Associated Equipment:
Front End
Digital Front End
NuForce Reference 8 and 8B Analog-Switching Monoblocks

Unleashing the Force of Music!


July 2005

For the past couple of years, I’ve been interested and curious as to the benefits and relative merits of digital amplifiers for high-end applications. Having heard a few highly rated models, I was always left with the feeling that in spite of their wonderful strengths there was always something lacking. I never heard a digitally-based amp sound quite “natural,” although I believed that one day, a new breed of digital amplifier would emerge that would finally sound convincing in the tradition of the highest quality analogue designs. That day has arrived.

Happily, it was a better day than I had envisioned because not only does this amplifier sound like a great analogue amplifier, it sounds considerably better than any other amplifiers I have evaluated in my two systems to this point in time.

During my past 10 years as a reviewer, never in all that time did I ever comment that a review product was a true breakthrough in audio design; but hold on tight because I may be about to use the B-word.

NuForce, an offshoot of Nphysics, was formed to design, develop, and market its own fine line of audio electronics. Their Chief Technical Officer, Tranh Nguyen, has a long history of designing high precision control and power systems for aerospace applications, and just happens to love audio. NuForce uses a fresh approach to switching amplifier design and holds several patents on the technology they’ve developed.

The NuForce switching amplifier is very different from the conventional class-D designs used by Tripath, IcePower, and others. NuForce's amplifier technology is based upon the principle that a power oscillator can be modulated by an audio signal – rather than a fixed sawtooth waveform, as in conventional class-D switching amplifiers. It produces an amplified audio signal obtained with a reconstruction filter, which is free of the normal bandwidth limitations inherent in PWM (Pulse Width Modulation) designs. Instead, NuForce employs an analog modulation technique, and ultra-fast, closed-loop control systems. Therefore NuForce proudly refers to its audio amplifiers as Analog Switching Amplifiers.

With the introduction of the Reference 8 amplifier, the age-old precept that an amplifier’s weight somehow correlates to better sonic performance is on the chopping block. Most of the weight (and many of the problems) with conventional amplifiers are directly related to power-supply inadequacies. A typical high-end amplifier uses a large power transformer to supply the current, which is responsible for its ability to supply steady, long-term power. But the NuForce switching power supply is much faster than traditional transformer-based power supplies. Once the dynamic peak passes, a big transformer cannot recover quickly enough, which causes sonic smearing and a general loss of resolution. The NuForce power supply can react much quicker to accurately track the music signal, thereby preserving its full impact without any masking or blurring of fine details.

Audiophiles prejudiced? Nah!
Knowing how the audio industry works to cater to audiophile preconceptions, I envision some enterprising company marketing an audiophile-approved amplifier (under license from NuForce). Naturally the audiophile version will utilize a heavy, laser etched solid-brass, copper-lined chassis, with tastefully beveled edges and optional zebrawood side panels. It will be massive; and in place of the token toroid will reside a magnificent Brazilian amethyst geode, backlit and cemented in just the right eye-catching position – completely non-functional, yet beautiful to behold. An oval plexiglass window in the top panel will highlight the backlit geode to perfect effect. A “passive” Teflon dual-layer, gold-trace circuit board chock-full of audiophile-brand capacitors and mil-spec resistors will comprise the central real estate while the actual NuForce module will be nestled strategically out of sight in a secret sub-chassis compartment.

Naturally it will be hideously expensive. Its sonic performance will be exactly the same as the standard NuForce amplifier, but no one who sees it will believe that for an instant. Now that I think of it, I could go for one of those myself!

The NuForce 8 and 8B amplifiers are small (6.5"W x 10.5"D x 1.75"H), black, plain-jane monoblocks weighing in at a scant 3 pounds. The black anodized chassis is aluminum and the faceplate on the 8B is thicker than that of the model 8 and has a nice bevel at the midpoint that adds a touch of class. The NuForce moniker and model are tastefully etched on the front panel. Price of the RCA-type Reference 8 is $1600/pr., and the balanced Reference 8Bs sell for $1900/pr.

The Reference 8s are rated at 100 watts RMS 8 or 4-ohms and will provide undistorted short-term peaks of 288 watts and 576 watts, respectively. NuForce uses Cardas gold-plated RCA or quality XLR input connectors and a unique, patented, quick-connect, rhodium-plated speaker terminal block, which only accepts spade lugs gracefully. The internal input wiring is high-grade silver-plated copper, which is Teflon coated. But the internal speaker wiring is really cool stuff. It’s a high-purity flat silver ribbon. The ribbons are protected by clear refrigeration tubing that says “do not use for ice maker;” I absolutely love it! It looks high-tech, and more importantly, sounds fantastic.

Cardas speaker connectors adorn the rear panel along with the power on/off switch, incorporated into the female IEC connector for use with after-market power cords. With many of the AC cords I tried, there was no problem operating the on/off switch. However, with some AC cords that use a larger diameter female plug, part of the plug can cover the recessed switch making it particularly difficult to access. I first used some stock 14-gauge Belden cords that I acquired through Monarchy Audio and later tried the NuForce Stealth M21 class, custom hand-made power cords. The Stealth cords are high-quality fully shielded cords designed to get the highest performance from the NuForce amps. They cost $480 US, per cord, and only one Stealth cord may be purchased with each NuForce amplifier.

In my system, I felt that the Stealth cords did indeed crank the performance up another notch. They seemed a bit faster than stock cords and provided more high-frequency air and detail without significantly affecting the overall frequency balance. I recommend them for folks looking to maximize the sonic potential of their NuForce amplifiers. (Please note that the Stealth AC cords worked well with the silver-ribbon internal speaker wire; but I did not test the Stealth with the Litz-wire version described later; so I’m not positive that the same synergy will occur.)

Technology/Schmeknology – how does it sound?
I can’t begin to tell you how many times I’ve listened to the marketing hype and the white-paper hoopla behind various products only to be markedly unimpressed by the actual sonic performance of the latest “breakthrough.” In fact, on a few occasions I was surprised to discover how terrible these marvels actually sounded. I’m happy to report that such is definitely NOT the case with NuForce.

Writing this, there is not a particle of doubt in my mind that NuForce has developed a superior technology that may well evolve, and eventually supplant, all that has gone before. I realize that this is an exceedingly bold statement to make. It is unprecedented in my reviewing career. I do not make it lightly, so please, do not take it lightly.

In truth, I have heard no other amplifier, in my 35 years as an audiophile that can match the sonic splendor and virtuosity of the tiny, but mighty, Reference 8s. How can I make such a statement; and, more importantly, how can I be sure of my judgment? Well, that’s a longer story that goes something like this:

Upon inserting the Reference 8s into my Newform system, I was immediately struck by their smoothness and the level of fine detail I was able to hear. I think the first song I played was “Dragnet” from The Art of Noise’s In No Sense? Nonsense! [Chrysalis VK 41570] CD. This is not one of my usual reference CD’s, I chose it more for its fun-factor than for its use as a reference tool. Yet, its ability to lay out a multifaceted soundstage with a few fast transient percussive attacks along the way caught my attention. As I played through more CDs I realized that I was having more fun than usual and that I was not concentrating so much on the usual sonic parameters; instead, I simply let the music wash over me and allow me to unwind from my day.

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NuForce Reference 8 and 8B Analogue-Switching Monoblocks