Toshi Kurashima Single Ended 71a

The amplifier below is one of the finest and rarest that I’ve owned so far. A simple little thing, it doesn’t look like much. A small greyish greenish box with 4 tubes and a can capacitor; but this is one of the very finest sound producers ever made on Planet Earth. Based on the 71a triode, this amp is the work of legendary audio designer and tube magician, Toshi Kurashima.

Mr. Kurashima is an audio artist based in Japan who not only builds his own amplifier designs, he even makes his own vacuum tubes! As seen on TubesUSA and YouTube, Mr. Kurashima’s amps are simple looking and unobtrusive, with hammertone finishes and old-fashioned speaker terminal strips. The plainly potted transformers are often vintage Western Electric that Mr. Kurashima has carefully rewound. Nothing is fancy or ostentatious here. To me, the understated and modest looks of the Kurashima amps must surely mean serious Japanese hifi mania! And based on the performance of the 71a amplifier below, they certainly deliver.

The 71a is one of my all time favorite power tubes. Although fairly plentiful and still affordable, its not a commonly used tube, mostly due to its extreme low output of less than one watt per channel. As unlikely as that sounds on paper, it is actually enough to fully energize a very sensitive speaker, and the reward is extremely good sound. The 71a is one of the very earliest triodes, the father of the 45, and it seems to have some kind of magic in the space and dimensional aspect of hifi. It’s presentation tends to feel quite spread out, but in a compact space, if that makes sense. Very relaxed. Maybe polite is a good term but that makes it sound soft and it isn’t. Its not stressful. It flows effortlessly out of the right speaker, but sounds far away on less efficient speakers. But if you have an uncomplicated 99-100+ db/wm speaker to present it with, I think there might not be a better sounding triode than the 71a.

The modest little platform that Toshi Kurashima has created for the 71a seems to really let this beautiful tube shine. With Western Electric transformers, a type 19 driver, and an 80 rectifier, the circuit uses all 1920’s period correct tubes. It is a 100 volt domestic Japanese amplifier and I’m using a step down transformer to power it. The little amplifier sounds very good immediately upon power on, but as is typical it settles in and blooms in 30 minutes or so, deepening and taking on a more euphoric flavor. Once fully warmed up there is a saturated feeling to the sound, like I’ve pushed vibrance up 30% in adobe lightroom. It feels very natural and is just gorgeous. Yes, its best with simple uncomplicated program material. Something like Gwyneth Herbert’s version of Only Love Can Break Your Heart takes on a glow and vibration that feels very present and unfolds precisely placed in front of you. You can almost see the waves of sound coming out of the speaker. Kina Grannis’s Beyond the Sea brought tears to a visitor who sat down and listened for a few minutes. But dialing it up a little with Issa Bagayogo’s Kalan Nege reveals that it doesn’t handle that dense heavy movement as adeptly as the 45 or 2A3 do on my Rullit Aero 8 drivers.

And this gets to the only “fault” I can find with this amplifier. It is only ¾ of one watt. With the 6AV11 preamp, this is still enough power to bring the Rullit drivers close to their sweet spot on the right program material, but the 71a is obviously not going to be for everyone and most speakers out there are a non-starter for this amp. But presented with an equal playing field, this tube and this amp offer a sound profile that is really just spectacular. Warmth, clarity and ease are all abundant. Gentle incisiveness. This amp’s performance is what triode sound is all about.

I’ve owned so many amps now at this point in my journey, and so many of them have been special and even exceptional. This one certainly resides in the exceptional category, and is a nearly unique destination amplifier. With the right speakers it will reward the listener with a delicate, revealing, and extremely present audio experience. But it does demand efficient speakers. One day maybe I will find a mate for my Georgian horn and perhaps that will be an ideal match. Until then I will continue to enjoy the mysterious and exotic 71a sound profile on my (almost) efficient enough wide band drivers. I hope to eventually be fortunate enough to try a platform built around one of Mr. Kurashima’s hand made vacuum tubes. What a special experience that must be. Highly recommended for the adventurous audio explorer with 100 db/wm + speakers.

I really like the badge on this amp! And the blue glass Arcturus tubes always make me smile. Their charm transcends all of the years and is just as powerful today as it was in 1928. Here with a supremely rare Cardon mesh plate 80 globe. These tubes are all ancient survivors, and this “100 Years” Toshi Kurashima amp is a tribute to them.

Simple and elegant go hand in hand with Toshi Kurashima’s little 71a. This is such a clean build.

The speaker terminal strip is a throwback to early tube amps of the old days, and is rarely seen on a modern amp. But this isn’t a modern amp, it's a tribute to another age. The terminals are marked on the underside, I assume so as not to spoil the clean look. Quite a departure from so many of the Japanese ultra-amps that have stickers all over them denoting tube placement, etc. There is nothing here to disturb the calm.

Here with a blue glass Arcturus 80 globe, a long serving tube that is getting a little tired unfortunately. But having the full lineup of blue glass is a treat.

The type 19, a strange little forgotten dual triode from yesteryear.

As seen above, the 71a is driven in this design by a single type 19 tube. This is a tube type that I was unfamiliar with before receiving this amplifier, but it seems to be a very early directly heated double triode dating to late 1932 or early 1933. It saw some popularity in the mid-1930’s as a DIY one tube twinplex radio, but I don't see much other reference to this tube anywhere, and it seems to have fallen out of favor before even world war 2.

Luckily, it turns out that the type 19 is extremely inexpensive now, and I was able to purchase 8 single new-in-box tubes of different brands to experiment with for just under $50. Try that with a 6SN7! Long story short, I can’t hear a difference between them. But, these are gorgeous jewels from loooong ago that are still available for a few dollars each; less than a quarter pounder with cheese. Imagine that.

The 19 seems to have come in two shapes, an ST and a straight bottle. Here then are a Silvertone, a Raytheon and an RCA. Just taking these photos I’ve noticed that the RCA has a different plate structure than the others. I’ll have to give it a spin, I’ve only tried 2 or 3 from the pile so far. Again, $6 each for these in 2024. Builders take note, this is a mostly unknown tube that's certainly doing its job in this circuit, and is worth some investigation.

This amp shines with the EML 80 mesh tube. It’s the “biggest” the little amp has sounded.

In comparison to the 45, which is the child of the 71a and makes roughly twice the power, I’d say the 45 feels like the 2nd or 3rd row, and the 71a is a little farther back but still close to the action. Both tubes make supreme sound. The 45 is ballsier; its quite a tube and is realistically a better choice for most listeners. One advantage the 71a does have is that’s its especially great for late night listening, as it comes alive, opens up, and glows at very low volume and pressure levels.

Cheers everyone, and Happy Listening!