Spectron Musician III Signature Edition mk2 - $2100

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Spectron Musician III Signature Edition mk2 - $2100
« on: 22 Jun 2018, 09:43 pm »
Sweet . . . Powerful . . . Beautiful

I've had very highly thought of amps in excess of $10K and this is my favorite amp to date. I'm only selling because I have 2 and only need 1.


Spectron Musician III Signature Mk2) Serial# 13422
Power Cord
Owners Manual
Factory packing and box

Here are some of the many very positive reviews of this amplifier on the Internet:






Musician III Mk2

Rediscover Your Music

Spectron is one of the very few companies in the world that develops their own proprietary switching amplification modules, digital and analog. Spectron's president and chief designer, John Ulrick, introduced the very first hi-fidelity switching design amplifier into the audio world, while he was the president of Infinity Systems, at CES 1974.

With each generation, Spectron amplifiers receive rave reviews in professional hi-fi journals and more importantly from new Spectron owners, who frequently report, "It's the most musical amp I have ever heard." Moreover, such acclaimed speaker designers as Albert von Schweikert, Anthony Gallo, John Dunlavy and others have used Spectron amplifiers in the development of their speakers. Why is that?


The uniqueness of our design is based on our approach to an amplifier as a control system. Consequently, we emphasize very high speed control loops, resulting in the amplifier’s remarkable ability to eliminate unpleasant distortion while reproducing minute detail that other amplifiers cannot reproduce.

This is achieved in the Musician III by Spectron’s use of very high speed digital logic along with densely packed surface mounted electronics, resulting in ultra short signal paths. Consequently, transit time (the amount of time it takes from when an error is detected at the input until it is corrected at the output) is almost negligible ( < 0.2 uS). Such a control loop thus forces the output to follow the input signal with the highest degree of precision, correcting even the smallest errors. Thus, it’s not surprising that many profesionals characterize the Musician III as: "...The amplifier is the closest I have heard to an old adage, "a piece of wire with gain".

In the typical amplifier, use of negative feedback results in ringing artifacts and increased odd-order harmonics which are so detectable to human hearing that even the smallest amount of these distortions are annoying. Delays in feedback also introduce transient and phase discrepancies, susceptibility to transient overload and vulnerability to disturbances at the output, such as reactive speaker interactions. This is why the conventional use of negative feedback is frequently criticized. However, when used in ultra high speed control loops, which only digital circuitry makes possible, it is indispensable to the most accurate reproduction of sound.

Group Delay: It is crucial for precise imaging that all of the frequency components of the original recording retain their time alignment. These are the position cues to the listener. Group delay is a measurement of time alignment. If a drum strike is being reproduced and the low frequency has one position in time and the high frequency has another, the spatial position of the drum will be confusing to the listener. Spectron's ultra fast control loop, however, retains highly accurate group delay and preserves each instrument's position in the 3D soundstage.

Stability and Speaker Matching: Due to its incredible control loop speed, the Musician III is stable to loads down to 0.1Ω, where it will actually deliver 300 watts – a feat few other amplifiers can match. This means it will drive ribbon, electrostatic, or other complex impedance speakers effortlessly. Because of this stability, along with its sophisticated ultra fast control loop design, the Musician III will yield remarkable sound and a nearly identical sonic signature to any speaker, whether easy or hard to drive.

Bandwidth: Wider bandwidth translates into faster transients, greater detail and better preserved phase information. However, the potential drawback is an increased level of distortion if the output filter is less than perfect. The Musician III avoids this by a mathematically optimized output filter and control loop for maximum phase margin. The Musician III’s bandwidth is an exceptional 100 kHz, resulting in optimum square wave response.

Spectron amplifiers have other unique characteristics which distinguish them from most if not all other power amplifiers. Probably the most important is our understanding of the role of headroom (both voltage and current) in authentic music reproduction.


Spectron's Musician III has a huge amount of headroom. This means that when the music hits loud passages, the Spectron will deliver undistorted power to the speaker. It is common in high quality recordings to see voltages around 100V peak, with medium efficiency speakers. However, most amplifiers use power supply voltages on the order of +/- 85V. The Musician III's peak is 120 volts! This means it can play much louder without clipping with virtually any speaker in use today.

The current headroom is primarily limited by the amplifier’s ability to deliver high currents into low impedance loads. There are many well regarded speakers whose impedance dips down, some even lower than 1 ohm. When a musical note is played at feequencies where the impedance dips, the current demands skyrocket. When this happens with amplifiers that do not have large output current capability, they “current clip”. These transients will be both attenuated and quite distorted. Moreover, most other amplifiers only deliver their rated peak current for sometimes a fraction of the time called for by the music. Spectron amplifiers can deliver peak currents of 65 amps, with a staggering peak power of 3500 watts per channel for over 500 msec (!), which allows the amplifier to deliver the full transient (burst of music) without current or voltage “clipping”. This means that it can not only drive everything from conventional speakers to complex loads such as ribbon speakers or electrostatics, but represent effortlessly the fury of a symphonic crescendo, unlike any other amplifier. As one of the reviewers wrote:

"I am hearing (and enjoying) some of my classical CDs for the first time. Now I get the FULL dynamics and powerful crescendos without the offending harshness and compression/congestion. With my normal system I never enjoy the music at loud volume... The Spectron seems to love it. I am playing louder than I normally do because it sounds so good."

The Musician III’s Main Power Supply is based on a 1300 VA traditional transformer with the highest quality iron core and high purity copper wire which minimize power supply noise, allowing the sound of each individual instrument to be heard with microscopic detail. Taking into account that Spectron amplifiers have approximately 95% efficiency, this power supply is equivalent to the enormous 6200 VA transformers used in class A amplifiers (with 20% efficiency), thus producing the extremely powerful "punch" that few other amplifiers in the world are capable of. Moreover, in these power supplies the energy storage is uniquely implemented with 100 capacitors (330uf ea.). This lowers the power supply impedance (ESR) dramatically i.e. more than 20 times, resulting in much improved midrange and high frequency fidelity as well as improved imaging and three-dimensionality of the soundstage.

Just as important is the Low Level Power Supply. It supplies voltage for the highly sensitive low level circuits in amplifier's input stage as well as the digital logic in the modulator. It must be regulated and isolated from the AC mains, and it must prevent the noise from getting into the music signal. To do this, we use a Spectron designed DC-to-DC converter as well as linear regulators and high frequency (100 kHz) isolation transformer. This gives about 500 times more isolation than deriving the low level power from the conventional line transformer. This isolation virtually eliminates the effect of noise and transients from the AC power line on the ultra sensitive low level circuitry.


Current limits: The Musician III has a full fold back current limit. This means that when the output is shorted or draws more than 65 amps, the current limiter reduces the maximum current to 12 amps. When the short is removed, the amplifier resumes normal operation automatically. Spectron provides modules to professional amplifier manufacturers where the amplifiers must be especially bullet proof. The Musician III meets this requirement.

Speaker protection: To protect your speakers, the Musician III has Spectron's protection circuitry that detects excessive DC or high frequency signals not associated with normal music. If excessive DC or a high frequency signal is detected at the output of either channel (which could damage your speakers), the protection circuit will latch the amplifier off. This protects the speaker from damage. The power is simply latched off and a red LED is illuminated on the rear panel. You need only to unplug amplifier and then plug it in again. If the fault still exists, it will just reset again until the fault is removed. Spectron knows of no other amplifier with this protection.