110TH Anniversary of Denon Vol.3 Interview With Takashi Arai, Amplifier Engineer

So many “firsts.” Do you consider the S1 series as the most impactful update in Denon’s 110-year amplifier history?

Arai: Yes, I think it is an essential product in the history of Denon amplifiers.

I see that many of the technologies first used in the S1 became breakthroughs and are still in use today as a part of Denon amplifier tradition.

Arai: I think it is fair to say that the UHC-MOS, the core of Denon amplifiers, and all-stage balanced amplifiers are the roots of today's Denon amplifiers.

What are the sound features of the Denon amplifier?

Arai: What I consistently say is "subtlety and strength at the same time.” This is a feature of UHC-MOS.

Is this possible because UHC-MOS is capable of instantaneous high-capacity current flow?

Arai: The "power" part is true, and the single push-pull circuit allows the signal to be amplified at a single point, which contributes to the "subtlety" of the sound.

So, this S1 is the origin of the Denon integrated amplifier.

Arai: That's totally right.

Model Changes of the PMA-2000 Series for a Quarter of a Century

What are some of the most memorable products you made over the years in the field of Denon amplifier engineering?

Arai: One of the models I worked on that is still in the series is the PMA-2000. The current regular model is PMA-2500NE, which already has a part number that exceeds 2000. The PMA-2000 series lasted for seven generations, followed by the current PMA-2500NE. So I guess it’s actually eight generations. Now, as it is our 110th anniversary, I wanted the PMA-A110 Anniversary Edition to be an adventurous model worthy of a commemorative product.

The PMA-2000 series has been through model changes for a quarter of a century, but which model is particularly most impressive to you?

Arai: The first generation. Up until then Denon amplifiers didn’t sell well in Japan. So when we were developing the PMA-2000, we changed the development process of the previous amplifiers and made them entirely new.

Were you determined to change Denon's amplifiers?

Arai: Yes, we were. That is why we engineered them with the goal of outperforming the amplifiers of other companies that sold well at the time.

That sounds like a lot of technical work.

Arai: I tried to improve the amplifier not only in terms of technologies such as output and distortion, but also in terms of its appeal as a product. That is why we put effort into creating a powerful amplifier, which ended up making it bigger and heavier. Denon’s previous amplifiers were small and light weight compared to those in the same price range. Size was an important factor in audio equipment at that time. One of the critics in those days weighed everything on a scale and used it in their evaluation criteria.

What other innovations did you make?

Arai: We used UHC-MOS, which was highly evaluated in the S1. The PMA-2000 was a model with the cost of 100,000 Japanese yen, so we had to find another element that was cost-competitive and could carry a large current.

That's more tough work.

Arai: It was not only difficult, but also caused unexpected problems. I found a good element earlier. I used it to make prototypes and conduct tests, but then the device suddenly became unavailable for sale. I was very surprised. So, we went back to the drawing board to find another element, and eventually we managed to find a solution.

We wanted to compete in the same retail price range as our rivals, so the price was set at 100,000 Japanese yen, but from a profit standpoint, we were supposed to sell it for 140,000 to 150,000 Japanese yen. The cost of materials was so high that we could not make a profit out of it. That's why the section manager said, "If we cannot be successful in this model, we'll stop making amplifiers all together.”

But the PMA-2000 was a big hit after all.

Arai: Yes. It was greeted with great interest by many audiophiles and was ultimately a hit. It became a long-selling series that continues today. I still use it as an example of excellent construction, and I have not changed a single part of the molds I made for the PMA-2000.

That's how perfect it was. What was the reason the PMA-2000 became a hit?

Arai: I think achieving the "combination of subtlety and power" that Denon is known for in the S1 was highly valued with the retail price of 100,000 Japanese yen. The PMA-2500NE is the backbone of Denon’s amplifier lineup, so I think it is fair to say the PMA-2500NE is the embodiment of Denon's sound. This culminates in the new limited PMA-A110 model, which even houses technologies that previously where only applied in the flagship SX series only available in Japan.

The Function of the Amplifier is Simple. But the Requirement Changes Depending on Components to Be Connected

How do you see the evolution of Denon's amplifiers in the future?

Arai: The function of an amplifier is simple: to increase the incoming audio signal and to make an expanded copy. We will not change the ability to reproduce music accurately, that’s for sure. I also believe Denon amplifier’s "subtlety and power" characteristics and the company’s new sound philosophy of "Vivid and Spacious" will carry us into the future.

However, the amplifier does not produce sound itself. Music is only played back when it receives a signal from a player, the source of a sound, and passes it onto speakers that produce sound. That is why I think the required capabilities will change as the connection partner changes.

For example, large speakers that were once commonly used, such as a 38cm (~15-inch) woofer, are not used much these days, so there are fewer cases that require large amounts of instantaneous power on the amplifier side. On the other hand, sound sources like SACD and high-resolution sound sources have increased, as well as the number of higher-density sound sources. As a result, amplifiers are required to be able to accurately amplify more delicate and detailed sounds. I believe that amplifiers will evolve in this direction in the future.

Find out more about Denon 110 year legacy in audio here.