GB2260639A

GB2260639A - A transcription turntable

Info

Publication number: GB2260639A
Application number: GB9122038A
Authority: GB
Inventors: John Ulrich Auer
Original assignee: Individual
Current assignee: Individual
Priority date: 1991-10-17
Filing date: 1991-10-17
Publication date: 1993-04-21
Anticipated expiration: 2011-10-17
Also published as: GB2260639B; GB9122038D0

Abstract

A transcription turntable comprises a rotatable platter assembly (12 to 18), a drive motor (20) for the platter (13) and a pick up arm (22) at least one of which is mounted on sharp spikes (19, 21, 24) thereby to reduce mechanical feedback to the pick up arm (22). <IMAGE>

Description

A TRANSCRIPTION TURNTABLE This invention relates to a transcription turntable for effecting pickup via a transducer of high quality audio frequencies from a record.

In the field of high fidelity audio reproduction, any mechanical vibration that is transmitted to the transducer results in an electrical signal being generated. The wanted signal produced by the interaction between a stylus and the record surface can be interfered with both by vibrations transmitted to the pickup mechanism from external sources and also from mechanical feedback resulting from drive mechanisms within the equipment itself.

A transcription turntable comprises three primary elements these being a rotatable platter assembly, a drive motor and a pickup arm which carries the stylus. In order to improve reproduction it would be ideally desirable to totally isolate the three basic components of the transcription turntable. However, it is necessary for these components to be mounted conveniently on a unit. The present invention results from an appreciation of the need to improve isolation between the three basic components and seeks to provide a transcription turntable in which mechanical interaction between the three basic components is reduced.

According to the invention there is provided a transcription turntable, comprising a rotatable platter assembly, a drive motor for the platter and a pickup arm at least one of which is mounted on sharp spikes thereby to reduce mechanical feedback to the pickup arm.

The rotatable platter assembly and/or pickup arm and/or motor may be mounted on three sharp spikes, for example steel spikes. These spikes may be located each in a centre punched recess.

The rotatable platter assembly, the drive motor and the pickup arm may be mounted on a common chassis. The common chassis is preferably a tripod framework which may be of tubular construction. The top of the tripod may be formed as a substantially triangular tubular framework and the rotatable platter assembly, pickup arm and drive motor may be mounted one at each corner of the framework.

The bottom of the common chassis may have sharp spikes for mounting the assembly on the floor thereby to reduce mechanical interaction from external vibration.

The rotatable platter assembly may comprise a framework in which the platter is resiliently mounted. The resilient mounting may be adjustable to level the platter.

The platter may be resiliently mounted on the framework by means of three spring supports.

In order that the invention and its various other preferred features may be understood more easily, embodiments thereof will now be described by way of example only, with reference to the drawings in which: Figure 1 is an elevational view of a transcription turntable constructed in accordance with the invention and mounted on a tripod framework and Figure 2 is an elevational view of the transcription turntable of Figure 1 taken from a higher elevational angle to show the entire tripod framework.

The transcription turntable shown in the drawings is mounted on a tripod framework 10 which is formed from metal tube of square cross section. The top of the tripod provides a substantially triangular tubular framework each corner of which extends beyond the triangle to facilitate the mounting of the various components.

A rotatable platter assembly shown generally as 11 comprises a tubular chassis 12 on which the platter 13 is rotatably mounted. The mounting is effected by three brackets 14 provided with resilient mounts formed by conical springs 15 with mounting rubbers each of which springs is coupled with the extremity of a different arm of a three armed spider 16. The body of the spider is provided with a bearing 17 for supporting the spindle 18 of the platter.

Towards one corner of the triangular top of the framework there are provided three sharp spikes 19 extending upwardly and engaging the tubular chassis 12 of the platter assembly in centrepunched indentations provided therein. These indentations are sufficient to locate the platter assembly and resist dislodgement by lateral forces.

A motor 20, located within a heavy construction e.g.

6 or 7 pounds weight 20A is mounted at another corner of the triangular upper portion of the tripod and is similarly supported by four spikes 21 similar to spikes 19 again extending upwardly from the triangular framework and locating with centrepunched indentations in the bottom of the motor housing. The motor drives the platter by means of a belt not shown. At the third corner of the triangular upper framework of the tripod there is similarly mounted a pickup arm 22. The pickup arm is rotatably mounted on a heavy base 23, e.g. 6 or 7 pounds and the base is supported on the third corner of the triangular framework again by means of four upwardly extending spikes 24 which engage centrepunched indentations provided in the bottom of the base.

The spikes 19, 21, 24 are shown in this preferred version as being adjustable in that they are screw-threaded and can be screwed into and out of the tubular triangular framework to adjust the relative heights of each of the supported devices and to effect levelling of the platter.

Although the spikes are shown as being upwardly extending it will be appreciated that the opposite configuration is possible with the spikes being mounted on the platter assembly of the motor and the pickup arm and engaging centrepunched indentations provided on the triangular framework. The feet of the tripod are themselves each provided with a spike 25 for ground engagement.

The point contact provided between the rotatable platter assembly 11 the heavy base 20A the heavy base 23 of the pickup arm 22 and the tripod framework 10 effectively isolates the three components one from another in that mechanical vibrations induced in one of them are not transmitted to the other or at least such vibrations are considerably attenuated. Similarly the point contact with the floor reduces considerably the transmission of vibrations from the floor.

The tripod construction of framework 10 is a preferred construction but it will be appreciated that the mounting of the three main elements of a transcription turntable on to any other form of supporting base by means of sharp spikes provides a construction falling within the scope of this invention.

Although the preferred construction illustrated employs three spikes on each of the basic elements of the transcription turntable as this provides adequate support and in the adjustable version permits adequate relative adjustment and levelling it will be appreciated that more than three spikes can be employed on each element.

The three main components i.e. 11, 20A, 23, are ideally best placed on a tubular steel fram work similar to that shown in the accompanying sketches.

Claims

1. A transcription turntable, comprising a rotatable platter assembly, a drive motor for the platter and a pick up arm at least one of which is mounted on sharp spikes thereby to reduce mechanical feedback to the pick up arm.

2. A turntable as claimed in claim 1, wherein the rotatable platter assembly is mounted on three sharp spikes.

3. A turntable as claimed in claim 1 or 2, wherein the pick up arm is mounted on three sharp spikes.

4. A turntable as claimed in any one of the preceding claims, wherein the motor is mounted on three sharp spikes.

5. A turntable as claimed in any one of the preceding claims, wherein the spikes locate each in a centre punched recess.

6. A turntable as claimed in any one of the preceding claims, wherein the rotatable platter assembly, the drive motor and the pick up arm are mounted on a common chassis.

7. A turntable as claimed in any one of the preceding claims, wherein the common chassis is a tripod framework.

8. A turntable as claimed in claim 7, wherein the tripod framework is of tubular construction.

9. A turntable as claimed in claim 8, wherein the top of the tripod is formed as a substantialy triangular tubular framework and the rotatable platter assembly, pick up arm and drive motor are mounted one at each corner of the framework.

10. A turntable as claimed in any one of claims 1 to 6, wherein the common chassis is a heavy metal plate.

11. A turntable as claimed in any one of claims 6 to 10, wherein the bottom of the common chassis has sharp spikes for mounting the assembly on the floor or a support thereby to reduce mechanical interaction from external vibration.

12. A turntable as claimed in any one of the preceding claims wherein the rotatable platter assembly comprises a framework on which the platter is resiliently mounted.

13. A turntable as claimed in claim 12, wherein the resilient mounting is adjustable to level the platter.

14. A turntable as claimed in claim 12 or 13, wherein the platter is resiliently mounted on the framework by means of three spring supports.

15. A turntable substantially as described herein with reference to the drawings.