signals at line-level back to the control room.
To prevent damaging the equipment in your system, it is a good idea to test your microphone cables
regularly to determine whether they have any open, shorted, reversed, or intermittent connections.
2
De-
fective cables can cause absence of signal which, as Richard Heyser once commented, is 100% distor-
tion. Even more potentially damaging, defective cables can cause loud “pops” or other noises, which if
the level is high can launch loudspeaker cones across the room.
Output Connections
There are two output connectors for each channel: an XLR-male (ref. #15) and a TRS-female (¼”
phone, tip-ring-sleeve) jack (ref. #14).
The
XLR
output (ref. #15) emulates a transformer-coupled output and can be used as either a balanced
or unbalanced signal (depending on how your cable/system is configured). When balanced, the maxi-
mum output level is +28 dBu; when unbalanced, the maximum level is +22 dBu. (These are as mea-
sured into a 600
Ω
load; the recommended load is > 10K
Ω
). At any gain setting, the balanced output is
6 dBu higher than the unbalanced output; 0 dBu = 0.7746 V rms. Polarity is: pin-1, ground;
pin-2, high; pin-3, low.
When unbalancing the XLR output, pin-3 must be tied to ground at the receiving end (i.e. the input of
the following device). Do not tie pin-3 to ground directly at the output of the RP
48
Q.
If your system requires “telescoping” the shield,
3
it is recommended that the shield be disconnected at
the output of the RP
48
Q and connected at the input to the next device in the signal chain.
The
TRS
jack (ref. #14) outputs an unbalanced signal, with a maximum level of +22 dBu, as measured
into a 100 k
Ω
load; the recommended load is > 10K
Ω
. Either a tip-sleeve (2-circuit) or tip-ring-sleeve
(3-circuit) ¼” phone plug may be used: tip is high; ring is tied to ground; sleeve is ground.
Either or both of these outputs may be used at the same time; however if the unbalanced phone jack
is to be used, it should not be plugged in or out while critical signal is being passed through the XLR
output, because doing so may cause a momentary drop in level.
As noted above, test your cables regularly to be sure that they are in proper working order.
Polarity Switch
OUT is normal; IN is inverted. (ref. #2) Use this switch to correct for polarity problems with micro-
phones or cables.
2
All ”portable cordage” (stage or studio) microphone cables always should have pin-1 (shield) connected at both ends, and
the connector shells should float and be insulated from the shield (pin-1).
3
“Telescoping” the shield refers to a line-level cable or connection where the shield is tied to ground at only one end. Com-
mon practice recommends grounding the shield at inputs and floating it at outputs when telescoping the shield for line-level
devices. Microphone cables should never have telescoping shields.
