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Yamamoto : Power Amplifier A-09S 300B - Excluding Tubes

Yamamoto : Power Amplifier A-09S 300B - Excluding Tubes

Brand: Yamamoto

Product #: A-09S Excluding Tubes


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Yamamoto Information Sheet:

300B single stereo amplifier A-09S
Non-feedback system single amplifier which adopted as the output tube 300B which occupies the status as a reference pipe of a present-day tube amp
A-09S is the power amplifier of the single stereo system which adopted famous 300B as the output tube.
The basic circuit has adopted the self-bias system of CR combination which uses 5 pole pipes for a voltage amplification pa300B single stereo amplifier A-09Srt.
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 outstanding sound which carried out the one rise in ranking with the amplifier of conventional our company by reexamination from refinement of the ignition system of 300B or a drive circuit and the foundations of the parts to be used was realized.
The troydal type transformer of an establishment meter is distorted by adoption and the combined use with a Teflon insulating paper to all the transformers, and outstanding sound with little admiration is realized.
The troydal core transformer of the high-B type which excelled [ all ] in the regulation extremely is adopted as the power transformer of this machine, an output transformer, and each choke coil.
A troydal core transformer is acknowledged because the performance and sound quality are excellent.
Usually, since the troydal and the transformer are using the core of the shape of a ring without a joint, they can obtain the sound which the regulation excelled in instantaneous power well.
However, since there was no joint in a core, it was not able to be used for portions which send DC current, such as an output transformer and a choke coil.
A part of core was cut for it at our company, the slit was prepared, and it was made not to be influenced by DC current.
The output transformer which was excellent in the characteristic and sound quality with the regulation saved which was excellent with this was completed.
Moreover, the overly low impedance coil was designed and adopted also as the choke coil using the troydal core which prepared the slit.
That usual in the impedance of the choke coil has realized the value of 30 ohms for the place of 100 to about 200ohms.
The sound where the influence of the voltage drop by a choke coil decreased by this and which was excellent in a feeling of a lively motion was obtained.
Those transformers are working for maintenance of quality, such as carrying out fill it up of the quality epoxy resin in the company, in order to maintain sound quality.
A standard considers it as an output tube option, and enabled it to select the product made by JJ and Emission Lab by liking so that an output tube can be chosen freely.
I prepared for the sales specification of A-09S what combined what combined 300B of JJ of Russia with the type of the output tube option, 5U4G made from Emission Lab (Emission Lab) of Germany, and a 300BXLS vacuum tube.
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-09S is designed so that almost all 300B of each company can substitute as it is, and adjustment is unnecessary at all.
Adjustment of ham balance etc. is also unnecessary and the sound highest by no adjusting is obtained.
Both the waves rectification DC ignition circuit by a Schottky diode is adopted 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-09S.
Since the current capacity of a transformer is fully taken and it enables it to correspond also to the big heater current up to about 2A, it is possible to substitute and use almost all 300B types of vacuum tube.
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.
We adopted the highly efficient Schottky diode of the U.S. IR company as the rectifier by audition.
Furthermore, what has daringly small capacity was selected to the smoothing condenser, the product was chosen, and the sound excellent in speediness has been obtained.
Usually, the ham balancer etc. to be used were 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 1/10th place, and makes current feedback of cathode the minimum.
The first rank highly efficient German highly efficient pipe C3m was adopted as the pipe, and the high-quality sound driver stage consisted of low noises.
Five highly efficient pole pipes C3m are adopted as the first rank of A-09S 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 locktal tube, 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.
A mesh plate is beautiful and this vacuum tube has charm also in appearance.
In A-09S, the stability which was excellent in stabilizing screen grid voltage in this vacuum tube, and the low rate of distortion have been obtained.


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