NAD 218THX User Manual

218THX

Stereo Power Amplifier

• 2 x 200 Watts continuous power into 8ohms (230 V version)
2 x 225 Watts continuous power into 8ohms (120 V version)

• Dynamic Power 250, 430, 660 W into 8, 4 and 2 ohms (230V)
Dynamic Power 280, 470, 700 W into 8, 4 and 2 ohms (120V)

• Low loss, massive Holmgren™ toroidal mains transformer

• Dual mono, Left and Right mirror image amplifier PCBs

• Fully balanced XLR inputs

• Soft Clipping

• Protection circuitry senses short circuits, DC and overheating

• Bridgeable; 700 W into 8 ; 1.2 kW dynamic power into 4

The all-new NAD Model 218 THX joins the award winning range of NAD Power Amplifiers combining the
traditional NAD virtues of excellent performance and value-for-money, further enhancing NAD's enviable
reputation for State-of-the-Art products at sensible prices.
The key design goals of the new range are PERFORMANCE and RELIABILITY, attained by efficient
innovative design, simple circuitry and meticulous engineering.

Circuitry

The NAD 218 THX is designed with the capability to drive all types of musical signals effortlessly into the
even most unreasonable of loudspeakers loads. To cope with difficult loads (even as low as 1ohms), the
NAD Model 218 THX is equipped with a high current output stage combined with a very generous power
supply. The massive "Holmgren" toroidal transformer, has even less hum and magnetic leakage than
conventional toroids, and retains the usual benefits of high efficiency and power-to-weight ratio.
Pioneered by NAD for the highly acclaimed Model 208 THX, the Model 218 THX uses a bank of reservoir
capacitors rather than a single pair. Besides being a more economical solution this is also technically
superior as many smaller capacitors have a faster recovery time and less total inductance than a single
pair of larger capacitors. The input stage is fed from a separate low-noise, regulated power supply which
isolates it from the high power sections eliminating interference.

Additional features

The Model 218 THX comes with fully balanced XLR inputs which allow it to be partnered with
professional equipment or with long stretches of cable between the pre- and power amplifier without the
risk of interference. The standard 19 inch rack mounting front panel further facilitate the use of the
Model 218 THX in a professional environment. The output relay protection circuit provides silent switch
on and off, together with non-evasive protection against unlikely error conditions such as short circuits
and overheating.
For maximum flexibility, the NAD Model 218 THX can also be operated in bridged mono mode, typically
tripling its output power rating. This makes the NAD 218 THX an ideal choice for a sub-woofer amplifier
or high powered amplifier in THX or other Home Theater applications.

The Model 218 THX also incorporates NAD's acclaimed switchable "Soft Clipping" circuit which
significantly reduces the risk of damage to loudspeakers due to prolonged high power operation.
NAD was the first company to introduce a THX certified power amplifier. It is therefore no surprise that
the NAD Model 218 THX passes Lucas Films' stringent THX requirements with flying colours.

The listening experience

Whilst there are other very powerful amplifiers available, the NAD Model 218 THX goes beyond just brute
force: It's sonic performance is among the very best available, be it at low or high power levels.

SPECIFICATIONS - NAD 218 THX
Unbridged (Stereo) Mode 120V 230V

CONTINUOUS OUTPUT POWER 225W (23.5 dBW) 200W (23 dBW)

(Minimum power per channel, 20Hz-20kHz, both channels driven, with no more than rated distortion)

Rated distortion (THD 20Hz-20kHz) 0.03%
Clipping power (maximum continuous power per channel) 240W (23.8 dBW) 210W (23.2 dbW)
IHF dynamic headroom at 8ohms 1 dB
IHF dynamic power 8 280W (24.5 dBW) 250W (24 dBW)

(maximum short term power per channel) 4 470W (26.7 dBW) 430W (26.3 dBW)

2 700W (28.4 dBW) 660W (28.2 dBW)
Slew rate >100V/µs
Damping factor (ref. 8ohms, 50Hz) >200
Input impedance 47k /700pF
Input sensitivity (for rated power into 8ohms) 1.4V
Voltage gain x 28.3 (29 dB)
Frequency response 20Hz-20kHz + 0.3 dB

-3dB at 2.5Hz / 80kHz

Signal/Noise ratio ref. 1 W 96 dB

ref. rated power 120 dB

THD + SMPTE I.M. + IHF I.M. <0.03%

Bridged (Monophonic) Mode

CONTINUOUS AVERAGE POWER OUTPUT INTO 8 780W (28.9 dBW) 700W (28.5 dBW)

(Minimum power per channel, 20Hz-20kHz, both channels driven, with no more than rated distortion)

IHF dynamic headroom at 8ohms 1 dB
IHF dynamic power 8 940W (29.7 dBW) 880W (29.4 dBW)

(maximum short term power per channel) 4 1.3kW (31.1 dBW) 1.2kW (30.8 dBW)

Physical Specifications

Dimensions 483 x 175 x 370mm
Net Weight 23kg
Shipping Weigth 30kg

Dolby is a registered trademark of Dolby Laboratories Ltd.
THX is a registered trademark of Lucas Film Co.
NOTE: NAD reserves the right to change specifications or design at any time without notice. All specifications are those in effect at time of printing.