Ariston Forte Turntable and Enigma Tonearm (Equipment Profile, Dec. 1988)

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Manufacturer's Specifications:

Turntable Drive System: Belt.

Speeds: 33.333 and 45 rpm.

Start-Up Time: 3.5 S to audible stabilization.

Wow & Flutter: 0.06% DIN weighted peak.

Rumble: -75 dB.

Platter Weight: 4 lbs. (1.75 kg).

Overall Weight: 10 1/2 lbs. (4.8 kg), less arm.

Price: Without arm, $500; with Enigma arm, $625.

Tonearm Type: Static-balance, straight-pipe, pivoted.

Horizontal Mechanism: One-point gimbal support system.

Effective Length: 9 in. (228 mm).

Overhang: 3/4 in. (18 mm).

Offset Angle: 23°45'.

Tracking Error: +2° to 1°30'.

Sensitivity: Vertical or horizontal, 50 mg (first action) except for lead friction.

Range of Stylus-Force Adjustment: 0 to 3 grams, direct-reading with 0.5-gram calibrations.

Cartridge Weight Range: 4 to 10.5 grams

Anti-Skating Adjustment: 0.5 to 3 grams.

Company Address: 12 Rte. 17 North, Suite 309. Paramus, N.J. 07652, USA.


Ariston Acoustics is not a familiar name to most Americans, although the company has been building high-quality turntables for many years. It is located in Scotland at the Prestwick International Airport, which isn't very far from Glasgow. I love to find the origins of words, so I looked in the dictionary and found that aristos is the Greek word for "best" and tonos is Greek for "a stretching or tone." I like it! The first time I heard of Ariston was back in 1973, when I read about their RD11 turntable, which achieved a new performance standard. It was a single-speed, 33 1/3-rpm belt-drive turntable which used a main platter spindle with an integrally machined conical bearing. This was unusual at the time; even today, most turntables, including the Ariston Forte, use a separate ball bearing between the bottom of the platter shaft and the thrust plate at the bottom of the main bearing well. Many turntables of this type allow the ball bearing to shift position, especially when the turntable platter is removed for inspection or to oil the bearing shaft.

Because all bearings tend to develop flat spots over time, allowing the bearing to change position with respect to the thrust plate can cause the bearing to move in a new but eccentric pattern. This may result in an increase in mechanical noise and rumble that can affect the sound. The Forte's ball bearing is locked in place to prevent motion. Since the bearing of the RD11 turntable was made an integral part of the rotating main shaft, it also eliminated the usual surface to-surface contact between the main shaft and a ball bearing, which also reduced mechanical noise and rumble.

When making the bearing part of the main platter shaft, the two principal problems that must be overcome are obtaining sufficient precision and hardening of the part.

The Forte that I tested came with the Ariston Enigma tonearm, and I used an Ortofon X3-MC cartridge, the same model that I used for the Dual CS 5000 test report (November 1988 issue) but a different unit.


MEASURED DATA: Ariston Forte Turntable

*Suspension resonance was difficult to measure because it was very highly damped.

First Impressions

The Forte's appearance is unusual, to say the least. It certainly doesn't look conventional, even though it uses many conventional, proven techniques in its engineering approach. The turntable platter is round, as expected, but so are the main chassis and the floating subchassis. Each of these three main parts is an aluminum casting. There is no separate base, or "plinth" as it is called in the British Isles. Instead, three round supports are bolted to the main support chassis. These supports have rubber grommet feet, which are not adjustable, screwed to them. Three matching supports are bolted to the subchassis, which is isolated from the bottom main chassis by springs inside these sup ports. Each spring is adjustable by turning a knob on top of each support. The knobs are held by cap screws that tend to loosen when the knobs are turned, which can be a nuisance.

The round, metal tonearm mount is a separate casting and is bolted to the right rear of the subchassis. It has a round plate to which the Ariston Enigma tonearm is mounted; blank boards and boards precut for SME or Premier's MMT arms are also available. When I tapped the Enigma tonearm tube, I heard a complex tonal quality which I find hard to describe. It was the same at both the cartridge and pillar ends of the tonearm tube, but it had a more damped quality in the center While holding the main tonearm pillar firmly in one hand, I tried to pull, push, and twist the tonearm tube to check for any play or looseness in the bearings and the headshell. I found none, which is good. The cartridge mounts to what appears to be a headshell, but it is firmly attached to the armtube and is not removable. Even though the entire turntable is made of metal, it is extremely light and weighs only 10 1/2 pounds.

Features

The Ariston Forte has a three-position rocker switch, mounted on a flattened section on the front of the main chassis, which is used to select 33 1/3 rpm, power off, and 45 rpm. The 3-pound, cast aluminum-alloy platter is painted to match the subchassis and main chassis. My sample was white, but a black and silver model is available. Strips of Ariston's patented Q-damping material, which resembles foam rubber, are fastened to the inside of the rim to damp out any ringing. The subchassis also has strips of Q-damping material around its inside periphery. The record mat, which weighs 1/2 pound, also damps out platter resonances.

The platter is driven by a belt from the motor pulley to a ring, 6 1/2 inches in diameter, which is cast into the bottom of the platter. Three large access holes in the platter allow the belt to be slipped over the motor pulley; the pulley is rather large and appears to be made of brass. These access holes are about 3/8 inch from the ring, which makes grasping the belt a bit difficult after the platter has been put in place. I found that the trick is to pull the belt through an access hole, place the belt around a pencil, and lay the pencil against the platter. This holds the belt so that it can be placed around the motor pulley at a later time. Positioning the belt must be delayed because the machining of the bearing well and the platter shaft is so precise that it takes up to 15 minutes for the shaft to slide down to its final resting position in the well, and for the oil at the bottom to move up the bearing well. The belt must be removed from the motor pulley before the platter can be removed.

The center post, for the record hole, and the main platter shaft are one continuous piece. The top is rounded, while the bottom has a slight taper with a small flat surface which rests on the ball bearing at the bottom of the bearing well.

The drive motor is rather small and is mounted on a spring like ring, which in turn is supported by three coil springs.

These are adjusted at the factory for minimum transmission of mechanical energy to the main chassis, on which the motor assembly is mounted. The main bearing well, which also appears to be made of brass, is mounted at the center of three spokes extending sis. The power for the motor is supplied by a small, 9-V transformer with two prongs that allow it to be plugged into a normal a.c. power socket. If room for the turntable is a consideration, the Forte can be slipped into a space about 16 inches wide by about 14 inches deep. There is no cover to vie for space above the turntable, but the clearance needed to change records conveniently is about 8 inches.

This could be reduced, in a pinch, since the distance between a shelf or platform and the top of the tonearm is about 5 1/4 inches. The turntable comes with a removable strobe disc for 33 1/3 and 45 rpm which fits down into the recess in the platter mat. However, since the Forte's speed control is not accessible when the platter is mounted (it's an unmarked factory adjustment, inside the base), it's better to leave it off so that the record can be in closer contact with the record mat, thus increasing sound clarity by further removing extraneous energy from the record.

The Enigma tonearm is a statically balanced type, with the tracking force provided by a movable counterweight on the rear of the tonearm tube. The weight is first rotated to the position which balances the arm. Then the adjustable scale, calibrated from 0 to 3, is set to 0, and finally the counter weight and scale are rotated together to set the tracking force. The rear of the armtube is lubricated with a thin film of viscous material that helps to damp any tendency for the counterweight to rattle.

With the Ortofon X3-MC cartridge, which weighs only 4.2 grams, the counterweight is close to the main pillar. This position is desirable because it reduces the dynamic mass of the tonearm, but it does make reading the tracking force scale difficult. A separate sidethrust force adjustment is provided by a knob that is also calibrated from 0 to 3 to match the tracking force chosen. The vertical bearings appear to be jeweled pivots, while the horizontal bearings appear to be the ball-and-race type. The damped cueing lever allows the arm to float down to the record in about 2 S.

The fingerlift on the headshell allows faster cueing for those with steady hands.

==============

MEASURED DATA

Ariston Enigma Tonearm

Pivot-to-Stylus Distance: 9.125 in. (23.2 cm).

Pivot-to-Rear-of-Arm Distance: 2.250 in. (5.7 cm).

Overall Height Adjustment: 1.00 in. (2.54 cm).

Tracking Force Adjustment: Knob on main pillar adjusts spiral spring.

Tracking Force Calibration: 1 to 3 grams, within 0.1 gram.

Cartridge Weight Range: 4 to 10 grams.

Counterweights: One, 97 grams.

Counterweight Mounting: Direct to tonearm tube, with viscous coating.

Sidethrust Correction: Calibrated knob on base of main pillar.

Pivot Damping: None.

Lifting Device: Fingerlift on headshell and damped cueing lever.

Headshell Offset: 23.0°.

Overhang Adjustment: Slots in headshell.

Bearing Alignment: Excellent.

Bearing Friction: Very low.

Bearing Type: Horizontal, ball race; vertical, jewel point.

Lead Torque: Very low.

Arm-Lead Capacitance: Left, 283 pF; right, 329 pF.

Arm-Lead Resistance: 0.5 ohm, both channels.

External Lead Length: 33 inches.

Structural Resonances: 1000, 3800, 4200, and 6200 Hz.

Base Mounting: Center hole for arm post and three screws for base.

Ortofon X3-MC Cartridge

Coil Inductance: Left, 515 uH; right, 530 uH.

Coil Resistance: Left, 78.3 ohms; right, 78.1 ohms.

Output Voltage: Left, 0.46 mV/cm/S; right, 0.39 mV/cm/S.

Cartridge Mass: 4.15 grams.

Microphony: Very low.

Hum Rejection: Excellent.

Rise-Time: 10 uS.

High-Frequency Resonance: 19.6 kHz.

Low-Frequency Resonance: 15.8 Hz (in Ariston Enigma tonearm).

Low-Frequency Q: 6.3 (in Ariston Enigma tonearm).

Recommended Load Resistance: 47 kilohms; greater than 1 kilohm has no effect.

Recommended Load Capacitance: Less than 1,000 pF has no effect.

Recommended Tracking Force: 2.1 grams.

Polarity: Plus, for RIAA Standard.

==============

The base of the tonearm is fastened by three screws, and the height of the tonearm pillar is adjustable after loosening two hex screws. The armtube is one continuous piece, from the nonremovable headshell to the rear. The tonearm is a bit shorter than others I have tested, and it appears that the tracking error has wider limits across the record surface.

The phono leads are captive, being soldered directly to a terminal block near the tonearm. The cartridge connectors are gold plated, and the phono cables have gold phono plugs. A separate ground wire, which is attached to all metal turntable parts, is also provided.

Measurements and Listening Tests


Fig. 1--Frequency response and interchannel crosstalk of the Ariston Enigma tonearm and Ortofon X3-MC cartridge, using B & K 2010 test record.


Fig. 2--Low-frequency arm cartridge resonance is at 15.8 Hz with a0 of 6.3.


Fig. 3--Low-frequency response of X3-MC cartridge and Enigma tonearm for vertical and lateral modulation, using slow sweep from 2 to 100 Hz. The damping is better in the vertical mode; see text.


Fig. 4--Slow sweep from 20 Hz to 1 kHz to test for structural resonances. No serious structural resonances are visible.


Fig. 5 Output vs. time of arm cartridge when mechanical impulse was applied to armtube; see text.


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


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


Fig. 8--Arm/cartridge. The difference at 20 kHz interchannel phase is -46.6° (6.5 4), difference vs. frequency.

The technical measurements were completed on the Ariston Forte turntable, Enigma tonearm, and Ortofon X3-MC cartridge combination before any listening was attempted.

This is my usual procedure because, unlike with amplifiers, loudspeakers, and other components, many adjustments have to be made when setting up a turntable, tonearm, and cartridge combination. If the adjustments are not done correctly, they can adversely affect the outcome of listening evaluations. During the technical measurements, the results of faulty setup adjustments can be seen and corrected. This ensures that the combination will be judged for its sound reproducing quality only after it has been adjusted for optimum performance.

The Ariston/Enigma/Ortofon combination was compared to a high-quality reference system by using a series of selections from different recordings. Each selection featured a type of instrument or voice as well as a type of music. The listening panel was comprised of both trained and casual listeners. Each panel member was given a form listing the different types of instruments to which they should pay particular attention, and they were also encouraged to make comments about anything having to do with the sound as they perceived it, even things such as rumble, hiss, background noise, etc. The reference and the tested combi nation were designated as systems A and B. For each musical selection, panel members rated the systems by placing an "X" in one of six boxes, marked from 0 to-5. A rating of 0 would mean that the listener heard absolutely no deficiency in the sound reproduction; a-3 would be good, and a-5 would mean poor reproduction. (Over the years, there have been almost no zeros awarded and very few -5s; most ratings have been between-1 and-4.) After the listening panel had made its evaluation, I tried to correlate their ratings and comments with the technical measurements. Although trained listeners provide the most astute observations, casual listeners usually provide very enlightening comments, since they seem to hear the music rather than the sound. It should be remembered that the comments are written, since the panel is cautioned against making any statements or gestures during the listening sessions. While some of the comments might seem severe, they are made in an attempt to describe very subtle differences between two systems.

Figure 1 shows the amplitude versus frequency response and the interchannel crosstalk of the Ortofon X3-MC moving-coil cartridge when mounted in the Ariston Enigma tonearm. There were comments from the listening panel about a "certain flatness" or "lack of spaciousness" which could be related to the fact that the leakage of left-channel sound into the right channel is rather high. Interestingly enough, this did not cause the panel to rate the Ariston/Enigma/Ortofon combination poorly for image localization.

Figure 2 shows the result of a slow sweep of tones from 5 to 20 Hz for left and right channels. The low-frequency resonance caused by the interaction of the compliance of the X3-MC stylus and the mass of the Enigma tonearm occurs at 15.8 Hz with a Q of 6.3; the left channel has about 2 dB more output than the right. Low-frequency sounds, such as those produced by the bass guitar, organ, etc., can be affected by this resonance. Usually it causes the bass to sound "fuller," as some of the panel members noted. The reference system has a lower resonance and a much lower Q, so the rise in its output at resonance is much less. The reference system elicited comments such as "tighter" and "more realistic" when reproducing bass instruments.

Figure 3 shows the response of the tested combination to vertical and lateral modulation between 2 and 100 Hz.

Because the resonance occurs at a lower frequency for lateral modulation than for vertical modulation, either the mass of the tonearm or the compliance of the cartridge-or both-is greater in the lateral plane of motion. Since the Q is also greater in the lateral plane of motion, it is safe to assume that the mass of the tonearm is the predominant factor. As far as sound quality is concerned, this means that for this pair the exact centering of the record is probably more important than a slight amount of up-and-down warp.

Figure 4 shows the output of the left and right channels for a very slow sweep from 20 Hz to 1 kHz, which is intended to excite any resonances in the tonearm/cartridge combination. These resonances can cause delayed energy reflections as well as simple vibrations that can color the sound reproduction and/or detract from the clarity. The tested combination does show minor resonances at 45, 80, and 130 Hz which might be due to the counterweight mounting and the main bearings. Comments were made about the Forte/Enigma/X3-MC combination which might correlate with these resonances; it was said to have "slightly less clarity" and to be "less transparent," especially during high level orchestral passages.


Fig. 10-Spectral analysis of the cartridge output when reproducing the signals of Fig. 9. Distortion at third harmonic is -25.5 dB for the 19.2-cm/S track and -17.5 dB for the 25-cm/S track. See text.


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


Fig. 12--Spectrum analysis of distortion products from signals shown in Fig. 11. At the 30-cm/S level (8 dB above the reference level of 10 cm/S), distortion at 250 Hz is only 0.69%, which is very good, but note the change in the relative levels of different frequencies for the two recorded levels.

I mentioned earlier that I found it difficult to describe the tonal quality of the Enigma tonearm's sound when I per formed the simple tap test. Figure 5 shows what the sound looks like, and when I saw these results I realized why I had had difficulty. The pattern is very complex and also lasts long enough to give a sense of tonality. In Fig. 6, a spectral analysis, there are a large number of harmonically unrelated resonances which make it difficult to assign a definite pitch to the sound. The presence of an energy peak at 1 kHz might account for comments about voice being "shrill" and violin being "brighter" and "grating." Figure 7 shows the interchannel phase relationship be tween the left and right channels. A straight line at 45° would indicate perfectly identical response in both channels.

There is a difference between the channels, though not very great, and Fig. 8 shows that it is mainly at the higher frequencies. No comments were made by panel members which could be directly related to the information in these two figures.

Figure 9 shows the output of the Ortofon cartridge for the two highest levels of the 1-kHz tone on the B & K 2010 test record. The waveform at the bottom of the figure shows that the X3-MC not only has difficulty tracking the 25-cm/S level, but has problems with the 19.2-cm/S level (top curve) as well. The spectrum of the distortion produced by these two levels is shown in Fig. 10. An interesting thing about the spectrum is that the sixth and eighth harmonics are predominant at the 19.2-cm/S level, while the sixth, seventh, and ninth harmonics predominate at the 25-cm/S level. I was able to correlate this with listeners' comments about the sound of low-level versus high-level strings and brass. At lower levels, the sound was described as "mellow" and "sonorous"; at higher levels, comments were made that it was "brighter" and even "zizzier"! Some panel members' remarks regarding the sound quality of cymbals can be related to the results shown in Figs. 11 and 12. The ability of the X3-MC/Enigma combination to track the 15-cm/S level of the 10.8-kHz shaped tone burst on the Shure TTR-103 test record is very good, as shown in the top curve of Fig. 11. The 30-cm/S level (bottom curve) reveals that the combination causes some flattening of the waveform, especially at the bottom. This can cause the sound of cymbals to take on a "slightly duller" quality. The increase in the levels shown for different frequencies (Fig. 12), especially at 800 Hz, can certainly contribute to this perception.

The response of the arm/cartridge combination to the 1-kHz square wave of the CBS STR-112 test record is shown in Fig. 13. The output of the right channel is slightly higher, which confirms the data of Fig. 1. One panel member described the sound of acoustic guitar, being played in a real acoustic space, to be "bigger than it should be." This was mainly due to the "boomier" quality caused by the increased lower frequency shown in the first four figures, but it could also be due to the difference in channel levels. This would shift the apparent location of a complex sound's spectral components.


Fig. 13--Response of arm/cartridge to 1-kHz square wave on CBS STR-112 test record.


Fig. 14--Wow and flutter spectrum of Forte turntable, from 0 to 100 Hz. See text.


Fig. 15--Speed drift over a 40-S period. The variations are at 1.8 S per cycle (0.56 Hz), related to the 33 1/3-rpm speed.


Fig. 16--Rumble spectrum. Most of the output shown is due to the tonearm/cartridge resonance.


Fig. 17--Output vs. time for mechanical shock applied to edge of record, with stylus resting in groove, to test for damping by turntable mat.

The mat does better at damping the platter's ringing than at removing energy from the record.


Fig. 18-Spectrum to 5 kHz (averaged) of output from 16 impulses applied to edge of record.


Fig. 19-Output vs. time for mechanical shock applied to stand on which the turntable was resting. Isolation is excellent.


Fig. 20-Spectrum to 5 kHz (averaged) of output from 16 impulses applied to stand on which the turntable was resting.

The spectrum of the Forte turntable's wow and flutter is shown in Fig. 14. I am not sure what is causing the spectral component at 6.75 Hz, but it is a little less than one-half the tonearm/cartridge resonance, which occurs at 15.8 Hz. The tonearm resonance is responsible for the energy in the range from 10.50 to 17.25 Hz. This data shows that the Ariston Forte turntable deserves to be rated very good for wow and excellent for flutter characteristics. No adverse comments were made by panel members that could be correlated directly with these characteristics.

The Forte's pitch variation over a 40-S period is shown in Fig. 15. The cyclical variations correspond to the rotational speed of the turntable at 33 1/3 rpm and occur at a rate of 0.56 Hz, or 1.8 S apart. There is evidence of some higher frequency components which caused the spikes in the waveform, and these may be related to the 6.75-Hz spectral output mentioned above. I did not try to analyze the turntable drive system to determine the exact cause. The sound of the piano, although described by one panel member as being "slightly wooden" for one selection, did not cause anyone to make comments which could be directly related to unsteadiness in tone.

The spectrum of the rumble, Fig. 16, shows a large spread of energy below the tonearm resonance, which is 15.8 Hz, down to about 6 Hz. The listening panel's comments regarding rumble and low-frequency background noise varied from record to record, indicating that the rumble from the Ariston Forte was well below that of the various records used for the listening evaluation.

The damping qualities of the Forte's record mat, with respect to removal of energy from the record, are plotted in Fig. 17. The output versus time is due to a single mechanical impulse applied to the edge of a stationary record, with the stylus resting in a groove. The mat is only moderately effective in this regard; it is really more successful in damping the platter's tendency to ring than it is in removing energy from the record. The spectrum of the energy due to a series of 16 impulses, applied to the edge of the record and averaged, is shown in Fig. 18. An energy hump in the range around 312.5 Hz could contribute to the "wooden" piano quality mentioned earlier.

The isolation afforded by the Forte's three-point spring suspension, for mechanical-induced energy due to outside shocks, is shown in Fig. 19. A mechanical shock was applied to the stand on which the turntable was resting, while the stylus was in a stationary record groove. The results shown are excellent. If in the past you've had problems with this type of induced energy-such as shocks from walking or even dancing in the same room as the turntable-the Forte will certainly cure them. Figure 20 shows the spectrum due to 16 mechanical shocks applied to the stand and averaged. There are peaks of energy at 112.5 and 137.5 Hz, but above about 400 Hz, the energy drops off rapidly.

Tests were also made to determine the susceptibility of the tested combination to acoustical feedback. The results, although not shown, indicated that isolation is excellent.

Conclusions

The Ariston Forte turntable has a distinctively different appearance and provides very good performance. I am not sure why Ariston decided to use a separate, though locked, main ball bearing rather than the single-piece, shaft-and-bearing design which they pioneered. However, I can't fault the company for this engineering decision because the turntable's rumble and wow and flutter are extremely low.

This turntable is easy to use, extremely light and yet rugged, compact enough to fit in a small space, and has good isolation from mechanically and acoustically induced energy. The Enigma tonearm is also very good and certainly easy to use, with everything working as it should, and it has no strange idiosyncrasies. I do wonder about the effect of its reduced length on tracking error across the record surface, but the Enigma performed very well during the listening evaluations.

If you compare the Measured Data Table for the Ortofon X3-MC which accompanies this report with the Table for the same model cartridge used with the Dual CS 5000 turntable and OPS tonearm (November 1988), you will see that the two samples performed a bit differently. I believe the differences in the Dual OPS and Ariston Enigma tonearms caused more subtle variations in the sound quality than did the cartridges. Despite the slight differences in the Measured Data, I regard the Ortofon X3-MC cartridge as an excellent value and capable of very good sound reproduction. The combination of the Ariston Forte turntable, the Enigma tonearm, and the Ortofon X3-MC cartridge provided excellent sound. Even more important, I enjoyed listening to the music that it reproduced.

-Edward M. Long

(Source: Audio magazine, Dec 1988)

Also see: Dual CS 5000 Turntable and Ortofon X3-MC Cartridge (Nov. 1988)

Dual Model 1249 Automatic Turntable (Feb. 1977)

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