Associated Equipment:
Digital Front End
AC Conditioners
Spectron Audio Musician III Signature Edition
Power and Finesse


January 2008


The Legacy Continues/The Evolution of an Amplifier:

Many feel Class-D amplifiers will some day become the dominant amplifier species. Few, including myself, realize their ancient and humble beginnings. If modern life forms can trace their ancestry back to a Paleozoic swamp, so too can modern Class-D amplifiers trace their ancestry to a swamp. The “SWAMP” (SWitching + AMP) was the first commercial Class-D amplifier produced. It was introduced at the Chicago CES in 1974. It wasn’t very pretty (things from the swamp seldom are) but it was the first. The Swamp was co-designed Dr. Jim Henderson and John Ulrick while John was president of Infinity Systems. Now John is the president and chief designer of Spectron Audio where the evolution of the digital amplifier continues. The latest descendent in the Spectron line is the Spectron Musician III Signature Edition (hereafter referred to as “Spectron”).

What makes Spectron DNA different from other digital pulse width modulation switching amplifiers? First, its Class-D modules are unique. They are Spectron’s own design. The Spectron amplifier uses digital logic that corrects for output errors ten times faster than conventional linear circuits. The fast feedback loop preserves accurate time alignment. The Spectron includes the modulator, power section and output filter all in the feedback loop to correct for errors caused by the varying speaker load. This allegedly results in an amplifier that sounds the same with different speakers. The Spectron is stable down to 0.1 ohms and virtually dares you pair it with difficult or complex impedance speakers including ribbon (my Apogees) and electrostatic.

The bandwidth extends to 100kHz resulting in faster transients, greater detail, and a larger soundstage with a more holographic presentation. Greater bandwidth does not come without potential problems such as distortion. Again, the output filter and fast feedback loop are important in minimizing distortion and preserving accurate time alignment.

More Power:
In contrast to many lightweight Class-D offerings, the Spectron feels (52 pounds) and looks more like a conventional solid state amplifier with a robust power supply. The Spectron uses a 1.3kVA transformer and one hundred 330uf capacitors to provide massive headroom. It is capable of delivering 120 volts peak and 55 amps peak current for a longer time than most amps. This provides powerful yet musical symphonic crescendos. Want to get Tim "The Toolman" Taylor scary crazy? The Spectron can be operated as a fully balanced monoblock with triple the power and double the headroom.

Listening to the Spectron made me do some serious consideration of how many audio systems are under-powered with the usual fare of 150-250 watts per channel. Despite the power, the amplifier runs very cool and draws only 40 watts at idle.

Behind the scenes:
The rear of the Spectron has both balanced and single-ended inputs. The XLR inputs are true balanced like pro-equipment. The RCA inputs are floating to eliminate ground loops that are common in standard non-floating RCA inputs. There are two sets of speaker connections, both Cardas patented single knob adjustment binding posts and Neutrik Speakon connectors. The Cardas binding posts are a change from the model reviewed and pictured.

The rear panel has several unique features. There is a phase inversion switch for each channel to correct for phase reversals in the original recording. Completing the rear panel is a warning light and a reset button. If protection circuitry detects excessive DC or high levels of unusual (not normal music) frequency signals, the amplifier shuts off.


Remote Sense Speaker Cable:
The Spectron is also unique in offering an optional “Remote Sense” speaker cable that connects to the amplifier via Neutrik Speakon connectors. The cable has four conductors but only two are for the audio signal. The remaining two conductors sense the actual voltage at the speaker end of the cable thereby including the speakers and cabling in the feedback loop of the amplifier.

Including the speaker cable in the feedback loop allows the errors caused by the speaker cable to be reduced thereby increasing bandwidth and reducing distortion and noise. With the Remote Sense in service, the Spectron controls the voltage at the speaker (where it is most important), not at the amplifier output. All this is a fancy way of saying Spectron designed a feedback loop to take care of what cable builders try to accomplish with exotic, patent pending designs and expensive materials.

Comparing the Remote Sense to Shunyata Phoenix (the only cable I had available during the review) made me question the theory, at least in this example. The Shunyata edged out the Remote Sense for inner detail, presence, and bass definition. Overall I preferred the Shunyata and used it for this review. It should be noted that the Shunyata is several times the cost of the Remote Sense and fragile (braided) by comparison. Considering the price of the Remote Sense cable, I consider it a fair value (a bargain in longer runs) and I really liked the solid feel of connecting the Neutrik Speakon connectors and Eichmann bayonet plugs.

Sound Check:
For the listening portion of this review I used a Nova Physics Group Memory Player with a LessLoss Filtering Power Cable and Cerious Technologies Liquid Ceramic digital cable. The preamplifier was a highly modified TacT 2.2X with a Shunyata Research Python Helix Alpha power cord and the new Harmonic Technology Magic Link Two. A LessLoss Filtering Power Cable was also used on the Spectron. All electronic equipment was connected to a Shunyata Research Hydra-8.

At first blush, Pirate Music by The Stimulators  [United Sounds CPS 5021] might seem like an unusual choice for evaluation purposes since it is impossible to sit quietly while the disc is spinning its infectious energy. “Tumbao Bonito” and “Rock the Boogaloo” are especially music to jump around by. But I have experienced this well recorded CD differently with different amplifiers. Some amplifiers never quite wake up to the full dynamic potential and have a somewhat less than enthusiastic presentation. Others spit it out like a bad grape. The seven-man group presents an up-tempo and eclectic mix of vocals and instruments that is well layered and timed. The Spectron captured the music dynamics and group complexities in such a way that I wanted to keep playing the disc over and over. So I did.

On the track “Rosewood” from Yo-Yo Ma Plays the Music of John Williams [Sony B00005YVQ8], the percussive strikes were crisp and explosive while the bowing was so detailed and clear I could visualize the lone performer caressing the strings and drawing me in. I had never heard Moussorgsky: Night on Bald Mountain/Pictures at an Exhibition [Telarc B000003CSH] before. Oh, I have owned the CD for years but I never really heard it before. The Spectron presented the softer passages with such inner detail they became seductive but the real surprise came in the crescendos. The peaks reached were a revelation. It wasn’t that the Spectron could play loud, it was that I wanted the music louder. For the first time the crescendos were reproduced with full fury but no smearing or harsh edge that demanded the volume be reduced. Now, after many years, I finally get this fine recording.

I have tried to avoid using this overworked descriptor but there really is no way to avoid it and do justice to the Spectron - musical. There, I said it and now I feel better. The Spectron is one of the most musical and engaging solid-state amplifiers I have heard at any price.

Some would describe the Spectron as “tube-like”. Tube fans would cry—No! The operative word here is like. While the Spectron does not have the full bloom (or exaggeration) of tube amplifiers, neither does it have the dry and clinical presentation of many solid-state amplifiers. What it does have is a well-balanced and even presentation with engaging warmth. I think of it as a neutral presentation with a smile. The top end is extended but not edgy or harsh. The middle range is full-bodied, detailed, and intimate. At the lower end there is power and control for remarkably solid, well-defined bass slam as well as the finesse to define an upright bass with all its subtleties and nuances. I found the soundstage to be spacious and deep but clearly defined and reflective of the respective recordings.

The Spectron virtually carves audio scrimshaw at all octaves while providing the power to drive difficult speaker loads with exceptional dynamic range. But dynamics without control is just noise. For all the dynamics displayed by the Spectron, it never ran wild or became harsh. It exhibited absolute control over my speakers where other amplifiers failed. I never experienced listener fatigue (if you don’t count the sleep lost by listening to more music instead of going to bed).

Conclusion: While toying with esoteric audio extremes can be a fun fantasy, eventually reality smacks one in the face. Many companies indulge their own egos by designing offerings that require a forklift to move, an auditorium to house, industrial-sized cooling, and a Swiss bank account. Spectron mocks that silliness with a truly amazing package that provides well above average power in an affordable, cool-running, user-friendly amplifier while simultaneously maintaining the highest build quality and establishing a new standard in audio performance. Evolution truly is a wonderful thing. Maybe Class-D will inherit the earth but with Spectron leading the way, there won’t be anything meek about it.


Spectron Musician III Signature Edition:
Power: (Watts per channel, both channels driven)
600 Watts at 8 Ohms
800 Watts at 4 Ohms
1400 Watts at 2 Ohms
Inputs: RCA and XLR
Speaker outputs: Cardas Patented Single Knob Adjustment and Neutrik Speakons
Input impedance: RCA and XLR 50,00 ohms
Output impedance: 0.018 ohms @1kHz, 0.095ohms @20kHz
Damping ration: 500:1
Gain: 26dB
Efficiency: >92% (Amp module)
THD: <.03% from 1W to 600W @ 8Ω ( in the listening range)
<.06% from 1W to 600W @ 8Ω ( > 22 kHz)
SNR: 115 dB
Line Voltage: 100, 120, or 240 VAC 50/60Hz (switch selectable)
Dimensions: 17”W x 5.25”H x 14”D
Weight: 52 Pounds (shipping 64 pounds)
Warranty: Three years
Price: $6495

Remote Sense Speaker Cable:
Neutrik Speakon connector at amplifier and spades or copper Eichmann Bayonet Plugs at the speaker.
Price: $595/pair up to 5 meters (longer lengths are available)

Spectron Audio
24101 Del Monte Drive, Suite 421
Valencia, CA 91355
Telephone: (818) 435-2090