GB1604805A

GB1604805A - Cassette tape recorders

Info

Publication number: GB1604805A
Application number: GB2994477A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1978-05-31
Filing date: 1978-05-31
Publication date: 1981-12-16

Description

(54) IMPROVEMENTS IN OR RELATING TO CASSETTE TAPE RECORDERS (71) I, VONG HOI TONG, a Portuguese citizen, of 179/180 Connaught Road West, Cheung Ka Industrial Building, 19th Floor, Block A, West Point, Hong Kong, do hereby declare the invention, for which I pray that a patent may be granted to me, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to improvements in or relating to cassette tape recorders.

According to the invention in one aspect thereof, there is provided a cassette tape recorder having first and second stereo playback channels arranged to feed first and second stereo audio signals to first and second loudspeaker arrangements respectively, in which recorder: means are provided for combining the first and second stereo signals to derive an additional composite audio signal; a third loudspeaker arrangement is provided for reproducing said composite signal; and the recorder comprises a casing having oppositely facing major surfaces, the first and second loudspeaker arrangements being arranged to radiate sound from one major surface and the third loudspeaker arrangement being arranged to radiate sound from the other major surface.

According to a preferred feature of the invention, an environment control is provided to apply a predetermined modification to the normal operation of an amplifier stage of each of the first and second channels to modify the signals in the first and second channels to suit predetermined listening conditions.

In order that the invention may be readily understood, an embodiment of the invention will now be described in more detail, by way of example, with reference to the accompanying drawings, in which: FIGURE 1 is a schematic diagram of part of a cassette tape recorder embodying the invention illustrating the derivation of an additional composite audio signal for a third loudspeaker arrangement of the recorder; FIGURE 2 is a schematic diagram of part of a cassette tape recorder embodying the invention, illustrating an environment control of the recorder; and FIGURE 3 is a circuit diagram of a portable combined radio and cassette tape recorder embodying the invention.

Referring to Figure 1 of the drawings, a cassette tape recorder embodying the invention has first and second stereo playback channels 1A and 1B on which first and second stereo audio signals are delivered. The two stereo signals are applied to first and second loud speaker arrangements 2A and 2B by respective output stages 3A and 3B.

Humming and selection circuitry 4 is connected to the outputs of the two output stages 3A and 3B and derives from the first and second stereo signals an additional composite audio signal which is delivered to a third output stage 5 feeding a third loudspeaker arrangement 6. The third loudspeaker arrangement 6 may be physically arranged between the stereo loudspeaker arrangements 2A and 2B.

In the embodiment of Figure 3, the summing and selection circuitry 4 receives audio signal; from the first and second stereo output stages on lines 7 and 8 via headphone jacks 9A and 9B and extension speaker jacks 10A and 10B.

The stereo signals on lines 7 and 8 are combined in a summing network comprising equal resistors 11A and 11B whose junction is connected via capacitor 12 and resistors 13 and 14 to the base of amplifying transistor 15 whose base is also connected to earth via capacitor 16. The junction of resistors 11A and 11B is connected to earth via resistor 17 and the junction of capacitor 12 and resistor 13 to earth via resistor 18 and the series combination of resistor 19 and capacitor 20. The junction of capacitor 20 and resistor 19 is connected to the collector of transistor 15 by resistor 21. The emitter of transistor 15 is connected to earth via fixed resistor 22 and is coupled to the junction of resistors 13 and 14 by capacitor 23.The emitter is also connected to earth via capacitor 24 and variable resistor 25, the composite signal for loudspeaker 6 being taken from the tap of variable resistor 25 and applied to the input of the third output stage 5 for driving the loudspeaker 6.

Figure 2 illustrates an environment control for modifying the stereo signals supplied to the stereo loudspeaker arrangements to suit low volume listening conditions.

Respective stereo signals are provided on first and second playback channels and supplied to respective volume control potentiometers 30A, 30B whose outputs are applied to first and second driver stages 31 A, 313 and thence to the first and second output stages 3A, 3B which feed the first and second loudspeaker arrangements 2A, 2B.

An environmental control switch 29 is connected to channels 1A, 1B via capacitors 32A, 32B, directly to fixed taps 33A, 33B of volume control resistors 30A, 30B, to the inputs of driver stages 31A, 31B via resistors 34A, 34B, and to the outputs of stages 31A, 31B via a series arrangement of a first resistor 35A, 35B, a second resistor 36A, 36B and a capacitor 37A, 37B. The junctions of resistors 35A, 36A and 35B, 36B are connected to earth via respective capacitors 38A, 38B. The switch also has two connections to earth via resistors 39A, 39B alone or by a series combination of resistor 39A, 39B and a capacitor 40A, 40B.

In a normal condition of the switch 29, i.e. with the switch in its "off" position, the connections of the capacitor 32A, the resistor 34A and the capacitor 37A at the switch are open circuit, and capacitor 32A, resistor 34A, resistor 3 6A and 3 7A do not affect the operation of the circuit. Tap 33A of volume control 30A is connected by the switch to earth via resistor 39A. Similar conditions exist for the components of the second channel 1B.

When the switch is moved to its "on" position, the input of volume control 30A is connected to its tap 33A via capacitor 32A and switch 29, and to earth via capacitor 32A, capacitor 40A and resistor 39A. The input of stage 31A is connected via resistor 34A, swtich 29, capacitor 37B, resistor 36B and resistor 35B to the output of stage 31B of channel 1B. Similar conditions exist for the components of the second channel 1B, the input of stage 31B being connected to the output of stage 31A via resistor 34B, capacitor 37A and resistors 36A and 35A.

In the embodiment of Figure 3 volume control potentiometers 30A and 30B are shown as receiving their signals from tone control arrangements 41A, 41B, and stages 31A, 31B comprise transistors 42A, 42B.

In a practical embodiment of the invention, the combined cassette tape recorder and radio has a substantially parallelepipedal form with a front major wall and a rear major surface. Preferably, the loudspeaker arrangements 2A and 2B radiate sound from the front surface and arrangement 6 from the rear surface.

WHAT I CLAIM IS:- 1. A cassette tape recorder having first and second stereo playback channels arranged to feed first and second stereo audio signals to first and second loudspeaker arrangements respectively, in which recorder: means are provided for combining the first and second stereo signals to derive an additional composite audio signal; a third loudspeaker arrangement is provided for reproducing said composite signal; and the recorder comprises a casing having oppositely facing major surfaces, the first and second loudspeaker arrangements being arranged to radiate sound from one major surface and the third loudspeaker arrangement being arranged to radiate sound from the other major surface.

2. A cassette tape recorder according to claim 1, wherein an environment control is provided to apply a predetermined modification to the normal operation of an amplifier stage of each of the first and second channels to modify the signals in the first and second channels to suit predetermined listening conditions.

3. A cassette tape recorder substantially as hereinbefore described with reference to the accompanying drawings.

4. A combined radio and cassette tape recorder substantially as hereinbefore described with reference to the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. loudspeaker 6 being taken from the tap of variable resistor 25 and applied to the input of the third output stage 5 for driving the loudspeaker 6. Figure 2 illustrates an environment control for modifying the stereo signals supplied to the stereo loudspeaker arrangements to suit low volume listening conditions. Respective stereo signals are provided on first and second playback channels and supplied to respective volume control potentiometers 30A, 30B whose outputs are applied to first and second driver stages 31 A, 313 and thence to the first and second output stages 3A, 3B which feed the first and second loudspeaker arrangements 2A, 2B. An environmental control switch 29 is connected to channels 1A, 1B via capacitors 32A, 32B, directly to fixed taps 33A, 33B of volume control resistors 30A, 30B, to the inputs of driver stages 31A, 31B via resistors 34A, 34B, and to the outputs of stages 31A, 31B via a series arrangement of a first resistor 35A, 35B, a second resistor 36A, 36B and a capacitor 37A, 37B. The junctions of resistors 35A, 36A and 35B, 36B are connected to earth via respective capacitors 38A, 38B. The switch also has two connections to earth via resistors 39A, 39B alone or by a series combination of resistor 39A, 39B and a capacitor 40A, 40B. In a normal condition of the switch 29, i.e. with the switch in its "off" position, the connections of the capacitor 32A, the resistor 34A and the capacitor 37A at the switch are open circuit, and capacitor 32A, resistor 34A, resistor 3 6A and 3 7A do not affect the operation of the circuit. Tap 33A of volume control 30A is connected by the switch to earth via resistor 39A. Similar conditions exist for the components of the second channel 1B. When the switch is moved to its "on" position, the input of volume control 30A is connected to its tap 33A via capacitor 32A and switch 29, and to earth via capacitor 32A, capacitor 40A and resistor 39A. The input of stage 31A is connected via resistor 34A, swtich 29, capacitor 37B, resistor 36B and resistor 35B to the output of stage 31B of channel 1B. Similar conditions exist for the components of the second channel 1B, the input of stage 31B being connected to the output of stage 31A via resistor 34B, capacitor 37A and resistors 36A and 35A. In the embodiment of Figure 3 volume control potentiometers 30A and 30B are shown as receiving their signals from tone control arrangements 41A, 41B, and stages 31A, 31B comprise transistors 42A, 42B. In a practical embodiment of the invention, the combined cassette tape recorder and radio has a substantially parallelepipedal form with a front major wall and a rear major surface. Preferably, the loudspeaker arrangements 2A and 2B radiate sound from the front surface and arrangement 6 from the rear surface. WHAT I CLAIM IS:-

1. A cassette tape recorder having first and second stereo playback channels arranged to feed first and second stereo audio signals to first and second loudspeaker arrangements respectively, in which recorder: means are provided for combining the first and second stereo signals to derive an additional composite audio signal; a third loudspeaker arrangement is provided for reproducing said composite signal; and the recorder comprises a casing having oppositely facing major surfaces, the first and second loudspeaker arrangements being arranged to radiate sound from one major surface and the third loudspeaker arrangement being arranged to radiate sound from the other major surface.