KST-150 Power Amplifier


The essential premise for KST-150 was to create a power amplifier that would amplify the incoming signal while preserving the greatest possible integrity of the signal structure. Music contains a highly complex myriad of constantly changing amplitude, phase, and harmonic information. Designing an amplifier to reproduce this information accurately resulted in three distinctive design elements :

An amplifiers speed, its ability to track the rise and fall of the input signal, is essential to the accurate re-production of music. This speed is known as the slew rate, and the majority of audio amplifiers on the market have a slew rate of around 40 volts per microsecond. The KST-150 has a slew rate of 250 volts per microsecond. This results in a very fast amplifier that can recreate more of the musical event.
Most audio amplifiers have limited bandwith and truncate the signal to only reproduce music within the audible range. But music within the audible range is also supported by harmonics far outside of the audible range. The KST-150 has a very wide bandwidth from DC to 630,000 kHz and can more accurately recreate the harmonic spectrum, giving more realistic tone and musical realism to your favorite recordings.
An amplifier is made up of a series of internal amplification stages. Standard audio amplifiers are designed using measurements at the final output stage. But what about the proceeding internal stages? The KST-150 was designed to have a perfect square wave response at each internal stage of the circuit. This is unique and an industry first. The result is a stunning increase in every aspect of subjective audible performance.


The KST-150 is DC coupled at the input and has no blocking capacitor. This ensures perfect square wave response at low frequencies. The KST-150 is optimized for fast rise time and zero low frequency square wave tilt or sag, even at 20hz. This greatly enhances bass definition and articulation.

The power supply of the KST-150 is equipped with a 700VA IU core transformer which provides superior regulation over a toroidal type. This superior regulation contributes to a dynamic headroom rating of 3db, which means the KST-150 is capable of supplying 300 watts per channel for short 100 millisecond bursts. Sonically this dynamic headroom translates to a higher audible power output that seems greater than the continuous power rating.

The KST-150 sounds more powerful than its rating and is unconditionally stable into reactive loads without a deterioration in performance. This feature gives it the ability to drive electrostatic loudspeakers with stability and ease. A high damping factor is maintained at all audible frequencies. This means that high frequency control of the tweeter diaphragm is equal to low frequency control of the woofer cone.

The transformers secondary output is incorporated with a two stage RF snubber circuit, which prevents spurious signals being introduced via the AC line. The bridge rectifier is a fast recovery type which maximizes the charging time to the large 54,000 uF capacitor bank.

Each amplifier channel incorporates a regulator circuit which provides isolation of the front end circuitry which reduces modulation distortion. A passive output filter eliminates unwanted RF signal injection into the active circuit. Manufacturing has been done with high parts quality throughout the entire circuit such as metal film resistors, polypropelene and polystyrene capacitors.

The KST-150 has a 85% efficiency, which makes it green and energy efficient similar to most digital amplifiers. It runs cool to the touch and is perfect for those concerned about heat and ventilation issues.



Price $3,000 USD


"It deserves to be listed in Class A of Recommended Components."

"If the KST-150 sold for $18k instead of $3k, hosannas of praise would be raining down from all sides."

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The KST-150 has been awarded the stereo power amplifier of the year award by audio review website Stereomojo.

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KST-150 User Manual PDF