Manufacturer's Specifications:
Frequency Response: 5 Hz to 35 kHz; 20 Hz to 15 kHz, ±0.5 dB.
Tracking Force: 1.2 grams (1 to 1.5 grams).
Channel Balance: 0.5 dB.
Channel Separation: At 1 kHz, 35 dB; at 10 kHz, 26 dB.
Output Voltage: At 1 kHz and 5 cm per S, 2.2 mV.
Stylus: Nude-mounted, natural-diamond MicroLine.
Cantilever: Boron.
Vertical Tracking Angle: 20°. Resistance: 240 ohms d.c.
Inductance: 85 mH.
Impedance: 550 ohms at 1 kHz.
Recommended Load Impedance: 47 kilohms.
Recommended Load Capacitance: 100 to 200 pF.
Weight: 7.5 grams.
Replacement Stylus Assembly: TKN10ML.
Price: $380.
Company Address: 4701 Hudson Dr., Stow, Ohio 44224.
When Signet introduced the TK10ML moving-magnet phono cartridge, it was the first in the United States to utilize the MicroLine diamond stylus.
The design of this stylus is claimed to surpass all others in virtually every aspect of performance. The MicroLine has a scanning radius of only 2.5 microns, half that of other small, thin stylus tips. This permits the tip to trace modulations too finely cut for conventional styli. The length of this 2.5-micron ridge is 210 microns, compared to only 67.5 microns for elliptical tips and 143 microns for van den Hul tips.
Signet calls the MicroLine's scanning radius and vertical contact dimension the narrowest and tallest "footprint" ever achieved by a cartridge manufacturer, and claims that its longer vertical contact line minimizes stylus pressure on the groove wall, even after taking the narrow scanning width into account. The end result, according to Signet, is wider frequency response, lower distortion, and less stylus and record wear.
Audiophiles with heavily played record collections should seriously consider the MicroLine stylus, because its extremely long footprint will contact parts of worn records' grooves which have never been played before. Thus, there should be a considerable reduction in surface noise and a cleaner sound-somewhat like that of a new record. However, to function properly, the stylus must be precisely aligned with the groove walls.
Fig. 1--Frequency response and separation (JVC TRS-1007 test record).
Fig. 2--Response to a 1-kHz square wave.
The stylus is made from a whole, natural octahedral diamond. It is grain oriented and ground with a square shank to fit the laser-cut hole in the cantilever precisely, for perfect alignment and positioning.
The cantilever is made of boron, among the most rigid and acoustically dead materials known. This rigidity eliminates spurious resonances, assuring smooth response within the audible range.
The Signet Twin-Flux generator system utilizes two completely discrete magnet/coil systems, one for each groove wall, each precisely aligned at a right angle to one of the walls. Each of these two samarium-cobalt magnets, along with its associated laminated ring core and toroidal coil, makes up an independent electrical generator that reproduces only the sound information on its own stereo channel. This results in very high stereo separation.
The omega-shaped coils themselves are of 99.9% pure, oxygen-free copper, and are wound on a unitized core/ pole piece made up of six wafer-thin metal laminations for the highest possible flux density. To eliminate crosstalk from one side to the other, a mu-metal shield is placed between the two coil assemblies.
The TK10ML is packaged in a plastic container. Besides the phono cartridge, the usual stylus brush, screwdriver and mounting hardware are included. The plastic container is boxed in a Styrofoam case which, in turn, is packaged in a reasonably good-looking display box.
Measurements
The Signet TK10ML moving-magnet phono cartridge was mounted in an EDS S-shaped tonearm, on an EDS 25F turntable. The TK10ML weighs 7.5 grams, and the headshell 6.9 grams, for a total weight of 14.4 grams. Each channel was terminated with 47 kilohms resistance and 180 pF capacitance. The Dennesen Geometric Soundtracktor was used to orient the TK10ML in the headshell and tonearm.
All laboratory tests were conducted at an ambient temperature of 72° F (22.22° C) and a relative humidity of 55%, ±3%. The tracking force for all reported tests was set at 1.25 grams and the anti-skating force at 1.7 grams.
As is my practice, measurements are made on both channels, but only the left is reported unless the two channels differ significantly, in which case both channels are reported for a given measurement.
The following test records were used in making the reported measurements: Columbia STR-100, STR-112, and STR-170; Shure TTR-103, TTR-109, TTR-110, TTR-115, and TTR-117; Deutsches HiFi No. 2; DIN 45.549 and 45.542; JVC TRS-1005 and TRS-1007; B & K QR-2010, and Ortofon 0002 and 0003.
above: The tall, thin "footprint" of the Signet's MicroLine
stylus scans fine details well.
Frequency response, measured from 40 Hz to 20 kHz with the JVC TRS1007, was among the flattest I've ever measured: +0.8,-0.25 dB (Fig. 1). Separation, using the same test disc, was 32 dB at 1 kHz, 26.5 dB at 10 kHz, 23 dB at 15 kHz, and 21.5 dB at 20 kHz. The frequency response from 30 to 50 kHz using the JVC TRS-1005 was -3 dB at 30 kHz,-5 dB at 45 kHz, and-7 dB at 50 kHz. The frequency response beyond 30 kHz was not remarkable. The 1-kHz square wave is quite flat, with no overshoot (Fig. 2). The arm/cartridge low-frequency lateral resonance for either channel measured a surprisingly low 6.5 Hz at + 7 dB. The vertical resonance was also 6.5 Hz. Given such a low arm/cartridge resonance, the measurement was repeated using a Technics EPA-A250 tonearm, with its anti-resonance device defeated. Again, the arm/cartridge resonance in both planes measured 6.5 Hz. Based on this, it seems that the TK10ML phono cartridge should be mounted in either a very light or a heavily damped tonearm.
Using the Dynamic Sound Devices DMA-1 dynamic mass analyzer, the arm/cartridge dynamic mass was measured at 16.5 grams, and the dynamic vertical compliance at 35 x 10-6 cm/ dyne at the vertical resonant frequency of 6.5 Hz. The harmonic-distortion components of the 1-kHz, 3.54-cm/S rms, 45° velocity signal from the Columbia STR-100 test record were: 1.12% second harmonic, 0.5% third harmonic, with less than 0.2% higher order terms. The vertical stylus angle measured 22° at the tracking force of 1.25 grams.
Other measured data are: Wt., 7.5 g.
Opt. tracking force, 1.25 g.
Opt. anti skating force, 1.7 g. Output, 0.51 mV/ cm/S.
IM distortion (200/4000 Hz, 4:1): Lateral (+9 dB), 0.6%; vertical (+6 dB), 2.2%.
Crosstalk (using Shure TTR109): Left,-24 dB; right,-27 dB.
Channel balance, 1 dB.
Trackability: High frequency (10.8 kHz, pulsed), 30 cm/S; mid-frequency (1 and 1.5 kHz, lateral cut), 31.5 cm/S; low frequency (400 Hz and 4 kHz, lateral cut), 24 cm/ S.
The Deutsches HiFi No. 2 300-Hz test band was tracked cleanly to 114 microns (0.0114 cm) lateral at 21.50 cm/S at + 12 dB and to 55.4 microns (0.00554 cm) vertical at 10.32 cm/S at +5.86 dB. In repeating the test using the DIN 45.549 test record, the TK10ML tracked to 120 microns in the left channel and 100 microns in the right channel.
The Signet TK10ML encountered no difficulty in tracking all the test bands on the Shure Obstacle Course Era Ill and Era IV musical test records as well as level 6 of the Shure Era V trackability tests.
Since commercial analog records rarely have peak recorded velocities exceeding 15 cm/S, the Signet TK10ML would be able to track any audiophile records, such as those issued by Sonic Arts, Telarc, Sheffield, Reference Recordings, RCA Point 5 or Mobile Fidelity.
One cautionary note: The MicroLine stylus must be kept pristinely clean at all times; otherwise, the music will sound somewhat muddy. Undoubtedly this occurs because the stylus' extra small scanning radius acts as a super scoop, penetrating deep into the record's groove and scraping dust and dirt particles from the groove's very bottom.
Use and Listening Tests
As usual, listening tests were performed both before and after laboratory tests. The following equipment was used: EDS 25F turntable and arm, Technics EPA-B500 tonearm assembly along with an A-250 S-shaped tonearm mounted on a Technics SP-10MKII turntable, Audio-Technica AT666EX vacuum disc stabilizer, Amoer Model 17FF preamplifier, two VSP Labs Trans-MOS 150 amplifiers (each used in the 300-watt mono mode), and a pair of B & W 801F loudspeakers.
Speaker cable, interconnecting cables, and the wall foam for the live-end/ dead-end (LEDE) listening room were from Discrete Technology.
Some of the super audiophile records I used to evaluate the Signet TK10ML were Gershwin: Rhapsody in Blue, An American in Paris (List, piano; Cincinnati Symphony, Kunzel, Telarc DG-10058), Saint-Satins: Symphony No. 3, "Organ" (Zamkochian, organ; Boston Symphony, Munch, RCA Red Seal Point 5 ATL1-4039), Adam Makowicz, Jazz Pianist (Sheffield Lab 21), Vivaldi: La Primavera, Opus 8, No. 1, etc. (H. Ohyama and the Cremona Chamber Ensemble, Sonic Arts LS-8), Schubert: Four Works for Violin and Piano (Matoulek, violin; Adamec, piano; Denon OX-7141-ND), Wild Bill Davison and Eddie Miller Play Hoagy Carmichael (M & K RealTime Records-Digital Recording RT 306), and David Foster, The Best of Me (Mobile Fidelity MFSL 1-123). At no time did I hear any coloration present except when the stylus of the TK10ML was dirty. Both applause definition and transient response were excellent. As expected, the TK10ML reproduced very high velocity cannon shots on the Telarc 1812 (matrix 2) with no apparent difficulty. The Bosendorfer piano, as well as the singing voices, were reproduced realistically. Both stereo imaging and depth were superior to the average phono cartridge. I found the bass sonically well-defined and tight.
Although the Signet TK10ML was put through the wringer, playing just about every type of music record commercially available, there was none it did not reproduce flawlessly.
After more than 40 hours of listening to the Signet TK10ML play practically everything, I judged it one of the best and most natural-sounding moving magnet phono cartridges available today. Those enamored with the mystique of the vaunted moving-coil phono cartridges would undoubtedly find it ear-opening to audition this extraordinary phono cartridge.
-B. V. Pisha
(Source: Audio magazine; Feb. 1985)
Also see:
Signet SK305 Electronic Stylus Cleaner (May 1982)
SOTA Cosmos Turntable / SME 309 Arm & Signet OC9 Cartridge (Sept. 1990)
Revolver Turntable, Standard Arm, and Bullet Cartridge (Apr. 1989)
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