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HIGH OUT JACKS
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Again, as per previous crossover discussion, this 1/4" jack supplies high frequency out signals from the activated crossover for
patching to this amplifier and/or additional power amplifier inputs. Unlike the low-frequency crossover output, that is automatically
routed to the associated channel, the high-frequency output signal must be patched to some suitable input in order to complete the
bi-amped system. This 1/4" jack provides an impedance balanced (TRS) output. Although 2-conductor balanced (TRS) cables will
provide better noise immunity, single conductor shielded (tip/sleeve) cables can also be used.
INDUSTRIAL AND COMMERCIAL INSTALLATIONS
For commercial and other installations where sustained high-power operation is required, the amplifiers should be mounted in a
standard 19" rack. It is a good idea to leave a rack space between each amplifier in the stack to prevent heat builup between units
and induced hum from transformer magnetic fields. Regardless, an adequate cool air supply must be provided for the amplifier
when rack mounted. The internal fan must have a source of air that is not preheated by other equipment. The amplifier will start up
in low speed fan operation and will normally stay at low speed unless sustained high-power operating levels occur. Then, as
temperatures in the amplifier heat sinks increase, thermal-sensing circuitry will cause high-speed operation to occur. Depending
upon signal conditions and amp loading, high-speed fan operation may continue or the fan may cycle continuously between high
and low. This behavior is by design. If cooling is inadequate, however, the amplifier thermal-sensing system may cause temporary
shut down of the unit, indicated by the front panel THERMAL PROTECT LED. Inadequate cooling may be due to preheated air,
reduced air flow resulting from blockage of inlet/outlet ports, amplifier overload, or short circuit conditions. Depending upon the
available cooling air, operation should be restored relatively quickly, and the power LEDs on both channels will again be
illuminated. In any event, action should be taken to correct the cause of the thermal shutdown. If the amplifier is not severely
overloaded or shorted and air flow is normal in and out of the amplifier, then steps should be taken to provide a cooler
environment for all the amplifiers.
As a general rule, most home and studio requirements will never cause high-speed fan operation. High-speed operation may
indicate that you have not taken the necessary steps to provide adequate cooling. The PV® Series should never be operated in a
fully enclosed cabinet.
BRIDGE MODE
When a 2-channel amplifier is operated in the Bridge mode, it is converted into a single-channel unit with a power rating equal to
the sum of the power rating for each channel, at a load of twice that of the single-channel rating. For example, the PV 2 is rated at
750 Watts RMS per channel into 2 Ohms. The Bridge rating is 1500 Watts RMS into 4 Ohms (minimum load). Bridge mode
operation is accomplished by placing the MODE switch in the BRIDGE position, using only the BRIDGE twist lock connector or the
red binding posts for the output, and using the CHANNEL A input. All CHANNEL B input functions are defeated and serve no
purpose now. Bridge mode operation can be used to drive sound distribution systems in very large public address applications.
Another common use for the Bridge mode is in subwoofer applications where very high power levels are required to reproduce
extremely low frequencies with adequate headroom. Such enclosures usually contain 2 or 4 loudspeakers to handle the power
levels involved. When using Bridge mode, the connected enclosure impedance must be 4 or 8 Ohms — never below 4 Ohms.
DDT™
Peavey's patented DDT (Distortion Detection Technique) limiter circuit enables the sound technician to maximize the performance
of the amplifier/speaker combination by preventing the power amplifier from clipping. When the onset of clipping is detected, the
limiter engages to prevent damage to the loudpeakers and degradation of sound quality. For this reason, DDT should always be
enabled.
2 STAGE OVERCURRENT PROTECTION
Another unique feature of the PV® Series power amplifiers is a 2 stage overcurrent protection scheme. The first stage of
overcurrent protection uses a preset current threshold to prevent excessive current through the output devices when driving loads
of 2 ohms impedance or higher (4 ohms bridged). The second stage dramatically decreases the output of the amplifier if the
detected load impedance is one ohm or less, effectively muting the affected channel and keeping the output devices within their
Safe Operating Area.
When the second stage current limit engages, output will be extremely weak, and the front panel DDT LED will be glow steadily,
pulsing with the input signal, but dimly. The signal will not return until the overload is removed and the input level is reduced below
clipping. This behavior is by design. If this condition occurs, try reducing the input level so that the DDT LED only lights on the
loudest peaks. If it continues, inspect for shorted speaker cables, or a total load impedance of less than 2 ohms per channel / 4
ohms bridged.
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