ExactBias™
Precision Against Entropy
At CH Precision, innovation begins with asking questions others often overlook. Amplifier designers have long understood the importance of bias current in setting the operating point of output devices, yet most accept the drift that inevitably comes with changing temperature, load, or musical demand. At CH, we took a different path. Rather than treating bias stability as a theoretical goal, we set out to master it under real-world conditions—creating a solution that would keep amplifiers as linear and responsive under dynamic stress as they are at idle. That pursuit led to ExactBias™.
ExactBias is a fully electronic system that monitors the internal temperature of each individual output device in real time, using an integrated sensor located directly on the same silicon substrate. Unlike conventional schemes that rely on delayed readings from the heatsink, ExactBias tracks both the static and dynamic components of thermal drift, continuously recalculating and adjusting the applied bias. The result is an output stage that remains at its intended operating point regardless of musical signal, load, or warm-up state.
Why Bias Matters
In any amplifier, the bias current applied to the output stage defines the conditions under which the output devices operate. Set correctly, it allows them to function in their most linear region, minimizing distortion and ensuring that the amplifier can track the input signal with accuracy. But in practice, this operating point is anything but fixed. As the devices heat under load, their demand for current rises, shifting the bias and pushing them outside their optimal envelope. The result is distortion that increases with temperature and stress, eroding resolution, compressing dynamics, and disrupting the natural proportion of musical events.
Many high-end amplifiers attempt to address this by using regulated bias supplies—circuitry designed to hold current constant. But simple regulation can only do so much. It cannot fully compensate for the complex, real-time interaction of signal, load, and temperature that defines the conditions of live playback. In theory, the bias remains stable; in practice, it drifts. Closing that gap between theory and reality required a new approach—one that led CH Precision to develop ExactBias™, a proprietary solution unique to our amplifiers.
How ExactBias Works
ExactBias™ is a fully electronic, dual-stage control system that maintains optimal output-stage bias under all operating conditions. Where conventional schemes treat bias as a fixed parameter—adjusted only for long-term drift—ExactBias™ recognises it as a dynamic equilibrium shaped by signal, load, and device temperature. By integrating dedicated sensing elements directly onto the same silicon substrate as each output transistor, the system monitors junction temperature in real-time and continuously adjusts the applied bias.
This two-fold process compensates simultaneously for slow ambient changes and the rapid thermal shifts induced by musical dynamics and varying load. As a result, the output stage remains locked within its ideal operating window—stable, linear, and free from crossover distortion—whether the amplifier is idling in silence or delivering sustained current into demanding loudspeakers. ExactBias™ is a proprietary CH Precision innovation: a precise, elegant solution that transforms a long-standing engineering constraint into a distinct musical advantage.
The Musical Result
The benefit of ExactBias™ is heard not in specifications but in music. By holding the output stage at a constant operating point—no matter the signal, load, or temperature—linearity is preserved even under the most demanding conditions. The amplifier tracks the input signal without strain, allowing micro- and macro-dynamics to emerge in natural proportion. Quiet passages gain texture and presence, while powerful climaxes arrive with conviction but without hardness or compression.
Just as important, ExactBias maintains tonal balance and harmonic integrity. Instruments retain their natural color and weight, and the transitions between notes flow without exaggeration or blur. The result is reproduction that feels effortless, fluid, and lifelike—an amplifier that responds to the music rather than reacting to its own limitations. For CH Precision, the true measure of technology lies not in recycling yesterday’s topologies, but in invention that serves the veracity of music reproduction.
Unwavering by Design
ExactBias™ is more than a circuit; it is an expression of CH Precision’s culture of innovation. Where much of the audio industry refines designs inherited from decades past, we look instead to the real challenges that undermine musical fidelity and create original solutions to overcome them. ExactBias ensures that our amplifiers remain stable, linear, and responsive under all conditions—protecting the time, proportion, and flow that make reproduced music believable. It stands as one example of our guiding principle: to engineer not for tradition, but for music itself.