D-fend SA300 User Manual - page 3
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D-fend™ SA300 User Manual
Introduction
The patent pending D-fend technology utilized within your SA300 makes use of advanced, high-efficiency power conversion
techniques to provide an unprecedented level of protection for your loudspeaker system. Due to the architecture of the
D-fend technology, the SA300 is the first device within the industry to provide programmable, high-voltage, high current, full
range signal protection for large loudspeaker systems. In the past, protection circuits were employed only for use with high
frequency devices due to the limited power handling of the protection circuits. These devices attempted to protect the
high frequency driver by dissipating the undesired power into resistive elements or even light bulb components. Obviously,
these power dissipative passive techniques resulted in limited power handling characteristics, no user programmability,
limited response speed, no frequency selectivity, and life-cycle concerns.
D-fend overcomes these deficiencies and provides you with the first-ever full-range, programmable loudspeaker protection
network for use within a myriad of applications. This technology operates upon the principle of reducing the power
delivered to the load, your loudspeaker, while also reducing the net electrical current required from your amplifier. In other
words, the D-fend technology is a non-dissipative technique in that it does not dissipate the undesired power into heat or
light output; rather it reduces the amount of power that is requested from the amplifier through the use of high-efficiency
digital factoring.
Obviously, we believe D-fend is groundbreaking technology that opens a door for users such as yourself to experience
peace of mind concerning your loudspeaker investment. With the D-fend digital attenuator under complete microprocessor
control, you have at your fingertips a world of protective configurations – enjoy!
Typical Applications of D-fend
Broadband protection of a loudspeaker or loudspeaker system
By enabling the All Pass function, one can set the maximum average power level that the device will see. As with all D-fend
applications, the Attack and Release times can be adjusted to facilitate natural sounding speaker protection.
High frequency protection
RMS and Peak power can be limited to prevent thermal and mechanical failures of high frequency devices.
Low frequency protection
Woofers and subwoofers carry the burden of the most demanding loads in audio. By properly choosing peak limits, one
can maximize the performance of these devices by preventing over-excursion events and heating issues.
What NOT to do with D-fend
The D-fend SA300 unit was designed to minimize speaker failure due to accidental transients (dropped mics, feedback,
etc...) and simple over-powering. It was not designed to afford the safe use of a 2000W amplifier powering a 15W speaker.
The D-fend unit’s thermal shut-off will trigger if it encounters a scenario such as this.
Do not place the D-fend unit on the output of any tube amps (guitar or otherwise). The D-fend circuitry was designed for
solid state amplifiers.
Do not assume the SA300 is sufficiently programmed right out of the box without any additional configuration via the set-
up Wizard or Advance Programming window. The unit ships with default settings intended for quality assurance testing
purposes only.
D-fend was not designed to prevent damage in improperly designed speaker systems related to woofer/cabinet designs
(excursion), crossover frequencies, and improperly chosen transducers.