The Geithain RL921K Black Ash draws inspiration from the timeless and iconic design of the revered RL901K. It captures the visual essence of its elder counterpart and faithfully emulates its tonal characteristics. This makes the RL921K an ideal choice when the RL901K's size or shorter listening distances present constraints. The RL921K caters to both professional users and dedicated music enthusiasts.

Thanks to its cardioid radiation pattern within the 30 to 250 Hz frequency range, the RL921K effectively minimizes reflections on the rear walls of listening spaces. Moreover, its transfer characteristics can be finely tuned to match the acoustic conditions of the room and the specific setup through an integrated room-matching filter.

The total directivity index of this monitor has been finely tuned for very brief listening distances, typically spanning two to three meters (6.6 to 9.9 ft). For exceptional impulse fidelity, it incorporates a highly linear 300-mm (12'') long-throw driver in a cardioid enclosure. A 100-mm (4'') cone and a 25-mm (1'') dome tweeter are coaxially positioned before the bass system, allowing for precise control over the directivity index. This configuration results in a lifelike and consistent spatial sound performance around the listening position, marked by exceptional uniformity and minimal colouration. The substantial diaphragm area of the RL921K ensures a high degree of durability while keeping distortion levels to a minimum. As a result, the RL921K is a precision studio tool, ensuring fatigue-free work over extended periods.

The speaker features a three-channel MOSFET power amplifier with an electronic crossover integrated into the cabinet's rear wall. The service-friendly design includes a hinged access point. An intermittent LED indicator alerts users when the overload limit is exceeded. At this point, the output level is reduced by 20 dB to prevent component overload.

Additionally, the speaker is available in a horizontal lying variant. Users can opt for the standard MOSFET amplifier enclosed in an upright-standing case or choose from the 19’’ compatible Class D amplifiers RL-Amplifier and RL-Amplifier 2.

A range of special stands and racks is available as accessories, with integrated fixing elements seamlessly incorporated into the loudspeaker cabinet for added convenience.