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First Listen: Triode Lab 2A3 Parallel Single-Ended-Triode RSR Monaural Amplifiers!

12-26-2021 | By Jeff Day |

Greetings, and a Happy Holiday Season to you all! I hope Santa brought you all your hearts desires this Christmas!

I'm feeling particularly blessed at the moment as I sit here listening to film and music and writing about hifi for you, and a big part of that blessedness is due to the presence of the Triode Lab parallel single-ended-triode RSR monaural amplifiers residing in my audio-visual system at the moment.

I introduced you to the beautifully constructed Triode Lab parallel singled-ended-triode RSR monaural amplifiers in my Today's Fresh Catch post of twelve days ago (HERE). 

Triode Lab 2A3 P-SET RSR monaural amplifiers. $22K USD a pair.

Monaural amplifiers are the purist approach to stereo amplification, as they have separate chassis, with each chassis having its own power transformer, output transformer, and everything else component-wise to achieve optimum performance, in a monaural build. 

In the monaural world nothing is shared, nothing is compromised, its the full-on approach for building state-of-art amplifiers.

Two monaural amplifiers are required for stereo applications, which accounts for their higher price compared to stereo amplifiers built on the same chassis. 

Triode Lab 45 EVO integrated SET amplifier. $7500 USD.

Most of you know I was absolutely bowled over by the performance of the Triode Lab 45 EVO integrated SET amplifier that I wrote about in Positive Feedback Issue 115 (more HERE), so much so that I awarded it a Writers' Choice Award for 2021.

The Triode Lab 45 EVO integrated SET amplifier is simply the finest sounding, most musical, most "real" sounding amplifier I've ever heard on my Tannoy Westminster Royal SE loudspeakers, and not just by a little, but by a lot.

The Triode Lab 45 EVO isn't your father's SET, or your grandfather's SET, its an evolutionary - or perhaps revolutionary - leap forward in SET performance, based on my experience with SET amplification over the last couple of decades.

To top it all off, the 2 watt Triode Lab 45 EVO easily drives my West's to live-like levels on 99% of the albums I've listened to, a feat that amplifiers more than ten times as powerful have failed at. 

It's a massive understatement to say I was impressed by the Triode Lab 45 EVO, and at its price of $7500 USD its the greatest amplification bargain out there that I've run across in the last couple of decades.

If you've got high-sensitivity speakers, this is your amp!

Triode Lab 2A3 P-SET RSR monaural amplifier.

Or is it? Frank thought I should listen to his Triode Lab 2A3 P-SET RSR monaural amps, as he thought it would be good for me to hear a pair of his state-of-art monaural amplifiers in comparison to the 45 EVO integrated SET amplifier, so I could experience what that extra amount of power - 8 watts versus 2 watts - brings to the music-making game.

Triode Lab 2A3 P-SET RSR monaural amplifiers.

The Triode Lab 2A3 P-SET RSR monaural amplifiers only have about 40 - 50 hours of run-time on them, so the vacuum tubes and the amplifiers themselves don't have anywhere close to their full run-in time on them yet, so I presume they are not yet at their ultimate level of performance.

Expect more updates in the future as I work towards the Triode Lab 2A3 P-SET RSR monaural amplifiers' feature review for Positive Feedback, which is the next review in my review queue schedule. 

In today's First Listen post I'm going to tell you about their performance in my vintage Altec A5 Voice of the Theatre loudspeakers based audio-visual system, and in a future post I'll discuss their performance in my Tannoy Westminster Royal SE loudspeakers based music system, my primary music system.

For preampfification I'm using the Leben RS-100U line-level preamplifier, coupled with the Leben RS-30EQ phono equalizer. Power cables are by Acoustic Revive, interconnects are a mix of the silver-copper hybrid Acoustic Revive Absolute (Oppo to RS-100U), and those classic recording studio favorites, the Belden 8402 tinned-copper microphone cable interconnects for everything else. Duelund DCA16GA tinned-copper speaker cables connect the A5s to the amplification. 

Leben RS-100U line-level preamplifier (left), Leben RS-30EQ phono equalizer (right).

The Leben RS-30EQ phono equalizer made a cameo appearance in the Positive Feedback feature article about the Triode Lab 45 EVO, along with the stellar sounding combination of the Audio Note (UK) Io I MC phono cartridge, AN-S4 SUT, AN-V silver interconnects, which provided the music signal from my CTC Garrard 301 turntable with excellent effect.

The Leben RS-30EQ CR-type phono equalizer was an ideal match for the Triode Lab 45 EVO, and so I suspected it would also be a great match to the Triode Lab 2A3 P-SET RSR monaural amplifiers.

I should point out that the '2A3' tubes I'm using in the Triode Lab 2A3 P-SET RSR monaural amplifiers are the Sophia Electric low-voltage (2.5V) 300B mesh-plate tubes, which are a compatible tube option for 2A3 amps. 

Frank tells me that the Sophia Electric mesh-plate 2A3 tubes are sold out, so thus the use of low-voltage 300B tubes in their place. Frank also told me he thought that they sound a lot like the Sophia Electric mesh-plate 2A3 tubes, which I haven't heard personally. 

Sophia Electric 2.5V 300B mesh-plate tube that is intended for use in 2A3 amplifiers.

By the way, Richard and Sue at Sophia Electric say the internal structure of their low-voltage 300B is similar to that of the famed Western Electric 300B (mesh plates excepted), but instead of the normal 300B filament voltage of 5V, the filament voltage has been reduced to 2.5V to make them compatible with 2A3 amplifiers. Intriguing idea.

The obvious visual difference is the use of the globe-style glass envelope rather than the original ST shaped glass used in the original WE 300B tubes. I like both styles, and the Sophia Electric 300B 2.5V mesh plate vacuum tubes are beautiful little works of art in their own right.

Low-voltage 300B tubes are new to me, back when I owned a pair of Don Garber's Fi 2A3 SET monaural amplifiers, such a vacuum tube design did not exist.

Sophia Electric 300B 2.5V mesh plate vacuum tubes for use in 2A3 amplifiers.

When I looked at the Sophia Electric webpage for the low-voltage 300B tubes, it said "Sophia Electric 300B 2.5V mesh plate tube adds more power, dynamics and transparency to your 2A3 amplifiers. High musicality will be your first impression."

At some point I'll have to ask Richard at Sophia Electric to tell me more about these tubes, so consider me intrigued. 

It turns out that the Triode Lab 45 EVO can also utilize 2A3 tubes in its circuit, so I'm looking forward to trying the 45 EVO with a pair of the low-voltage 300B mesh-plate tubes in place of the Sophia Electric 45 mesh-plate tubes, to hear what they sound like as single-ended-triodes (vs. parallel single-ended-triodes), at some point in the future.

Triode Lab 2A3 P-SET RSR monaural amplifiers.

More on that later, as now my focus is on the Triode Lab 2A3 P-SET RSR monaural amplifiers in my vintage Altec A5 Voice of the Theatre loudspeakers based audio-visual system.

Vintage Altec A5 Voice of the Theatre loudspeakers based audio-visual system.

My vintage Altec A5 Voice of the Theatre loudspeakers based audio-visual system resides in a modestly sized spare bedroom in my home. The A5s are situated in room corners, about 7.5 feet apart (center to center), with the seating position being about 8.5 feet from the A5s' drivers. 

That's relatively close to being a near-field sort of setup, and the big A5s were originally intended to fill a medium sized movie theater with great sound, typically using 300B amplifiers from Western Electric.

Vintage Altec loudspeakers can sound fantastic in any sized room, small to large, but you have to optimize their crossovers so that you get proper low-frequency and high-frequency driver integration in the room to realize their full potential.

When the crossovers are optimized the A5s throw an enticingly immersive presentation of the sound-field that places me as the listener/viewer into the soundscape in a way that makes me feel like I'm a part of the films or shows I'm viewing. 

Hiraga-style A5 crossovers with multiple adjustments for optimizing driver integration in any size of room.

The crossovers I use with my A5s are based on Jean Hiraga's A5 circuit, with two methods of adjustment built into them - as suggested by our friend Yazaki-san - to make it possible to optimize driver integration in any size of room, with this system's prime directive being maximum fun for watching video, whether it be from DVD, Blu-ray, or streaming platforms.

The A5s make video watching a lot of immersive fun, and reminds me of the sort of presentation I heard in the small town American movie theaters of the Pacific Northwest of my youth. 

While the Altec Voice of the Theatre loudspeakers look like big beasts from a bygone era, which they are, they are surprisingly articulate and nuanced in the way the present a soundscape. I've had friends say after looking at them, and then hearing them, "I sure didn't expect them to sound like this!"

Those vintage industrial looking Altec A5s can sound magnificent when setup correctly, which is why they are so legendary, and are so popular with collectors and enthusiasts around the world, making them more difficult to come by every day. 

I should mention that the crossovers are optimized to be at their best with my video sources, spanning the cultural treasures of the cinematic eras that I enjoy watching: the pioneer era (1895 to 1910), the silent era (1911 to 1926), the 'talkie' era (1927 to 1940), the 'Golden Era' of film (1941 to 1954), the 'change' era (1955 to 1976), the dawn of the 'modern' era (1977 to late 1990s), and the 'new millennium' era (late 1990s to present). There's more HERE on the History of Film website for those who are interested.

It turns out that those 'film focused' crossover settings also work quite well for playing music on my vintage Thorens TD124 turntable across the four eras of music recording: the acoustic era (1877 to 1925), the electric era (1925 to 1945), the magnetic era (1945 to 1975), and the digital era (1975 to present). 

It's all good!

Triode Lab 2A3 P-SET RSR monaural amplifiers with Altec A5s.

Truly, if you want the authentic and spacious "theater sound" of bygone eras from the A5s, you want to couple them with the single-ended-triode amplifiers the A5s were designed for at the time of their release, way back in 1945. 

The A5s can sound great with any well designed amplification, but there is a certain sort of magic that occurs when powering them with single-ended-triode amplification. 

Sir Arthur Conan Doyle circa 1914. Public domain photo courtesy of Wikipedia.

I've been a fan of Sir Arthur Conan Doyle's fictional detective Sherlock Holmes forever, it seems.

One of my personal treasures is a rather well-used book boxset of The Annotated Sherlock Holmes (1967) that includes Doyle's four novels and fifty-six short stories, edited by William S. Baring-Gould, which includes a massive amount of Holmes related factoids, maps, drawings, and other stuff. 

Another Holmes personal treasure is the complete Granada television series with Jeremy Brett as Sherlock Holmes on DVD. For me Jeremy Brett is the Sherlock Holmes in film, and nobody has captured the classic Holmes of Conan Doyle better than Brett. The film quality isn't all that good, but the acting and overall production is brilliant!

Elementary with Jonny Lee Miller as Sherlock Holmes and Lucy Liu as Dr. Watson.

Jazz guitarist and friend David Gitlen is also a Sherlock Holmes aficionado, and told me about the modern adaptation of Sherlock Holmes in the Elementary television series from 2012 featuring Jonny Lee Miller as Sherlock Holmes and Lucy Liu as Dr. Watson.

Somehow I missed Elementary, so needless to say I bought all 7 seasons of Elementary on DVD to watch, and I have been having a ball.

Set in modern day Manhattan, the series is full of Holmes trivia that makes for delightful watching. Holmes is presented as the detective we all know and love, but in this adaptation Holmes met with failure in London, moved to the US in a depressed state, and descended into heroin addiction and recovery. This somewhat autistic version of Holmes is learning to cope with his addiction, his emotions and social skills, as he solves mysteries with the help of Dr. Watson. It's a creative and fun version of Sherlock Holmes.

Holmes can be seen listening to 78 records on his gramophone is various scenes, which of course resonated well with me, as I do the same from time to time on my old gramophone.

The video quality of Elementary is very good, and the sound quality is not too shabby either.

Triode Lab 2A3 P-SET RSR monaural amplifiers powering Altec A5s.

The Triode Lab 2A3 P-SET RSR monaural amplifiers sound utterly natural, nuanced, and "real" powering the Altec A5s while watching Elementary.  

The amount of resolution of nuance in the soundtracks I found to be quite impressive through the Triode Lab 2A3 P-SET RSRs, with all kinds of foley sounding very realistic and tangibly present. The sense of ambient 'space' (artificial of course) in the soundtracks fills my AV room, envelops me, and makes me feel immersed in the scenes. 

Voices sound so natural and tangibly present its spooky at times, and the accompanying soundtrack music is presented as ... well ... very musical. 

In audiophile-style aural visuospatial terms, the soundscape is presented wall to wall in all dimensions, from side to side, front to back, and top to bottom, filling the room with the film audio experience.  

With the close to the front wall positioning of my Altecs, depth into the soundscape isn't exaggerated in the same way it is in audio systems setup to maximize soundstage depth for recorded music, like my Tannoy Westminster Royal SEs are in my primary music system, for example.

Still, the depth dimension is impressive in the way it's portrayed, with every element of sound - voices, foley effects, music, etc. - are layered back into the depths of the soundscape with each having its own definitive aural imaging. 

Dynamics are superb, and not even once did the Triode Lab 2A3 P-SET RSRs ever run out of dynamic headroom with my Altec A5s, and in fact I never opened them up beyond about half-throttle while watching videos. The Triode Lab 2A3 P-SET RSRs have power to spare with the big Altecs.

Whether I am watching DVDs, Blu-rays, or streaming, the Triode Lab 2A3 P-SET RSRs seems to bring out the best in all of them regardless of their overall sound quality, which is of course, an important factor for me in enjoying watching video. 

Bing Crosby's 'Merry Christmas' album.

One of my all-time favorite entertainers, movie stars, musicians, and lawyers was Bing Crosby, of Spokane, Washington. What an amazing talent.

Here's a funny Bing Crosby factoid for you: Bing Crosby was a pothead, who had picked up on smoking marijuana in the 1920s while hanging out with jazz musicians, like his buddy Louis Armstrong, before marijuana was made illegal.

In fact, some associated Bing's laid back crooner style with smoking weed, and if you check out some of his old films you'll see the squinty eyes, big smile, laid-back style, and fine and mellow voice that came with that.

Bing would later be an advocate for the decriminalization of marijuana when it was made illegal in the Marihuana Tax Act of 1937.

Reportedly, Bing also recommended marijuana to friends and family who were having trouble with alcohol addiction, and the devastation that alcohol addiction was causing in their lives and families.

Bing's home state of Washington would finally heed Bing's advice and legalize marijuana in 2012, thirty-five years after his death. 

As I mentioned, Bing was from Spokane, Washington, and my grandparents had a horse ranch in Mica, Washington, just outside of Spokane at that time.

Bing was of course a well known local character, and my grandfather once witnessed a very intoxicated Bing climb up on top of a dining table in the restaurant of the Davenport Hotel in Spokane, and Bing began to sing and carry on. Apparently, at that moment Bing's singing and entertaining wasn't appreciated quite as much as usual by the other diners, and the bouncer tossed him out. What a guy. I wish time travel was an option, I'd love to go back for that Bing moment! 

The reissue of Bing Crosby's Merry Christmas album is a must hear for me during the holiday season, along with a few other Christmas albums.

My vinyl front end in my audio-visual system, my Thorens TD124 turntable, is fitted with a Schick tonearm & headshell, mounted with the always musical Soundsmith Carmen Mk II high-output moving-iron phonograph cartridge (no SUT needed).

Ten of the songs on Merry Christmas were recorded during the electric era of recording (1925 to 1945), back when my parents and grandparents listened to the 78 versions of the album.

When I was growing up as a kid the re-released album on LP got frequent play during the holidays, so it always brings back fond memories for me of holidays past with family and friends.

The 78 transfers on Merry Christmas aren't quite as stellar as some of the 78 transfers I've been listening to of late, but they're still great fun to listen to, and they have a certain sense of authenticity and musicality associated with their recording era that fully comes through courtesy of the Triode Lab 2A3 P-SET RSR monaural amplifiers exceptional performance. 

When listening to 78 transfers my main goal is a presentation that preserves their musicality and emotional impact, which the Triode Lab 2A3 P-SET RSRs do in spades.

The 'A Jolly Christmas from Frank Sinatra' album.

Another album that got a lot of play during the Holiday Season in my parents home when I was a youngster was Frank Sinatra's A Jolly Christmas from Frank Sinatra, which was a magnetic era recording released in 1957, the year of my birth. 

When listening to albums from the magnetic era like A Jolly Christmas from Frank Sinatra the impressive abilities  of the Triode Lab 2A3 P-SET RSRs are put on full display.

Through the Triode Lab 2A3 P-SET RSRs A Jolly Christmas from Frank Sinatra is beautifully presented, with gorgeous tonality, an abundance of instrumental and vocal nuance, and deep emotional engagement.

Listening to A Jolly Christmas from Frank Sinatra through the Triode Lab 2A3 P-SET RSRs made me think, "This is what recorded music should sound and feel like." Warm, natural, nuanced, beautiful, and very emotionally engaging.

The Triode Lab 2A3 P-SET RSRs brings out the beauty of the music in stellar fashion, have a naturally warm and vibrant presentation, and have an almost haunting quality in the way that they resurrect the 'life' of the music and musicians in my audio-visual system. 

It is still early in the run-in process for the Triode Lab 2A3 P-SET RSRs, but even at this early stage they're sounding superb. The amount of nuance recovered from the music is remarkable, as is the naturalness of its sound quality.

Musical elements like tone, timbre, melody, beat, rhythm, dynamics, etc., are just superb. I'll have more to say about the Triode Lab 2A3 P-SET RSRs audiophile-style visuospatial performance when I move them into my Tannoy Westminster Royal SE loudspeakers based music system.

Sophia Electric 300B 2.5V mesh plate tubes in the Triode Lab 2A3 P-SET RSR monaural amplifier.

Seeing the Triode Lab 2A3 P-SET RSRs glowing mesh plate low-voltage 300B vacuum tubes in a darkened audio-visual room is almost as alluring as the film soundtracks and music albums I've listening to.

If I had deep enough pockets, I can tell you for sure that the Triode Lab 2A3 P-SET RSRs would never leave this system, as they imbue music and film with an aural magic that one only rarely encounters in life.

As I get more time on the Triode Lab 2A3 P-SET RSRs, I'll dig deeper into describing their performance in terms of musicality and audiophile-style visuospatial attributes, but for now I'm just going to sit back over the Holidays and soak in their magic.

As always, thanks for stopping by, and may the tone be with you! 

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