How a long-standing engineering tradition gave rise to modern three-way reference monitors for stereo and immersive workflows

When developing reference loudspeakers, one central question has always been at the forefront: How can audio professionals make reliable sonic decisions? This challenge already occupied the engineers at Klein + Hummel and continues to shape the development of Neumann studio monitors to this day.

In 1967, Klein + Hummel introduced the OY, one of the first active studio monitors, featuring an active crossover and integrated power amplifiers for the low-frequency and mid/high-frequency sections, all carefully matched as a complete system. The OY quickly became a standard in broadcasting facilities, control rooms and outside broadcast vehicles.

Another milestone followed in 1982 with the O 98. This compact active three-way monitor combined high linearity, low distortion and accurate transient response, even in smaller control rooms. Its arrangement of tweeter, midrange driver and woofer closely resembles that of today's KH 310 II. Even details such as the mounting brackets on the rear of the cabinet can still be found in modern form today.

Over subsequent generations, key performance characteristics were continuously improved. Harmonic distortion decreased, maximum SPL at low distortion increased, and measurements demonstrated improvements in transient response and acoustic neutrality. At the same time, waveguides were introduced to precisely control directivity and reduce the influence of room acoustics.

When Neumann acquired Klein + Hummel's studio monitor division in 2010, this development philosophy was preserved. The KH 310 combined the compact, sealed three-way design with low group delay and a dedicated midrange dome driver for high resolution in the particularly critical vocal range.

KH 310 II and KH 350

The KH 310 II continues this tradition, adding modern DSP technology. This allows further optimization of frequency and phase response, while increasing maximum SPL compared to its predecessor. In addition to the analog XLR input, a digital AES3id input is available. DSP control also enables automatic room alignment using the MA 1 software and measurement microphone, adapting frequency response, level and time alignment to the respective listening environment. Particularly in multichannel and immersive setups, this contributes to a consistent and homogeneous sound image.

Also new is its sister model, the KH 350. Featuring the same driver configuration and DSP control but a larger bass-reflex cabinet, it extends the low-frequency response down to 27 Hz (±6 dB) and is suitable as a full-range monitor for greater listening distances.

From the O 98 to the current KH generation, technologies have evolved fundamentally. The goal, however, has remained unchanged: to provide the most neutral tool possible, enabling sound engineers to make reliable decisions. 60 years of engineering tradition – one goal.

See also our article in the VDT Magazine. (In German)

(Translated with the assistance of AI)