|Only the Best Will Do
I first became aware of Yamamoto products about seven years ago. Renowned American SET designer Gordon Rankin of Wavelength Audio fame and I collaborated on the Custom 45 amplifier project that was to be Gordon's first attempt at building a state-of-art 45 monoblock amplifier [lower left]. The circuit was parafeed and Gordon used Yamamoto Teflon tube sockets [lower right] -- "the best tube sockets in the world" according to Gordon -- for the Western Electric 437A input and NOS 45 outputs. The wire was silver and so were the MagneQuest trannies. There were oodles of Black Gate caps inside the polished stainless steel chassis that was capped with a gorgeous slab of Padua wood and a snazzy polished-brass Wavelength emblem. Gordon is a class act and it showed in the beautiful end result of my Custom 45 monos. Gordon made three other pairs that went to audio industry insiders and SET aficionados who proclaimed them to be the "best SET amplifiers in the world" at the time. That's lofty praise. You'd probably be shocked if names were named of who said that. Of course 'best' is a very subjective term, particularly in hobbyist HiFi so I won't go there. Let's just say that the Wavelength Custom 45s were very, very good amplifiers.
However, time hasn't stood still and neither has Gordon. He's been refining his 45 amplifiers and the Custom 45 has morphed into the Signature 45 [lower right]. The Wavelength Signature 45 again uses Yamamoto Teflon tube sockets and a Yamamoto composite chassis because only the very best will do when Gordon builds an amplifier. When premier SET designers like Wavelength Audio select Yamamoto hand-made precision parts for their own assaults on the state-of-art, that's very telling, isn't it?
Mr. Shigeki Yamamoto and the Yamamoto Sound Craft Inc. of Ono-City Japan
Mr. Shigeki Yamamoto has been working in the audio industry for about 30 years. He first worked at Japan's prestigious Lux Corporation for 5 years before leaving and launching his own company, Yamamoto Sound Craft about 25 years ago. Yamamoto Sound Craft is a small specialty audio design and manufacturing firm that currently employs 6 people. Mr. Yamamoto's specialty is industrial and graphic design and he personally designs all of the Yamamoto Sound Craft products. His knowledge of electrical circuits came the hard-won way: He taught himself via practice and patience and trial and error over many years. The Yamamoto Sound Craft designs embody all of the insight and wisdom Yamamoto-San has acquired over the last 30 years of pursuing audio and musical excellence.
Mr. Shigeki's first product was a hand-crafted wood hornspeaker. About 15 years ago, he began to use numerical control milling machines and at present uses 2 CNCs to manufacture wooden horns, Teflon sockets and various amplifier components from the best materials and to very high quality tolerances a characteristic that has contributed to the Yamamoto Sound Craft reputation for quality around the world. YSC originally produced for the home market exclusively and did not start exporting until 2000 when exposure on the Internet created international interest in their products. Yamamoto-San has been reluctant to engage international business because he does not speak English. He communicates sparingly when necessary because his language translation software makes carrying on meaningful discussions tricky due to the software's quirkiness.
Because of his preference for efficient horn-loaded loudspeakers, Mr. Yamamoto designs very high-quality and low- powered singled ended triode amplifiers. The A-08 amplifier under review is Yamamoto's 8th amplifier model and incorporates everything its designer has learned. Yamamoto says he uses a simple but clever circuit and a minimum of very high-quality parts, many of which are created in-house to provide the ultimate performance from the circuit. Yamamoto-San regards the design of the A-08 to be a novel and elegant approach that deviates somewhat from conventional thinking.
He believes that to achieve the best combination of music and sound, advanced knowledge of each device in the signal chain is necessary. To that end, he has studied amplification, loudspeaker drivers and wood horns, the effects of enclosure composition and construction, analog sources, semiconductors for microphones, phono stage design and analogue cartridges. Mr. Yamamoto believes further that the best approach is to build everything possible from scratch which has become his general rule for audio design at Yamamoto Sound Craft.
In the photograph below taken at the Vacuum Tube Audio Fair held in Tokyo this year, you can see a Yamamoto Sound Craft audio system from source to speakers: YC-02 moving coil cartridge (available in December); HS-1 African Ebony wooden head shell; SUT-01 step-up transformer for moving coil cartridges; CA-03L preamplifier; A-09 SET 300B stereo amplifier [also above], and the YS-604 speaker system using the venerable Altec 604 driver. Let's see - that's a combination of analog, single-ended triode amplification and horn loudspeaker. Now that's living la dolce vita audiophilius!
Yamamoto Sound Craft Product Line
Yamamoto Sound Craft sports a rather prolific product line that includes superior-quality electronic custom parts such as Teflon tubes sockets, Teflon-insulated silver-coated hookup wire, capacitors, connectors and anything else you might need for an audio project or to upgrade existing equipment with ultra-premium parts. Though I would usually not describe a complete lineup as part of a review, my stellar experience with today's amp combined with the fact that Yamamoto remains virtually unknown in the US compel me to do so regardless.
Mr. Yamamoto is currently working on the design of an MC cartridge (the YC-02 mentioned above) and shell lead that should become available in a few months. He is also working on a new headphone amplifier expected to launch in 2005. All Yamamoto products sold through Venus Hi-Fi carry a U.S.-based warranty so there should be no reason to ever deal with Japan in the unlikely event of service requirements. The standard versions of the A-08 and A-09 amplifiers described below are also available in partial kit forms if you want to save a little money and enjoy the kit-building process. For that, contact Brian at Venus Hi-Fi for the full scoop.
All Yamamoto Sound Craft designs feature point-to-point hand-wiring (amplifiers) or a combination of point-to-point and printed circuit boards (preamplifiers), with all parts being chosen by ear for best sound and tone. Below are select photos and, where available, brief descriptions of the imported goods and you gotta cut me some slack here as my Japanese translation skills are dependent on that aforementioned quirky translation software. Note that some of the designs pictured on Yamamoto's own website are out of production by now. What Brian imports below represents what's currently available.
A-09 SET 300B stereo amplifier - $4100/$3,750 without power triodes [above]
The A-09 is an 8wpc 300B SET with auto-biased circuit available as kit or fully assembled. The tube complement includes the relatively unknown mushroom-style 717A US military pentode in its first stage and a 5U4G rectifier. The design uses the best quality resistors, polypropylene film capacitors and condensers throughout. The chassis is a Cherry/resin composite with the appearance of laminated cherry wood. The A-09 uses a champagne-gold anodized aluminum-alloy transformer cover and solid African Ebony legs chosen for their tonal quality. The custom Yamamoto-designed transformers are manufactured with Yamamoto-supplied materials by a specialty contractor. The connectors are designed and manufactured in-house. The amplifier comes with a detachable 6N hospital-grade power chord with gold-plated contacts. Brian outfits this amp with the premium Emission Labs "Gold Series" 300B.
A-08 SET 45 stereo amplifier - $2250 (also available as a 2A3 on special order - $2450)
The A-08 is today's review subject and a 2wpc 45 SET built to the same high standards as the A-09 (the circuit can be optimized for a 2A3 by special order). The tube complement of the A-08 duplicates the first-stage 717A pentode and 5U4G rectifier from the A-09 and uses the same kind of chassis details and detachable 6N hospital grade power chord with gold-plated connectors and comes assembled or as a partial kit. Tube complement is two NOS 45 output triodes, two 717A input tubes and one 5U4G rectifier.
|A-08 Western Electric 205-D stereo amplifier - $2650
The A-08 WE 205-D uses the rather rare, gorgeous and hardly ever spotted-in-the-US spherical Western Electric 205-D to produce 1.1 watts. The A-08 WE 205-D's circuit and parts are optimized to obtain the best tone from the tubes and is available only as a finished amplifier. Mr. Yamamoto keeps a stock of NOS replacement tubes should you need them. Mr. Yamamoto says he's achieved a "wonderful result" using the WE-205D and continues that "the A-08 WE 205-D is transparent, clear, with great penetration power and tone." Admittedly, I don't have a clue as to what penetration power implies but it makes audio lust bumps erupt all over my body! With the WE-205D as direct-heated output triode, the driver tube is a WE-717A and the rectifier tube a 5U4G. Frequency response is 22Hz - 24kHz (-3dB).