The reference machine of the power amplifier with input volume which was compatible in high-quality sound and high cost performance

300B single stereo amplifier A-014 With input volume


* I would like to enjoy the sound of a 300B vacuum tube more easily. It is the 300B with input volume non-feedback system single amplifier developed for such persons.

A-014 is the power amplifier of the single stereo system with input volume which adopted famous 300B as the output tube.
A speaker can be sounded with a sound wonderful as it is if CD player etc. is connected, since it has input volume.
The basic circuit has adopted the self-bias system of CR combination which uses a pentode for a voltage amplification part.
In the amplification part, the natural acoustic field has been obtained taking advantage of the merit of the basic characteristic without the negative return with the non-feedback system.
The basic performance was not dropped, but it devised so that cost might be held down as much as possible, and the sound excellent in the price for which it is easy to ask was realized.

* The cut core output transformer which adopted the Hi-B coar as the output transformer is distorted by adoption and the combined use with a Teflon insulating paper, and realize outstanding sound with little admiration.

Hi-B type the cut core transformer and R core transformer which excelled all in the regulation extremely are adopted as the power transformer of this machine, an output transformer, and each choke coil.
The output transformer of the Teflon insulation which uses the Hi-B type cut core of 0.1mm thickness is adopted as the output transformer of this machine.
Furthermore, a 16-ohm terminal is also prepared in the output transformer in addition to an 8-ohm terminal, and it is improved so that it may carry out just fit also to 16-ohm speakers, such as ALTEC 604E of a vintage.
An output transformer is a portion which influences sound quality greatly.
About this portion, it has the composition that it is comparable to A-09S of a high-end model kind.
Moreover, by using a high-voltage circuit and the heater winding of 300B as another transformer, I devised the power transformer so that those interference might be prevented.

* An output tube makes an output tube option a standard so that it can choose freely, and it enabled it to select JJ and the product made by Emission Lab by liking.

We prepared for the sales specification of A-014 what combined 300B of JJ with the type of the output tube option, and the thing which combined the 300BXLS vacuum tube made from Emission Lab of Germany.
To the output tube 300B, the difference in sound is great respectively, and I also regard that you exchange by liking and look for a favorite sound as one of the pleasure of an audio.
A-014 is designed so that almost all 300B of each company can substitute as it is, and adjustment etc. is unnecessary at all.
Adjustment of ham balance etc. is also unnecessary.
The sound highest by no adjusting is obtained.

* Adopt both the waves rectification DC ignition circuit by a Schottky diode as the ignition circuit of the heater of a 300B vacuum tube.
The capability of 300B was pulled out to the maximum extent.

DC ignition circuit by the Schottky diode of low impedance is adopted as the output tube portion of A-014.
It is possible to use the current capacity of a transformer for almost all 300B types of vacuum tube, substituting, since it enables it to correspond also to the sufficiently big heater current up to about picking 2A.
Both the waves rectification system was adopted as the portion which supplies the heater voltage of a 300B vacuum tube.
Since the regulation is excellent, both waves rectification becomes advantageous also to the sound quality of 300B.
To the rectifier, adoption and what has the daringly still smaller capacity to the smooth capacitor were selected for the highly efficient Schottky diode made from U.S. IXIS corresponding to large current, the product was chosen, and the sound excellent in speediness has been obtained.
Usually, the ham balancer to be used was omitted and improvement in the freshness by the simplification of a circuit was aimed at.
Balance adjustment resistance of a heating circuit adopts the usual small value of the 1/5th place, and makes current feedback of cathode the minimum.


* The high-quality sound voltage amplification stage consisted of adoption, and a long-life life and a low noise for the highly efficient German pentode C3m of the vintage in the driver tube.

Five highly efficient pole pipes C3m by German Siemens are adopted as the driver stage of A-014 amplifier.
Although this vacuum tube is seldom generally known, it is the high performance and the vacuum tube of high reliance which were designed for telephone lines in Germany and which were developed comparatively in the second half.
A development age will be most as a vacuum tube in the second half in 1962, therefore various kinds of electrical properties are excellent, and it is the feature that sound quality is very beautiful.
Although this vacuum tube is enclosed with the case of the metal as a Loctal pipe, it removes that case and is using it at our company with a glass tube.
Thereby, the sound in which sound quality is still more natural was obtained.
This vacuum tube is designed as business use of Germany, and the fundamental design life is made into 10,000 hours or more.
Usually, it is also a big merit that the exchange period of a vacuum tube becomes very long in use for a long-life life.
Moreover, a mesh plate is beautiful and there is charm also in appearance.
In A-014, the stability which was excellent in stabilizing screen grid voltage in this vacuum tube, and the low rate of distortion are gained.

The driver circuit was separated with the output circuit, the rectification circuit for exclusive use was prepared and the high-quality sound driver stage was constituted by constant-voltage-circuit.

It dissociates with an output circuit, and the driver stage of A-014 amplifier rectifies for the product silicon first made by IXIS soft recovery type diode of the highly efficient U.S., adopts the constant voltage circuit using MOS FET, and constitutes the power supply circuit for exclusive use.
Usually, since current change of an output circuit is very large, if the power supply of the driver stage is taken from the same power supply, the operation will be influenced considerably.
However, by this another circuit system, it was lost that the driver stage is influenced by an output circuit, and the clearer sound was obtained.

* The combination of the molded cherry tree plywood and the chassis made from steel of high rigidity realizes an attractive style.

The high rigidity chassis made from 2mm thick and steel of a gold color is adopted as the chassis of this machine.
Original and attractive appearance was realized by adopting and combining with a front panel and a transformer cover the formed plywood which fabricated cherry tree material in the shape of an R.
The soft appearance could enjoy the joy to be used fully, though it is high intensity.

* The function which can check both the current of an output tube and the voltage of the driver stage was newly added to meter.

The meter of the new model which both the current of 300B of the output stage and the plate voltage of the driver stage can change and display was adopted as the meter of this machine.
Thereby, operation of the driver stage can also be checked now as well as the situation of the output stage of operation.
Judgment of the life of a vacuum tube can also be immediately checked as well as the situation of operation when using it usually.
Also when there are abnormalities of amplifier of operation, in which portion, whether it is the cause can judge immediately.
The necessity of taking out to a check is almost lost to a maker one by one, and it is very convenient.


* The inhouse Teflon socket currently evaluated highly by high performance and high reliability from all over the world is adopted extensively.

The tube socket of our original currently evaluated highly by the merit of the reliability and sound not only the inside of Japan but overseas is extensively adopted as the sockets of this machine.
The body of the socket of our company gives gilding thick for next door bronze to adoption and a pin part, and is using Teflon excellent in temperature characteristics and an electrical property as the reliable socket.
All the pins have structure which begins to be deleted from the round bar of next door bronze, puts in a slit, and holds the leg of a vacuum tube exactly.
Therefore, where a vacuum tube is put to a socket, the leg of a vacuum tube is held firmly, there is no shakiness of a vacuum tube, and there is an effect which prevents the influence which external vibration has to a vacuum tube.

* Adopt a polypropylene film capacitor with little distortion product for a sufficient sound / Resistors made by DALE adopt by a main part.

The resistance currently used for A-014 has adopted the product made by U.S. DALE as almost all portions.
To the resistor of the cathode portion of 300B, a winding type highly precise in an inside capacity type is properly used for the metal clad type of a unguided type, and metal tunic resistance is properly used in the type of small capacity.
It excels, so that the sound quality can compare neither with the thing of this domestic class by the same product made by DALE.
moreover, the reliability is also markedly boiled for the parts made according to U.S. MIL specifications and standards, and is high.
Moreover, the polypropylene capacitor is adopted as a capacitor at the key point.
This polypropylene capacitor is excellent in the response to the signal of that palace nature compared with the usual chemical capacitor, and a capacitor's own rate of distortion is also very excellent.
Since the difference in the sound quality in this capacitor influences greatly not only in a signal circuit but in a power supply circuit, it has measured the improvement in sound quality by adopting a polypropylene type for the capacitor of a main part including a power supply circuit.

* Compared with adoption and use of a print and a substrate, improvement in a raise in rigidity and reliability was sharply achieved for the board of 3mm thickness bakelite to internal wiring.

The internal wiring of this machine does not use a printed circuit board, but is performing fixation of parts, and wiring using the bakelite board of 3mm thickness.
The attachment intensity of parts went up by this, and reliability also improved.
This bakelite board is fixed to the chassis made from direct steel, and parts, a vacuum tube, etc. which are attached to it are fixed firmly.
If the attachment intensity of parts goes up, the influence of vibration will be reduced and it will lead to the improvement in sound quality.


* Adopt as an input terminal the speaker terminal which began to delete the original pin jack of our company of chromium copper adoption from brass for a speaker terminal.

The input terminal of this machine has adopted the highest-class pin jack of our original which adopted the round pin terminal of next door bronze shave out as the internal pin for the shave out terminal of chromium copper, and adopted Teflon as the external conductor as an insulation material.
I have adopted the quality terminal of Teflon insulation as an output terminal by gilding which it began to delete from brass.
It is using at this that the speaker cable to the thickness of 4mm is also connectable.

* Specifications

Form: 300with input volume B single stereo power amplifier
Use vacuum tube: 300B A 2 pcs. (as for standard specification, a 300B vacuum tube is an option), and C3m A 2 pcs., 5U4G 1 本 It is attached except an output tube.
Maximum output: 8W+8W,
Frequency characteristic: 15Hz - 22kHz (-3dB)
Remains noise: 0.8mV,
Input impedance: 100komega
Weight: 16.2kg,
Outside dimension: 500(W)294(D)208 (H)
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