A Breakthrough: Measurable and Audible
By combining—for the first time—high-power, full-bandwidth audio reproduction with unprecedented frequency and phase linearity, the Bluehorn System marks a breakthrough in studio monitoring. The best of prior monitoring systems have achieved a high degree of linearity in frequency response, but realizing the same degree of perfection in phase relationships had proven elusive.
Now, after six years of intensive research and development, Meyer Sound has achieved the supreme goal: linear frequency and phase response from 25 Hz to 22 kHz.
The extraordinary linearity of the Bluehorn System is apparent in the phase and frequency plots shown in the following figure. The difference is even more revealing in a critical listening session. The Bluehorn system faithfully reproduces fine timbral details and subtle nuances, even at the lowest levels of audibility, and it reveals the ambience in recordings from naturally reverberant spaces with breathtaking realism. Regardless of output level, the response is neutral and transparent.
Frequency and Phase Response: BLUEHORN System 6.0 M Ground Plane
Pursuit of the Ultimate
Achieving perfectly linear response from a loudspeaker system has been a lifelong goal of company co-founder John Meyer. His first breakthrough came with the HD-1 studio monitor, introduced in 1989, which for decades has set the standard for accuracy and transparency in near-field studio monitors. The HD-1 marked a major leap forward in loudspeaker linearity, yet the technology of its time could not fully overcome the inherent obstacles presented by the physics of loudspeaker systems.
Sources of Phase Shift
Complex sounds such as music comprise intricate patterns of air compression and rarefaction. High frequency sounds develop quickly and are tightly spaced, while lower frequencies develop more slowly with peaks and troughs further apart.
But it is not only frequency and amplitude that matter; changes in the relative time relationships among various frequencies during propagation can also produce audible effects. All larger, multi-way loudspeakers are inherently prone to such alterations—popularly known as phase shift—due to the mass and mechanical resistance of the drivers, crossover filtering, variations in driver alignment, and cabinet resonances.
Open-air electrostatic headphones come close to zero phase shift, thanks to their single drivers with extremely low mass. But in larger, multi-way systems that require the higher power of dynamic drivers, phase shift becomes an unavoidable compromise.
A Patented Solution
If phase shift cannot be eliminated from the acoustic output, then the only alternative is to compensate for the anomalies by introducing correction to the input signal. Phase correction in the analog domain has been implemented with some success in the past, but now the Bluehorn System applies advanced digital modeling to realize the ultimate goal: absolute phase accuracy across the entire audio bandwidth.
The first step was to develop an integrated, self-powered monitoring system capable of flat amplitude response from 20 Hz to 22 kHz at high output levels with extremely low distortion. The project involved development of a new amplifier and inclusion of the newest driver technologies from the LEO Family line arrays.
The next step was meticulous measurement of the system’s phase behavior in Meyer Sound’s anechoic chamber, creating a precise model in response to all types of complex input signals. The final step was to create computer algorithms to cancel phase anomalies of the physical loudspeaker systems, ensuring that the phase relationships in the original program input are preserved in the acoustical output. The digital filters fundamental to the Bluehorn System have been awarded a United States Patent (9,992,573 B1).
Unflattering Transparency for Seamless Translation
The acoustic output of the Bluehorn System replicates the input signal, revealing every detail. It does not introduce flattering characteristics that could prove misleading when mixes have to translate to other rooms and other systems later in the production process. Monitoring on a Bluehorn System ensure s that nothing is overlooked.
Bluehorn System in Use