JPS6043580B2 - tape recorder circuit - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a tape recorder circuit, and in particular, it is possible to display an appropriate recording level so that recording with less distortion can be made by simply setting the optimum recording level while looking at the recording level display. Related to tape recorder circuits.

Conventionally, as a level display device for a tape recorder, one having a compensation circuit with a frequency characteristic opposite to the saturation level frequency characteristic of the magnetic tape is known.
No. 17261, Utility Model Publication No. 131220/1983).

In other words, magnetic tape has frequency characteristics such that it is saturated in the high frequency range and its output decreases relative to the middle frequency range, whereas a level meter operates under the same conditions regardless of the frequency characteristics.
Therefore, even if the value indicated by the meter is optimal, it may actually reach the saturation level and cause distortion. Therefore, the above-mentioned conventional level display device is designed to compensate for this. However, such a recording level display device for a tape recorder is still insufficient for recording with little distortion.

That is, as shown in FIG. 1, the conventional tape recorder circuit guides a recording signal 11 through a recording amplifier 12 and a recording level control volume 13 to a recording amplifier 14 that enhances bass and treble frequencies, thereby enhancing the bass and treble ranges. After converting to the enhanced recording signal current 15, the bias circuit 16
The bias current is applied to the magnetic tape 18 and is supplied to the recording head J17 to perform bias recording on the magnetic tape 18. The bass and treble boost recording amplifier 1
4 is intended to improve the recording and reproduction frequency characteristics, and converts the frequency characteristics of the recording signal shown in FIG. 2a to current characteristics with enhanced bass and treble frequencies as shown in FIG. 2 i.

Therefore, the level of the signal 15 actually supplied to the recording head 17 for recording is different from the level of the original recording signal 11. Therefore, the recording level display circuit must naturally display the actual recording signal level 15.

One possible way to do this is to connect a recording level display circuit to the output side of the bass and treble boosting recording amplifier 14, but since the output end of the recording amplifier 14 is connected to the recording head 17, The differential characteristic, that is, the characteristic that the voltage increases in proportion to the frequency, is directly applied to the level display circuit, resulting in a completely erroneous level display. Therefore, conventionally, as shown in FIG.
A recording level display circuit 22 consisting of a rectifier circuit 20 and a level meter 21 is connected. However, with such a configuration, as is already clear, the recording signal current supplied to the recording level 17 and the recording level meter 21
There is a level difference in the bass and treble ranges between the recording signal that drives the Therefore, this recording level meter 2
1 and set the recording level to the optimum state, the recording level will actually be excessive in the bass and treble ranges by the amount of the enhancement. In general, distortion (mainly 3rd harmonic distortion) increases in proportion to the square of the recording level.
In this case, low-frequency and high-frequency distortion during recording increases by the square of the amount of enhancement of the recording signal current, resulting in recording with large distortion. The present invention has been made in view of the above points, and an object of the present invention is to provide a tape recorder circuit that can display the current level of the recording signal actually supplied to the recording head and can perform recording with little distortion. This is something that should be taken into consideration.

The present invention is capable of displaying the correct recording signal level by providing the recording level display circuit with an amplification circuit having frequency characteristics substantially equal to those of the low-frequency and high-frequency amplification recording amplifiers provided in the recording circuit. This is what I did.

The present invention will be explained in detail below with reference to the drawings.

FIG. 3 is a block diagram showing an embodiment of the tape recorder circuit of the present invention. In the figure, a recording signal 31 is transmitted through a recording amplifier 32, a recording level control volume 33,
The signal is supplied to a recording head 36 via a bass and treble boosting recording amplifier 34 and recorded on a magnetic tape 37. Nao 3
5 is a bias oscillator. Such a recording circuit is the same as the conventional configuration shown in FIG. The tape recorder circuit of the present invention is different from the conventional one in that the recording level display circuit 43 enhances the bass and treble regions of the recording signal by the same amount as the amount of enhancement of the bass and treble region enhancing recording amplifier 34, and the output thereof The point is that a bass and treble range enhancement circuit 38 is provided so that the frequency characteristics of the recording signal current are equal to the frequency characteristics of the recording signal current shown in FIG. 2b. That is, by connecting this bass range and treble range enhancement circuit 38 to the input side of the bass range and treble range enhancement circuit 38, an output equal to the frequency characteristic of the recording signal current flowing through the recording head 36 can be obtained. Amplified by meter amplifier 39 and rectified circuit 40
rectify the current. Furthermore, even instantaneous overrecording input signals can be detected, and in order to eliminate distortion increase due to instantaneous overrecording input signals, the peak level detection circuit 41 detects the peak value and drives the level meter 42. There is. According to such a configuration, it is possible to completely match the recording level indicated by the level meter and the recording signal current level over the bass, middle, and treble ranges of the recording signal. Therefore, even if the recording level is set based on the level indicated by the level meter, there is no need to worry about over-recording in the bass and treble ranges, unlike in the prior art. Therefore, recording with little distortion is possible. Furthermore, according to the present invention, since the recording level of the level meter and the recording signal current level match, by lowering the recording level of the level meter below a certain value,
Distortion in the tape head system that occurs during recording can be kept below a certain value regardless of frequency characteristics. Furthermore, the mixture tone distortion that occurs in the tape head system can be significantly reduced because there is no increase in distortion during recording. On the other hand, according to the present invention, an increase in distortion during reproduction can also be prevented. That is, in the circuit of FIG. 3 again, the voltage generated at the reproducing head 51 has a differential characteristic, that is, it increases in proportion to the frequency. Therefore, in order to compensate for this, the bass range is adjusted by the time constants Tl and T2 (low range 1590 μS, high range 120 ps, or low range 3180 ps, high range 70 μs for cassette tapes) defined in the playback circuit by the playback amplifier 52 and the frequency compensation circuit 53. Reproduction frequency compensation is performed to reduce the high frequency range and to make the reproduction output equal to the signal recorded on the recording tape 51, that is, the recording input signal. Therefore, its frequency characteristics are as shown in FIG. 4a. On the other hand, due to such reproduction frequency compensation, the distortion during reproduction (mainly third harmonic distortion) increases in the bass and treble ranges as shown in FIG. 4b due to the effect of these compensations. Time constant of cassette tape recorder 159
The third harmonic distortion increase on the theoretical curve due to playback frequency compensation of 0 μs and 120 μs is approximately twice as much in the low range of 20 Hz and approximately 2 times in the high range of 6 KHz as compared to the mid range.
．． Increased by 4 times. Therefore, in the circuit of the present invention shown in FIG. 3, a third
By making it possible to further increase 1/2 of the amount of increase in the bass and treble ranges of the harmonic distortion (FIG. 4b), it is possible to prevent an increase in distortion during reproduction. As a result, it is possible to maintain constant distortion rates in the bass, midrange, and treble ranges during recording and playback. During this Yanghe recording, the meter displays higher than the actual recording signal level in the bass and treble ranges, and does not necessarily indicate the accurate recording level, but
In this way, when displaying a higher level than the actual recording level, there is no need to worry about over-recording as in the past. Incidentally, in the embodiment described above, the booster circuit in the level display circuit was shown to enhance both the bass range and the treble range.
A predetermined effect can be obtained even if either the bass range or the treble range is enhanced.

[Brief explanation of the drawing]

Figure 1 is a diagram showing the configuration of a conventional tape recorder circuit, Figure 2a is a frequency characteristic diagram of the recording signal, Figure 2b is a frequency characteristic diagram of the recording signal current supplied to the recording head, and Figure 3 is a diagram showing the frequency characteristic diagram of the recording signal current supplied to the recording head. FIG. 4a is a block diagram showing the configuration of a tape recorder circuit according to an embodiment of the present invention, FIG. 4a is a frequency compensation characteristic diagram in the reproducing circuit, and FIG. 4b is a diagram showing changes in distortion rate due to frequency compensation. 31... Recording signal, 32... Recording amplifier, 34...
・Bass range and treble range enhancement recording amplifier, 36... Recording head, 37... Magnetic tape, 38... Bass range and treble range enhancement circuit, 39... Meter amplifier, 40...
- Rectifier circuit, 41... Zeke level detection circuit, 42...
・Level meter, 1 stand...Level display circuit.

Claims (1)

[Claims] 1. A recording amplifier that converts a signal to be recorded into a recording signal current having frequency characteristics with enhanced bass and treble frequencies;
a recording head connected to the output end of the recording amplifier; and an enhancement circuit connected to the input end of the recording amplifier that converts the signal to be recorded into a frequency characteristic with enhanced bass range, treble range, or both; A tape recorder circuit comprising: means for rectifying the output of the intensifying circuit and displaying the level thereof. 2. The tape recorder circuit according to claim 1, wherein the booster circuit has a frequency characteristic substantially equal to that of the recording amplifier. 3. Claim 1, characterized in that the amplification circuit amplifies the bass range or the treble range, or both, of the signal to be recorded at a ratio greater than the ratio of the amplifier by the recording amplifier. tape recorder circuit.