**■ A Surprising Statement: The Truth About Capacitors**

One of the most striking moments came from a very direct technical statement.

Among audiophiles and some repair technicians, there is a belief that changing capacitors can alter the sound, which leads many to prefer using original or specified parts.

I had also thought that capacitors might play a role in shaping the sound.

However, the engineer put it very clearly:

“In a DC amplifier, capacitors do not change the sound.”

He explained that, unlike in the vacuum tube era where capacitors were directly in the signal path, their role in DC amplifiers is fundamentally different.

From the 07 series onward, Sansui had already moved toward designs where individual components would not directly alter the sound in that way.

Yet, he added something interesting:  
“Even so, I still care about how it looks inside.”

He sources original specified components, such as **SILMIC capacitors**, from around the world and carefully installs them.

“In theory, it doesn’t change the sound. But restoring it to its original form matters.”

That mindset revealed a certain kind of craftsmanship — preserving not just function, but identity.

  
**■ The Invisible Foundation: Eliminating “Ground Fluctuation”**

There was one question I really wanted to ask:  
Where exactly did Sansui focus when shaping their sound?

His answer pointed to something almost invisible.

According to him, Sansui paid great attention to eliminating “ground instability” and preventing unwanted noise from entering the system.

In other words, they focused on making the foundation of the sound — its baseline — absolutely solid.

What stood out to me was how far they pushed this idea.  
It’s reflected in a signal-to-noise ratio of over 110 dB — a figure that can rival even modern high-end amplifiers in this price range.  
And this was achieved not through complex digital control, but through the strength of the physical design itself.

Because of that, even under heavy input, the sound remains stable and controlled.

That sense of stability — almost a kind of physical presence — seems to come from this unwavering foundation.

At the time, much of the marketing focused on circuit design innovations.  
But beneath that, this invisible groundwork was doing the real work.

  
**■ The Craftsman’s Advice: How to Keep Vintage Gear Alive**

Even the latest Sansui models are now over 25 years old.

I asked how to keep them in good condition over time.

The answer was simple:  
“Just keep using it regularly.”

Turning it on and off, operating all switches — this helps prevent deterioration.

This seems to apply to many types of vintage electronics.

I also asked about using the amplifier in colder environments.

He recommended allowing about 15 minutes of warm-up time before serious listening, especially in winter.

Sansui amplifiers are equipped with robust protection circuits, so the key is simply to trust the design and use them patiently.

  
**■ Closing: A System Reconnected Across Time**

After the overhaul, I connected the AU-X111 MOS VINTAGE to my ATC SCM19.

The first thing that stood out was the silence of the background.  
A signal-to-noise ratio of over 110 dB is not just a number.  
The soundstage opened up with a wide range, and within its depth, the positioning of each instrument became clearly defined — almost as if it could be seen.

The ATC tweeter is known for its natural and composed character.  
With this amplifier, that character remained intact, but the texture of the sound seemed to gain a new sense of clarity — more open, more luminous.

The change in the low frequencies was just as striking.  
What the engineer described as a “solid ground” felt very real here, fully controlling the heavy ATC drivers.  
Unwanted resonance disappeared, leaving behind a tighter, faster, and more precise low end with no sense of ambiguity.

This concludes my AU-X111 MOS VINTAGE revival project.  
But it also raises a question — how long can we continue to live with machines like this?

The dedication poured into this amplifier nearly 40 years ago still feels fully intact, even when driving modern speakers.

If you happen to have a piece of vintage gear resting somewhere, it might be worth bringing it back to life.  
There may be something there that you won’t find just by browsing modern catalogs.

Thanks for reading — and until next time.

  


【Part 2】The Truth Behind the Sansui Sound — What Lies Beneath the Surface