Crown 137769-3 Wiring, Analog, Digital and Auxiliary Inputs, Speech Mic, speech DBm/dBV

DBC Network Bridge

3Setup

3.3Wiring

Chapter 1 describes how to make connections to the DBC Network Bridge. The information below describes the connections in detail.

3.3.1 Analog, Digital and Auxiliary Inputs

Analog Line Input: DB25 female connector accepts eight balanced ana- log line-level analog inputs. Pinout matches Dolby CP-650 analog output. See Table 2 on page 5.

Digital Audio Input: DB25 female connector accepts eight AES3 digital audio signals. Pinout matches Dolby #778 AES input/output card for CP- 650. See Table 1 on page 5.

Auxiliary Inputs: Two female XLR balanced inputs for speech reinforce- ment or announcements (see Figure 3.2).

Each input has an input selector switch.

•Slide it to the left (M) for microphone signal levels up to +7dBu (0dBu = 0.775 volts).

•Select the center position (L) for line-level signals up to +20 dBu.

•Slide it to the right (P) to provide 24VDC to mics requiring phantom power.

Each input has a screwdriver-set, calibrated gain control to compensate for different input source levels. The slot on the control shaft points to the gain setting. The settings are labeled for line-level input. Add 25 dB to the scale if the inputs are switched for microphone level signals.

Use a screwdriver to adjust the gain pot so that the input signal level plus gain equals roughly 0dBu. You will need to know, or estimate, the level of the input source. Setting the source signal level to approximately 0dBu will provide 20dBu of headroom in the input preamp. Some recommended set- tings are given in Table 4.

Figure 3.2 Aux Input Level Controls, XLR connectors and

Mic/Line/Phantom Slide Switch

	Pro Audio Equip-	Semi-Pro or con-	Dynamic mic,	Condenser mic,	Hot condenser
	ment	sumer equipment	speech	speech	mic, speech
dBm/dBV	+4 dBm	–10 dBV	–75 dBV	–65 dBV	–45 dBV
(nominal)
dBu (nominal)	+4 dBu	–8 dBu	–73 dBu	–63 dBu	–43 dBu
Suggested Setting	–4 (L)	+8 (L)	+20 (M)	+18 (P)	+11 (P)

Table 4. Suggested Audio Input Gain Control Settings

0 dBm = 0.775 Vrms with a 600-ohm load. 0 dBV = 1 Vrms.

0 dBu = 0.775 Vrms.

Operation Manual page 17