In our Class D amplifier survey in Issue 166, some of my colleagues were unconvinced that the current crop of Class D was ready to take on the Class AB Old Guard in a head-tohead. In a couple of instances I agreed, but I was also fortunate to have been assigned the Spectron Musician III. And when I said that “regardless of ‘class’ the Spectron Musician III punched my time clock like few other amps I’ve ever heard,” I meant it. It was neutral and grain-free, with exceptional dynamics and pitchperfect low-frequency extension. The one issue that lingered for me at the time was a slightly muted top end—an attenuation of the energy, details, and harmonic excitation that launches acoustic music heavenward. It didn’t dampen my overall enthusiasm, but I secretly longed for a bit more treble magic.
Meanwhile, John Ulrick, the founder and designer behind Spectron, and the man credited with designing the first Class D amp back in the 1970s, was busy chipping away at what has become the Signature version. Ulrick redesigned core elements, from the power supply and input stage to the reconstruction filter and RF-filtering circuit. He says the results are increased ultrahigh- frequency bandwidth, improved signal-to-noise ratio, and superior headroom (due to a boost in peak power). The Spectron Signature also received a 50W bump in continuous power and is now rated at 600Wpc into 8 ohms.
As I listened to the Signature, two things seemed to have been enhanced. Soundstage dimensionality and resolution, aspects that I had previously lauded, had improved—especially the amount of detail the Musician III Signature managed to retrieve from the deepest recesses of the stage. Perhaps because of the amp’s slightly quieter backgrounds, orchestral layering was better resolved, as I found out when I revisited Glinka’s Russlan and Ludmilla Overture (Chicago, Reiner [RCA]). Micro-dynamically this was a more colorful amplifier— particularly in the upper octaves. Anne Sophie Mutter’s violin had more depth in its tonal and dynamic shadings. The action of her bow as it moved across the strings revealed volume distinctions, textural details, and transient information that were previously not as well communicated (Tchaikovsky-Korngold, LSO, Previn [DG]). In the low end, the Spectron’s already excellent bass extension also received a retuning. The bass intro to Norah Jones’ “Cold, Cold Heart” (Come Away with Me [Blue Note]) was reproduced with a combination of transient speed and thick, chocolate-like resonance, as if each string-bass note has been sweetened with a greater portion of color and air than before. During Jones’ cover of “The Nearness of You” the piano’s noteto- note articulation was cleaner at both ends of the keyboard, especially during the slow fade of the closing notes, which she holds with the sustain pedal.