"...I confirmed the KST-150's character: open, airy, transparent, harmonically right... and fast. 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..." - Sam Tellig, Stereophile May, 2007

"I wanted to let you know how much I have been enjoying using the Luminance KST-150 amplifier. I have had several friends of mine come by who have heard it and were very impressed with it as well. This amplifier is . . . the only game in town, in my opinion, at the $3000 price point." - Michael Wright, Stereotimes.com

Reviews
- Dagogo, August 2006

- Stereo Times, April 2006

Rich harmonics, air, presence and absolutely non-fatiguing detail. This is the amp for those not persuaded by the lure of switching digital amps. This amp has the warmth, life and body that many of those amps do not have. Bottom line: The KST-150 has the speed of digital with the organic richness of analog.

About Luminance
Luminance Audio was founded by Rick Schultz of Virtual Dynamics, Circuit designer Steve Keiser, known for the legendary B&K ST-140, and Mike Tseng, music lover and proud father of concert pianist Cindy Tseng.

The KST-150
The Luminance Audio KST-150 is a balanced, cascade-based, 3-stage design with a common mode rejection ratio of 90db+, and a declared objective of being among the top three fastest amplifiers with wide bandwidth and low distortion.

Circuit designer Steve Keiser incorporated an ultra high-current-gain complimentary push-pull cascaded amplification stage to drive a quadruplet of high-gain power MOSFETS per channel to attain a substantial damping factor of 100.  As this damping factor is sustained fully by the driver and output stages from 20Hz to 20kHz, the KST- 100 is able to control a loudspeaker’s woofer movements and tweeter movements with equal vigor.

Overall negative feedback loop bandwidth is constant from DC to 63kHz and open loop bandwidth and closed loop bandwidth frequency domain time constants are matched using 1% tolerance polystyrene capacitors.  All resistors on the amplifier circuit board are of 1% tolerance.  The input stage uses a differential amplifier which inputs the signal from the source as well as from the output and performs the necessary voltage gain, which is 26dB.  The driver stage is a fully complimentary push pull cascaded common emitter amplifier, which in turn drives a complimentary, two parallel push-pull source follower Hitachi MOSFET output stage.  The power supply utilizes a total of 56000 mfd of storage capacity and is parallel distributed, meaning that total of six 8200 mfd capacitors are used connected in parallel, instead of the usual two.  The input AC is terminated with 3-pole AC line filter to remove power supply line noise.

The Design Process
Music contains highly complex myriad of constantly changing amplitude, phase, and harmonic information. Designing an amplifier to reproduce accurate sine waves into a resistor makes the design process easy for the designer. Designing an amplifier by ear is farm more relevant, but evolutionary in nateur as the design can always "sound better".

Combining an engineering approach with detailed perceptual listening can produce an amplifier which is essentially obsolescence proof, as is the case with the KST-150.

How the KST-150 works
The main distinguishing characteristic which puts this amplifier so far ahead of the competition is speed. The faster the amplifier, the better is can keep up with the details in the input signal. Linearity is defined as the ability to retain input waveform accuracy. Luminance Audio employed cascadin and complimentary symmetry in our circuit designed to preserve linearity.

Lightning fast, and measurable too
At 250 Volts per microsecond, the Luminance KST-150 sets a revolutionary industry first when compared to even the fastest of similar solid state designs. Flagship amplifiers offered today of similar design boast slew rates of 100 V/ms, regardless of the fact that many are as much as 27 times the price. The industry standard for this design is 40 V/ms.

Why is this so important? Consider a single string resonating on a guitar: The amplifier needs to control the speaker so that the movements of that single string can be replicated, yet amplified. The advantage of a high slew rate is a cleare reperesentation of complex musical passages, which would include the tonality of the wood behind the acoustic guitar.

The KST-150 achieves high speed, high transient attacks with a not so conventional analog circuit and is revolutionary as it performs as well as even the fastest digital amplifiers in speed. Speed however is not all that this amplifier gets right, in fact it is just the start.

The Analog Advantage
Speed is not the only requirement necessary to outperform other amplifier designs. S