Analog Switching Amplifier^TMTechnology

NuForce™ Analog Switching Amplifier technology is built on the principle that a power oscillator can be modulated by an audio signal so that it produces an amplified audio signal via a reconstruction filter without the bandwidth limitation of a conventional, fixed-frequency, carrier-based PWM control. Our design employs a high-performance analog modulation technique and closed-loop control system, which is why we refer to our product as an Analog Switching Amplifier.

NuForce developed its revolutionary amplifier technology from the ground up to reassess and redefine faithful music reproduction.  The first impressions of listening to NuForce amplifiers are those of pristine clarity, natural tonality, expansive imagery, and realistic proportions of the musicians and their instruments.  Bass notes are well defined and articulate, with addictive rhythm and drive.

NuForce believes that uncompromised and uncompromising music reproduction requires the following:

High Bandwidth

Our Analog Switching Amplifier produces a flat response from 20 to 120,000 Hz with very low variations and extend toward 150Khz at -3db. Only a handful of very expensive linear amplifiers can boast that kind of bandwidth. Indeed, many linear and digital switching designs fall short of a 20-25,000Hz bandwidth.

Low Distortion

The majority of today's amplifiers claim less than 0.1% Total Harmonic Distortion (THD). It’s important to note, however, that the seemingly low figure is normally achieved when measured at 1W using a 1000Hz sine wave. At full power, these distortion figures can be as much as 100 times greater, and as frequencies rise, distortion increases further still. NuForce's patented and patent-pending technologies cancel distortion at every aspect of operation. Our Analog Switching Amplifier boasts vanishingly low distortion characteristics at high output power level or audio frequency.

Unique close-loop design

Rather than a sawtooth waveform to achieve modulation, our Analog Switching Amplifier employs a proprietary, naturally occurring modulating signal that does not add noise to the system, nor does it suffer from the 180-degree phase shift an output filter characteristically produces. Our high-bandwidth and closed-loop system provide a high gain with frequency of up to 1MHz, thus greatly diminishing non-linearities. We achieve an operating power bandwidth as high as 150kHz, while maintaining consistently low distortion across the frequency spectrum.

Near Zero Phase Shift

Phase shift produces inaccuracies, particularly with respect to spatial information. Most amps produce phase shifts of greater than 45 degrees at 20kHz, approaching 90 degrees as frequency rises. Nuforce amps exhibit close to zero phase shift at all frequencies.

Damping Factor

To compute an amplifier’s damping factor, a reference input signal is applied to output voltages without load (Vno-load) and with an 8-ohm speaker load (Vload).
Damping Factor = Vno-load / (Vno-load – Vload).
The industry standard has its problems. We see a critical need for our closed-loop response to include the speaker load for the PWM switching oscillation to have relevance. Output without load tells us nothing. We measure output with an internal 100-ohm Zobel network. Using the industry’s measurement method, we get a Vload almost identical to or slightly higher than a Vno-load at the filtered MOSFET output, i.e., an infinite damping factor.

Since Nuforce requires a closed-loop response to oscillate for the PWM controller to function, and the closed-loop transfer function changes with loads, NuForce technology renders conventional damping-factor measurements irrelevant.