Crest Audio CA, Owner'S Manual

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13-14. Balanced 1/4" (TRS) & XLR Input Connectors.
These connectors accept input signals on balanced TRS and XLR input plugs.
See the figure at the left for information on polarity. Connectors for each chan-
nel are in parallel; the unused connectors may be used for “loop through” con-
nection to other amplifiers.
NOTE: Unbalanced “Tip/Sleeve” plugs may be used with the balanced TRS
“Tip/Ring/Sleeve” connectors. The “ring” terminal or negative input will be
connected to ground internally. When using three-pole (‘stereo’) TRS connec-
tors, make sure that the ring connection is made either to the cold (–) output of
the source equipment, or to ground. Incorrect connections may cause a 6dB loss
in level.
15. Fan Inlet Ports & Filters.
Cooling air enters the amplifier through the fan inlet ports located on the rear of the amplifier chassis.
Be sure not to block these ports when installing the amplifier or other associated equipment. Air must flow
unimpeded through these ports. Fan filters (removable without tools) are provided to minimize entry of dust
and dirt.
Internal Configuration and Control
Input XLR Polarity
CA Series amplifiers are supplied standard with the XLR configured as “Pin 2 hot” (+). On models CA2,
CA4, CA6, CA9 and CA12, an internal jumper makes it possible to alter the amplifier to “Pin 3 hot” (+).
NOTE: This jumper is NOT user configurable. Please consult your supplier or local Crest Audio service
center if you wish to have the input XLR polarity changed
On the CA18, an external XLR polarity switch is featured. (See Appendix E).
Input Sensitivity
The CA Series amplifiers have a standard input sensitivity of .775 Volts for rated power at 8 Ohms. Models
CA2, CA4, CA6, CA9 and CA12 are fitted with an internal jumper which allows optional gains of X20 or
X40. Model CA18 features an external voltage gain/input sensitivity switch (See Appendix E). Standard
and optional voltage gains/input sensitivities are detailed below.
CA2 CA4 CA6 CA9 CA12 CA18
Gain Sens Gain Sens Gain Sens Gain Sens Gain Sens Gain Sens
Std. X45 .775V X61 .775V X68 .775V X86.5 .775V X97.5 .775V X115 .775V
Opt. 1 X40 .866V X40 1.12V X40 1.32V X40 1.66V X40 1.87V X40 2.24V
Opt. 2 X20 1.73V X20 2.24V X20 2.65V X20 3.32V X20 3.74V X20 4.47V
NOTE: This jumper is NOT user configurable. Please consult your supplier or local Crest Audio service
center if you wish to have the voltage gain / input sensitivity changed.
Page 8 Crest Audio CA Series Power Amplifiers
Models CA2, CA4, CA6, CA9, CA12, CA18
Tip - Positive (+)
Ring - Negative (-)
Sleeve - Ground ( )
+
2 - Positive (+)
3 - Negative (-)
1 - Ground ( )