The HD-1 is a self-contained, ultra-precise loudspeaker for near-field sound monitoring in tracking and mixing. Aligned to closely approximate a point-source radiator, the HD-1 features exceptionally broad directivity to maintain a large"sweet spot." Patented circuitry tightly controls time delay response for minimal deviation from linear phase, and individually hand-tuned equalization circuits assure flat frequency response within extremely tight tolerances across the full frequency range of operation.

The HD-1 is an active bi-amplified two-way system comprising an 8-inch cone driver and 1-inch soft dome tweeter in a vented cabinet. The low-frequency driver features an exceptionally large magnet structure and 2-inch voice coil for high efficiency and rapid heat dissipation. The tweeter is a specially developed, impregnated silk dome that affords extremely smooth response while minimizing breakup and coloration.

The HD-1 presents an active balanced input (switchable for +4 dBu or -10 dBV nominal operating level) and an active crossover with optimized pole-zero filter combinations for acoustical transparency and linear phase.

The integral power amplifier features complementary MOSFET output stages operating as class A at low-to-moderate levels (less than 90 dB SPL) and class AB at high levels. The HD-1's free-field frequency response is flat within ±1 dB from 40 Hz to 20 kHz, and it delivers high peak SPL with greater than 100 dB dynamic range and extremely low distortion.

More info from Meyer Site:
HD-1 : High Definiion Audio Monitor
HD-1 Datasheet