SOULNOTE Chief Designer Kato's Design Philosophy Series Part 9.

SOULNOTE Chief designer Kato continues his essay series with the topic of how the chassis structure affects sound.

Chassis Structure Affects Sound

Previously, we have discussed Static performance, which is performance that can be expressed by measurements, and Dynamic performance, which is performance related to the time axis that is difficult to express by measurements, with electrical circuit examples such as non-NFB, NOS, and LPF. This time, we will discuss the question that has long plagued audiophiles: "Why does the structure of the enclosure affect the sound?" The following is a discussion of this issue. This is also a change in sound that is not expressed in measurements, and is truly dynamic performance. It is a factor that can only be judged by listening.

SOULNOTE products have mechanical features such as unfixed top panel, unfixed board, unfixed terminal base, and thin and light cable. This is the exact opposite of the heavy, rigid construction that is common in high-end products. Why is this so? In this article, we will discuss why mechanical structure affects sound and the secrets of SOULNOTE's enclosure. This is a new idea that perhaps no one else has mentioned, but of course it is only my hypothesis. It is SOULNOTE and you who will verify it.

The influence of the enclosure on the sound is stronger than that of the electrical components.

We feel that the enclosure has a very strong influence on sound. For example, during development, it is common to consider leaving the top panel open to increase efficiency. However, it is an everyday occurrence that the wonderful sound that has been painstakingly refined in this state is instantly ruined as soon as the top panel is closed. The sense of openness disappears, the sound field that had been spread out three-dimensionally becomes narrower, and the performance becomes cramped. On top of that, the sound becomes hard and tiring to listen to. This should be experienced by any engineer who designs while listening to sound.

Why does the enclosure change the sound?

I believe the reason for this is the same as the main reason cables change the sound or electrical components change the sound. Vibration. To be more precise, I believe that the frequency characteristics of the vibration of each component is a factor in the sound.

Vibration is bad. However...

As it has become clear that vibration has a negative impact on sound, various measures have been taken to prevent vibration. For example, anti-vibration measures such as attaching anti-vibration rubber to cables and capacitors and placing weights on them have been implemented. As a result, the sound changes. And then, "The sound is better because of the vibration countermeasures! I think. Isn't this similar to the previous story? "The LPF reduced the noise, so the sound is better!" It is the same as an engineer who thinks

I have rarely felt the sound of rubber or weighted vibration isolation to be good. I feel that the sound atrophies, the echoes disappear, and the sound is often boring and dead.

Of course, vibration is evil, so it might be good if it could be completely eliminated. However, rubber and weights are not enough. The faster the vibration, the stronger the vibration isolation, and the slower the vibration, the less vibration isolation. In other words, the materials used for vibration isolation have their own frequency characteristics, which affect the sound. This is the reason why rubber makes a rubbery sound. This is also the reason why heavier parts for vibration isolation also make the sound heavier. This is because the faster vibration is suppressed, the more strongly it is suppressed, and this effect affects the sound. In fact, it is almost impossible to suppress vibration by weight. Even buildings vibrate. Furthermore, the element of resonance, which will be discussed later, also becomes stronger.

In other words, rather than trying to suppress vibration badly, it is better to make it light and free, so that strange habits do not take over. It is better to leave it free, and if it moves, to be able to move fast and without habit. Lightness also has the advantage of faster convergence, and the fact that SOULNOTE's cables are thin and light is the result of a choice made based on sound, which is consistent with my hypothesis about vibration.

In the next article, I will discuss another important element of vibration: resonance. I will also discuss my discovery of "invisible anti-vibration rubber that kills sound. Stay tuned!

On the photo above, the M-3 heat sink. The ends are lightweight and not mechanically constrained.