Our intention in developing the HA 200 was to build a headphone amplifier with the finest sound quality available anywhere in the world, and suitable for all kinds of dynamic and magnetostatic headphones. This means that the amplifier section would have an absolutely crucial part to play in the overall design. And that’s why we decided to adopt the principles of our HV series: pure analogue Class-A design with special MOS-FET transistors, no op-amps, no chips and a separate 100-Watt analogue mains section. Even the crossfeed function is generated by an analog filter circuit. The XLR and Cinch inputs take the same form as in the HV series, and the pre-amplifier is designed in such a way that it feeds the output stage in the optimum manner. Gas-tight encapsulated gold contact relays take over the volume control and adjustable loudness function and bridge the tone control completely (flat) on request, they are absolutely free of distortion and noise. Even after many years of operation these components are not subject to contact problems due to corrosion, dust or ageing effects. The relays are integrated directly into the circuit design, keeping the signal paths as short as possible.
Since we had decided to cater for different headphone types, the output stage needed to be extremely sophisticated. Normal loudspeakers have impedances in the range 2 to 10 Ohm, which is not critical. However, headphones may have impedances in the range 10 to 1000 Ohm, and this certainly presents a challenge. Low-impedance types draw high currents, whereas the currents flowing in high-impedance types are relatively low; however, the voltage must be very stable. We overcame this problem by designing the output stage of the HA 200 to be capable of effortlessly delivering relatively high currents, while the mains section transformers (2 x 50-Watt) are extremely stable and constant. Sound quality can be fine-tuned by selecting different output impedances for each output (6.3 mm, 4.4 mm Pentaconn, XLR 4-pin), and Crossfeed-mode can also be switched in. The XLR 4-pin output can be used to drive loudspeakers if the user wishes to connect a stereo power amplifier (such as the AMP 8); in this case we can supply an XLR-4 to 2xRCA adapter.
In addition to the conventional high-quality analogue inputs we have equipped the HA 200 with a large number of high quality digital inputs. This makes it possible to operate the unit as a stand-alone device, and connect it to various digital sources according to personal taste and requirements. There is no doubt that the HA 200’s digital input section is currently the world’s finest, since the USB-B inputs are based on the new high-resolution Thesycon chip, which can process up to DS 1025 and PCM 768. Professional AES/EBU and BNC sockets are also present, as are optical and co-axial SP/DIF. The Bluetooth input is fitted with AptX™ HD, two HDMI inputs (Stereo only) and one output ARC are available as options.
The extremely high quality of the inputs is maintained in the converter. The proprietary T+A True 1-Bit digital / analogue converter, which provides an incredible DSD 1024 for Bitstream, and the T+A quadruple converter with 32 Bit / 768 kHz for PCM, reflect the current State of the Art, and represent the limit of what is feasible today. The digital section features its own power supply, and is galvanically separated from the analogue section.
Although the primary purpose of the HA 200 is to be an amplifier with an extraordinarily high performance, this unusual flexibility on the input side is very helpful to various types of user. Since the amplifier employs our very finest DSD and PCM converters, the sound quality of the digital inputs is just as good as that of the analogue ones.
The wide range of connection facilities requires a very sophisticated control system and display for the amplifier as a whole. In fact, the HA 200 is intuitive and simple to operate, thanks to an ingenious combination of operating buttons and menu control system. The two VU meters (QPPM = Quasi Peak Programme Meter Type 1) are accurate indicators which display the variation in various parameters, as in studio applications and measurement engineering. The level at the D/A converter and the amplifier can both be displayed, as can input level and output level, temperature and stream quality (which can be used to check the frequency of the data stream and even the cable quality). The pin-sharp screen displays the user’s selected operating modes, such as output impedance, volume, data rate, oversampling filter type or crossfeed. The brightness of the display, the LEDs and the VU meter is adjustable. You can even adjust the colour of these.
Since we have also designed the HA 200 for use in professional applications, the case is designed to be extremely solid and robust. The heatsinks are manufactured using an extrusion tool, the front panel is machined from solid metal, and the top, bottom and back panels are made from aluminium plates. Ultra-close tolerances and accurate fits are the hallmarks of this case, and at the same time the design provides for homogeneous heat distribution, leading to optimum operating conditions for the electronics as a whole.
