BackstageAn Engineer's Perspective

Project Whisper

by William R. Dudleston

“My goal with Whisper® was to create the most undistorted mirror of the microphone to date. Whisper was built in prototype stages using electrostatic, ribbon, Heil and and moving coil transducers. The speaker that resulted represents our best efforts and has remained essentially unchanged over the last three years. I have resisted any and all temptations to flavor the design. In short, this speaker is selfishly designed to satisfy a very personal goal.

Being a life-long recording technique fanatic*, I literally wanted Whisper to be able to discern the differences between a Schoeps-Collette, AKG 414 or  Neumann U-47 microphone in application.

To test Whisper for coloration in the design phase,  I would literally play a solo performance through  Whisper and re-record it as a live event using comparable  mic technique. This in turn would be played back  and re-recorded again. Such a process is brutally  revealing of any colorations and room dependencies. I  have learned more with PROJECT WHISPER than any  other project in which I have been previously involved  and feel grateful for the acceptance Whisper has  received in recording studios around the world.”

The design criteria for PROJECT WHISPER:

1. Minimize room ‘noise’ that normally masks the  ambient information and spatial cues of the actual  recorded event while maximizing channel separation.

2. Minimize low frequency room resonances that  mar transient detail and cause coloration in tonal  response.

3. Provide sufficient radiating surface as a function  of frequency to control dispersion and minimize  THD.

4. Maximize dynamic range and efficiency.

5. Provide a sweetspot large enough for multiple  listeners: 

Whisper’s radiation pattern is computer optimized   to provide a wide horizontal sweetspot without   interaction with the sidewalls. Its highly controlled   directivity pattern results in gradual, linear, and wideband   attenuation as the listener moves off axis; i.e. as   the listener moves off-center, the near speaker gently   drops in SPL allowing the far speaker to retain its audibility. 

Differential technology:

Whisper’s compound alignment is rooted in Harry   Olsen’s early papers more than twenty-five years ago.   (Olsen is legendary for his mathematical and acoustic   modeling of microphones). Olsen suggested such an   alignment as a way to effectively steer low frequencies. 

Whisper is the first broadband realization of this  differential technique and includes a few proprietary  twists in the free air driver design and crossover execution  by transforming the impedance. Whisper also  takes advantage of a sophisticated room algorithm  that also allows the user low frequency adjustment  capabilities.

The low frequency drivers operate in phase with  each other and combine acoustically as a pair of figure-  of-eights, one behind the other. The result: a compound  null formed at the sides of the enclosure, which  minimizes resonances and room reflections.

*Recently, while in New Orleans, Dave  MacMillan, recipient of three Academy Awards  for sound engineering, offered recognition of  Whisper’s design topology. Dave noted that  differential microphone techniques have  allowed him to capture more than 97% of dialogue  on movie sets without resulting to overdubbing.  He relies on the Neumann U-87Ai, as  do I for vocals and strings. Dave also shared stories regarding recent work with actors Gene Hackman and Kevin Costner.

Listen to Legacy Legacy Backstage Building a Legacy