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Industrial Applicability The present invention relates to an improved automobile radio for
operating a loudspeaker via a power amplifier, wherein the linear frequency characteristic of the
prior art amplifier is set in such a way that the loudspeaker reproduces the audio at original
volume Only when the adjustment is chosen, it guarantees an undistorted reproduction of all the
frequencies in the music. When the volume is lower, the bass is retracted, and when the volume
is higher, the bass is emphasized. The cause is that the sensitivity of the ear to the volume
depends on the frequency. In the case of setting and adjusting the volume lower, it is necessary
to increase the volume of the bass in order to maintain the sound quality hearing that matches
the sound quality hearing in the case of the reproduction with the original volume. When the
volume is relatively low, the need for high-pitched emphasis is somewhat less than in the case of
the bass, because in this case the experience with listening to the sound is due to the fact that the
hearing depends on the volume It is because it overlaps. A small sound belongs to a sound source
at a far distance, and since the high sound is attenuated more strongly than the low sound if the
distance is further increased, the sense of hearing corresponds to its natural sense of acoustic
hearing I also feel a loud volume. A tone control circuit is known in which low frequencies, and
possibly high frequencies, are automatically enhanced by the knob rotation of the volume
adjuster. These circuits assume a configuration in which the volume regulator controls a fixedstage final amplifier, but recently a configuration in which a so-called booster is connected to the
original car radio, i. Many are adopted. The power amplifier booster is selected by the vehicle
owner from among the devices offered for incorporation into the vehicle according to his
preference. When this type of booster is post-connected to the end of the car radio, this design of
the tone controller no longer provides adequate reproduction for listening. The problem to be
solved by the invention The object of the invention is to eliminate the abovementioned
drawbacks. Means for Solving the Problem This task is solved by the combination of features as
indicated in the characterizing portion of claim 1. DESCRIPTION OF THE PREFERRED
EMBODIMENT A car radio which will now be described with reference to the drawings will
receive a broadcasting station set in the tuner 2 via the antenna l. In the intermediate frequency
stage ZF stage 3, the received modulated signal of the broadcasting station is separated from the
carrier wave. Further, the modulation signal is supplied to the speaker 5 at the output side of the
NF stage 4 which is a low frequency stage post-connected to the ZF stage.
As shown in FIG. 2, connected to the NF stage 4, the volume adjuster 6 and the tone adjuster 7
are activated. Usually, the speaker 5 is directly connected to the final stage amplifier 8. A tone
controller is also designed for this mode of operation. As described above, the booster 9 is newly
connected in the middle between the final stage amplifier 8 and the speaker 5. This booster has
linear frequency characteristics. Depending on the model, this booster has a different degree of
amplification, ie the same input signal corresponding to the output signal of the final stage 8 is
reproduced by these boosters at different volume levels, but only via the final stage The volume
is louder than that. If the sound volume of the sound should not change in the vehicle, it is
necessary to turn the knob in the direction of volume reduction in the low frequency stage after
the installation of the booster. However, along with the low volume setting adjustment of the
volume adjuster, the bass is emphasized by the sound quality adjuster 7. When setting and
adjusting the volume adjuster to the original volume level, the bass is overemphasized in the
intermediate frequency range. In the circuit shown in FIG. 2 to avoid this drawback, a sensor 10
is connected to measure the amplification of the booster amplifier. This sensor can, for example,
be configured as a selection switch. Furthermore, a volume setting unit 11 is provided, whereby
the volume is selected. Both quantities, ie the switch position of the sensor 10 and the position of
the volume setting device 11, are optionally input into the memory 12 as an address, respectively
via an AD converter. The memory 12 contains all data for commonly controlling the volume
adjuster 6 and the sound quality adjuster 7. These data are recalled by the addresses assigned to
the corresponding addresses of the switch position of the sensor lO and the switch position of
the volume controller 11, the data pairs for the position of the volume control and the position of
the sound quality controller are then controlled Input to the device 13, the control device makes
the corresponding setting adjustments. The setting adjustment of the regulator according to the
predetermined digital value is known per se. Therefore, the description of the details of the
control device 13 is omitted. The important thing is that always both regulators are changed
under mutual dependencies. Effect of the Invention According to the present invention, even if
different boosters are connected to the original car radio, the configuration that allows the
reproduction suitable for listening by the adjusting action of the sound quality adjuster ensures
the reproduction proper for the listening of the received signal. Configuration is provided.
Brief description of the drawings
FIG. 1 shows a block diagram of a car radio, and FIG. 2 shows a block diagram of a volume
controller and a sound quality controller.