Pass Aleph 1.2 monoblock power amplifier Page 2

So they're hot, they're happening, and they're pretty damn awesome. But exactly what qualities make the Aleph 1.2 so sonically stupendous? My listening notes include copious references to the 1.2's lack of any sort of electronic signature. This is a midrange to die for—clean without a trace of an electronic signature. In addition to its nonelectronic nature, the 1.2 also has unflappable suavity. Nothing ruffles its calm. Even the most dynamic material in my arsenal, like the JGH/SS private recording of the 1812 Overture, complete with howitzers, didn't rock the 1.2's world. This sense of ease is something the 1.2 shares with other big power amplifiers; but unlike most big solid-state power amps, the 1.2's lack of electronic artifacts is special.

Up against the Pass Aleph 0
My first compare-and-contrast exercise pitted the Aleph 1.2 against the smaller, $8000/pair Aleph 0. While the amps shared certain family traits, they did not sound identical. The 1.2 had a certain ease, regardless of the music's demands, that eluded the 0. Paradoxically, the Aleph 0s did have a slightly more specific soundstage focus, but that precision broke down when they were dynamically stressed. Also, the Aleph 0 seemed to be faster-sounding on dynamic transients. The horns on Paquito D'Rivera's Grammy-winning Portraits of Cuba (Chesky JD145), hit faster, but got a wee bit woolly during their crescendos.

The Aleph 1.2s did project a slightly larger soundstage with a bit better depth rendition. On LeeAnn Rimes's Blue, the wall of sound behind her was farther back through the 1.2s. With sensitive speakers (more sensitive than the 91dB/W Dunlavys), the Aleph 0s could probably maintain their superior dynamic immediacy and focus. In my main system, the 1.2's overall dynamic ease added substantially to the listening experience, tipping the scales in its favor.

Boulder comparisons
I also spent several days comparing the Aleph 1.2 to my reference amplifier—the $9900/pair Boulder 500AE monoblock. Both models share the ability to produce copious amounts of volume without stress, but each excels in dramatically different sonic parameters. My JGH/SS DATs of the Young Philharmonic Orchestra of Munich performing in Boulder's Chatauqua Auditorium had superior three-dimensionality through the Alephs. Car-engine noise outside the hall sounded much farther away (the Chatauqua is a shed rather than an enclosed auditorium, so noise from "outside" is far more noticeable than on a commercial release). However, through the Boulder 500AEs these low-level low-frequency noises had more detail and more specificity.

While the orchestra sounded harmonically more natural with the Pass amps, with the Boulders I was able to pick out individual parts more rapidly. Also, the Boulders more readily revealed problems in intonation and ensemble. The Pass amps were seductive; instead of being bothered by these little mistakes, I found myself wrapped up in the fabric of the music. If I listened carefully I could hear the same mistakes that were so obvious through the Boulders, but it's far easier to overlook the blemishes on a few trees when a redwood forest looks so magnificent.

While both amps produced images of similar size, the Alephs did a superior job of fleshing out the three-dimensional quality of musical instruments. Instead of the pinpoint lateral specificity of the 500AEs, the Pass amps produced a slightly more diffuse but multidimensional instrument location. On a recent JGH/SS recording of Engelbert Humperdinck's Hänsel und Gretel, singers move around the stage as they sing. The Pass captured the way their voices bounce off the floor and sidewalls with a bit more spatial accuracy than the Boulders. As the singers move, they often turn their heads away from the single stereo M/S pair of microphones flown over the front of the stage. The Pass amps' spatial acuity made it possible to tell which way the singers' heads were turned. Through the Boulders it was harder to make such a determination.

On dense pop mixes like "Orphan Girl," from Gillian Welch's Revival CD, produced by T-Bone Burnett (Almo Sounds AMSD-80006), the Boulder amps did a superior job of differentiating each instrument's specific part; the Alephs delineated the various dimensional layers of the mix with better specificity. "Orphan Girl" is a paradoxical recording: At first it seems to be a simple two-voices-and-two-guitars acoustic recording. Actually, it's a dense arrangement with six-string bass, electric guitars, and multiple Optigan tracks. The Aleph had the ability to locate each instrument with greater three-dimensional precision, while the Boulder individualized each instrument's particular lines with greater acuity.

This is akin to the difference between tube and solid-state electronics: Tubes often do better at re-creating three-dimensional space, while solid-state amps excel at rendering inner details. The Pass 1.2 was a very "tubey" amp in the way it handled dimensionality—it got the spaces right. While it was easier to pull a mix apart through the Boulder amp, through the Pass I could sit back and luxuriate in its dimensional complexity.

There were noticeable differences between these two amps at the frequency extremes. The Pass Aleph had a slightly softer, sweeter top end than the Boulder amp. On some recordings the 500AE seemed to have more top-end air, while on other recordings the 1.2 had greater delicacy. On my own recordings I preferred the Boulder's more extended high-frequency rendition, but on most pop and commercial recordings the Pass's slightly mellifluous, more reticent top end was very welcome. Again, the differences between archetypal solid-state and tube-amp sounds come to mind. If you're a "tube person," you'll feel right at home with the Pass 1.2's top-end rendition.

Bass through the Pass had exemplary pitch definition and "tunefulness," but lacked the dynamic drive of the Boulder amp. On Rickie Lee Jones's "Beat Angels" (Traffic from Paradise, Geffen GEFD-24602), John Leftwich's acoustic bass lines were more melodious with the Pass, but the Boulder amps transmitted more energy and dynamic life. If forced to choose which rendition was more accurate, I'd say "Both." Ideally, bass rendition should be melodious and dynamic, but these two amps demonstrate that perfection is still a goal, not a reality.

The Pass Aleph 1.2 is more dynamically relaxed than the Boulder. The horn attacks on Portraits of Cuba were just that—aggressive, with more dynamic energy through the 500AE amps. Through the Alephs, everything was just a bit softer, with less edge and dynamic punch. Dynamic peaks also seemed louder through the Boulders, with superior punch. While the Aleph lacked a bit of dynamic contrast, there was a natural-sounding harmonic envelope to the horn sound, especially the decay. Once more, the absence of any sort of electronic edge to the Pass sound created a convincing illusion of "realness" that was hard to ignore and easy to love. Which is right? Once more, the elusive ideal is the Boulder's dynamic energy coupled with the Pass's timbral finesse.

On John Gorka's "Can't Make Up My Mind" (Between Five and Seven, High Street 10351-2), producer-guitarist John Jennings's Martin Backpacker guitar solos had a more precise transient attack through the Boulders. The Pass amps transmitted a softer, more "wooden" body tone. Once again, this begged the question: "Which is right?" Like Gorka, I can't make up my mind which is "better"—I value the strengths of each amp. Might as well compare apples and oranges. If I just wanted to enjoy the music, the Pass's natural timbre was wickedly seductive. If I needed to analyze a recording, the Boulder's superb resolution made it the perfect tool for the job. The 500AE is the ultimate pro-audio workhorse amp, while the Pass is a preeminent recreational amplifier.

It's unfortunate that I no longer have a pair of the Manley Reference 240 monos that I reviewed in May '96 (Vol.19 No.5, p.163) in my possession—comparisons to the Pass Aleph 1.2s could have filled up at least another page. Both amps excel at portraying the emotion and magic in music. The Virgo in me wonders just how close the Pass can come to the Manley's superb three-dimensionality. I also wonder if the Manley could possibly match the Pass's suavity and ease.

Pass or Fail?
So, did the Pass Aleph 1.2 live up to my exalted expectations? Perhaps that's more my problem than yours—expectations get in the way of accurate assessments. The Aleph 1.2 is certainly the most musically seductive high-power amplifier I've ever experienced. It's capable of turning any attempt at serious left-brain listening into a glorious right-brain bacchanalia. For those audiophiles convinced that only tubes can permit excursions into musical ecstasy, the Pass 1.2 may have them boogieing in their kilts. If I listened to music soley for pleasure, I'd buy a pair of 1.2s in a heartbeat. Like superior tube amplifiers, the Aleph 1.2's colorations are subtractive and superbly musical.

Like the Pass Aleph 0, which Dick Olsher called "the solid-state amplifier of the decade" (Stereophile, March '95, p.88), the Aleph 1.2 makes it possible for audiophiles to have the best of all worlds: musicality, dimensionality, brawn, and low maintenance, all in one two rather weighty black boxes. If you purchase any high-power tube amp without auditioning an Aleph 1.2, you've failed to fully investigate your options. The Pass Aleph 1.2 is a class-A solid-state amp that reduces the gap between silicon and glass from a yawning chasm to a thin, glowing blue line.

Pass Labs
P.O. Box 219, 24449 Foresthill Road
Foresthill, CA 95631
(916) 367-3690

kiosa's picture

He managed to explain pretty well the setup and the whole system of a Pass Aleph 1.2 monoblock power amplifier, but his analog source was a VPI TNT III. If he had chose a RF combiner for example, because it manages to combine RF from a number of different sources, he might have been much more to the point. Anyway, interesting presentation, he totally worked for it.