CLASSIC HI-FI EQUIPMENT

The mission of the reading arm is reduced to keeping the tip of the needle in the groove of the disc without giving any distortion or resonance. The arm is a high precision instrument. It basically has a vertical and horizontal movement that is performed around a horizontal and vertical axis respectively. This allows you to follow the groove throughout the length of the disc. As the force that moves the arm comes out of the support and guide that represents the groove, the arm must meet a number of conditions:  1) Maximum rigidity with...

The velocity of the plate depends on parameters external to the turntable, such as the supply voltage, the frequency of the electric network and the greater or less effort involved in the friction of the needle on the disc. For this reason, the speed of rotation of the plate can differ somewhat from the nominal of the disk and to avoid it have been devised devices that allow to adjust the speed of the plate to its exact value, the so-called...

The plate is the mechanical element that physically supports the disk and prints a rotational speed of the highest possible accuracy at each instant and over time at the speeds at which it was recorded. If this does not happen, variations of pitch are produced in the music played with respect to the original. If a 33 rpm disc is played at 34 rpm, all frequencies are shifted to treble. Material of the platter and shape thereof. The platters are made of iron (iron) or antimagnetic materials (zamag, aluminum). The ferrites have...

The movement of the arm with respect to the disc can be radial, as occurs in the majority of the turntables the needle describes an arc of girth) or it can also be linear (the needle describes a radius of the disc). This last system is taking strength in the market, although its prices are quite superior to conventional. Radial or conventional movement arm. It is the most extended system and the arm is equipped with a movement around a vertical axis and a horizontal that allows it to follow the furrows. The force necessary to move...

Belt traction. The movement between the motor shaft and the plate is carried out by means of a rubber strap that hugs on one side a pulley located on the motor shaft and on the other a drum placed under the plate and concentric with it. The displacement is achieved by means of a movable pin. This system is widely used as it provides good filtering of motor vibrations. The rubber band is usually synthetic rubber and its active face is rectified to obtain a high uniformity of movement. Direct drive.  In these record players,...

Definition We understand by turntable, the devices intended to reproduce the acoustic information stored on the records discs, giving a faithful electrical signal reflecting the sound that was recorded on the disc. Its main elements are three: a) Platter intended to support the disc and rotate it around its own axis and on a horizontal plane (there is some exception to this condition of horizontality). Its movement is achieved...

A good quality of reproduction depends, in a very important way, on the perfection of the silences, therefore: 1) Frequently examine the tip of the needle. A powerful magnifying glass, or better, a microscope of about 100 magnifications, can detect harmful wear to the discs or dirt embedded in the needle. 2) Check the vertical support force and the horizontal freedom of the arm. 3) Preserve the needle from the dust, heat and grease. A cartridge in bad condition can destroy the treble of a disc in a single pass, and alter the...

This feature reports the amount of signal the cartridge will provide to succeed the pre-amp. The tension varies with the speed, so it is accustomed to refer it at a certain speed, being common the value of 3.54 cm/sec. In general the minimum value for current high-fidelity equipment that must provide a needle is 3 millivolts; Under that tension it is necessary to use a preamplifier or transformer to adjust the appropriate level of input to the preamplifier stage. Between the limits of 3 and 7 millivolts the output is acceptable, being...

As the separation between channels reports the existing interactions of one channel on another, the balance of channels clarifies how each channel responds to each frequency. Both channels must respond, in the most identical way possible, to the same frequency of a given amplitude. ...

This specification informs about the shape of the needle tip and its size as well as the shape of its assembly. It is customary to express this value in thousandths of an inch. In tapered needles, sizes greater than 0.7 thousand should not be allowed, and between two tapered needles, the smaller radio is better, as it will better read the walls of the furrow, reducing the effect of the tap. Conical needles should not be greater than 0.3 thousand the radius smaller or greater than 0.7 thousand the largest. ...

In musical reproductions there are no pure sounds, but a set of simultaneous vibrations that influence each other, giving rise to intermodulation distortion. New vibrations appear equal to the sums and differences of the originals in the event of intermodulation distortion. Since musical sounds are usually composed of a fundamental vibration and a series of harmonics, and in an orchestra or ensemble there are many instruments playing at...

This feature indicates the interaction of signal that can exist from one channel to another. If this value were very small, less than 15 db, it would have a poor separation between the musical information collected in one furrow and in another, and the musical information of a furrow would go through the two channels of amplification. This would result in a loss of the panoramic sense that provides a stereo recording. The separation...

According to design and construction, the manufacturer facilitates the maximum and minimum limits within which it can work; the smaller the lower limit, the better the cartridge as a whole, but without forgetting that generally the work support force will not be the minimum, but the average between maximum and minimum. Minimum support forces of 0.75 gr indicate, in principle, that it is a cartridge. In general, for Hi-Fi equipment, we can...

This measure indicates the capacity of the cartridge to reproduce the frequencies and how it will play. This feature must necessarily contain the variation margin expressed in decibels (dB) of the frequency that responds to greater amplitude and the frequency at which the amplitude is minimal. In stereo cartridges It is sufficient that the indicated limits are between 20 Hz and 20000 Hz, but attention if it is specified +/-1 dB in a cartridge and...

To select a magnetic cartridge the first thing to consider is that the Hi-Fi equipment will not be able to give better characteristics than the component that limits it. It is important that it be highlighted here again that the investment in the acquisition of the equipment must be made with balance between all the components, meaning it is worth investing in the capsule cartridge to be sure that it does not limit the quantity, always higher,...

To decrease the effective mass of the mobile assembly and obtain sufficient output voltage to excite the pre-amp input of the equipment, the ADC firm introduced in 1960, the system called induced magnet. With the same principle of operation as the previous systems, this system has a powerful magnet or several outside the mobile assembly. This system combines the advantages of the two previous systems, since the very low effective mass provides...

In this type of design, a small magnet, as powerful as possible, is associated with the needle-holder lever and when moving into motion, it modifies the magnetic flux that crosses fixed coils where a current is generated. The technical problem to overcome in this type of system is the weight of the magnet that is associated with the lever, because, one of the basic parameters to obtain good results is a very low mobile mass or effective. Reducing...

The system patented by Ortofon in 1948 is synthesized in the following way: A coil loop in two different positions, one at rest where the magnetic field crosses the coil without inducing any current. When changing position, carried by a movement that would transmit the needle through the lever in the loop (coil) is induced a current that runs through a tension at its ends. In fact, in practice, to produce stereo capsules are used two coils, one per channel. In the construction of the coil so that it does not add mass, the coil must be...

The dynamic range of the music source can be expanded by employing of the dynamic processors as stereo system adapter unit. No processing is needed and only ordinary program sources, such as records, FM broadcasts or tape music, are required. The dynamic range is broadened  by upward and downward expansion, resulting in a powerful and sharp rendition of the source. This has the effect of bringing performers right into the listening room, and...

One of the biggest advances in systems Hi-Fi was the appearance of magnetic tape cassette. It was first introduced by Philips in 1963 as Compact Cassette. The unit uses a magnetic tape cassette mounted in a plastic case for storing sound signals. To record is passed by a tape recording head amplifier. The signals recorded on the tape can be "read" later by one or more playback heads. The cassette unit requires a motor to wind the belt...

The experimental studies carried out by Faraday and by Lenz in the mid-19th century led them to enunciate the fundamental laws of electromagnetic induction, based on that whenever the magnetic flux that crosses a closed conductor circuit appears in it a current called induced. These principles gave origin to the magnetic cartridges, which had a phase where they were relegated to second term by the ceramics; the time for high fidelity had not yet come, and depending on their weight and quality problems they lost popularity in a transient way,...

The fundamental principle of a crystal cartridge is to apply the pressures that the needle can communicate in its displacement so that they are converted into tension by a crystal that possesses these properties. In general, a disadvantage of these crystals is their fragility because they are affected by heat and humidity, and they can dissolve the crystal so they are covered with varnishes or gelatins, which also have the characteristic of cushioning the resonances difficult to suppress in these crystals, so they are used rubber gaskets between...

It is understood by needle the part of a capsule cartridge that makes the contact with the furrow of the disc, and to this part we will refer in this section. In its construction different materials have been used having been adopted in recent times by its hardness the sapphire, ruby and diamond; of these practically nowadays the diamond is used exclusively in the construction of capsules destined to the reproduction of high fidelity. The wear of any needle must be monitored to avoid damage to the furrows of the discs irreparably, because in high...

A cartridge capsule is a mechanic-electric transducer destined to convert the mechanical movements that transmits the groove of a disc in electrical signals, so that this conversion or transduction is as faithful as possible and insert no signal more than those that gave rise to the windings of the disc groove. General strength and mass concepts of a cartridge. The mission of a cartridge capsule is extremely difficult. The...

A tuner is an instrument intended to select a specific frequency wave, separating it from all others that could be received – condition called selectivity - even if the received signal is very low - condition called sensitivity - and extract from that radio wave the information sound by means of the detector, introducing the least distortion possible, final condition that is fidelity. The described process is valid for the two systems of modulation...

In digital sound systems, the frequency and amplitude of sound waves are measured and converted into electrical impulses. The pulses are encoded as a series of numbers or digits, in binary form. The binary code recognizes only two digits, 0 and 1, which correspond to "no pulse" and "pulse". When playing a digital recording, the signals are decoded by translating them to the usual analog signals that activate and excite the loudspeakers. A...