September 2024

World Premiere Review!
TriangleArt I-20 Single-Ended Integrated Amplifier Review
Taking the single-ended triode to a new realm.
Review By Paul Schumann

   The single-ended triode is the most venerable of amplifier designs. The Western Electric amplifier designs of the 1930s have stood the test of time. Kondo Audio Note, Audio Note (UK), WAVAC Audio, and Wavelength Audio, among others, pushed the envelope of SET design during the triode revival 30 years ago. Today, designers are continuing to revisit this classic configuration. TriangleArt has thrown its hat into the ring with its new I-20 Single-Ended Integrated Amplifier.

TriangleArt is already familiar to Enjoy the Music.com readers because of its phenomenal equipment, which has garnered several Blue Note awards. So I was stunned when the I-20 Single-Ended Integrated Amplifier fell into my lap. The I-20 is TriangleArt's first venture into single-ended amplification. Like many of its components, it takes a different tack on the tried-and-true SE design.

Last year I reviewed the Finale F-6 Hommage integrated, which uses a 6V6 pentode strapped to operate in triode mode to produce 4.5 Watts per channel. The I-20 also uses pentodes in single-ended triode mode, the ubiquitous EL 34. With this configuration, the I-20 produces 20 Watts per channel (Wpc), a big number in the SET world.

The I-20 Single-Ended Integrated Amplifier is a large integrated amplifier. It is the heaviest amp to cross my threshold since I reviewed the Line Magnetic LM 218ai. It weighs in at 70 pounds. While its footprint is 16" by 14", it is 13" tall. I know the official number is 11" tall, but we need to take into account an extra 2" for the feet. I found that out when I placed the I-20 in my smallish stereo cabinet.

The packaging was the most impressive I've ever seen, with the 1-20 arriving in a wooden crate strapped to a small pallet. After unscrewing the crate's top and side, I was treated to a beautiful integrated: flat black with the golden triangle emblem on the faceplate.

The input selector and volume controls featured large black knobs that looked like they would be home on some 1950s test equipment. But a lot is going on under the faceplate. The volume control is an Elna stepped attenuator and the selector is for two balanced and two unbalanced inputs. The I-20 is a dual mono design, with short signal paths, silver wire, and a 2.5mm thick PCB with a four-ounce solid copper plate circuit board for optimal signal flow. The driver section utilizes 12AX7 Tube and 12AU7 per channel.

As mentioned, the output section uses EL34 tubes paired with hand-coiled balanced output transformers. In addition, it is equipped with Mundorf capacitors, AMRG and Vishay resistors, and rhodium-plated PTFE-insulated RCA input connectors. Every inch of the I-20 screams high quality.

So the big question I had was, "How did Triangle Audio get 20 Wpc out of those EL 34 tubes in SET configuration?". So, I called up and asked Tom Vu, the brains behind TriangleArt. Well, it turns out he runs his output tubes hot. I mean really hot. Tom said that he had the voltage across the plates at 650 Volts. I looked at the spec sheets for EL 34 and this is literally off the chart. Tom believes that by running the tubes at this voltage, they are operating optimally. He said he could run them like this without turning the insides into molten lava because he keeps the grid current low. I had some inkling that he was operating the tubes differently when I first turned them on because of the cracking sounds they made for 30 seconds every time they powered up.

Additionally, there was a high-voltage sound the tubes made when I was close to the amp that was reminiscent of the operational sound of a transmitting-tube amplifier. Tom said that this was normal. As I said, this integrated amp is different.

This has been "The Summer of Vinyl" for me. I did a final culling of the records I inherited from my Dad, before getting rid of the rest. One of the ones I kept was Mark Knopfler's soundtrack for the movie Local Hero [Warner Bros. Records – 9 23827-1]. After I cleaned it up and started playing it, I was stunned by the quality of the recording. On the track "Wild Theme", Mark's guitar rang out with stunning clarity. Steve Jordan's drums were remarkably punchy as they underpinned the mellow groove of "Boomtown". The song "The Way It Always Starts" builds to a nice crescendo while never sounding overly busy. The last track on Side A, "The Ceilidh & The Northern Lights", is played by the traditional Celtic band The Acetones and Knopfler on synth for a swirling atmospheric moment. I'm a huge fan of the movie, so discovering the greatness of this soundtrack with the I-20 Integrated was a special moment.

I finally got around to buying Radiohead's The Bends on vinyl [XL Recordings – XLLP780]. I'd listened to it many times on CD, but experiencing it on vinyl with the I-20 was next-level stuff. On "High and Dry", Colin Greenwood's bass had more growl, and Tom's singing along with the guitar solo was easily discernible. On "Fake Plastic Trees", Jonny's acoustic guitar had a three-dimensional feel, and Hammond was haunting. On "(Nice Dream)", Tom showed off vocal chops with impeccable phrasing and range. No matter the track, the I-20 Integrated brought out oodles of detail while never sounding harsh or bright. It also showcased Radiohead as a cohesive band with impeccable timing and brilliant musical instincts.

Two of my favorite artists have recently followed similar career paths. On their previous releases, Maggie Rogers and Lizzie McAlpine put out high production-value albums designed to grab more media attention and possibly Grammy buzz. Both of them followed these albums with extensive tours. Both said later they were disillusioned by the process and wanted to return to a musical happy place. In response, each made an album with a full-time band. The product of Maggie Rogers's efforts is Don't Forget Me [Capitol Records – 00602458199581] The album I bought is a beautiful evergreen color. I guess black vinyl has become passé now.

I found listening to this album a real joy through the I-20 integrated. Maggie refused pitch correction on her vocals on this release. On the stripped-down "All The Same", she is accompanied by piano, guitar, and backing vocals. Listening to it with the I-20 gave me the illusion of her fronting a small ensemble in my living room. The last track, "Don't Forget Me, " sounded like a group of musicians playing together in the same room. In this century, listening to someone making music the old-fashioned way is wonderful.

Turning to some older vinyl, I put on Stravinsky's The Rite of Spring by Pierre Boulez and the Cleveland Orchestra [Columbia Masterworks – MS 7293]. There's been quite a bit of discussion over the years as to which recording of this seminal piece is the best, but this one is up there. My favorite moment of this piece is the introduction of "The Sacrifice". Listening to this movement with the I-20 Integrated, the muted horns were more menacing than usual. Additionally, the woodwinds seemed to have a little extra bite as things ramped up. With the I-20, the entire disc was exciting, vibrant, and dynamic.

I love single-ended triode amps. If paired with the right speakers, they get right to the heart of the music. Despite their simplicity, they come in many flavors. The first SET amp I had in my living room was Don Garber's 2A3 X vacuum tube amplifier. Since then, I've been hooked. Each time I've managed to get my hands on a new SET amp, I've been intrigued by their differences. The TriangleArt I-20 Integrated sounds unlike any other SET amplifier I've listened to. In comparison to direct-heated SET amps, I would say it sounds closest to a 211 amplifier. It has that same top-to-bottom power and crispness. But there is more to it than that.

It has such a low-noise floor, that even at low-volume levels, details of the music come through. The I-20 Integrated will never give you that 300B golden glow. It's more neutral than that. But that doesn't mean the supple strings and burnished brass of the LA Philharmonic playing Holst's The Planets [London Records – CS6734]  didn't come through. Dynamically, the I-20 was a champ. Cymbal crashes or rimshots would always take me by surprise. Even with the most complex music at the highest volume levels, the I-20 never sounded strained or muddy. At all times, the I-20 quietly and confidently delivered the music into my living room.

I wish to congratulate Tom on his accomplishment of creating the I-20 Single-Ended Integrated Amplifier. At 20 Watts per channel, it has the power to drive many different speakers, yet it retains the forthrightness of a low-powered SET.  I know there are many top-notch SET amps one can choose from, but I would certainly recommend the I-20 Integrated as one to audition.

Specifications
Type: Vacuum tube integrated amplifier
Frequency Response: 20Hz to 20kHz
Power Output: 20 Watts @ 5% distortion
      10 Watts @ 2% distortion
Tube Compliment: Two EL34, two 12AX7, and two 12AU7
Gain: 40dB
Sensitivity: 200mV for full power, 30mV for 1W
Rise time: 13uS
Noise And Hum: 25uV RMS input referred
Distortion: THD+N: 0.58% at 1W
IMD: 2.5% at 1W
Operating Voltage: 115V / 230V / 50-60Hz
Dimensions: 16" x 14" x 11" (WxDxH)
Weight: 70 lbs
Price: $12,500

Company Information
Triangle Art
Anaheim, California 92808

Voice: (714) 553-6474
E-mail: info@triangleart.net 
Website: TriangleArt.net