Amp/Preamp Asylum: REVIEW: Edge Electronics NL-12 Amplifier (SS) by hexenboden

Model:	NL-12
Category:	Amplifier (SS)
Suggested Retail Price:	$15,500
Description:	300 Watts/Channel (8 ohms), Dual-mono design, (2) 1500 VA Transformer. 106 lbs.
Manufacturer URL:	Edge Electronics
Model Picture:	View

Review by hexenboden ( A ) on April 14, 2006 at 13:05:42
IP Address: 65.219.214.60

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I should start by saying that I find minimal audible differences between reasonably designed solid state amps as long as the partnering speaker is a resonable load match. I'm not at the Audio Critic extreme but somewhere in the middle between that and the "tweakers". But a few years ago I purchased the Edge NL-12 based on the TAS accolades (I know...). The Edge laser technology was theoretically appealing so I took the plunge and put the NL-12 in my system. This experience drove me to reconsider my views (from a consumer standpoint) on amplifier design and speaker partnering.

In my room, the NL-12 drove efficient speakers with great poise, such as Silverline Sonatas and DeVore Fidelity Gibbon 8s. It is indeed a "sweet sounding" transistor amp, perhaps with even a tube-like sound. However, when I tried the speakers with Soundlab electrostatics they were clearly not up to the task and fell short in term of dynamics and ultimate loudness. The Soundlabs drove the NL-12 to clipping even with moderate loudness. I was surprised given the manufacturer specs until I read the Stereophile measurements, as I shall describe below.

An electrostatic panel uses very high voltage (about 15,000 volts in Sound Labs M-1), so the amplifier signal has to be stepped up with a transformer, which presents high impedance at low frequencies, steadily decreasing to a low impedance at higher frequencies (the opposite of moving-coil loudspeaker drivers, whose impedance usually rises with frequency). In the M1 impedance decreases from a high 30+ ohms in the bass, to 6-10 ohms or so in the 500 Hz ballpark (where the crossover is). The impedance then goes back up into 14+ ohms (depending on the midrange level control setting) and from there drops to 2 ohms or even less in the high treble. This is s truly horrid load to drive, and only the best high power amps need apply. BTW, the new Soundlab panels are said to have higher efficiency and this problem could be much reduced.

In 2004, J. Atkinson measured in the NL-12 a 1% THD clipping point at 250W into 8 ohms (not 300W as specified) and 400W into 4 ohms, with pretty high distortion levels for a large supposedly muscular solid state amp. The amp had problems delivering high currenty into 2 ohms. All I can say is this was exactly what I was hearing using the Soundlabs. Measurements do matter... In fact, the pricey Edge performed only a little better than the modestly priced Marsh A400S with the Soundlabs.

I had to take a large loss selling the Edge and buying a pair of Parasound JC-1 monoblocks, which actually exceed their published specs, and drove the Soundlabs' tough load with relative ease. The Parasounds also sound very clean, but a tad less "sweet" than the NL-10, when driving easier load speakers.

I would not buy a (used) NL-12 to drive any speaker that offered a difficult load. There are better options at that price level. But for highish impedance, moderate load speakerss this is a great sounding amplifier. Edge has released the NL-12.1 and NL-10.1 which may behave ina different way.

Product Weakness: power and current limitations into difficult loads
Product Strengths: sweet tube-like sound

Associated Equipment for this Review:
Amplifier:	Parasound JC-1, Marsh A400S
Preamplifier (or None if Integrated):	Tact 2.2X, Bryston
Sources (CDP/Turntable):	Muse Model 9 Signature
Speakers:	DeVore Gibbon 8, Silverline Sonata
Cables/Interconnects:	Nordost Blue Heaven
Music Used (Genre/Selections):	classical, rock
Type of Audition/Review:	Product Owner

Product Weakness:	power and current limitations into difficult loads
Product Strengths:	sweet tube-like sound