NEW!! The Nuforce Amplifier Tweeks Page

Experience a paradigm shift in amplifier design that rivals and surpasses most linear and tube amplifiers

"...The sound they evoked from an old pair of Sound Dynamics loudspeakers was downright voluptuous...." - Soundstage

-"...Transients, Soundstaging, Rhythm and Pace, Dynamics, Macro and Micro detail, and most of all Musicality are all Hallmarks of this Amp. In Short this is the Halcro with Soul...." - full review

"...nothing I have done to my system has improved the overall presentation of each disc as much as using the NuForce Reference 8 amps. Bad recordings sound good, good recordings sound great, and great recordings are almost unbelievable." - full review

All this from such a small package?
Don't be fooled by the "heaviness factor" of amps any longer. Most of the weight (and many of the problems) with conventional amplifiers are the power supplies. In a typical "heavyweight" amplifier, you will find a large transformer. That basically is what supplies the current, that gives your amp its musical muscle. The problem is, next to the Nu Force switching power supply, the transformer based power supply is slooooow. Not just on the rise time, but on the decay as well. Once that dynamic peak is over, that big transformer cannot recover fast enough, and ends up hurting the audio signal. Skeptical? Try a Nu Force amp in your own system and see if it doesn't supply better transient speed, and (at least) equal force than your heavyweight, megabuck amp.

NOT a Digital Amp
NuForce developed its revolutionary amplifier technology from the ground up to tackle absolute and faithful music reproduction. Unlike Conventional Class D Amplifiers, they do not rely on a sawtooth waveform for modulation, instead they use a high performance analog modulation technique that produces an amplified audio signal without the bandwidth limitation of a fixed-frequency carrier-based PWM control. Likewise, NuForce amplifiers offer unparalleled high bandwidth (5 -100kHz), with virtually no phase-shift in the audible frequency range. Therefore all audio frequencies and their pitch-defining harmonics are faithfully reproduced. Additionally, the output stage is fully regulated providing an extremely high damping factor (exceeding 4000) which ensures tight, articulate bass reproduction.

No other solid state amplifier could compare with NuForce Analog Swtching Amplifiers™. While the best of vacuum tube amplifiers may share the pristine midrange reproduction similar to NuForce amplifiers, they inevitably have attenuated high frequencies, phase shift errors, and do not have the bass control or resolution.

The Reference 8.5 puts out 140W into 8 ohms while retaining its 0.05% THD+noise rating from 10Hz to100kHz, from first watt to last. Most other amplifiers will only provide distortion specs over a limited operating frequency range, and at limited output. They don't tell you that at their full rated output, the distortion could be 10 to 100 times worse. Not so with Nuforce amps. You get the benefit of low 0.05% distortion at all frequency ranges from the first watt to the last.

Specs

*Continuous RMS power is the maximum continuous power of the power supply and it is constant

• Power bandwidth: 100 to 20 kHz +/- 0.8 db 10 Hz -0.5 db 60 kHz -3 db
  
• THD+N = 0.03%, 1kHz, 10W
• Input impedance: 45K ohm
• Gain: 27 db
• SNR = 100 db at 100W
• Eichmann Cable Pod binding post for spade and banana plug (the plastic cap at the end of the binding post can be removed for connecting a banana plug)
• Chassis is made of high-grade anodized brushed aluminum to reduce audio resonance
• Dimension: 8.5" x 14" x 1.8" (height does not include feet)
• Worldwide AC voltage (84VAC to 264VAC). No need for AC regulator if the AC voltage falls within the specified range.
• Weight: 8 lb

Amplifier FAQ

What is an Analog Switching Amplifier? What's the difference between NuForce's amplifier and other digital amplifiers?

NuForce's switching amplifier is a drastic departure from conventional approaches to switching amplifier design. Most class-D amplifiers use a fixed sawtooth waveform to modulate an audio signal, and suffer from the 180-degree phase shift of the LC reconstruction filter, which would normally cause feedback from the load to the error amplifier to oscillate unless phase compensation is used. That compensation network drastically reduses the amplifier bandwidth to below the corner frequency of the LC reconstruction filter. Thus most class-D amplifiers have narrow bandwidth and high distortion due to the limited gain of the phase-corrected error amplifier at audio frequencies.

NuForce's amplifier technology is based upon the principle that a power oscillator can be modulated by an audio signal (rather than the fixed sawtooth waveform) so that is produces an amplified audio signal obtained with a reconstruction filter, without the bandwidth limitation of a fixed frequency carrier-based conventional PWM (Pulse Width Modulation) control. It uses an analog modulation technique and closed-loop control systems. Therefore NuForce refers to its audio amplifiers as Analog Switching Amplifiers.

What are the problems with traditional Class-A and Class A/B amplifiers?

Traditional linear amplifiers such as Class-A and Class A/B amplifiers are bulky and inneficient. The inefficiency compromises the reproduction of the music signal's full dynamic range. Its resulting higher operating temperature also shortens the useful life of the electrolytic capacitors used in abundance int these amplifiers. To get around that problem, today's better amplifiers employ bulky heatsinks and costly linear power supplies to provide enough headroom to handle the full dynamics. These huge power supplies are unregulated and could add noise and ripples at low volume. Besides being inefficient, linear power amplifiers depend on transistors of MOSFET devices to enerate power. Big (high power) bipolar transistors or MOSFETs have inherently low bandwidth and do not provide adequate audio performance. Therefore, smaller (up to 20+) MOSFETs with decent audio bandwidth performance are paralleled to provide sufficient power. Each MOSFET has an inherent junction noise - and the aggregated noise corrupts music reproduction. What you hear is haziness and veiling in music reproduction. MOSFETs are used in parallel because technically, they are easier to drive although they have inherantly higher distortion than bipolar transistors, which are much harder to drive when they are paralleled. Class-AB amplifiers - the most populer amplifier circuit - have to overcome the inherent crossover dstortion that occurs when the audio signal goes from negative to positive and vice-versa, crossing the zero region where gains of transistors are much reduced. They are actually down to zero when the transistors stop current. Closed-loop system designers know that lower gain means higher inaccuracy of the amplification loop.

What are the problems with Class-D amplifiers digital switching amplifiers?

Digital Switching amplifiers (commonly known as Class-D) have been around for years. Neverless, it is nearly impossible to engineer a conventional Class-D amplifier that handles the full requirement, 20-20,000Hz, for full -bandwidth music reproduction. A Class-D amplifier works by utiliing a high-frequency sawtooth waveform to modulate the music signal. The constant presence of the sawtooth waveform, which is very high in the frequency spectrum and its inevitable frequency jittering, can mask or corrupt low-level music signals. The output filter is designed to filter our noise and overtones caused by the sawtooth waveform, adds a 180 degree phase-shift to the Class-D output stage, causing possivle instability and adding distortion due to its owne inherent non-linearities. Additionally, the output filter presents frequency-variant output impedances that can interact with a speaker's complex impedance. Variants of Class-D amplifiers with the addition of Digital Signal Processing claim to improve music reproduction. However, because of their lack of closed-loop design, especially from the speaker's terminals, spurious interaction between the speaker's complex impedance and back-EMF with the amplifier's resonant output filter can result in harsh sound reproduction. The fundamental flaws of conventional Class-D amplifiers remain unresolved.

Why is a switching amplifier better than a linear amplifier in the reproduction of music? Music is just a series of blended sine waves isn't it?

While any waveform theoretically consists of sine waves, that mathematical decomposition assumes that the waveform is poeriodic, in other words, a repeating waveform. Musical instruments, on the other hand, produce waveform with full sharp transients that even trained eyes have a difficult time discerning the fundamental frequency. Even a single note produced by an instrument is full of attacks and decays (with the exception of instruments that are based on natural resonance, such as the pipe organ or the flute). A violin produces a very complex waveform full of harmonics. Harmonics are so named because their frequencies are multiples of the fundamental frequency of the note being played. Faithful reproduction of such complex waveforme requires an amplifier capable of very high bandwidth, and more imprtantly, with no crossover distortion. The most popular amplifiers use a class of amplifying circuit identified as class-AB. It is actually a compromise between the huge inefficiency of class-A amplifiers - the simplest circuit universally used in low power amplification - and the high distortion but higher efficiency of class-B amplifiers. Class-A amplifiers theoretically have no crossover distortion. This is the main reason why audiophiles are willing to pay sky high prices for some class-A amplifiers. Likewise, NuForce's analog switching amplifier circuit has no crossover distortion. And while typical linear amplifiers have a bandwidth that is barely over 20 kHz - lower still in boomboxes and in conventional switching amplifiers - NuForce's analog switching amplifier uses proprietary technologies to achieve bandwidth up to ten times higher than typical linear amplifiers. This huge bandwidth allows NuForce amps to amplify complex music faithfully, much beyond what is currently considered audiophile standards.