June 2017 ~ CLASSIC HI-FI EQUIPMENT

stereo turntable June 2017 ~ CLASSIC HI-FI EQUIPMENT

Studer REVOX

For more than 40 years, Revox has been producing loudspeakers.
Pioneer PL-530

Japanese Audio Manufacturer with a reputation for producing extremely high quality equipment.
Technics Tape Deck RS-M95

Technics is a subsidiary of Japanese Matsushita Electric Industrial Co Ltd and produces Hi-Fi products including turntables, amplifiers, receivers,etc

2017-06-29

TURNTABLES. TONE ARMS.

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 minimum inertia and consequently low resonance frequency.

2) Softness in the joints of horizontal and vertical movement.

3) Minimum reading error

4) Null lateral thrust.

5) Longitudinal and lateral balance.

Posted by hifisnecma on 3:29 PM No comments »

2017-06-28

TURNTABLES AND FINE ADJUSTMENT OF THE SPEED AND ITS CONTROL

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 "fine adjustments" of the speed. These turntables must have a system to denote if the platter speed is less than, equal to or greater than the nominal. The most common system is the so-called strobe that is based on the flashes of a lamp powered by the alternating voltage network, which illuminates at a rate of 100 flashes per second (in 50 Hz electric networks) a row of holes or recorded scripts In the periphery of the plate. The interaction of both flashes and marks makes them visually appear stopped, when the speed is correct or with an apparent advance or delay movement depending on the speed greater or less than the nominal speed. This system allows to verify if the speed is accurate or must be corrected.

Posted by hifisnecma on 4:11 PM No comments »

2017-06-27

THE PLATE, MATERIAL AND SHAPE.

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 advantage of presenting a shielding for the pickup cartridge with respect to the dispersion field of the motor and the transformer if it carries it. The antimagnetic platters avoid the interaction of the dispersion field of the phono cartridge magnet on the plate if it were of ferric material.

The platter should oppose to the maximum to the variations of speed, reason why it is very important the effect of steering wheel that can represent its mass. For the above, when talking about a platter, the important thing is not its physical weight (which would give a balance) but the way in which that weight is distributed. What is really important in the platters is the so-called moment of inertia that takes into account the weight and the distance to the center of rotation of that weight.

Posted by hifisnecma on 5:27 PM No comments »

2017-06-26

ARM MOVEMENT IN STEREO TURNTABLE.

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 it comes out the furrows of the disc that are like guides for the needle. Therefore the great care with which the tone-arm should be designed for a smooth operation throughout the all path and to demand in this way the binomial needle-furrow as little effort as possible.

Linear or tangential motion arm.

The improvement of the servo-assisted movements and the photoelectric position detectors has made it possible to make this type of turntable in which the arm is mounted on a trolley that slides on rails, driven by a controlled engine. Another advantage of this system is that the arm can be shorter and, consequently, lighter and does not need lateral thrust compensatory force.

Posted by hifisnecma on 2:46 PM No comments »

2017-06-25

STEREO TURNTABLES. TRACTION SYSTEMS.

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, the motor shaft coincides with that of the platter, which is why the motor must rotate at the same speed of rotation required by the disc and must have two speeds (33.3 and 45 rpm).

It is in principle the simplest system, although it requires quite complex and highly elaborate motors, since there is no filter element or damper of the vibrations of the motor that if they were would be transmitted directly to the platter and then to the cartridge and to the loudspeakers.

This system appeared in the market in the year of 1970 obtaining great popularity that in turn caused that the cost of its production lowered.

Posted by hifisnecma on 9:48 AM No comments »

2017-06-23

PLATE TURNTABLE

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 by means of an electric motor and a transmission system between the motor shaft and the plate itself.

b) Tone arm is named for its elongated shape in order to follow the movement of the disc furrow to furrow from the periphery to the center.

c) Cartridge or element that translates in electrical signal the information contained in the furrow, a signal that then passes to the amplifier stage, where it will reach the level required to exit a loudspeaker and thus reproduce the acoustic message that was recorded on the disc.

Posted by hifisnecma on 3:06 PM No comments »

2017-06-22

PRECAUTIONS AND TIPS FOR GOOD REPRODUCTION.

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 transparency and clarity of the middle tones.

4) The noise due to the dust of the discs is very annoying and damaging to the disc and the tip of the needle, because that dust is abrasive and bites and polishes the surfaces. Keep discs free of dust.

5) Do not use chamois that sometimes introduce dust into the depths of the furrows.

6) Do not use anti-static fluids for discs, because underpin the dust on the needle and reduce the introduction of the needle in the furrow and causing it to jump over them, causing scratches and damage.

7) Use anti-static brushes, which at the same time clean the surface dust of the discs; carbon fiber brushes give good results.

8) If a needle has lost qualities, replace it immediately with an original replacement and ensure proper installation of the needle in the cartridge. A good installation is verified by the absence of any noise by the loudspeakers when the turntable is connected to an amplifier.

Posted by hifisnecma on 3:51 PM No comments »

OUTPUT VOLTAGE OF MAGNETIC CARTRIDGE.

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 the differences of that tension the cause that in the same preamp it is necessary to modify the control of gain (volume) according to the type of cartridge that used in order to obtain the same acoustic level.

Posted by hifisnecma on 3:43 PM No comments »

2017-06-20

CHANNEL BALANCE OF MAGNETIC CARTRIDGE

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.

Posted by hifisnecma on 1:09 PM No comments »

STYLUS TIP

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.

Posted by hifisnecma on 1:06 PM No comments »

INTERMODULATION DISTORTION IN MAGNETIC CARTRIDGE

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 the same time, the intermodulation distortion is very annoying in the reproduction if it exceeds a certain value that we can situate in 0.5% for the cartridge, as maximum admissible value.

Posted by hifisnecma on 12:59 PM No comments »

2017-06-15

SEPARATION BETWEEN CHANNELS OF MAGNETIC CARTRIDGE.

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 between channels in average frequencies of 500 Hz to 15 khz is not sufficient data because the critical frequencies for this parameter are greater than 15 khz and less than 500 Hz. If the separation between channels in the half-frequency zone is less than 20 db, it is possible to ensure that the cartridge is of very low performance.

Posted by hifisnecma on 8:26 AM No comments »

2017-06-14

SUPPORT FORCE OF A MAGNETIC CARTRIDGE.

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 set a higher limit of 2 gr. if its use is intended for manual turntables.

Posted by hifisnecma on 8:24 AM No comments »

2017-06-12

FREQUENCY RESPONSE OF MAGNETIC CARTRIDGE

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 +/-3 dB in another; the smaller number indicated by the variation range will be better. If this indication does not appear, it is necessary do not trust in the cartridge.

Posted by hifisnecma on 4:24 PM No comments »

2017-06-10

CHARACTERISTICS OF MAGNETIC CARTRIDGE

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, destined to the turntable, amplifier and speakers.

To choose the cartridge it is necessary to analyze its parameters and characteristics meticulously and keep in mind that the data supplied by the manufacturer sometimes omit some of the information.

Posted by hifisnecma on 3:07 PM No comments »

MAGNETIC CARTRIDGE. INDUCED MAGNET SYSTEM.

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 a very high output voltage. These systems are also called under the generic names of variable reluctance, and of mobile iron. As the mass of the very small moving set, the cartridge can work with low support forces, which facilitates the movement of the needle in the furrows and promotes the reproduction and preservation of the discs. Obviously not only that the cartridge works with the smallest mass, but with the minimum, without detriment of quality, avoiding the jumps of needle, especially in the ends of the disc.

Posted by hifisnecma on 2:59 PM No comments »

MAGNETIC CARTRIDGE. MOBILE MAGNET SYSTEM

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 weight of the magnets reduces their efficiency and therefore the output voltage. However, it is a system that provides sufficient good results for the technological development achieved in the manufacture of magnets. Among the manufacturers using this system are Shure, Audiotecnica and AKG.

Posted by hifisnecma on 2:51 PM No comments »

MAGNETIC CARTRIDGES. MOBILE COIL SYSTEM.

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 of very few whorls and of a very fine wire that can come to contribute a negligible weight less than 1 mg between the two coils.

In general this system gets a good response in frequency and separation between channels, being its very low mobile mass. In general, they are cartridges of good characteristics. The manufacturers that use this system are: Ortofon, although in not all models, Dynavector, which has introduced very refined techniques in the construction of cartridges.

Posted by hifisnecma on 2:45 PM No comments »

2017-06-08

DYNAMIC PROCESSORS

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 especially sources such as rock and soul are given a broad new dimension. A noise reduction effect is also included which reduces underlying source noise. Tape hiss, motor rumble and other background noises are reduced by the circuit properties of the dynamic processors.

1) Pioneer Dynamic Processor RG-2. 1980.

2) Dynamic Processor RG.

Posted by hifisnecma on 3:12 PM No comments »

2017-06-06

CASSETTES DECKS

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 system, and also has devices for improving sound quality and to avoid distortion. An essential device is the sound level meter can be a VU (volume unit)

Each cassette unit contains an oscillator bias (bias) which produces a high frequency signal on the tape inaudible. This signal is combined with the sound before it reaches the recording head. Its purpose is to help reduce the distortion in the recording system. It can also be used to clear signals before recording.

1) Stereo cassette deck Denon DR-F3.1980. 3 Heads System.

2) Marantz Deck SD-930 with auto Azimuth Control. 1983.

Posted by hifisnecma on 5:30 PM No comments »

MAGNETIC CARTRIDGES

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, but recovered it in a short time with the development of high density artificial magnetic materials, so that nowadays the magnetic cartridges are used fully and completely in the reproduction of high fidelity.

All types of magnetic cartridges can also be called variable reluctance, because they use all the same principles but in different ways.

Today it is possible to group the existing types into three fundamental groups or variations of them:

(a) Mobile Coil

(b) Mobile Magnet

(c) Magnet induced

Posted by hifisnecma on 2:57 PM No comments »

CRYSTAL CARTRIDGES

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 the needle holder and the crystals. The main advantages of the capsules of this type are that they provide a high output voltage, they are insensitive to the humming and their construction is cheap, reasons why they are employed in modest sound equipment, but they are not used in hi-fi equipment.

Posted by hifisnecma on 1:55 PM No comments »

STYLUS NEEDLES FOR TURNTABLES

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 fidelity the cost of the collections of discs far exceeds the price of a set of replacement needle. We'll appreciate the wear by the appearance of noises; the reproduction will lose transparency and distortion will appear in high frequencies with losses of these high frequencies. The user of a hi-fi team must be aware that you will need to change the needle of your capsule every 300 hours of use if you want not to endanger your discs, and take care of their cleanliness with a certain frequency, as it usually deposits particles of fat and dust that prevent the needle from tracing the furrow.

Posted by hifisnecma on 1:42 PM No comments »

2017-06-04

CARTRIDGE CAPSULE

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 techniques of micro electromechanical in it employed require a careful elaboration and a constant investigation.

The precision of the capsule needle should be such that, in the passages strong of the music do not lose the groove and do not even try to get out of it, what will happen under the influence of any kind of distortion or in the presence of a wear importance in the disc.

Each manufacturer specifies the support force margin for which the cartridge is designed in order to obtain the best results.

Posted by hifisnecma on 5:46 PM No comments »

2017-06-03

STEREO TUNERS

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 (AM-FM) but each one of them needs for its treatment completely different tuners; although it is normal to mount both as a single unit, taking advantage of common parts.

1) Sansui TU 717 AM-FM Stereo Tuner (1978).

2)Technics ST 9600 FM-AM Stereo Tuner (1976).

Posted by hifisnecma on 2:31 PM No comments »

CD PLAYERS

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 digital system has to store a lot of information about the sounds it records and it does so in the form of digits or bits. Since there are too many bits, the compact disc is used to store them.

1) SONY CD PLAYER CDP-11S.1983

2) Philips CD 350. 1985.

Posted by hifisnecma on 2:16 PM No comments »