BBE Sonic Maximizer BBE 422A - Manual (Page 3)

Congratulations!
Thank you for buying the BBE 422A Sonic Maximizer. You now own a very unique signal processing device with no
other equal in the audio world. Whether you purchased the BBE 422A for your home studio or club P.A. system, you will
find the unit’s rugged construction and careful electronic design a welcome addition to your audio system.
This manual will help you use the BBE more effectively and in ways of which you may not be aware. Review of the
information contained in this manual will answer most of the common questions that our service department receives. But
if you still have questions, please feel free to call (714) 897-6766.
The BBE® Process—**What Is If
Loudspeakers have difficulty dealing with the electronic signals supplied by an amplifier. These difficulties cause such
major phase and amplitude distortion that the sound reproduced by a speaker differs significantly from the sound pro­
duced by the original source.
In the past, these problems proved unsolvable and were thus delegated to a position of secondary importance in audio
system design. However, phase and amplitude integrity is essential to accurate sound reproduction. Research shows that
the information which the listener translates into the recognizable characteristics of a live performance are intimately tied
into complex time and amplitude relationships between the fundamental and harmonic components of a given musical
note or sound. These relationships define a sound’s “sound”.
When these complex relationships pass through a speaker, the proper order is lost. The higher frequencies are
delayed. A lower order frequency may reach the listener’s ear first or perhaps simultaneously with that of a higher fre­
quency. In some cases, the fundamental components may be so time-shifted that they reach the listener’s ear ahead of
some or all of the harmonic components.
This change in the phase and amplitude relationship on the harmonic and fundamental frequencies is technically
called “envelope distortion.” The listener perceives this loss of sound integrity in the reproduced sound as “muddy” and
“smeared.” In the extreme, it can become difficult to tell the difference among musical instruments, for example, an oboe
and a clarinet.
BBE Sound, Inc. conducted extensive studies of numerous speaker systems over a ten year period. With this
knowledge it became possible to develope an ideal speaker and to distill the corrections necessary to return the fun­
damental and harmonic frequency structures to their correct order. While there are differences among various speaker
designs in the magnitude of their needs for correction, the overall pattern of correction needed is remarkably consistent.
The BBE® process is so unique that 42 patents have been awarded by the U.S. Patent Office.
*How It Works’
The BBE® process imparts a pre-determined phase correction to the high frequencies where most harmonic informa­
tion exists. This is done by breaking the signal into three sub-bands or groups: the low frequency group which is crossed
over at 150Hz, the mid-range group which is crossed over at 1200Hz and the high frequency group that handles every­
thing else up to 20kHz.
The low group is delayed about 2.5 ms (milliseconds) via a group delay within a passive low pass filter. The front panel
control allows for either a flat response, a cut or a boost of the lows at 50Hz.
The mid-range group is delayed only about 0.5ms and passes through an active band-pass filter while the high fre­
quency group is passed through a high quality VGA (Voltage Controlled Amplifier). The high group is used as a point of
reference to make dynamic amplitude corrections in both positive and negative directions to the high frequencies.
Two RMS average loudness detectors continuously monitor both the mid-range and high frequencies to compare the
relative harmonic content levels of the two bands and apply the appropriate amount of control voltage to the VGA, thereby
determining the amount of high frequency harmonic content present at the final output of the BBE® processor.