-fiber and miner al-filled composite bearing housing.
Air Filter: Disposable, 2 to 3 years average life expectancy.
Price: $850 including air pump.
Company Address: 508 Cactus St., Tallahassee, Fla. 32301.
Cartridge
Type: High-output moving coil.
Stylus: Van den Hul Type I.
Cantilever: Boron rod.
Output: 1.8 mV for 5 cm/S at 1 kHz.
Recommended Load Impedance: 47 kilohms.
Internal Impedance: 105 ohms.
Frequency Response: 15 Hz to 32 kHz, ±2 dB.
Channel Separation: 35 dB at 1 kHz.
Channel Balance: 0.5 dB.
Compliance: 15 x 10^-6 cm/dyne.
Recommended Tracking Force: 2 grams ±0.25 gram.
Weight: 7.5 grams.
Price: $800; replacement stylus, $465.
Company Address: c/o Sumiko, P.O. Box 5046, Berkeley, Cal. 94705.
The quest for a way to retrace the grooves of a phono graph record as perfectly as possible always leads back to "linear" or "straight-line" tracking. The original master lacquer, which is used to produce the record, is made by a cutterhead which is driven across its surface in a straight line, so it seems obvious that the best way to retrace a record would be by using a straight-line method. This is easier said than done, and the fact that most tonearms in the world are pivoted certainly bears this out. It is much easier to produce a low-friction conventional arm, which has bearings only at its pivot, than to produce a good straight line arm which must maintain low friction along a bearing that runs across the record from the outside to the inside grooves.
Many really great innovations are the result of someone's desire to produce something that seemed impractical, at least to the "bean counters" or money-oriented mentalities of the time. The Eminent Technology Tonearm 2 is the result of Bruce Thigpen's desire to produce a linear-tracking tonearm which would overcome the biggest problem of such tonearms: Friction. It was a long time coming and makes an interesting story.
When Bruce was still a student at Florida State University, in the late 1960s, he met Lew Ekhart. Lew was developing air bearings which could be used by students to perform physics experiments. When Bruce mentioned that such a bearing would probably be just the thing to make a really great turntable, Lew told him that he had made one and asked if he would like to see it. I can just imagine Bruce's excitement at the prospect!
In the early 1970s, both Lew and Bruce were employed by the Wayne Coloney Company, which worked on military contracts. The company was looking for other products to manufacture, and Lew's air-bearing turntable was developed. (This turntable is now being produced by the Maple-knoll Company.) In 1982, Bruce decided to start his own company and use his expertise in air-bearing technology to produce a linear-tracking tonearm. The air bearing, which is the main feature of the design, results in almost zero friction.
The first version of the tonearm lacked some of the refinements of the present version. Many of these were the result of input from Edison Price, the owner of an engineering company in New York City, who bought one of Thigpen's first tonearms. Price applied some of his mechanical engineering expertise to add some features which he thought would make the tonearm easier to adjust and use. Bruce welcomed these design improvements and has incorporated them into the present version of the tonearm. Most small companies rely on good word-of-mouth advertising by satisfied customers; Edison Price has proved to be the ultimate satisfied customer, because he actively promotes the tone arm and has even set up a demonstration listening room in his own facility in New York.
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MEASURED DATA
Eminent Technology Tonearm 2
Pivot-to-Stylus Distance: 7.0 in. (17.8 cm).
Pivot-to-Rear-of-Arm Distance: 2.75 in. (7.0 cm).
Overall Height Adjustment: 0.8 in. (2.0 cm).
Tracking-Force Adjustment: 0 to 5 grams.
Tracking-Force Calibration: None; separate gauge required.
Cartridge Weight Range: 0 to 12 grams.
Counterweights: Lead, two 4.8 grams, two 14.9 grams.
Counterweight Mounting: Leaf spring for horizontal, solid vertical.
Sidethrust Correction: None needed.
Lifting Device: Lever, no damping.
Headshell Offset: Not needed.
Overhang Adjustment: Slot in armtube (see text).
Bearing Alignment: Excellent.
Bearing Friction: Very low.
Lead Torque: Slight near inner and outer grooves.
Arm-Lead Capacitance: 47 pF.
Arm-Lead Resistance: 1.9 ohms.
Structural Resonances: 1,100, 1,550, 2,650, and 5.700 Hz
Base Mounting: Single center hole.
Talisman Virtuoso B Cartridge
Coil Inductance: Left, 310 µH; right, 280 H.
Coil Resistance: Left, 103.8 ohms; right, 102.3 ohms.
Output Voltage: Left, 0.36 mV/cm; right, 0.38 mV/cm
Tracking Force: 2.0 grams used.
Cartridge Mass: 7.5 grams.
Microphony: Excellent.
Hum Rejection: Excellent.
High-Frequency Resonance: Left, 20.8 kHz; right, 22.7 kHz
Rise-Time: 15 µS.
Low-Frequency Resonance: 10 Hz (in Eminent Technology Tonearm 2).
Low-Frequency Q: Less than 1 (in ET2 tonearm).
Response to Load Capacitance: Unaffected by normal input capacity.
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First Impressions
"Solid" and "massive" were the first adjectives that came to my mind when I first encountered the Eminent Technology Tonearm 2 (which I will refer to as the ET2, for the sake of brevity). It is finished entirely in black, with white markings. The horizontal bearing is composed of a long spindle or tube which slides back and forth inside a rather large, solid housing. This housing is called the bearing manifold because it is the device into which air is pumped. When the air pump is turned off, there is a bit of friction between the horizontal bearing tube and the bearing manifold as the tube is moved back and forth. I was surprised that there is so little play in the bearing when the air pump is off, and even less when the pump is on. But the main surprise, to me, was how slippery the bearing felt when the air pump was on. The friction was reduced to practically nothing.
Unlike some other linear-tracking tonearms, whose horizontal bearings are located out over the record, the ET2 has its main bearing set back along the right edge of the turntable. Because of this, it doesn't have to be moved out of the way to change a record, but it does require that the armtube that carries the cartridge be longer and therefore have greater effective mass. The armtube of the ET2 still has a lower effective mass in the vertical plane than most pivoted tonearms.
I was at first both impressed and disheartened by the large number of adjustments offered by the ET2. Being able to vary many parameters allows the tonearm to be adjusted perfectly, but it also means that great care must be taken.
As I proceeded with my evaluation of the ET2, I began to appreciate what could be accomplished by carefully manipulating each of the interrelated adjustments. Eminent Technology offers some optional set-up fixtures that can make the job easier, but if you have any trepidation, the dealer should be able to set up the ET2 on your turntable.
Features
The main feature of the ET2 is the air bearing, which has 6.8 square inches of surface. The moving part of the air bearing, which is called the spindle tube, is made of 6061 T6 hard-anodized aluminum. It has a 0.6110-inch outside diameter and a 0.014-inch wall thickness, and is machined to a tolerance of ±0.0003 inch. The stationary part of the air bearing, which is called the manifold assembly, is made of carbon-fiber composite material. The armtube is 5052-T5 hard-anodized aluminum with an outside diameter of 0.5 inch and a wall thickness of 0.035 inch. The cartridge end is tapered to a flattened surface and has a compressed Teflon insert. The armtube also has a vinyl sheath on the outside and closed-cell foam inside to control resonances. The interconnect plug for the phono leads and the fastening screw for the armtube are located near the vertical pivot; this lowers their contribution to the effective vertical mass.
The armtube is interchangeable and performs a function similar to that of the headshell on other tonearms. The armtube slides over a solid-aluminum joint insert, located at the end of the bearing spindle, which expands to meet the inside of the hollow armtube when the single fastening bolt is tightened. Because the joint insert is relatively heavy, it too is located near the vertical pivot to reduce its contribution to the effective vertical mass. To allow for different cartridge heights, the spindle bearing end of the joint insert can be located in any of three vertical positions, and it is locked in place by a bolt. A slot in the armtube, over the joint insert, allows the overhang to be adjusted over a 0.5-inch range to allow for different cartridges' stylus-to-mounting-hole distances. Because this slot is slightly wider than the locking screw, the armtube can be rotated slightly. This allows adjustment of the vertical azimuth (the stylus' perpendicularity to the record, as viewed from the front).
The bearing manifold is indirectly attached to the mounting post, which is also made of carbon-fiber composite material, through a vertical gear system which allows the vertical tracking angle to be adjusted. Since a straight up or down movement of the bearing manifold would cause the position of the stylus to move back or forth, the tracking-angle control lever moves the bearing manifold through an arc. This causes the overhang adjustment to remain constant. The VTA can be adjusted while a record is playing if the turntable suspension permits it. A supplied snap-on gauge allows adjustments as fine as 0.1°; the company offers an even higher precision gauge at extra cost.
The counterweight, located at the end of the spindle bearing away from the armtube, is an I-beam with graduated markings. These are for reference only and are not calibrated in grams. The beam is attached to the spindle bearing by a leaf spring, which is compliant only in the horizontal plane. To balance the arm, two 15-gram and two 5-gram lead weights are supplied, allowing adjustment from 5 to 40 grams in 5-gram steps. For fine dynamic balancing, the counterweight assembly can be raised or lowered and moved in and out along the I-beam track. After balancing the arm, tracking force is set by sliding the counterweight assembly along this track.
The lead wires inside the armtube are van den Hul linear-crystal silver, with oxygen-free litz wires available on special order. The cartridge ends of these leads are attached to gold-plated connectors which can be slipped over the cartridge pins. The wires are color-coded to match the coding on most cartridges. The other end of these wires exit the armtube near a slot in the joint insert and are attached to a five-pin plug. After the armtube is slipped over this joint insert, the plug can be inserted into the socket in the end of the bearing spindle. The leads then continue across the inside of the bearing spindle and exit on the side near the counterweight assembly. They are then looped down through a hole, which must be drilled in the tonearm mounting board, and routed to the outside of the turntable base.
There they are terminated to two gold-plated phono jacks which are mounted on a small plastic box. This box can be attached to the rear of the turntable base.
The air pump is a bit noisy. However, since it is supplied with a 24-foot hose, it can be located in another room. That is what I did during the listening tests.
Measurements and Listening Tests
Fig. 1--Frequency response and crosstalk, Talisman Virtuoso B cartridge in Eminent
Technology Tonearm 2, using B & K 2010 test record.
Fig. 2--Low-frequency tonearm cartridge resonance is at 10 Hz with a Q of less
than 1, B & K 2010.
Fig. 3--Response to vertical and horizontal modulation from 2 to 100 Hz (slow
sweep). Note differences between horizontal and vertical response due to
arm and counterweight construction (see text).
Fig. 4--Slow sweep from 20 Hz to 1 kHz. Note resonances at about 40 and 150
Hz.
Fig. 5--Output vs. time of arm/cartridge when mechanical impulse was applied
to armtube, with arm on rest.
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. With arm aligned so stylus is on the radius that runs at right angles
to the armtube, slight phase errors appear (A); with arm adjusted so stylus
is 0.125 inch ahead of this radius, channels are better synchronized (B).
Fig. 8--Interchannel phase difference vs. frequency for B & K 2011, band
7, pink noise. Top curve, for normal stylus location on radius at 90° to armtube,
shows phase error of 39.2° (equivalent to 5.4 µS) at 20 kHz; bottom curve,
for stylus 0.125 inch ahead of this radius, shows error reduced to 3.3° (0.5
µS).
Fig. 9--Time delay between right and left channels. Right channel leads left
by 7 µS.
Fig. 10--Tracking of arm/ cartridge with 1-kHz test tones at 25 cm/S (highest
level on B & K 2010, top) and 19.2 cm/S (bottom).
Fig.
11--Spectral analysis of the cartridge output when reproducing the 19.2-cm
S signal of Fig. 10. The third harmonic (at the cursor position) is 0.78% in
the left channel and 0.88% in the right.
Fig. 12--Output from 30- and 15-cm S 10.8-kHz pulse test, Shure TTR-103 test
record.
Fig.
13--Spectral analysis of distortion products from signals shown in Fig. 12
(average of 16 samples at each level). Distortion is highest (1.5%) at 50 Hz
on 15-cm/S level.
Fig. 14--Output from 1-kHz square wave, using CBS STR-112 test record.
The Talisman Virtuoso B cartridge was used with the Eminent Technology Tonearm 2 to obtain the data shown in the technical measurements (Figs. 1 through 14) and also during the listening tests. I did use some other cartridges during the technical measurements to double-check some results. The Virtuoso B is a high-output moving-coil cartridge with a boron rod cantilever, which accounts for the "B" designation. It was operated directly into the phono preamp with a 47-kilohm resistive load shunted by about 200 pF of capacitance from the leads and phono preamp input. The Virtuoso B has a moderate compliance, and it worked very well with the ET2 tonearm.
Figure 1 shows the frequency response and separation of this arm/cartridge combination. Most of the drop in separation at the low frequencies is due to crosstalk on the B & K 2010 test record. At higher frequencies, there is a bit more crosstalk from the left channel into the right than vice versa, but it is still very good, less than 30 dB at frequencies up to a little above 6 kHz. The image stability was considered by the listening panel to be excellent.
Figure 2 confirms that the low-end response of this arm/ cartridge combination does indeed drop off below 20 Hz, as suggested by Fig. 1. The slow sweep from 5 to 20 Hz provided by band 15 of the B & K 2010 test record shows that a very well-damped resonance occurs somewhere around 10 Hz with a Q of less than 1. The consensus of the listening panel was that the ET2 had slightly less bass than my reference system but that the bass was of exceptionally good quality. For some panel members, the difference in timbre between the tuba and trombone was more easily distinguishable on the reference system, and the double bass sounded deeper and more powerful.
Figure 3 is a test of the ET2/Virtuoso B combination's response to vertical and horizontal (lateral) modulation from 2 to 100 Hz. The response of the combination in the horizontal plane is very low, with a tiny, low-Q resonance at about 4 Hz and another at about 9 Hz. The response to vertical modulation is more pronounced, with a resonance of about 9.5 Hz and a Q of about 1.9. This confirms that the ET2 does have more mass in the horizontal than in the vertical plane and that the counterweight, which has more compliance horizontally than vertically, is working properly.
Figure 4 shows resonances in the ET2 at about 40 and 150 Hz. This indicates that there are mechanical interruptions to the flow of energy which cause cancellations to occur at these frequencies. I do not know exactly what effect the air-bearing interface has upon this flow of energy, but because it acts as a barrier, it doesn't allow energy to be transferred and dissipated in the tonearm board, as is the case with other tonearm designs. These resonances tend to correlate with most panel members' perception of a slightly brighter sound from the ET2/Virtuoso B combination for voice, trumpet, and strings. This is not to be taken as a negative statement, because most panel members rated the combination as being slightly preferable to the reference system when reproducing these sounds.
Another test for the effect of delayed mechanical energy is the mechanical impulse test, shown in Figs. 5 and 6.
Figure 5 shows the output versus time for a mechanical impulse applied to the tonearm near the cartridge. There are some oscillations with a time period of about 2 mS which exhibit alternating polarity reversals. This is a clue that reflected energy is present. Figure 6 shows the spectral output due to a series of mechanical impulses applied to the ET2 near the cartridge. Averaging the output produced by 16 separate impulses imparts a greater reliability to the test and therefore greater validity to the results. The graph reinforcement and cancellation of energy and the relative levels at the peaks. One panel member commented that rapid piano tones were a little more distinct when reproduced by the reference system as compared to the ET2, and this would correlate well with the data of Figs. 5 and 6.
Figures 7A and 7B show an interesting phenomenon for which I have not discovered a satisfactory explanation.
Figure 7A shows the left- versus right-channel output for the pink noise of band 7 of the B & K 2011 test record. If the channels were perfectly synchronized, with no time delay between them, the pattern would be a straight line at 45°.
Moving the cartridge forward in the armtube, creating an overhang of 0.125 inch between the stylus and the record radius that runs at right angles to the armtube, produced the output shown in Fig. 7B. This more closely approximates the 45° line that should result when the channels are synchronized. Figure 8 shows the difference in interchannel phase versus frequency for the two cartridge positions, averaging 16 samples of the B & K 2011 test record. Further tests with other cartridges and overhang settings indicate that it is not simply a cartridge or overhang problem. Tests with other records (which had music and test signals) made with different cutting systems also indicate that the type of cutter-head isn't the answer either. The dimensional discrepancies which cause these interchannel phase or synchronization errors are extremely tiny, however. The 7-1.1.S error at 1 kHz shown in Fig. 9 (the leading edge of the 1-kHz square wave on band 1 of the CBS STR-112 test record) represents a difference between the left and right channels of 0.00014 inch for a record rotating at 33 1/3 rpm with the stylus in a groove at a 5.75-inch radius. The dimensional difference for the same signal at an inner groove of the record is even smaller, because the information density is greater. All of this may seem trivial, but since interchannel differences are being shown for Compact Disc players, I thought that a comparison might be interesting. I think further investigation by others might lead to some interesting insights and might even allow further advances in the quality of analog record reproduction.
Figure 10 shows the output of the combination when trying to track the high-level 1-kHz test tones of the B & K 2010 test record. There is some mistracking at the highest level (25 cm/S), but it is very symmetrical. I think this is interesting because it shows how a linear-tracking tonearm, which neither has nor needs any sidethrust correction, can produce a very symmetrical output under difficult conditions. The limit to tracking ability, in this case, is the cartridge, not the tonearm. The Virtuoso B cartridge is very good, however; the lower trace, representing the output at 19.2 cm/S, and the spectrum of the distortion (shown in Fig. 11) verify this.
The output of the ET2N/Virtuoso B combination produced by the 10.8-kHz tone burst of the Shure TTR-103 test record is shown in Fig. 12. Even at the highest level, which is for a 30-cm/S groove modulation, the results are quite good. The spectra produced by both the 30- and 15-cm/S levels are shown in Fig. 13. The distortion levels listed in the figure are very low and indicate that the high-frequency tracking capability of the combination is excellent. No adverse comments were made by any of the listening panel members regarding the sound of cymbals, bells, or other difficult-to-reproduce, high-pitched instruments. In fact, one panel member said that the sound of these instruments from both the ET2/Virtuoso B combination and the reference system were really fabulous.
Figure 14 shows the output of the combination for the square wave on band 1 of the CBS STR-112 test record. The characteristic decrease in output immediately following the sharp initial transient is normal for a cartridge which exhibits the type of roll-off shown previously in Fig. 1. This type of characteristic is also associated with the phase or time delay exhibited by any band-limited device or circuit. It would be interesting to determine whether any difference could be heard if a phase-correction circuit were inserted between the cartridge and the loudspeakers.
Conclusions
My initial trepidations about the apparent complexity of the Eminent Technology Tonearm 2 were completely gone by the time I finished the technical measurements and the listening tests. The Talisman Virtuoso B cartridge is practically identical to the Virtuoso/DTi, which I reported on in the June 1986 issue of Audio, but less expensive. The ET2 does have a feel that's different from the usual pivoted tonearm, and it takes a little time to get used to it. However, it is certainly worth the effort, because the ET2's performance is excellent. The level of low bass from the ET2Nirtuoso B combination is less than that from other tonearm/cartridge combinations, but after listening to this setup for a while, the others sound bass-heavy! The final judgment of the listening panel and myself is that the Eminent Technology Tonearm 2 and the Talisman Virtuoso B cartridge make a fantastically accurate and musically pleasant combination. If you love music, you will love them.
-Edward M. Long
[adapted from Audio magazine/Feb. 1987 ]
Also see:
Eminent Technology LFT-III Loudspeaker (Auricle, Feb. 1989)
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