Community Professional Loudspeakers
MVP™ Series II Owner’s Manual
11
About Dyna-Tech™ Driver Protection
Community’s Dyna-Tech™ circuitry provides repeatable protection for the loudspeaker system as a
limiter that converts excessive current into heat. This reduces the current, and thus the power, to the
driver. When triggered by excessive inputs, a red LED on the rear panel provides indication. When the
current limiting system is activated, there will be a noticeable drop in the system’s level. The red LED
serves as a warning to the operator about the excessive power and the need to reduce the input level to
the system.
How Community’s Dyna-Tech™ Circuitry Works
Community’s Dyna-Tech™ circuitry not only provides protection for all drivers in a loudspeaker but
offers multiple levels of protection. Dyna-Tech™ does not use light bulbs. Instead we use High Positive
Current Coefficient Resistors (HPCCR’s) specifically designed for Community with the precise
parameters needed for this application: predictable impedance and a very smooth relationship between
current and impedance.
For short term excessive power inputs occurring at high frequencies, the excess power to the HF drivers
is absorbed by the HPCCR’s wired directly in series with the high frequency driver. For longer term,
lower frequency, or more excessive inputs, a voltage sensitive relay that normally bypasses the signal
around the current limiters, is activated. It is tripped when the input voltage reaches a pre-determined
level. When open, it puts high-wattage resistors in series with the entire system to dissipate excess
current. The relay resets itself when a pre-determined reduced input voltage level is reached, taking the
resistors out of the signal path. However, if the excessive voltage condition continues, the relay will re-
open and reduce power to the drivers again.
Figure 1 – Example of MVP™ Series II Protection Circuit
There are numerous advantages to this type of voltage sensitive protection circuit. The trip point is pre-
set on the crossover to trip into protection at exactly the same time on all speakers powered from the
same amplifier. The protection circuitry does not rely on, and is not affected by, heat build up. Circuit
breakers (both mechanical and solid-state) rely on heat build-up before they will trip, which severely
limits their ability to protect a cold speaker. The trip points of these breakers are affected by heat, small
variations in speaker impedance and other component tolerances, all of which will cause them to be
erratic. Because the circuit does not rely on heat, it can react almost instantaneously to excessive increases
in level. The circuit will also remove protection as soon as a reduced level is reached, it does not need to
wait for a circuit breaker to cool down. This means your speaker can operate at its full dynamic range and
still react quickly to excessive musical transient peaks without worry of damaging the speaker. It also
means your speaker is protected from the instant the power amplifier is plugged into it and/or turned on.
