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Power Amplifiers

Audio Note(TM) balanced, transformer coupled mono power amplifiers - First Principles

The shortest signal path is generally the best, this is the professed aim of almost all the manufacturers of high quality amplification in the audio industry.

However, when it comes to executing this ideal, most of the rest of the industry has been wilfully forgetting this truth and has become addicted to complexity and technology as marketing statements, in stark contrast to this Audio NoteTM has continued to focus on studying and refining our understanding of how to achieve the above goal in order to create products that deliver better and more realistic music, lasting value and overall quality.
Unsurprisingly, the more we explore, the more it becomes obvious that simplicity – and in particular keeping passive components completely out of the signal path or at least to an absolute minimum – is desirable for better and more faithful music reproduction.

Our ideas eventually led to a decision to develop a better sounding power amplifier circuit, a potential successor to the original parallel single-ended 211 based Gaku-On. In pursuit of ultimate simplicity, we decided that it would comprise just two active stages and three transformers; one on the input, one as a driver and one on the output. This topology reduces the number of passive parts in the signal path to just two resistors.
Designing the circuit was relatively easy on paper. However when we came to building a prototype we discovered why such nothing like it had been implemented before, and it was more than half a decade before we could bring the new Gaku-On to fruition.

Our finding was that such a simple amplification circuit demands a degree of transformer quality never seen before in professional or domestic audio. Audio NoteTM  is unique in our facility to design, model, prototype and wind our own transformers in house, yet in spite of this it took even us six years to research and develop the necessary materials know how to achieve a musically transparent magnetic coupling from input to output in such a simple circuit.

Each transformer has to be complimentary in every aspect of behaviour to the one next in line. It must not impose any bandwidth, phase, linearity or low level abnormalities which can be amplified by the following stage or stages. It was no small task getting to a point where each transformer was as invisible as the next, despite differences in core size, design and passing signal level. To read more about the art and science of transformer design, click here.

In the event, the new Gaku-On has repaid our efforts and sets a fresh benchmark in audio amplification at the top of Audio Note TM Performance Level Five.

The circuit topology cannot be bettered, simplicity cannot be taken any further than this, the valve choice, a directly heated VT25 driver with a pair of paralleled VT4-C/211 directly heated triodes as power valves, will be hard to improve on as well, so all that remains would be to develop even better components parts, materials and transformers.

In order to beat this we will continue to research and develop our understanding, and until we find the necessary solutions to further improve the materials, simply put, we believe nothing will come along that beats it.

Everything we learned in the process of developing the Gaku-On we have applied subsequently to a new and partnering family of balanced, transformer coupled monoblock amplifiers. The P4 Balanced, Ginrei, Baransu Balanced, Kageki Balanced and Kegon Balanced are each an expression of the simplest circuit and purest musicality that we believe can be achieved at Audio Note TM Performance Levels Three, Four and Five.

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