5. The First Sound Impression of the Early Ookubo-san’s WE310A-PX25A(DA30) Mono SET

Well, in early August 2012, my roughly six months' worth of parts gathering was almost complete, and also the long-awaited aluminum chassis with a beautiful pale green Hammertone paint finish arrived from Yokoyama-san of “Valves' World”.

The rugged US-made huge output transformer, painted simply black, was also finished with the same original TANGO color, a brownish-grey Hammertone paint, and the appearance was unified with the heavyweight power transformer and the choke transformer, so it was easy to imagine that the finished product would be a more authentic and luxurious mono amplifier than I had imagined. 

All that remained was to assemble the parts into the chassis, and thanks to the high precision of the hole processing on the top chassis, assembly went smoothly. And then I moved on to the soldering work of the wiring. But it was a mono configuration, so there was plenty of room for component placement, and the wiring work progressed also smoothly. Well, for the wiring, I used Western Electric 20GA single-wire cables for the extremely low-current signal wiring and WE16GA cables with more ample capacity for the parts with larger currents. The soldering was done with the well-known KESTER44, whose sound quality and finish are impeccable. 

Now, all the wiring was finished, and soldering of capacitors, resistors, etc., was also complete. After checking that everything was according to the circuit diagram, I inserted all the vacuum tubes into their designated sockets and turned the power on for the first time. 

Because of the self-biasing single-ended amplifier, there were no adjustments to be made, and by checking that the heater voltage did not exceed the specified value and that the plate voltage and cathode voltage of the WE310A and DA30 were at the appropriate DC voltage. 

As a result, I was fortunate enough to find that both L/R channel SETs were working properly. Then, on the following day, Sunday, August 26th, 2012, I handed it over to Ookubo-san, who was probably eagerly awaiting the completion of the mono SET. 

The location for the handover was the listening space at SPEC Corp., where I worked at the time, and I managed to prepare the listening environment where Ookubo-san and I could check and hear the sound and waited for Ookubo-san's arrival. 

To be honest, the delivery date, in other words, this final stage seemed to arrive suddenly, without even running the amplifier for a long period of time to check its reliability, and without even having the chance to listen to any reproduced sound of it myself. Of course, before Ookubo-san arrived, I finished setting up the DV-AX10 DVD player and some small and inexpensive B&W speakers I had nearby and tried out the first sound. 

The impression at that time is vivid also now for me. Yes, the sound was still raw and unrefined, but I was deeply moved by the powerful, three-dimensional sound that seemed to leap out at me. And with such wonderfully finished amplifiers, I was confident that I could hand it over to Ookubo-san, who had been waiting for its completion for over six months without any concerns. I breathed a sigh of relief. 

Thankfully, Ookubo-san's reaction was just as I had imagined. Now when Ookubo-san arrived and heard the sound for the first time, his usually stern expression changed completely and was filled with joy and a smile. After listening to a few songs together, Ookubo-san took out his cell phone and, with a beaming smile on his face, called Nakamura-san, a mutual audio friend of ours, who was the one who was most eager to hear the results. 

I remember Ookubo-san only said one thing during that phone call: "It's amazing." I was reminded that when we are truly moved by the sound, there would be no need for various adjectives or any audio-related expressions to describe it, and all that comes to mind would be a simple exclamation.

Even after handing this amp over to Ookubo-san, this sound field expression, like something I had never experienced before, which seemed to bring a three-dimensional space to life before my eyes, has always been etched in my mind, and I hope to hear it for myself again. 

I never imagined that 13 years later, through some mysterious guidance, my thoughts or wish would come true. My reunion with the mono SET amplifier exceeded my imagination. Perhaps the late Ookubo-san's intangible will that he wanted me to hear the sound of that mono SET amplifier one more time. I will keep my gratitude to Ookubo-san in my heart.

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