2018/09/07 created
2022/03/15 updated

[2021/02/04 Revised] {The explanation on this page was complicated. So, I re-wrote the whole page. The point remains unchanged}

Basically, the goal of Gaudi II is hi-fi (high fidelity). The term 'hi-fi' is almost dead language in Japan. So it may be better to call it 'Hi-Res' (high resolution). It's a more contemporary expression.

Definition of hi-fi

It is rather difficult to define 'hi-fi'.
In short, 'hi-fi' means not adding anything to the original audio signals, nor subtracting anything from the original, nor changing the original at all. In other words, to suppress noise, distortion and deviation in frequency response to the lowest possible levels.
'The original audio signal' is the audio signal stored in music media (as for digital source, it is the coded audio signal).
I define hi-fi as converting the original audio signals to actual sounds accurately. Not reproduction of live sounds of musical instruments.

The original audio signals are created by musicians. It's not a mere recording of an audio signal picked up by a microphone.
The recorded sounds are edited and processed in the mixing and mastering processes. Those engineered sounds are stored in media and come onto the market. In this digital age, SE (sound effect) is common technique. It is not unusual to process the original sound to the extent that it sounds rather different from the original. Besides, using synthesized sounds is very common in the modern pop music.
Those 'artificial sounds' are also musical expression. They must be reproduced in hi-fi.
By the way, the term 'musican' here includes not only performer but other staff who participate in creation of music such as composer, arranger, recording engineer and producer.

I experienced before that Gaudi sounded as if its SPL frequency response is flat when the measured frequency response at the listening position was not flat, and vice versa. I concluded psychological hi-fi didn't match physical hi-fi, and the former one was more important (for details, see this).
Now I know I misunderstood the fact.

There are two reasons for my misunderstanding.
First, I wasn't familiar with acoustic measurements, and the measured data weren't reliable.
Secondly, I didn't consider the mechanism of human perception. A man cannot perceive vibration of the eardrum directly. The audio signal from the ear undergoes complex process in the brain before it is perceived. Individual experience, knowledge, will and attention have strong influence to this process. Belief, illusion and preconception greatly influence the sound quality.

Human perception has a function that can be said 'automatic correction'.
Though the sound radiated by the loudspeaker is distorted to some extent by the room acoustics, the automatic correction reduces the distortion. It's because the man learns the room acoustics subconsciously and reduces the distortion according to the knowledge.
For example, I recorded the sound of Gaudi with a microphone at the listening position, and replayed the recording and listened to it with headphones. I felt excess reverberation. It's natural because my room is acoustically live. However, when I listened to Gaudi, I didn't sense the reverberation. The reverberation was automatically reduced in my brain due the perception mechanism.

Consequently, it can be said that the sound quality of the audio system itself (not including the room in this context) is the most important. In other words, ensuring fine characteristics in quasi-anechoic measurement is the first step to realize the hi-fi system.

Placebo Effect

The term 'placebo effect' means that preconception and preoccupation make sound quality better.
The placebo effect has strong influence to human perception. It isn't negligible when sound qaulity is discussed.

For DIY audiophiles, placebo effect is so strong. Everyone overvalues what he/she makes efforts for. He/she believes his/her work is the best in the world.

I hesitate to say this, but evaluation of audio equipment by the designer/builder shortly after the completion of the work is not so reliable. The designers/builders tend to ignore shortcomings of his/her work.
As time goes by, this preconception gets weakened.

Importance of Appearance

Appearance is an important factor for audio equipment. Stylish appearance produces placebo effect, and it improves sound quality.

Every DIY audio device looks stylish for the builder himself/herself, no matter how good or bad he/she is at designing.
I have to be a good designer, since Gaudi II is installed in the living room and the components are stylish too from eyes of my family members and friends.

I learned lately that a theme is crucial in product design.
The theme is Gaudi II is 'cozy atmosphere'. I think it's a good theme for an audio system installed in a living room.
The design of each component in Gaudi II should harmonize the interior of the room. It shouldn't be too eye-catching, but moderately appealing.

Importance of User-friendliness

I believe user-friendliness influences sound quality.
It may be exaggeration to say user-friendliness will improve sound quality, but bad user interface could cause adverse placebo effect.

It is necessary to materialize stress-free user interface by, for example, employing remote control feature.

Wrap-up

The goal of Gaudi II is Super hi-fi that results from adding psychological effect like placebo effect to physical hi-fi.

The physical hi-fi can be measured. I'll evaluate physical hi-fi based on measurement data.
Not only each component, but the whole sysem will be measured. Fine tuning is to be done to minimize distortion, noise and deviation in frequency response.

I'd like make Gaudi II to be an audio system that satisfies not only myself but also family members and friends. Espcially, I'd be glad if ladies praise Gaudi II, because women tend to have better ears than men.

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