Усилители мощности стерео — Dartzeel NHB-108 Model Two

The NHB-108 was the first power amplifier designed and built by darTZeel, the Swiss company of engineer Herve Deletraz, and the Model Two is its reworked current form after years of regular updates. The original Model One took more than 16 years of research and was introduced in New York in 2002. The letters NHB stand for Never Heard Before, and the design follows the brand's stated principles of simplicity, purity and reliability. Deletraz holds the patents on its circuitry. List prices start at USD 63,030, EUR 61,905 or CHF 51,620, and the UK figure has been GBP 39,995.

Key specs that matter

Rated output is 150 W RMS per channel into 8 ohm and 225 W RMS into 4 ohm, and voltage gain is 26 dB into 8 ohm. Bandwidth runs from 0.8 Hz to 600 kHz within 3 dB, rise time is below 0.8 microseconds and slew rate exceeds 88 V per microsecond peak to peak. Harmonic distortion stays under 1% from 7 Hz to 77 kHz across the output range, channel separation is better than 90 dB from 20 Hz to 20 kHz, and signal to noise exceeds 112 dB A-weighted at nominal power. DC at the output is held within 50 mV. The chassis is 440 mm wide, 170 mm high and 350 mm deep, or 415 mm with the handles, and weighs 30 kg. Idle consumption is 50 W, climbing to 900 W at full output.

Engineering and use context

Circuits patented worldwide keep the amplifier free of global negative feedback. It is a class AB, single-ended design with symmetrical supplies, and the Model Two uses two pairs of output transistors per channel where the earlier version had one. Each channel has its own transformer, power supply, audio circuit and heatsink, so the only shared item is the mains cord and the unit works as two mono amplifiers in one case. A toughened mineral glass top shows the interior, where crescent-shaped, fine-brushed bus bars of 24 carat gold link the six large capacitors of each channel. Outside, the front and rear panels are gold aluminium and the heatsink fins are red.

Pairing

There are three input types - balanced XLR and single-ended RCA, both above 30 kilohm, plus a 50 ohm BNC Zeel input specified from 1 Hz to 1 MHz. The RCA impedance figure is given for 5 Hz to 100 kHz. Loudspeakers connect to one pair of gold-plated copper WBT binding posts. Output impedance measures 0.33 ohm across the audio band.

Alternatives

darTZeel makes no other stereo power amplifier, since its larger NHB-468 is a monoblock rated at 475 W into 8 ohm.