This review page is supported in part by the sponsors whose ad banners are displayed below

Like a faraway gun shot, the Iridium 20 made an ugly pop when powered up. And as though someone indeed was shot, everything went deathly quiet then. Until there was signal. Now one would quickly grok why previous commentators who'd perhaps not heard single-ended transistors before fell over themselves in astonishment. In a hifi culture which claims that to enjoy realistic dynamic range one must have kilowatt amps, satisfaction from a fistful of watts seems ludicrous. Why even bother giving it a try? For those who still do, the contrast between the psych setup of very low expectations and the brilliance of delivered actuality could then really sting. And the Tellurium Q is such a stinger. In more ways than one.

To backtrack on expectations, those familiar with single-ended tube amps know about 2nd-order distortion. They will also know how push/pull circuits tend to be dominated by 3rd-order THD (unless a tricky designer massaged a single-ended driver circuit through an interstage phase-splitting transformer to inject some deliberate 2nd-order elements). To talk in further generalities whilst remaining properly mindful of various dosages and degrees, 2nd-order is lush, warm, sweet and slightly thick. 3rd-order is quick, cleanly separated, incisive, cool and lean. In color terms it's golden yellow versus bluish Platinum. For transducer diaphragms it's paper versus metal.


In those terms and despite SEtransistors, the Iridium 20 sounds like a 3rd-order adherent. It's piquant. It has bite. It knows how to cut and separate out with extreme clarity. Even on mellow Jazz piano à la Tord Gustavsen, this propensity for handling transients with brisk incision can telegraph despite the Norwegian's generally gentle touch. The upshot is great articulation and clarity with the edge you'd expect particularly in the nearfield, there close to stage where transients are keenest and not yet softened by the mist of predominant venue reflections. High-efficiency hornspeaker aficionados often cultivate the same attack-mode balance. You could also call it more edge of seat or espresso charged. Such expressions all point at this quality. It's distinct from the mellower lusher reading most think of when confronted by the three letters SET. That's the core differentiator one must get straight about Tellurium Q's amp. Here it doesn't conform to expectations.

Where it does again particularly for those well familiar with other transistor single-endeds is that no-veil directness or tacitness. Those new to the genre but well versed in superior passive preamps—think TVC from Bent Audio or Music First—already have their own prior reference. That's because compared to most active preamps, a premium passive in a copasetic context will act like a pipe cleaner and accelerator. It strips away cobwebs. Clarity goes up. In some cases one might even feel compelled to talk of a certain type of crystallization with a high refractive index. Scintillating. Lucid.

It's because so many valve SETs inject unduly high amounts of 2nd-order distortion that the breed isn't generally known for very high levels of clarity. Yet it only takes a quick listen to a SET of Ancient Audio or David Berning pedigree to realize just how colored perception is when based exclusively on inferior examples. On directness then the Iridium 20 plays directly and completely to top-level SET expectations. But interrelated with our first deviation is absence of sweetness. This British amp doesn't do mellifluous. It also doesn't do that peculiar but readily sensed elasticity one gets from valves. If something about that viscosity is soft, the Tellurium Q isn't. That doesn't make it hard though. It's simply non-soft in that Zen way of positive negation. Like happiness as non-attachment.
 

Relative to its treble, the amp's ability to bite when a recording demands it can translate to a mixture of tintinnabulation and mild piercing. That also depends on your physical drive unit. This isn't the amp to showcase a hot tweeter to best advantage. If you've got an unusually dynamic tweeter like a pleated Heil type or Anthony Gallo CDT³, close-mic'd cymbals will reveal a lot more energy and crashing power than cheap soft domes can deliver. A side effect is quasi single-driver action with their very lively dynamic reflexes in the presence region. The concomitant sense of charge and forward projection can be quite similar.


From this quick rundown of core traits it ought to be crystal that the Tellurium Q doesn't aspire to membership in the tube sector of Club Single-Ended. While Nelson Pass' SIT amps or J2 don't either, they overlap more closely as we'll see next. In terms of sonics rather than circuit concept, the Iridium 20 within the FirstWatt catalogue would be related directly to the F5.