Nuforce Reference 18 Mono Amplifier

8/2011 Soundstage Review

Stereo Times Review

The Ref 18's every aspect has been evaluated against those of the Ref 9V3SE in order to identify areas of improvement. Input-stage circuitry, solid-state and passive components have been reconfigured with an ear to providing a quieter, more distortion-free environment, and greater speed via the Cross-Matrix Array (CMA) capacitor board, the effectiveness of which becomes especially apparent in the supremely fast delivery of musical transients (read more about Nuforce Capacitor Array Technology)

Capacitor Array Technology
Its not exactly rocket science, its the smart implementation of several varying values of power supply filter capacitors. This is done to minimize electrical resonance issues one would encounter if all of the PS filter capacitors were the same. Let me explain.

Along with other amplifier components, a capacitor possesses features that are often hidden from obvious view. In engineering terms, we refer to these concealed aspects as parasitic parameters. In the case of capacitors, inductance and resistance comprise the principal parasites. In practice, they combine with capacitance to produce an unwelcome resonance at certain frequency bands. Among other potential negative effects, if left unattended, this resonance can reduce the speed of power delivery significantly below what theory would otherwise suggest. Simply using larger sizes or quantities of a single value, as is commonly done, leads to a single resonant frequency of a large magnitude. From a design standpoint, this is a worst-case arrangement.

And so Nuforce developed the CMA as a no-compromise route to the ultimate in performance. The Ref 18 CMA employs the highest-quality capacitors of various values arrayed in a quasi-random pattern in order to spread resonances over a wide range of low-amplitude frequencies. In order to minimize stray magnetic fields, and hence, to reduce parasitic inductance, the capacitors are positioned so that their polarities are reversed with respect to each other. By lowering inductance, any remaining resonance is elevated to frequencies where its elimination becomes an easier task. Finally, low-value resistors combine with capacitors in strategic locations in order to dampen residual resonances. In engineering terms, the resonant peakî–¸ Q, in other words, its steepness, is reduced to a value of 0.707 or lower, thus enabling damping to operate to a degree where resonance no longer poses a problem.

At 16 pounds per amp , the Ref 18’s weight is a tick less than double that of the Ref 9V3SE. They are shipped in a hinged wood crate with luxurious and ample padding inside. This accounts for the 60-pound shipping weight.

Soundwise, the Ref 18 bears a resemblance to the Ref 9V3SE, as it should. Both amps employ the Version 3 (V3) amplifier board. As, again, no surprise, one will hear superb transparency, resolution, dynamic finesse, textural integrity and a rock-steady, well-detailed soundstage. The sonic improvements over the Ref 9 V3SE are many. and include sweeter, more natural highs. A near-palpable midrange and harmonic structure, resulting in a more natural and relaxed presentation. A beautifully textured low end exceeding even that of the Ref 9V3SE's exemplary authority and control. A deeper, more coherent soundstage.

If you are a fan of the 9V3Se, you will be absolutely bowled-over by the Ref 18. Call us at 888-998-9335 today and inqure about upgrading!

Specifications

• Frequency Response: 20 Hz -0.3 dB - 120 kHz -3 dB
• THD+N = 0.01%, 1kHz, 1W to 10W, A Weighted.
• Input impedance: 22K ohm
• Input sensitivity = 252mV, 1W @ 8 Ohm; 2.57V, 100W @ 8 Ohm; 1.81V, 100W @ 4 Ohm
• Input sensitivity for maximum power: 3.33V
• Gain: 21 db
• SNR > 100 db at 100W
• 12V DC Trigger Input
• WBT binding post for spade and banana plug 
• Chassis is made of high-grade anodized brushed aluminum to reduce audio resonance
• Dimension: 17"x 15" x 2.95"
• Worldwide AC voltage (84VAC to 264VAC). No need for AC regulator if the AC voltage falls within the specified range.
• Weight: 16 pounds
• AC Fuse: Slow blow, 5A, 250VAC