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
15. Fan Inlet Ports & Filters.
Tip - Positive (+) Ring - Negative
Sleeve - Ground (
)
+
1 - Ground (
)
3 - Negative
2 - Positive (+)
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 |