Mode Switch - Peavey PV 900 Bedienungsanleitung

(9) SPEAKON OUTPUTS
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PV amplifiers utilize three 4-conductor Speakon connectors, one for each channel and one for
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BRIDGE mode. Please refer to the BRIDGE MODE section of this manual before attempting to use
this mode. For each channel Speakon, the same impedance rules apply as with the binding posts.
Internally, all the Speakons are wired in what is called the "high current" mode, with pins 1+ and 2+
in parallel, and pins 1- and 2- in parallel. For the CHANNEL A and CHANNEL B Speakons, the
respective channel output appears on pins 1+ and 2+. Pins 1- and 2- are chassis ground. For the
BRIDGE Speakon, CHANNEL A appears on pins 1+ and 2+, and CHANNEL B appears on pins 1-
and 2-. Always check the Speakon connector wiring carefully before using.
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MODE SWITCH

This switch is used to select STEREO or BRIDGE mode operation. It is a conventional push-push
type, requiring a small "tool" to activate. The IN position is BRIDGE mode; the OUT position is
STEREO mode. Exercise care when selecting the BRIDGE mode. Accidental selection of this mode
could damage loudspeakers, particularly in bi-amped systems. Amplifier BRIDGE mode theory will be
covered later in this manual.
(11) DDT (DISTORTION DETECTION TECHNIQUE) SWITCH
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This switch is used to enable or defeat the DDT compressor circuitry. It is also a conventional push-
push type, requiring a small "tool" to activate. The IN position is DEFEAT; the OUT position is
ENABLE. Normally, the DDT function should be enabled to minimize the possibility of either or both
channels going into clipping or overload. With this feature defeated, a severe overload could cause
the mains circuit breaker to trip. The Peavey DDT compression system will be covered in greater
detail later in this manual.
(12) FAN GRILL
A two-speed DC fan supplies cool air to the amplifier. THIS INTAKE SHOULD NEVER BE
BLOCKED! The fan switches to high speed automatically when the unit requires additional cooling. At
idle and cool, the fan should be in low speed. The fan should never stop unless the amplifier is
switched OFF or the AC mains power source is interrupted.
(13) INPUT BARRIER STRIP
A barrier strip is provided for input connections using bare wire or spade lug connections. PV
amplifiers employ low-noise, electronically balanced input circuitry. This circuitry offers a very wide
dynamic range capable of handling virtually any input signal level, while providing excellent common
mode rejection to minimize hum and reduce interference. This strip accepts balanced and unbalanced
audio signals. The "+" and "-" terminals are the positive and negative inputs to the respective
channels. The GND terminal is the common ground to both channel inputs. For use with an
unbalanced source, connect the "-" input terminal of the channel to ground with a jumper. If the "-"
input is left floating, a 6 dB loss in channel gain will result and the floating input terminal may pick up
outside noise.
(14) COMBO INPUT CONNECTOR
The combo connector offers both female XLR and 1/4" phone jack balanced inputs for each channel.
The XLR is wired with pin 1 as ground, pin 2 positive input, and pin 3 negative input. The 1/4" phone
jack is a tip/ring/sleeve (3-conductor) type, with the tip being positive input, the ring negative input,
and the sleeve ground. It is important to realize that the XLR, 1/4" jack, and barrier strip inputs are all
in parallel; therefore a balanced input to the associated channel can be accomplished using a male
XLR, a 3-conductor phone jack, or bare wires connected to the barrier strip.
As an alternative, the 1/4" input can also be used with a regular tip/sleeve (2-conductor) type plug
commonly found on single-conductor shielded patch cords. In this case, the input becomes
unbalanced, with the tip as positive input, and the sleeve ground (the ring being grounded by the
sleeve of the plug). An additional unique feature of this 1/4" input jack is something called a "quasi-
balanced" input. The sleeve of this jack is connected to chassis ground through a relatively low-value
resistance that is part of a ground loop elimination circuit. This circuitry will provide hum-free operation
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