The NAD (New
Acoustic Dimension) brand name has existed in Europe for about many years but
is probably unfamiliar to most American audiophiles. NAD is an unusual company,
involving an international group of independent dealers whose needs and
suggestions play a major part in the development of its products, which are
designed to sound as good as the state-of-the-art. Permits and to sell at
prices within the reach of a broad segment of the buying public.
In designing
its Model 3020 integrated amplifier. NAD began with the assumption that, for a
given power-output level, a state-of-th-art. Unit need not cost significantly
more than a poor or mediocre one. They focused on the design areas that can
cause listening problems - for example, protective circuits that cause
distortion with very low or highly reactive speaker loads, phono preamplifiers
whose circuits interact with phono-cartridge inductance to affect
high-frequency response, and circuits whose excessive bandwidth mekes them
vulnerable to interference from radio transmitters and overload from infrasonic
turntable rumble or disc warps.
The NAD 3020
is a no-frills, moderately-prieced amplifier designed to provide
state-of-the-art. Performance at volume levels far in excess of what would be
expected from its conservative 20-watt per channel power rating. This
remarkable characteristic is made possible by high-voltage, high-current output
stages which can deliver short-term burst of two to five times the rated
continuous power output into loudspeakers of widely varying impedances. The
3020's exclusive "Soft Clipping" circuit permits listening levels
even beyond these limits by reducing harshness aat high volume settings.
The phono
preamplifier section of the 3020 contains a sophisticated 6=transistor circuit
which has been enginereed for extremely low noise and nearly distortion-free
performance. Built-in infrasonic and ultrasonic filters further reduce the
interference of non musical signals caused by turntable rumble, floor
vibration, tone arm or stylus resonances.
These
uniquely designed input and output stages combine to create an inexpensive
amplifier which is easily capable of driving the very best loudspeakers.
Designed for
Real_Word Performance
If you read
specificatoions and test reports you will find that the majority of modern
amplifiers measure well on the test bench, with impressive figures for
signal-to-noise ratio, power output at 8 ohmsm and ultra-low harmonic
distortion. But outside the laboratory many of these products don't perform as
well as their specifications suggest. In the home you don't listen tosignal
generators and 8 ohms test resistors; you listen to complex musical waveforms
generated by phono cartridges and reproduced through loudspeakers whose
impedance is seldom 8 ohms.
Rather than
incorporating costly refinements that may test well, but yeld little audible
improvement, NAD's engineers have designed the 3020 for optimum performance in
every day use.
Effective
Control Features
Like every
other part of its design, the 3020's controls have been carefully considered
for genuine usefulness. The Bass and Treble controls are tailored for musically
effective response in the high and low frequencies without altering the
critical mid-range tonal balance.
For
listening at low volume levels or with sensitive headphones, the 3020's Audio
Muting button reduces levels by 20 dB, expanding the useful range of the Volume
control and subduing any residual circuit noise. A simple, elegant set of five
LED's accurately displays the peak power level which the amplifier is
delivering to the loudspeakers, form 1 to 35 watts into 8 ohms or 2 to 70 watts
into 4 ohms. The circuit monitors both channels and displays the higher output
at each instant.
High-Performance
Design
Wide Range
Phono Preamplifier
In a
moderately priced amplifier you might expect to find an economy preamp circuit,
but the NAD 3020 contains a phono preamp stage which is audibly identical to
the finest separate professional preamps. The 3020 preamp interfaces correctly
with the impedances of real phono cartridges (as many preamps do not), it is
quiet enough for use with either moving-magnet or high-output moving-coil
pickups, and its distortion is extremely low, not only with sine-wave test
tones but also when reproducing complex high-level music signals. The 3020 was
designed to achieve the best signal/noise ratio when a cartridge is plugged in
(rather than with the usual, but inappropriate, short-circuit input). The total
dynamic range of the 3020 is typically 107dB, ample even for the
digitally-mastered recordings of the 1980s.
Infrasonic
and Ultrasonic Filters
Audio
signals are often contaminated with interference at frequencies below and above
the audible range, such as acoustic feedback, disc warps and radio
interference. Amplification of such signals yields no sonic benefit, wastes
amplifier power, and may cause intermodulation distortion muddy bass, excessive
woofer cone motions, and even tweeter burnout. The NAD 3020 contains a precise,
minimum-phase audio-bandpass filter which strips off such interference and
preserves a clean musical waveform.
Dual-Mode
Power Supply
The power
supply circuit for the output stage is only loosely regulated, so it is free to
supply the high voltages needed for a high IHF headroom factor (at 8 ohms) and
also to supply the large currents at lower voltages needed for driving
low-impedance loads (down to 2 ohms). An entirely separate power supply
circuit, operating from another secondary winding on the power transformer,
supplies extremely stable, noise-free, regulated operating voltages for the
preamplifier and tone control stages; thus distortion and blurring of the
stereo image due to power supply modulation cannot occur in the 3020. The NAD
3020 has earned a world-wide reputation among audio reviewers for its sensible
and efficient design and superb performance.
Numerous
test reports, comparing the 3020 with equipment of far greater power rating and
cost have proven the 3020 to be an outstanding value.
The power
supply for the NAD 3020 output stages is loosely regulated - that is, when
there is little or no audio signal present, the supply voltage is relatively
high, giving the amplifier a large short-term power-output capability (which is
reflected in its very high IHF dynamic-headroom rating). A heavy load, whether
from high average signal levels or from aa very low load impedance, causes the
power supply voltage to drop, limiting the current through the output
transistors to a safe value.
Specifications
Pre-Amp
Section
Phono Input
Input
Impedance (R and C): 47 kΩ/ 47pF
Input
Sensitivity (1kHz): 2.5 mV ref. 20W
Signal-to-Noise
Ratio (A-weighted with cartridge connected):
75 dB ref. 5mV
Line Level
Inputs
Signal-To-Noise
Ratio (A-weighted ref 1W): greater than
86 dB
Channel
Separation: greaer than 60 dB
Frequency
Response: 20 Hz - 20 kHz (±0.5 dB)
Infrasonic
Filter: -3 dB at 15 Hz, 24 dB/octave
Ultrasonic
Filter: -3 dB at 35 kHz, 12 dB/octave
Power Amp Section
Continuous
Output Power (into 8 W )*: 20 W (13 dBW)
Rated
Distortion (THD 20Hz - 20kHz): 0.02%
Clipping
Power (maximum continuous power per channel):
30W
IHF Dynamic
Headroom (at 8W): +3 dB
IHF Dynamic
Power (maximum short term power per channel):
40 W
at 8 Ω
58 W
at 4 Ω
72 W
at 2 Ω
Physical Specifications
Dimensions
(W x H x D): 420 x 96 x 240 mm
Net
Weight: 5,3 kg
Shipping
Weight: 6,7 kg