What Is a Dictaphone?

A recorder is a machine that records sound for playback. It uses hard magnetic material as a carrier and uses the residual magnetic properties of magnetic materials to record sound signals on the carrier. Generally, it has a playback function. Most home recorders are cassette tape recorders.

[lù yn j]

A recorder is a machine that records sound for playback. It uses hard magnetic material as a carrier and uses the residual magnetic properties of magnetic materials to record sound signals on the carrier. Generally, it has a playback function. Most home recorders are box-type

Phonetic script (Hanyu Pinyin): lù yn j

English name: recorder

In 1888, O. Smith of the United States published a paper on the use of residual magnetic recording, which laid the theoretical foundation for the recorder. In 1898, Denmark V.

Earlier tape recorder called

The magnetic head is an electromagnetic transducer in magnetic recording and a key component of a tape recorder. The quality of the magnetic head largely determines the recording and playback effect of the whole machine. Therefore, it is particularly important to properly clean, adjust and replace the magnetic head. When the recorder is used for a period of time, it will often result in low playback sound, turbidity, distortion and noise, and poor frequency response (high frequency attenuation is particularly serious). ), Poor recording effects and other problems, this phenomenon is particularly prominent on machines that often use low-quality tape. The reason is that, except for the failure of the circuit part, most of the causes are due to the magnetic head. First, the magnetic head is dirty (dirty blockage), and the second is the magnetic head.

Recording Step 1: Hardware Preparation

Transcription of a tape into MP3 is a simple process and a complicated process. To put it simply, take a pair of line output of a recorder and line input of a sound card, find a suitable software for recording and then compress it; it is complicated, that is, there are a lot of things to pay attention to during the re-recording process. Will affect the recording quality.

The hardware includes a computer and a recorder, and the necessary connection cables (usually a 3.5 / 3.5 transcription cable).

computer

1. It is recommended to choose a PC with a frequency above 300MHZ. Too low a main frequency will increase the difficulty of processing and reduce the processing speed. I don't think anyone wants to reduce the noise of a song all night!

2. The sound card is best to be independent rather than the motherboard integrated sound card (of course, some motherboard integrated sound card performance is not bad, the recording effect is not worse than the discrete sound card), such as innovation, Qiheng, Imperial League, 8738, etc. Among them, 8738 is best to use the public version of the driver, and some noise is larger, even worse than the onboard sound fighter card.

3 The sound card should not be close to the graphics card, nor should it be close to the side of the chassis. If your motherboard has more than three PCI slots (Mine is 5), I recommend installing the sound card in the second slot (counting from the chassis bottom plate) so that it is separated from the AGP graphics card by 3 PCI slots. it's the best. If the graphics card is too close, and the graphics card is a miscellaneous brand, it may cause silk noise interference and increase processing difficulty.

4 Network cards other than sound cards, cats,

1. Before transcription, download one first

1. When the recorder is not used for a long time, the battery should be removed to prevent the battery fluid from flowing out and corroding the parts. The power plug should be unplugged.

2. When the recorder is not in use, all buttons should be set to the "stop" position.

3 Don't act too fast when operating each function key. And press the program operation function key. For example, after recording, you should press the stop button first, and then press the rewind button.

4 Depending on the tape material, use the tape selection switch. For example: chrome belts and metal belts cannot be used in ordinary belt positions.

5. After the tape is loaded into the recorder, it is best to press the fast forward or rewind button to run it first before recording or playing back.

6. Do not subject the recorder to severe vibration, and do not place it near a strong magnetic field such as a television to prevent the magnetic head and magnetic tape from magnetizing.

7. The recorder should not work for too long. If you work for several hours, the life of the movement inside the machine will be shortened.

8. The recorder is used for about half a year, and it is best to clean the magnetic head, main shaft, pressure roller and other components once. You can add some watch oil to the mechanical transmission part.

9. The volume of the recorder should not be too loud. Excessive sound is not only distorted, but also

Close Loop Dual Capstan Drive: Two capstans drive the tape transport method at the same time; the front capstan is 1% faster than the rear capstan, maintaining good contact between the tape and the magnetic head; it can effectively isolate the supply tape The vibration of the disc reduces the shaking rate.

Tape Speed Deviation: The difference between the actual tape speed v and the nominal tape speed V, expressed as a percentage.

Wow and Flutter: The percentage change in the running speed of the tape, reflecting the degree of spurious frequency modulation caused by the movement.

Dolby Noise Reduction: A complementary noise reducer that reduces noise by compressing and expanding dynamic range and dynamically increasing low-level signals. It uses the masking effect of the human ear to focus on solving the noise in small signals, and uses a large-scale compression and expansion of high-frequency signals. Raise the low-level signal during recording and decrease the low-level signal during playback. There are four types of Dolby noise reduction systems: A, B, C and S. The most commonly used Dolby B / C noise reduction system in the recording stand.

Copy effect Magnetic Printing: The effect of the magnetic field of a signal on one layer of the recorded tape on the adjacent layer.

Contour Effect: During playback, the low-frequency signal recorded on the magnetic tape has a wavelength equal to that of the playback magnetic head and is canceled by the wavy drop of the low-frequency end caused by the short-circuit of the head iron core.

Bias Bias: In magnetic recording, in order to avoid the initial non-linear segment of the magnetization curve, a method of adding a bias current to the recording head.

Frequency Compensation: The high and low frequency parts are improved during recording to reduce distortion and improve the signal-to-noise ratio.

Frequency Response: Abbreviation for frequency response range, representing the gain characteristics of audio equipment to restore audio signals of different frequencies.

Harmonic Distortion: A distortion form that generates new higher harmonic components when a signal is replayed after recording. It is expressed by the ratio of the effective value of these newly added harmonic components to the effective value of the total output signal. The harmonic distortion of the recording base is mainly the third harmonic distortion.

Signal-to-noise ratio S / N: The ratio of the specified output signal level to the output noise level after the input is shorted. The voltage is expressed as: S / N = 20log (signal output voltage / noise output voltage) dB.

Auto level control: A device that automatically adjusts the recording level to avoid magnetic saturation distortion caused by excessive signal strength.

Auto Bias: Use a microcomputer to control the magnetic bias current of the tape to obtain the best frequency characteristics and distortion.

Direct Drive: A method of directly driving a magnetic tape with a motor shaft as a capstan. Used in high-quality recording bases, the capstan is relatively thick, and the motor uses a brushless DC motor with a highly stable speed.

Optimum bias: It can make the recorded signal have small distortion, large output and high frequency performance.

1. ALG-automatic recording level control

This function has the function of automatically controlling the recording level during automatic transmission. Even if the input recording signal suddenly increases, it will not cause tape saturation distortion. But in the manual file, you need to manually make the volume button during recording to adjust the recording level;

2. MONITOR-monitor function switch

The three-head deck is generally equipped with this function, which is two levels of TAPE and SOURCE, which respectively can monitor "the signal already recorded on the tape" and "the signal of the source before recording", so when using this function to switch, it will Obviously there is a certain time difference between the sound in the headphones and the sound is out of sync.

3 REC MUTING-recording mute switch

When this switch is turned on, the signal can be attenuated by a few tens of degrees at a time, which is convenient for creating a no-signal zone on the tape;

4 MEMORY-with long memory function

Turn on this function to make the counter to [000]. When rewinding after playback or recording, it can automatically rewind to the [999] position and stop. There is no need to remember the number of the counter or observe with eyes. It is usually connected with the counter when it is OFF Same function

5. EDIT-Edit function

When this function is turned on, the recording and playback heads of the machine are not completely separated from the magnetic tape, and functions such as automatic song selection, recording editing, etc. can be realized by fast forward and reverse and other function keys;

6. FLUORI METER or FL METER-fluorescent screen display

Used in higher-level recorders, there are two series of cursors with obvious colors, which show the level changes of the left and right channels during recording and playback;

7. PEAK HOLD-level peak hold function

The recorder with liquid crystal and fluorescent display functions has a display time that can hold the display position reached by the maximum peak level in the music signal for several seconds.

First, you need to select the tape. The blank tapes on the market are mainly the following:

Ordinary voice tapes: These tapes have a narrow bandwidth and a small dynamic range, and are suitable for recording voice signals. There are mainly TDK's D series, Sony's EF series, and domestic nature AE series.

Ordinary music tapes: These tapes have a wide bandwidth and a large dynamic range and are suitable for recording music programs. There are mainly TDK's AD series, Sony's HF series, Maxell's CD' series, and domestic nature AD series.

High bias tape (chrome tape): This type of tape has a wide bandwidth, extremely low noise, and a large dynamic range, and is suitable for recording music programs with a large dynamic range. There are mainly TDK's SA series, Sony's UX series, and Maxell's CD's series. No domestic chrome belts are sold.

Metal tape: This type of tape has extremely wide bandwidth, low noise, and great dynamic range. It is suitable for recording music programs with large dynamic range and wide frequency. It can be used as a recording master tape. It is generally used in conjunction with the three-head cassette. There are mainly TDK's MA series, Sony's ES-Metal series, and Maxell's CD's Metal series on the market. There are also no domestic metal belts for sale.

For the recording tape of the Walkman with recording function, limited to its recording circuit and head performance, the choice of ordinary voice tape is sufficient. TDK's D series and Sony's EF series are good choices.

For making CD tracks on the deck for Walkman appreciation, general popular songs can use ordinary music tapes (such as TDK AD, Sony HF), and when not required, ordinary voice tapes (TDK D) can also be used. Large classical music should use low-noise chrome bands (such as SA-X, Sony UX). It is generally not recommended to use a metal band. Unless you use a three-head deck to record and use a high-end Walkman with an amorphous magnetic head to play, you will not be able to take advantage of the metal bandwidth frequency response and great dynamics.

The second is the choice of the combination of the deck and the tape. The grades of the general deck are divided into the following.

1. Low-grade deck: Generally use mechanical movement, no Dolby system or only Dolby B.

2. Mid-range card deck: Generally used electronically controlled movement, with Dolby B-C NR and HX Pro systems.

3. High-end deck: It adopts a three-head multi-motor movement, with Dolby B-C NR and HX Pro systems.

Generally, low-grade decks can use ordinary tapes, medium-grade decks can use ordinary tapes and chrome tapes. If you use the more high-end tapes above, you can't feel any improvement, and high-end decks are best to use metal tapes to maximize their performance. Good performance.

The other is the recording method. Due to the limitation of the noise floor of the tape, its dynamic range has a large gap compared to CD (about 65dB for high-grade chrome tape and 96dB for CD), so it is necessary to use a noise reduction system. Commonly used is the Dolby noise reduction system, which is divided into four types: A, B, C, and S. The Dolby A system is mainly for professional use, and the cassette deck is not used. The Dolby B-C system is often used on mid-range decks, which can reduce high-frequency noise by 10dB and 20dB, respectively. The Dolby S system is generally used in a three-head recording base, which can reduce high-frequency noise by 24dB and low-frequency noise by 10dB. Generally, the mid-range Walkman has a Dolby B system, and a few high-end machines have a Dolby C system. According to experience, the Dolby C system is used for recording tapes, and the Dolby B system is used for noise reduction during Walkman playback. It feels better than the Dolby B system for both recording and playback. The reason is that the Dolby B system has a high-frequency drop at a high level, a large distortion, and a poor listening experience, and most Walkman's Dolby B systems have a higher high-frequency attenuation than the standard, making the listening experience worse. The Dolby C system performs relatively well, but the high frequency is slightly improved. Therefore, even if the Walkman does not have a Dolby C system, it is recommended to use Dolby C recording as much as possible.

When recording, pay attention to the input signal level not to exceed the tape MOL level, otherwise it will cause greater distortion. The new recording circuit on the deck should be used as much as possible to improve the recording quality. If there is a deck with an automatic recording control function (CCRS stands for Computer Controlled Recording System), it can automatically determine the recording level according to the input signal level to achieve the maximum dynamic range, and can avoid manual adjustment of the recording level error. There is also an Auto Bias function, which can detect the best bias current of the magnetic tape used, so that the tape is in the best bias state, which is very good for recording. In general, the bias current of different types of magnetic tapes of the same type are different. The signal-to-noise ratio decreases when the bias current is too small, and the frequency response becomes narrower when it is too large. In the past, it was necessary to manually adjust the bias current when the requirements were high, but the procedures were complicated. With this circuit, this operation can be completed in an amateur environment. As for the Dolby HX and HX Pro functions, the bias magnetic current is automatically adjusted according to the high-frequency components in the input signal during recording, so that the high-frequency frequency response is increased by 1 ~ 2kHz.

In general, in order to reduce noise and improve dynamic range, 70s recording compensation method is used for chrome tape recording. Although this improves the signal-to-noise ratio, it makes the high-end frequency response almost the same as that of high-end ordinary band. Here's a trick, which is to use the 120s compensation method of ordinary tape when recording on chrome tape. This will reduce the signal-to-noise ratio by 2 ~ 4dB, but its high-frequency performance can be greatly improved, which is almost comparable to that of metal tape. However, there is a prerequisite that the general tape recording audio width of the deck is large, and some decks only set a 15kHz bandwidth for the ordinary tape, which does not get the expected results. Specifically, the mechanical card holder directly dials the tape quality selection switch to the ordinary belt position, and the electronic control card holder can seal the identification hole of the chrome belt with tape (may need to adjust the bias magnetic current). TDK has several types of chrome tapes (such as CD Power) stating that 70s and 120s are universal. In fact, many foreign record companies use this method to record chrome tapes. Generally, the original tapes recorded by this method are marked with Chromiun Dioxide 120s.