Device for damping tonearm

Abstract

The invention relates to the field of audio- and precision equipment, specifically to damping devices for turntable tonearm tubes and platforms for highly sensitive apparatuses. The device comprises a sealed reservoir filled with a viscous liquid and a lid with a flat bottom surface for contact with the object being damped. A high-density weight is suspended inside the reservoir by one or more flexible threads. The threads are secured to a plate having through holes formed in the form of petals, allowing for vertical oscillation of the weight. The device is made as a hang-on module and can be attached to the tonearm tube using a rubber ring, glue, or clamps. The invention provides damping vibrations in six degrees of freedom, signal reading accuracy increase, and sound quality improvement through effective horizontal and vertical damping.

Description

[0001] DEVICE FOR DAMPING TONEARM

[0002] Field of Technology

[0003] The invention relates to devices for eliminating vibrations from internal and external sources affecting sound reproduction devices. It can be used in the playback of gramophone records, as well as in other technical fields where the impact of vibration on various types of sensitive equipment must be reduced for stable operation.

[0004] Background Art

[0005] High-precision audio equipment such as gramophone record players is particularly susceptible to external vibration sources, which can significantly affect the audio performance of said equipment. Ideally, the player should be completely isolated from ambient vibrations, including air disturbances in the listening room, vibrations transmitted through the floor and equipment rack, and seismic vibrations. To isolate audio equipment from sources of parasitic vibration, special flooring, equipment stands, and various types of isolation pads and platforms are typically used for turntables and other audio equipment. However, complete isolation is never achieved. The energy of parasitic vibrations often accumulates within the equipment itself, requiring damping to dissipate the vibrations and reduce their amplitude. Vibrations are also transmitted through the turntable body and tonearm to the cartridge, where they are converted into a parasitic audio signal, thereby distorting the audio information of the record being played. It's worth noting that turntables contain internal sources of vibration that distort the audio signal and cannot be isolated by adding anti-vibration pads and platforms, such as the platter bearing, motor, and cantilever. When playing vinyl records, the cantilever mounted in the cartridge vibrates in the modulated groove of the disc. These cantilever vibrations are transmitted through the rubber surround of the cartridge body into the tonearm tube, reach its end, and return to the cartridge mount, where they are superimposed on the useful audio signal along with vibrational noise from external sources. These examples of parasitic vibrations are often found within the audio bandwidth.

[0006] In addition, tonearm tube vibrations caused by eccentricity errors in the records occur, leading to unwanted horizontal movements with frequencies of 0.56 Hz and 0.75 Hz for standardrotation speeds of 33 1 / 3 rpm and 45 rpm, respectively. The frequency of unwanted vertical movements, which are primarily caused by record deformations, depends on the amount of these deformations. It can be calculated that the fundamental frequency of such movements ranges from 0.56 Hz to a maximum of 3 Hz, which is the unusual case of a record with four deformations played at 45 rpm. Thus, the maximum frequency of fundamental errors in the horizontal and vertical planes is well below 20 Hz, which is significantly below the lowest frequency of the audio passband, although harmonics can exceed 20 Hz. The frequency of the distortion signals will depend on the combination of the rigidity of the stylus mounting in the cartridge suspension and the mass of the arm with the cartridge (the alignment of the cartridge and the tonearm arm). Without damping, a fundamental resonance condition may occur at or near this frequency, causing the stylus to drift out of the recording groove, for example, due to groove deformation or modulation. Without damping, the assembly can vibrate with an amplitude many times greater than the original input signal, and large distortion signals will be transmitted to the cartridge. These distortion signals can range from approximately 5 Hz to 20 Hz. While it is desirable for such resonances not to occur within the audio bandwidth, even those at subsonic frequencies tend to alter higher-frequency audio signals through cross-modulation and can overdrive the audio amplifier, which can damage both the amplifier and other equipment, such as speakers, and also lead to excessive wear on the record. Thus, a mechanical filter or damping means is required to ensure tonearm movement with minimal resistance and friction, to minimize unwanted cartridge movement at frequencies within the audio bandwidth, and to dampen any resonance between the arm and cartridge.

[0007] To improve turntable sound quality, tonearm designers aim to create a tube that does not transmit vibrations to the cartridge, using tubes made of various rigid materials with a resonant frequency above the audio frequency or with a high damping coefficient. However, the combined effects of vibration noise on the turntable's structural components, and in particular the tonearm, significantly degrade the sound of high-performance audio systems and degrade the sound image.

[0008] To suppress vibrations by damping the tonearm, audio equipment manufacturers use various devices. For example, the tonearm design of SME utilizes viscous damping, specifically silicone oil. A paddle attached to the tonearm tube near the bearing axis is immersed in an arcshaped basin filled with viscous fluid. The downside of this solution is the additional resistance it creates when tracking the record's groove, which increases wear and reduces record life, and distorts the soundstage of the recorded music. It's important to note that at a distance from the arc-shaped basin containing the viscous fluid from the axis of rotation of the tonearm arm, theamplitude of tonearm vibrations caused by the resonance of the tonearm-cartridge combination will be approximately 10 times smaller than at the cartridge mount and the groove tracking point, which also reduces the effectiveness of this solution's vibration damping.

[0009] Another tonearm manufacturer, Kuzma, uses two viscous fluid baths in its pivoting tonearms: the first replicates the SME design, while the second, a cylindrical, open-topped bath with a submerged float, is added to reduce vertical oscillation. This manufacturer also uses linear baths filled with viscous fluid to improve tracking in tonearms with linear (tangential) movement. However, their drawback is increased resistance to movement of the tonearm tube along the axis of movement, which distorts the stereo image of the musical material and requires compensation. Linear-tracking tonearms sometimes use air-hydrostatic bearing bushings to reduce friction during tonearm arm movement, but the viscous fluid bath used for stabilization actually adds resistance to movement. A known tonearm design features an arc-shaped tray containing a viscous liquid located in the track tracking area and the end of the tonearm tube (patent US4277070, IPC G11B 3 / 00, G11B 3 / 18, December 28, 1979, July 7, 1981). Although this technical solution is highly effective at suppressing vibration, the increased torque increases the tracking resistance, which increases wear, reduces record life, and introduces distortion into the stereo image of the musical material. Furthermore, the open tray containing the viscous liquid has the potential to spill and become clogged with dust, leading to a loss of its technical properties over time.

[0010] A tonearm damping device (patent US4305147, IPC G11B 3 / 00, G11B 3 / 18, G11B 3 / 32, 18.09.1979, 08.12.1981) and a tonearm (copyright certificate SU1084871, IPC G11B 3 / 18, 23.11.1978, 07.04.1984) are known, which propose the placement of an annular or spherical container with liquid in the region of the tonearm's axis of rotation. This solution allows for additional reduction of tonearm tube vibrations in the vertical plane, but has the same disadvantages as the devices listed above. A tonearm is known to have a vibration-damping device using a copper plate in the field of two magnets, attached to the tonearm tube (patent US4121837, IPC G11B 3 / 00, G11B 3 / 12, June 8, 1977, October 24, 1978). When this plate accelerates due to horizontal vibrations, eddy currents arise and a magnetic field is generated, inhibiting the plate's movement between the magnets. However, as with the devices described above, the damping efficiency is reduced due to the damping device's close proximity to the axis of rotation and the fact that it can only operate in the horizontal plane.

[0011] A phonograph pickup design with dynamic damping is known, wherein a sealed vessel containing a weight on an elastic suspension (spring), stabilized by a pair of magnets, is located in the tonearm tube near the counterweight attachment (patent US4079943, IPC G11B 3 / 00,G11B 3 / 14, G11B 3 / 18, 15.12.1976, 21.03.1978). By varying the position of said weight relative to the suspension, the resonant frequency is adjusted, specially selected to compensate for the resonance frequency of the tonearm-cartridge pair. This design utilizes a dynamic resonant damping method, which requires that the damper be adjusted precisely in accordance with the resonant frequency of the tonearm. Such adjustment must be performed each time the pickup cartridge is replaced. In this case, the tonearm's weight and conformity must be taken into account, so adjustment can only be performed in a laboratory setting. Therefore, this device is only effective in a narrow frequency range, to which it is pre-tuned, and it is also difficult to manufacture and adjust.

[0012] Disclosure of Invention

[0013] The technical objective of the claimed invention is to create a mechanism that reduces vibration and provides horizontal and vertical damping for the tonearm tube of a record player and other audio equipment. This results in increased precision, improved audio performance, and improved sound quality by reducing vibration in the tonearm arm (tube) and reducing parasitic vibrations of the pickup head (cartridge). These vibrations are transmitted further into the audio path, leading to distortion of the audio signal, reduced clarity of sound images, and blurring of overtones recorded on the record. The stated technical problem is solved, and the technical result achieved, by a tonearm arm damping device consisting of a reservoir with one open end and a lid with a flat bottom surface. The reservoir is installed in a groove on the lid's upper surface, corresponding to its open end, coaxial with the lid's center. A retaining ring is located inside the reservoir, above which is a plate. A flexible, inextensible or extensible thread, inert to the chemical action of the viscous liquid, is secured to the edges of petal-shaped through holes. A weight is suspended from this thread so as not to touch the inner surface of the reservoir walls filled with the viscous liquid or the upper surface of the lid.

[0014] The reservoir may have one of the following three-dimensional shapes: a cylinder, a pyramid, a parallelogram, a cube, a complex streamlined shape, or another.

[0015] The weight may be made of steel, lead, tungsten, or another high-density material (large weight with a small occupied volume).

[0016] The load may have one of the following volumetric shapes: a cylinder, a sphere, a parallelepiped, a prism, a pyramid, a drop, or another volumetric shape symmetrical to its perpendicular cross-section.

[0017] Depending on the shape of the load, the load is suspended by one or more flexiblethreads that are inert to the chemical action of the viscous liquid.

[0018] The flexible, inextensible thread, inert to the chemical action of the viscous liquid, can be made of nylon, nylon, polyamide, Kevlar, or other synthetic or natural fibers, such as silk. The flexible, stretchable thread, inert to the chemical action of the viscous liquid, can be made of elastomers or rubber, or it can be a steel spring.

[0019] The viscous liquid can be silicone oil, glycerin, or other synthetic or mineral oils.

[0020] The lid and base are made of a material inert to the chemical action of the viscous liquid and unaffected by the environment, such as light metals or their alloys (aluminum, titanium), plastic, polyamide, fiberglass, composite materials made of carbon fibers, or Kevlar.

[0021] To seal and prevent viscous liquid from spilling, the reservoir and lid are additionally secured at the joint with glue or epoxy resin.

[0022] To ensure better contact with the tonearm tube, the bottom surface of the lid may contain protrusions, hooks, prismatic feet, a groove of any cross-section, or a recess of a circular or oval cross-section.

[0023] Brief Description of Drawings

[0024] The claimed invention is shown in general view in Fig. 1 and in section in Fig. 2 using the following designations:

[0025] 1 - retaining ring;

[0026] 2 - reservoir;

[0027] 3 - thread attachment plate;

[0028] 4 - flexible thread;

[0029] 5 - weight;

[0030] 6 - lid.

[0031] The tonearm damping device is a sealed container filled with a viscous liquid, specifically silicone oil. The container consists of a reservoir 2 with one open end and a lid 6 with a flat bottom surface. Reservoir 2 fits into a groove on the top surface of lid 6, corresponding to its open end and coaxial with the center of lid 6. A chamfer around the groove ensures a tight fit between lid 6 and reservoir 2. For additional fixation, the open end of reservoir 2 and the groove in lid 6 are lubricated with glue or epoxy resin.

[0032] The interior of reservoir 2 is filled with a viscous liquid. A weight 5 made of a high-density material is positioned within this space so as not to touch the inner surface of reservoir 2or the top surface of lid 6. Weight 5 is suspended by a flexible thread 4, which is chemically inert to the viscous liquid. To suspend the load 5, depending on its shape, one, two, three or four flexible threads 4 are used. The long length of the flexible threads 4 ensures the maximum possible oscillation amplitude of the load 5 inside the reservoir 2. Depending on the weight of the load 5 and the stretch coefficient of a particular material, an inextensible or stretchable flexible thread 4 is selected, for which the resonance frequencies and oscillation amplitudes are determined. The flexible thread 4 is fixed at the edges of through holes made in the form of petals on the plate for fastening the thread 3, located above the locking ring 1, which is located inside the reservoir 2 and prevents the plate for fastening the thread 3 from falling out. The bending of the through holes allows the vertical oscillation of the load 5. In a particular embodiment, the cover 6 contains protrusions located on opposite sides, using which, with the help of a rubber ring, it is possible to tightly press the claimed device by the cover 6 to the arm of the tonearm. In this case, the rubber ring is hooked onto one protrusion, slid under the tonearm arm from below, and hooked onto the second protrusion. Other mounting options for the tonearm arm damping device include gluing it to the arm, taping it in place, or using something similar to a clamp or clip.

[0033] Unlike known analogs, which are integrated into the tonearm design during production and constitute an integral part thereof, the present invention is an add-on device that can be installed on most existing tonearms, thereby improving their technical characteristics and enhancing sound quality without replacing the existing hardware. Due to its rigid attachment via a rubber ring, the tonearm arm damping device does not introduce resistance to the tonearm's tracking of the record groove.

[0034] When the tonearm arm vibrates due to resonance in the cartridge-tonearm system, the tonearm arm itself and the rigidly attached tonearm arm damping device can vibrate with significant amplitude. However, the weight 5 suspended by the flexible thread 4 will tend to remain stationary relative to the turntable due to gravity. In this case, the viscous fluid filling reservoir 2 will exhibit the same oscillatory motion as the tonearm damping device itself, while weight 5 will experience viscous resistance and friction to its movement in the viscous fluid, damping the amplitude of the oscillations. As the tonearm arm oscillates, weight 5, secured to thread attachment plate 3 in the upper portion of reservoir 2, oscillates horizontally, similar to a pendulum. Thanks to the flexible thread and its attachment to the edges of petal- shaped through-holes in thread attachment plate 3, weight 5 can oscillate vertically, providing additional damping for the tonearm arm during vibrations of the record, platter, and turntable body. The maximum efficiency of the viscous resistance of the load 5 in the audio and subsonic frequencyranges is achieved due to the optimal viscosity of the liquid and the shape of the load 5 and its weight of the load 5. Vibrations transmitted to the tonearm arm from the cartridge, the player body and other excitations, such as air mass vibrations, will also be damped by the present invention over a wide frequency spectrum.

[0035] The tracking force at the cantilever tip where it contacts the record is precisely specified by the cartridge manufacturer. Typically, the cartridge tracking weight at the cantilever-record contact point ranges from 1 to 5 g with a possible error of ±0.1 g, for example, 1.65-1.85 g for the Lyra Delos cartridge. Fine adjustment of this tracking force is accomplished when changing cartridges by moving the counterweight on the tonearm arm. Mounting the claimed invention on the tonearm arm at its closest point to the cartridge significantly increases the tracking force. Therefore, to compensate for the added mass, the tonearm design must either include a counterweight of sufficient mass or be able to move it further relative to the tonearm's axis of rotation.

[0036] When using the invention, for example, on a turntable or on a platform with optical equipment or a microscope mounted on it, the weight of the counterweight 5 must correspond to the weight of the platform itself, the table, and the equipment on it. For example, to stabilize an optical table with equipment weighing a total of 45 kg, a weight of several kilograms would be required. A cover with a flat bottom surface would provide a larger contact area with the table or the ability to be bolted or otherwise connected to the table or a clamp for improved vibration transmission to the device.

[0037] The claimed device is capable of damping vibrations in six degrees of freedom. Easy installation on flat, conical, and cylindrical tonearm arms makes this invention versatile, enabling significant damping and vibration reduction in most current and historical tonearms without replacing them, thereby enhancing their performance and improving the sound of high-end turntables. The invention can also be installed not only on pivoting tonearms, but also on tonearms with linear tracking, such as those based on air bearings.

Claims

I claim:

1. A device for damping a tonearm arm, comprising a sealed container filled with a viscous liquid and a suspended weight, characterized in that the container consists of a reservoir with one open end and a lid with a flat bottom surface, wherein the reservoir is installed in a groove corresponding to its open end on the upper surface of the lid, coaxial with the center of the lid. A retaining ring is located inside the reservoir, above which is a plate wherein a flexible, inextensible or extensible thread, inert to the chemical action of the viscous liquid, is secured to the edges of through holes formed in the form of petals. The thread suspends the weight so as not to touch the inner surface of the walls of the reservoir filled with the viscous liquid and the upper surface of the lid.

2. The device according to claim 1, characterized in that the reservoir is made in one of the following three-dimensional shapes: a cylinder, a pyramid, a parallelogram, a cube, a complex streamlined shape, or another.

3. The device according to paragraph 1, characterized in that the load is made of steel, lead, tungsten, or another high-density material.

4. The device according to paragraph 1, characterized in that the load is made in one of the following three-dimensional shapes: a cylinder, sphere, parallelepiped, prism, pyramid, droplet, or other three-dimensional shape symmetrical to its perpendicular cross-section.

5. The device according to paragraph 1, characterized in that the load is suspended by one, two, three, or four flexible threads that are inert to the chemical action of the viscous liquid.

6. The device according to paragraph 1, characterized in that the flexible, inextensible thread that is inert to the chemical action of the viscous liquid is made of nylon, capron, polyamide, Kevlar, or other synthetic or natural fibers.

7. The device according to claim 1, characterized in that the flexible, stretchable thread, inert to the chemical action of the viscous liquid, is made of elastomers or rubber, or is a steel spring.

8. The device according to claim 1, characterized in that silicone oil, glycerin, or other synthetic or mineral oils are used as the viscous liquid.

9. The device according to claim 1, characterized in that the reservoir and lid are made of a material inert to the viscous liquid and not susceptible to environmental influences.

10. The device according to claim 1, characterized in that the reservoir and lid are additionally secured with glue or epoxy resin.

11. The device according to claim 1, characterized in that the lower surface of the lid contains projections, hooks, prismatic legs, a groove of any cross-section, or a recess of a circular or oval cross-section.

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