Static Performance Degrades Dynamic Performance!?

SOULNOTE Chief Designer Kato’s Design Philosophy Series Part 6, in which Hideki Kato discusses other interesting topics such as non-NFB circuits, static performance vs. dynamic performance, etc.     

Social Experiment

If it were proven that “raising Static performance too much degrades Dynamic performance,” it would be a discovery so significant that it would turn the audio world upside down. However, this has not been proven theoretically at this time. Of course, I am convinced that with proper experimentation, statistically useful results can be obtained. I would like to do it someday. But unfortunately, I don’t have the time right now. I am a designer, not a scholar. SOULNOTE is also a global social experiment to prove the theory.

Sushi can only be evaluated by eating it.

I have always been aware of the fact that “raising static performance too much degrades dynamic performance,” and this is an everyday occurrence for me in product development. This is not something special, but something that anyone who can honestly listen to music can clearly understand if audio equipment is to be used as a machine for enjoying music. The wonderful sound that makes music resonate in our hearts, stirs up various emotions, and sometimes brings tears to our eyes, can easily be drowned out by extra methods used to increase static performance. I have experienced this countless times. I will illustrate this with specific examples below. However, please understand that the evaluation of sound quality and musical expression (evaluation of Dynamic performance) is my subjective opinion. The only way to evaluate sushi is to eat it.

non-NFB circuit

Negative feedback circuits are a common way to improve static performance. 99% of audio circuits in the world use negative feedback circuits. I used to design amplifiers with negative feedback circuits, but the deeper the negative feedback is applied, the better the static performance, but the more the music loses its life force and sounds boring. In other words, it is time-worn sushi because the output is perpetually being returned to the input. This seems to be becoming known around the world, and these days there are fewer audio amplifiers with as deep a feedback as in the past.
SOULNOTE’s analog stage is a non-NFB circuit that has eliminated negative feedback. Naturally, the static performance is worse, but the sound is fresher, the music is more vibrant, and the heart is more resonant. The amount of feedback is an example of a very easy-to-understand trade-off.

SN ratio in phono equalizer development

Generally, to improve the signal-to-noise ratio, it is common sense to reduce N (noise), because S (signal) is fixed in nature. However, in designing a phono equalizer, I discovered that the measured value and the audible signal-to-noise ratio become the exact opposite from a certain point. Phono equalizers need to amplify minute signals significantly. When amplifying with two stages of transistors, it is better to amplify as much as possible in the first stage to reduce noise, because reducing the gain of the second stage reduces the amount of noise from the first stage transistor that is amplified in the second stage. This is common sense in transistor circuits. But! The opposite is true as far as music is concerned. Lowering the gain of the first stage improves the freshness of the sound, and conversely, it sounds as if the SN has improved. In fact, when the signal-to-noise ratio is actually measured, the numbers get worse. This was really strange, but now I can explain it.
In other words, by reducing the gain of the first stage, which is the load of the cartridge, the Miller effect is reduced and the high frequency characteristics, or transient response performance (dynamic performance), is improved. In other words Static performance is kept as low as possible.
Prioritizing dynamic performance made for more enjoyable music reproduction.
E-1 and E-2 are phono equalizers designed in this way. If you turn up the volume of the amplifier to the max without putting a cartridge on the record, you will hear more noise than with any other phono equalizers from other manufacturers. However, if you actually play the record, you will not be bothered by the noise, but rather, the signal-to-noise ratio will be better than any other phono equalizers from other manufacturers, and the music will resonate in your heart. In other words, the sound with good transient response (excellent dynamic performance) will reach the human ear more clearly. In other words, even if the N of the signal-to-noise ratio increases, the S increases (presence increases) even more.
This is a long story and will be continued in the next article.
Next time, we will finally talk about NOS. It will truly be a battle between Static performance and Dynamic performance. And why is Dynamic performance more sensitive to the human ear? I will also write about my hypothesis. Stay tuned!