Klein + Hummel O 400 D Active Studio Monitor

Excellence in design results in excellence in audio reproduction
For an active studio monitor to reproduce a recording with true-to-life accuracy, there must exist complete harmony among all its elements. The O 400 has its roots in KLEIN + HUMMEL`s years of experience and profound familiarity with the professional studio environment. This monitor draws upon a large number of outstanding components and features to achieve a new level of authenticity in audio reproduction.

The O 400 is an outstanding reference monitor for mid-sized recording studios, radio and television control rooms, or for larger broadcast vans. It is also an excellent choice for mastering rooms, post-production facilities, etc.

Superiority of the three-way design
For a mid-sized monitor to produce extremely neutral, transparent sound with the lowest possible coloration and distortion even at high monitoring levels, a three-way design is clearly superior to of a two-way system. We therefore selected the same sophisticated three-way design for the O 400 that has proven itself time and again in our larger studio reference monitors for over 40 years.

Superbly matched drivers and electronics
In pursuit of absolute tonal neutrality and accuracy over the entire frequency spectrum, we used utmost care and exacting test procedures in selecting drivers to insure that they would all work superbly well with one another. The 8½" (220 mm) polypropylene cone woofer system has been specially modified for use in a bass-reflex enclosure. Its modern construction ensures tight, articulate bass reproduction with no distortion even at high volume levels.

A special fabric dome with a voice coil diameter of 3" (76 mm) handles the midrange. The membrane weight of a dome is significantly lower than that of a cone system, so it offers significant advantages such as outstanding transient response and extremely uniform frequency response. The overall effect is impressive in its authenticity and neutrality, especially in the range of the human voice.

The tweeter system is comprised of a sophisticated 1" (25 mm) titanium fabric dome that combines the transparency of titanium with the low distortion of a fabric dome and reveals extraordinary detail. All three loudspeaker drivers are magnetically shielded, allowing the monitors to be placed adjacent to a video monitor or disk drive without any adverse effects.The directivity of the O 400 is extraordinarily uniform thanks to the computer-designed wave-guide that surrounds the tweeter system and the particular design of the baffle. The optimum listening area (sweet spot) has been extended to +/-30° off-axis, providing the engineer greater freedom of movement at the mixing console, and allowing for closer monitoring in smaller rooms.

Superb linearity provides extraordinary accuracy
Three elements work together to produce the superb frequency linearity and perfect interplay of the O 400`s three drivers: the active crossovers with a slope of 24 dB per octave, the sophisticated equalization network, and the well chosen crossover frequencies. The result is a wonderfully neutral sonic image that opens a revealing view into a clearly defined stereo soundstage with precise image focus and depth.

Power amplification: refined, reliable
KLEIN + HUMMEL has been engineering and manufacturing high-quality amplifiers for over fifty years. The three discrete MOS-FET amplifiers that have been implemented in the O 400 embody our total experience with regard to continuous power reliability, minimal distortion, and maximum impulse fidelity. Integral protective circuitry prevents speaker overload and protects the amplifiers from overheating. The O 400 is equipped with a superior transformer-balanced floating input that, even at high volume levels, helps achieve extremely low distortion reproduction even in the low frequencies. The input sensitivity ranges from +6 dBu to 0 dBu, allowing the connection of all standard studio signal sources.

Enclosure: rock-solid, resonance-free
The O 400 enclosure is made of high-quality MDF wood (medium-density fiberboard), which has a high degree of self-damping, and is constructed in such a way that resonant behavior is nearly completely suppressed. The charcoal-gray enamel finish lends the monitor a professional appearance that fits very well into the studio environment.

The only internal acoustic damping material we use is natural wool, rather than fiberglass. This environmentally friendly choice avoids the prospect of micro particles being expelled from the bass reflex ports and adversely affecting the air quality in the room. With a KLEIN + HUMMEL monitor, you can literally and professionally breathe easy."