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Bridged Mono
"Bridged Mono" mode is used to tie the two amplifier channels together thereby doubling the power of the amp into a mono
load. To configure the amplifier for "Bridged Mono" operation, change the output configuration switch located on the back
panel of the amplifier. When in the "Bridged Mono" setting connect the input signal to CH2 input (CH1 input is disabled in
"Bridged" mode). Connect the speaker(s) to the two red or (+) speaker terminals. The CH2 (+) terminal is the high (+, or
non-inverting) side, and the CH1 (+) terminal is the low (-, or inverting) side. When connected in this way, each channel
"sees" one-half the impedance of the speaker(s) that are connected between them. If an 8 ohm speaker is used, each channel
will see a 4 ohm load. Therefore it is not recommended that any load lower than 8 ohms be connected between the speaker
terminals in this mode of operation. Use Parallel Mono operation for lower impedance loads. (CH1 input and CH1 level
c o n t rol are disabled).
1) C A U T I O N : In "Bridged Mono" operation, the output connections are actually a balanced output configuration. T h i s
means that both output terminals have voltage present (neither one may be grounded). If through negligence you should become the
ground, the voltages may be dangerous.
2) Never change the output configuration switch from one mode to another with the amplifier powered "ON". Always make sure that the
proper connections have been made for the operating mode selected before turning power "ON".
Parallel Mono
"Parallel Mono" mode allows both channels to be driven simultaneously with a single (mono) input. To configure the amplifier for
Parallel Mono operation, change the output configuration switch located on the back panel of the amplifier. Connect the input source to
CH2. Connect speaker(s) to CH1 or CH2 or both. (CH1 input and CH1 level control are disabled).
N o t e : To daisy chain the input signal to additional amps, use the unused input connector on CH2.
7 0 V Distribution Systems
The PXm amplifiers can be used to drive 70V distributed systems using Carver Professional output distribution transformers (available
separately from your Carver Professional dealer. Order XO125 for the PXm250. Order XO200a for the PXm450 and for the PXm900
order the XO450a. Connect one transformer to the output of each amplifier channel to deliver 125 watts for the PXm250, 225 watts for
the PXm450 and 450 watts for the PXm900 to the 70-volt system. As with all 70-volt systems, step down transformers are required at
each loudspeaker. The XO125 has taps for 25Vand 70Vsystems, the XO200Ahas taps for 25V and 70Vsystems and the XO450Ah a s
taps for 70Vand 100Vsystems. When using the amplifier in a 70Vdistributed system with transformers, it is advisable to set the “High
Pass” filter to “On” and the “Cut-off Frequency” to 80 Hz. This prevents frequencies below 50 Hz from possibly saturating the
transformers, and appearing to the amplifier as a short circuit.
7 0 V D i rect Drive
The PXm900 has sufficient output voltage to drive a 70V distributed system without the use of a step-up transformer, in the "Bridged
Mono" mode. The PXm900 can deliver 900 watts to the 70-volt system in the "Bridged Mono" mode.
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High Pass Filter Cut Off Frequency
The High Pass Filter Cut Off frequency is independently selectable for each channel at a frequency of either 30Hz or
80Hz.
In the 30Hz position this filter performs much like a subsonic filter, eliminating power-robbing low frequencies below
the audible or useable range. In the 80Hz position the High Pass Filter protects sensitive high frequency drivers from
low frequency transients that could damage voice coils or diaphragms. The 80Hz position also is effective when used
in conjunction with a 70V distributed system by preventing low frequencies from saturating the transformers. The DIP
Switch positions for the High Pass Filter Cut Off are position #2 for CH2 and position #6 for CH1. The High Pass
Filter Cut Off is set at the factory to the 30Hz position, however the High Pass Filter is disabled when the unit is shipped
from the factory.
NOTE: When using the PXm amplifiers, or any high powered amplifier, in multi-way systems
as a high frequency amplifier, it is recommended that a capacitor be used in series with the high
frequency drivers. This will ensure that the delicate high frequency voice coils are protected in
case of a catastrophic amplifier failure.
Clip Limiter
The Clip Limiter when engaged will reduce the negative effects of clipping when the source signal
overdrives the amplifier. It should be noted that if the input signal contains clipped signals when
it arrives at the amplifiers input, the Clip Limiter will not eliminate this unwanted distortion. The
Clip Limiter is engaged independently for each channel on the DIP Switch located on the rear
panel of the amplifier at switch position #3 for CH2 and switch position #7 for CH1. The Clip
Limiter is set at the factory to its disabled position.
Input Sensitivity
The input sensitivity can be changed to 1.5Vrms. The input sensitivity is set independently for
each channel on the DIP Switch located on the rear panel of the amplifier. Input sensitivity is
switched at position #4 for CH2 and at position #8 for CH1. The input sensitivity is set at the
factory to .775Vrms for rated output.
Output Wi r i n g
(See page 18 for recommended Carver Professional A c c e s s o r i e s . )
Use heavy gauge cable for speaker connections. As the distance between the amplifier and the speakers increases, the cable diameter
should be larger to minimize power loss across the cable, and to improve the damping of the speaker. Cable thickness specifications (or
gauges) get smaller as the cable gets thicker, thus a 14 gauge cable is thicker than 16 gauge cable. Use the following as a guide: up to 25
feet use 16 gauge cable, up to 40 feet use 14 gauge cable, up to 60 feet use 12 gauge cable, up to 100 feet use 10 gauge cable, up to 150
feet use 8 gauge cable and up to 250 feet use 6 gauge cable. This will ensure that the resistance of the speaker cable is less than 5% of 4
ohms, resulting in a transmission loss of less than 0.5dB. Class 1 (NEC) cable must be used.
Multi-way Binding Posts: This output connector can accept a spade lug, bare wire, or banana connections (except CE approved
versions). Be sure that all the fine strands of the cable are twisted together and contained within the connector. If even one strand is loose
and can touch the adjacent terminal, a short circuit may result.
Polarity
Loudspeakers must be connected with consistent polarity for correct phasing between them. Incorrect phasing will do no physical harm,
but frequency response will be affected. The key is to make sure that all speakers connected to the speaker terminals are hooked up the
same way. Connect the black post (-) at the speaker output of the amplifier to (-) on the back of the speaker, and the red post (+) on the
speaker output of the amplifier to (+) on the back of the speaker.
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Dip Switch