Sophia Electric Aqua II 274B Rectifier Tube with Live-Like Sonic Performance

Regular price: $299.99
Sale price: $299.99

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2023 Positive Feedback Writers’ Choice Award: "The new Aqua II 274B is impressive: a beautifully natural tonal balance, a huge sense of recorded acoustic, gorgeous tone color, a vivid sense of imaging presence, excellent dynamics, and increased clarity and resolution of nuance " -- Jeff Day

Jeff Day's Positive-Feedback Online Review:

"I've listened to a ton of CDs and LPs with the new Aqua II 274B rectifier in the Triode Lab 45 EVO, and it has all of the natural sounding tonal properties, vibrant musicality, excellent dynamics, and spectacular sound-staging abilities that make the original Aqua 274B so desirable, and yet the Aqua II 274B manages to take everything up another notch in performance.

The 'superpower' ability of the Aqua II is that its additional resolution and more vivid imaging meant that I could still hear everything in the music even at lower volumes, a trait that comes in handy with low-powered SET amplifiers. I didn't get a sense I was missing anything in the music even at lower SPL levels, the music was just projected with more authority to me as a listener.

To borrow from baseball parlance, Richard and Sue have been on a 'home run streak' with their newly developed product lines of Sophia Electric's 'sexy blue tubes'.

I've really been impressed with the premium Sophia Electric EL34-ST, KT88-ST, and Aqua 274B blue glass vacuum tubes that I've listened to over the last few years.

You can now add the new Aqua II 274B rectifier to that list, which is another 'out of the ballpark home run' in a 274B design. Kudos to Richard, the Aqua II 274B is an impressive accomplishment.

If you can use a 274B rectifier in your amplifier, the Sophia Electric Aqua II 274B is an easy recommendation, and I heartily recommend you give one a try. I cannot imagine anyone being less than thrilled with its performance."

User Experiences

Reviewer Jeff Day:

"As soon as I put Richard's new Aqua II 274B rectifier in the Triode Lab EVO 45 SET amp I knew something special was going on.

Fresh out the box the Aqua II 274B sounded gorgeous: beautifully natural tone, a huge sense of recorded acoustic, gorgeous tone color, a vivid sense of imaging presence, and excellent dynamics.

I've been impressed by how good the new Aqua II 274B is sounding in place of the original, even with only a couple hours of listening time on it. It's definitely better, and that's saying something, as the original Aqua 274B was a stonking good tube, as you can read about in the linked article."

Click here to read the article

The latest Sophia Electric design and production of this premium 274B rectifier tube was originally planned for Sophia Electric’s 20 Year Anniversary in 2021, but due to the Covid-19 pandemic, this product was delayed.

Thus, we elected to rename it as the Aqua II version of the popular original Aqua blue glass 274B rectifier tube.

The Aqua II 274B (filament current: 2.8 ma) features a number of technical innovations:

The Aqua II has a higher current output (max 220ma) compared to the original Aqua 274B (max 180ma), and way more compared to the WE 274B (max 150ma)."
The Aqua II has a lower impedance than any other 274B ever made, thus higher efficiency in converting AC into DC.
Higher dissipation power rating with visibly bigger and heavier internal construction.
New generation of spark arc suppression technology to eliminate arc possibility (WE274B is the internal spark arc king).

What does Aqua II 274B sound like?

First, we describe it as far more musical than any other 274B or 5U4G tubes ever made. It has a higher resolution – akin to watching 8K video instead of 1080 – and even more live-performance-like sound. Every musical instrument and voice are more clear-cut from the rest of the orchestra. It gives you the feeling that you've just upgraded your amp / preamp with a boatload of Black Gate capacitors. With Aqua II 274B the type of performance improvement one desires from Black Gate capacitor upgrade is fulfilled.

A brief history of 274B tubes:

Western Electric was the first company to make 274 tubes. The 274 rectifier was launched in the 1930s to complement its WE 300B tubes in the WE 91 amplifiers that were used in movie theater cinemas across the USA.

The Western Electric Model 274A has a 4-pin 300B-like tube socket while the Model 274B would fit into an octal socket designed for 5U4G. Other than the tube socket difference, the rest is the same.

Note: octal tube socket is the most commonly seen standardized socket in the later years. The 6SN7 or 6L6/EL34/KT88 tube socket of later years also utilize an octal tube socket.

Compared to the industry standard rectifier tube, namely the RCA 5U4G tube, the 274B offers much lower power supply impedance; thus, it has a better resolution and high frequency extension. Given such a big sonic advantage of 274B over RCA’s 5U4G, it begs the question of why the WE 274B did not get used more in other amps and preamps.

What was the limitation?

The WE 274B requires that the power supply's first capacitor’s capacitance value to be 4uf or smaller, otherwise it would trigger a big electrical flash spark. Sometimes it may even blow out the fuse.

When most equipment in the marketplace was designed for the 5U4G rectifier that permitted 47uf of capacitance, it became impossible to directly replace a 5U4G with a WE 274B without power supply modifications.

For this strict requirement reason, the WE 274B did not get any significant market. As a result, the RCA 5U4 tubes had the dominant market share.

Fast forward to the era of the mid-1980s when Japanese currency has appreciated significantly over time. Powered by their new purchasing power, the Japanese audiophiles re-discovered and bid on vintage American vacuum tubes and tube electronics.

Two of the most well-known and sought-after items were the Western Electric 300B and 274B tubes.

By the time American audiophiles got into high-end tube audio in the mid-1990s, the WE 274B and WE 300B tubes were commanding stratospherically high prices.

In 2023, a single vintage WE 274B untested tube may be listed for $4999.99 in an auction. That is an incredibly high price for a 274B rectifier.

Sophia Electric’s proudest milestones since 2001:

In 2001, Sophia Electric debuted the Princess 274B rigid plate rectifier to fill the gap left by the WE 274B.

In 2002, Sophia Electric introduced a mesh plate design of 274B (above). As much as we love the mesh plate 274B tube, the requirement of low capacitance of 10uf or lower at the first capacitor limited its potential use.

In 2016, Sophia Electric released the revolutionary blue glass Aqua 274B that lifted the capacitance limitation (above), broadening the 274B market to be almost fully interchangeable with a 5U4G.

This MK II version of Aqua 274B tube is the ultimate 274B from Sophia Electric. It delivers an unforgettable magical sound that is the trademark of Sophia Electric vacuum tube house sound.

Along with Aqua II 274B tube, a new Classic II 300B tube was also debuted.

Price:
Option 1: $299.99 per tube with one year warranty (blue glass)
Option 2: $250 per tube with 30 days warranty (blue glass)
Option 3: $275 per tube with one year warranty (clear glass)
Option 4: $225 per tube with 30 days warranty (clear glass)

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