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The RX-7 is a sophisticated mixer with many functions. Details on important functions are
shown below in order for you to get the best operation and performance and also to avoid
mistakes in operation.
* Phantom Power Switch
The switch on the front panel of both IPM-7 and PHM-7 provides for 48V DC phantom
powering for condenser microphones through the input connectors on the modules. Fig. 16
elaborates on the phantom powering circuit, and shows that balanced outputs of associated
equipment should be connected to the inputs. Connection with unbalanced outputs does not
damage the RX-7, but may cause troubles like noise, etc. Accordingly, turn the switch "off"
whenever unbalanced inputs are connected.
Function Details
The Lift position on the ground lift switch cuts the phantom power even if the phantom power
switch is "ON". The ground lift switch therefore must be set at "Normal" position whenever
phantom power is required.
* Phase Switch
The use of more than one microphone for picking up the same program source may cause an
out-of-phase condition resulting in acoustic phasing cancellations. The acoustic phasing
cancellation is particularly noticeable in the low frequencies and the low frequencies may not
be sufficiently reproduced. Accordingly, all inputs on the mixer must be in principle in the
same phase. The following method is advisable for checking inputs for correct phase.
1. Place mics 1 and 2 close to the same sound source with appreciable bass, setting the phase
switches at Normal positions.
2. Adjust the level of both mics, using the input level switches and trim controls on the mixer.
3. Listen to the blend of the two mics through the cue headphones.
4. Reverse the phase of mic 2 Phase switch.
5. If the bass increases, leave the switch in the Reverse position. If the bass decreases, return
the switch to the Normal position.
6. Check all other mics in the same manner, comparing with mic 1.
In some cases it may be desirable to intentionally reverse the phase of certain mics for
improving the sound.
(Fig.
16)
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