Technical Features

Our amplifiers are the latest designs of Steve Keiser, well known for his ST-140 amplifier produced by B & K Components. There are a number of unique technical features that make Luminance Audio stand far apart from traditional designs, and are responsible for the outstanding audio performance.

Square Wave

The basic premise behind Luminance Audio amplifiers, is that continuous sine wave signals and harmonic distortion analysis do not completely or even adequately define an amplifiers performance under real world music input signal conditions. In order to establish a more useful test criteria, the square wave is used instead of a sine wave. A square wave consists of a fundamental frequency with a large number of added harmonics, in addition to an instantaneous change in amplitude.

Slew Rate

An amplifier's ability to respond quickly to a sudden change in input is called the slew rate. The square wave test evaluates an amplifiers ability to respond to a sudden change in input amplitude, and a specification for slew rate is generated by this test. In order for an amplifier to have a high slew rate, it must pass a large number of harmonics which results in a wide frequency response bandwidth. Thus slew rate and bandwidth are inherently related to each other.

Clean Output

In addition to slew rate and bandwidth, a square wave output should appear free from ringing and other distortion aberrations which can be evaluated by visual inspection. In other words, a square wave test can evaluate every important parameter in both the frequency and time domains that relates to performance in real world use.

Fast Amp Topology

To accomplish this remarkable transient performance, a fast amp circuit topology is used featuring a cascoded Class A common emitter driver stage, operating in complementary symmetry mode. Cascoding provides five times the bandwidth of a conventional common emitter stage and is responsible for the fast slew rate. A secondary benefit of cascoding is a 20db reduction in harmonic distortion over an uncascoded common emitter amplifier. In addition the complimentary symmetry operation cancels even order harmonic distortion for reduced THD and IMD performance.

Transient Response Optimized

An additional insightful engineering accomplishment is the incorporation of a "transient response optimized" design approach which ensures square wave fidelity at every internal point inside the circuit. This means the input and output of each amplifier stage has a square wave response, including the negative side of the input diffential where overall feedback is applied. The result is as an input signal passes through the circuit, transient intermodulation distortion does not develop, which gives our amplifiers a significant advantage over the competition.