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permission of NAD Electronics International. © 12/04 NAD Electronics International.
www.NADelectronics.com
The C720BEE also incorporates NADs acclaimed switchable Soft
Clipping circuit, which signifi cantly reduces the risk of damage to
loudspeakers due to prolonged high power operation.
Design: PowerDrive :
NAD takes a stance to the overblown power ratings quoted by many
competitors, which dont give a realistic indication of an amplifi ers
true capabilities. NADs Full Disclosure Power ratings give the
guaranteed minimum continuous power output under the worst
case loading of 4 Ohms and 20Hz to 20kHz with both channels
driven simultaneously, as well as the more meaningful in actual use
dynamic power ratings.
The C720BEE benefi ts from NADs proprietary PowerDrive
topology, this further refi nement of Power Envelope and ISC, is
now well established and used throughout the NAD product range.
PowerDrive endows the C720BEE with tremendous dynamic power
and low impedance drive capability, seemingly contradictory traits
to be found in a single amplifi er. This is accomplished by using a
multistage power supply with a very sophisticated analog computer
determining whether to switch in a high voltage or a high current rail
depending on the specifi c operating condition. This optimization
is fully automatic and utterly transparent in operation; the result
is that the C720BEE sounds far larger and more powerful than its
continuous power rating would suggest.
PowerDrive is a practical approach to enable an amplifi er to easily
deal with musical dynamics and diffi cult speaker loads. Most
impressive are the C720BEEs dynamic capabilities; up to 220 Watts
into 2 ohms and up to 50 amps peak current capability!
Performance:
The C720BEE features many circuit refi nements trickled down from
NADs award winning amplifi ers including active current sources
and common base current followers in the power amp section.
This dramatically reduces dynamic intermodulation distortion
between music signal components in different frequency ranges,
and between the music signals and the power supply ripple and
distortion components. In measurement terms, both static and
dynamic IM distortion are reduced by between 10dB to 20dB. (to
between -90dB and - 100dB.)
In audible terms this improves defi nition, purity and resolution,
hence imaging.
Compared to its predecessor the C740, we have improved the
accuracy of the tone controls, increasing their boost/cut range by
1.5dB and have specifi ed a better quality volume control. While
some of these are small improvements in and of themselves, there
is an additive effect that results in a more refi ned and authoritative
sound, building on the strengths of the already very good design
of the C740 and making it the equal of the C320BEE. The sensible
Tone Control characteristics, sonically transparent relay input
switching, and Pure Class A modular preamp stages and power amp
driver stages, are directly carried over from the C320BEE. So are the
patented power amp output stages, unique low resistance binding
post design, copper bus bars for high-current paths, and low-noise
discrete regulators.
Pre-Amp Section
Line level inputs
Input impedance (R+C)
Input sensitivity, rated power
Frequency response (-3dB - 70kHz)*
Line level outputs
Output impedance
Record Out/Zone 2
Maximum output level
Pre-Out
Tone Controls
Treble
Base
Remote Control
Power Amp Section
Continuous output power -
Rated distortion (THD 20Hz-20kHz)
Clipping power -
IHF dynamic headroom at 8-
IHF dynamic power at 8-
IHF dynamic power at 4-
IHF dynamic power at 2-
Damping factor (ref. 8-, 50Hz)
Line level inputs
Input impedance
Input sensitivity (for rated power into 8-)
Frequency response; 20Hz-20kHz
Signal/noise ratio; ref 1W (A-weighted)
Signal/noise ratio; ref rated power
Tuner Section
Usable input sensitivity; FM mono
50dB Quieting sensitivity; FM stereo
Harmonic distortion; FM mono
Harmonic distortion; FM stereo
Signal/noise; mono
Signal/noise; stereo
Channel separation at 1kHz
Frequency response; ± 1.5dB
Physical Specifi cations
Dimensions (W x H x D)
Net Weight
Shipping Weight
200k- / 320pF
220mV
±0.3dB
220-
Source Z + 1k-
Zone 2 out >10V
>12V
±5dB at 10kHz
±5dB at 100Hz
SR-5 / ZR-3 2nd Zone
50W (17dBW)
0.03%
68W (18dBW)
3.4dB
100W (20dBW)
145W (21.6dBW)
180W (22.5dBW)
>60
20k-/ 470pF
630mV
+/-0.3dB
100dB
117dB
16.1dBf
36.1dBf
0.25%
0.5%
60dB
55dB
40dB
30Hz - 15Hz
17 1/8 x 5 3/16 x 13 3/4 (435 x 132 x 350mm)
14.33 lbs (6.5kg)
16.98 lbs (7.7kg)
