Veritone Minimum Phase Speakers

The VMPS speakers employed phase coherent drivers (for best stereo imaging) by employing first-order "minimum phase"[3] filters and drivers wired electrically in-phase.[4] Such first-order filter designs typically do not provide full low-frequency attenuation for mid-range and tweeters. Speaker designer Brian Cheney viewed high-order filters as undesirable since they were not "minimum phase", meaning their phase response was not flat with frequency. He also avoided high-order filters because he believed they often required drivers be wired electrically out-of-phase and, in his opinion, had inferior stereo imaging.

Brian also believed direct measurements should not play a significant role in the design process or evaluation of a loudspeaker. Instead, speakers should be designed and evaluated based on how they sounded. In this sense, VMPS speakers did not follow a conventional design philosophy which strived for a "flat" frequency response within a set tolerance, e.g. ±2.5 dB. In Brian's belief, most listeners could tolerate moderate fluctuations in frequency response. Furthermore, such measurements performed in the laboratory (anechoic chamber) were a poor representation of the customer's listening environment, meaning a speaker that "measured flat" in the laboratory would likely never measure flat in the customer's home. Thus, he felt that flat frequency response was both unnecessary and practically impossible to achieve, unlike the vast majority of other speaker designers throughout audio history.

Brian approached speaker design like a musician, using his ear for primary feedback. Minimum phase filters and drivers wired in-phase were used because they sounded the best. This philosophy was directly expressed in the name of his company: Veritone Minimum Phase Speakers, which taken literally means: variable tone (or frequency) minimum phase distortion speakers (drivers wired in-phase with linear phase response). The choice of term "tone" (musician's terminology) over the term "frequency" (scientist's terminology) also may have expressed his belief that the musical characteristic of the speaker was more important than scientific measurement.

The most recent VMPS speakers were a three-way design that featured ribbon drivers for the mid-range and tweeter. The high bandwidth of the mid-range "Neopanel" complemented the use of first-order filters. Woofers were used for bass and mid-bass, along with a passive radiator or port for the 626 bookshelf model. The "RM" in the speaker name (e.g. RM40) stood for "Ribbon Monitor". The RM40, RM/X, 626, RM30, RM-V60, and RM-50, all used a "Neopanel" mid-range, and a modified Aurum Cantus ribbon tweeter, except for the RM50, which used a Beston ribbon tweeter. Woofers had woven carbon fiber cones and phase-plugs. The VMPS bass management system used one or more high-compliance down-firing passive radiators that was tunable by adding or removing putty from the diaphragm.

Passive radiator mass tuning, along with level controls for mid-range and treble on the rear of the speaker, allowed the listener to tune the sound of the speaker to their listening room and personal preference. Tuning of VMPS speakers was time-consuming to achieve optimal sound and required some experience. Brian Cheney would frequently visit a customer's home, often at his own expense, to optimize the sound of the speaker system in the listening environment.

VMPS conducted a series of live versus recorded demonstrations at CES using the RM-V60 and RM50 speakers.[9]

The Live versus Recorded events led to dipole and bipole speakers designs (RM-V60 and RM-50) to better mimic the radiation pattern of live acoustic musical instruments.