Tube Power Amp Reviews

The Tung Sol KT120 is a relatively new tube. It's also among the most powerful tubes available, with a plate dissipation rating of 60W vs the KT90's 50W; a pair is said to be capable of delivering over 150W in push-pull configuration. I've been using KT120s in my Rogue M-180 monoblocks, and they've quickly become my new favorite output tube, offering much of the midrange magic of the KT88, but without the thickness I often hear from the latter. The KT120 also has the drive, punch, and dynamics of the KT90, minus the grain and leanness that tube often has. Oh, and the KT120's treble reminds me a bit of the shimmery grainlessness of an EL34. As I said, it's my new favorite output tube.

The KT120 draws 100–300mA more filament current than a KT88, so it won't work in every amplifier, but Rogue has found out that the Atlas Magnum's supply is able to handle the higher filament current, and has begun offering the KT120 as an option for new Atlas Magnum owners. Since I had some KT120s on hand, I thought I'd put them in Rogue's budget amp to see if it could then give me what I love about my favorite new output tube.

With the KT120s in the Atlas, voices had greater body and weight than with KT90s. With Chanticleer's excellent Magnificat (CD, Teldec 8573-81829), a disc of music dedicated to the BVM (that's the Blessed Virgin Mary, you heathens), this music and recording were both well served by the Atlas Magnum. Chanticleer has never been known for the richest of tones, but they're the masters of singing with transparency and clarity, and with a care for intonation that brings a certain sweetness to their music. The Atlas Magnum gave needed body to the voices on this album of polyphonic music, while maintaining the clarity of each vocal line. Sibilants via the KT120'd Atlas Magnum were rendered with clarity, and were perfectly in line with the rest of the audioband.

Complicated mixes were nicely resolved by the Atlas Magnum. Cornelius's Point (CD, Matador OLE 332-2) sounds a bit more congested than his aptly titled Sensuous, but the Atlas did a nice job of making sense of this album's blend of electronics, stacked vocal harmonies, and environmental sounds. The treble of Point can be a bit hot, and the Atlas made this overcooked record sound musical without completely covering up the underlying dirty truth of its over-hot mastering. Low bass from the kick-drum samples and low synth notes sounded a bit loose and overfull, but all in all, the Atlas Magnum did a pretty darned good job of controlling the Revel Performa F30s' woofers while providing body and weight to the music's foundation.

The greatest compliment I can pay the Atlas Magnum is that I sort of forgot it was in my system. This amplifier had enough dynamic power, enough timbral accuracy, enough soundstage illusion, enough resolution, and enough musicality to turn off the analytical part of my brain and let me simply listen to music. This is no small feat. I've listened to many components, at two to three times the price, that insisted that I listen to the gear, not my music.

Competition in the Marketplace
So how did the Titan Atlas Magnum stack up against the other amps I've reviewed, every one of them more expensive? The Mystère ia21 integrated amplifier (Stereophile, March 2011) is closest to the Atlas in both sound and price ($2995). The Mystère amp offers solid-sounding instruments but is a bit more opaque, and imparts a tad more of its signature to everything played through it. The ia21 is also less dynamic-sounding than the Atlas, and has far more trouble driving speakers to high volumes with real authority.

The Manley Labs Stingray iTube ($6000, March 2010) has one of the most glorious midranges and most shimmery trebles I've heard. It also has a slightly tipped-up top end and offers little in the areas of dynamics, drive, or bass control. The Rogue Atlas is a far more versatile amplifier that will be able to drive more speakers with greater ease. In many ways, the Atlas Magnum offers the best overall performance of all of the reasonably priced amps I've reviewed, while also being the cheapest. That's called value, ladies and gentlemen.

The most interesting and least fair comparison was between the Titan Atlas Magnum and Rogue Audio's own M-180 monoblocks ($5495/pair, December 2010), as both use the same output tubes and (duh) come from the same designer. I wanted to know how much of the M-180s' performance the Atlas Magnum could capture. Surprisingly, the Atlas's sonic signature was very similar to the M-180s'. Both were open, dynamic, accurate, musical, and immersive. However, the M-180s were simply more open, more dynamic, more accurate, and more musical than the Atlas. In some areas, especially tonally, the Atlas and the M-180s were extremely close in performance. In other areas, such as soundstaging and dynamics, the monoblocks were much, much better. As they should be—the M-180s, already a tremendous value in the world of audio, cost almost three times as much as the Titan Atlas Magnum. The comparison never made the Atlas Magnum look bad—it just made the M-180s look better.

In his review of the original Titan Atlas, which uses EL34 output tubes, Fred Kaplan said he heard "a slight midbass bulge, a deep-bass rolloff, or both," and that the Atlas may have been "rolling off the uppermost overtones." He also noted that the Atlas "wasn't ideally suited for big, loud music." I feel that the Titan Atlas Magnum, with its tube and other upgrades, put many of these criticisms to rest. The new KT120 tubes reduce the EL34s' typical bass bulge, and the Magnum's improved output transformers offered plenty of top-octave air, to my ear. I agree that the Titan Atlas Magnum is still not the best amp for big, loud music, but it's certainly good enough to get the job done most of the time, especially when paired with the right loudspeakers.

We are the 99%
Rogue Audio's Titan Atlas Magnum offers the audio world exactly what we need exactly when we need it. As the audio crowd ages, the Atlas Magnum offers true high-performance amplification that the beginning audiophile can afford. In a world where iPods and downloaded music put convenience over sound quality, the Atlas Magnum is a tube design that will reward the owner who also wants to enjoy audio as a hobby. In an audio industry obsessed with creating the next kilobuck component, the Atlas Magnum is a beautifully built, great-sounding amp that's designed and made in the US, and it costs $1995. Go listen to a Titan Atlas Magnum. It's a product that actually does something for the 99%.