Integrated amplifiers — Dartzeel CTH-8550

The CTH-8550 is an integrated amplifier from the Swiss company darTZeel, built on a dual-mono architecture and presented by the maker as its first integrated amplifier without compromise. The analogue design accepts line sources on several connector types, including the brand's own Zeel format, and optional phono modules for MM or MC pickups. A Mk II version followed the original, and the US price of the first version was USD 20,300.

Key specs that matter

Output power is 200 W per channel into 8 ohm, 330 W into 4 ohm and, with a software limit, 400 W into 2 ohm. The original version was limited to 330 W into 2 ohm. Frequency response extends from 2 Hz to 200 kHz, with noise more than 115 dB down A-weighted, referenced to a 2 V output. Output impedance is below 0.33 ohm into 8 ohm, crosstalk is under 90 dB between 20 Hz and 20 kHz, and distortion stays under 1 percent across the output range. Line gain is adjustable by the user from 0 to 22 dB, set to 12 dB on delivery. The case measures 440 x 350 x 170 mm, or 415 mm deep including handles, and weighs 28 kg.

Engineering and use context

The standard input set consists of one Zeel BNC socket with a 50 ohm impedance, one RCA line input and one XLR line input, both above 30 kohm, and the total can be expanded to as many as nine analogue inputs. The Zeel connection treats the link between source and amplifier as a matched 50 ohm transmission line, the same principle darTZeel uses between its own components. The optional moving coil phono stage offers user-defined gain between 50 and 70 dB. Power draw is 3 W in standby, 40 W at idle and up to 1 kW at full output, so the amplifier needs a mains outlet able to supply that peak. The separate left and right channels are laid out as mirror images in the dual-mono chassis.

Pairing

With an output impedance this low and power rising into very low loads, the CTH-8550 keeps control over difficult floorstanders with large woofers and low impedance dips. Sources with a Zeel output connect over a BNC cable, and a turntable can plug in directly once the phono option is installed. No DAC is built in, so a CD transport or streamer has to connect through an outboard converter with analogue outputs.

Alternatives

darTZeel also offers the LHC-208, an integrated amplifier that adds a network player and a DAC to the same chassis.