Shure M625 Schematic

107 MM

(4-7/32 IN.)

FIGURE 1

OVERALL DIMENSIONS

Phase:

Corresponding pins of Input and Output connectors are in phase.

Impedances:

I n p u t Lo-Impedance

Hi-Impedance

O u t p u t LO-Impedance

Hi-Impedance

D e s i g n e d f o r U s e W i t h	A c t u a l I m p e d a n c e
Balanced or unbalanced 25 to	680 ohms f25%
600 ohm microphones	balanced
Unbalanced IOk t o 50k ohm	130K ohms f25%
microphones	unbalanced
D e s i g n e d f o r U s e W i t h	Actual Impedance
Balanced or unbalanced 25 t o 600	150 ohms i 1 5 %
ohm microphone level circuits	unbalanced
Unbalanced IOk t o 50k ohm	2k ohms 2 1 5 %
microphone level circuits	unbalanced

Temperature Range:

Operating: -7OC to 57OC (20°F to 135OF) Storage: -2g°C to 710C (-200F to 160°F)

Weight:

M625: 1.93 kg (4 Ib, 4 oz)

M625AM: 1.48 kg (3 Ib, 4 oz)

Dimensions:

See Figure 1

Operating Voltage and Power:

Ac Operation:

M625: 108-132 volts, 50/60 Hz, 3 watts

Dc Operation:

30 volts &20%, 5.5 mA, and 9 volts +35%, 20 mA with Gate lamp illuminated (M625AM and M625).

CONTROLS AND CONNECTORS Hold Time:

The Hold Time control sets the period of time that the Voicegate maintains unity gain after the input signal drops below the trigger level. At minimum (full counterclockwise) position, it sets the hold period to approximately '/4second; at maximum (full clockwise) position the hold time is approximately 45 seconds.

Sensitivity:

The Sensitivity control sets the level at which the input signal triggers the control circuit to increase the Voicegate gain to unity. With a high-impedance input, the trigger level may be varied from approximately -40 dBV (10 mV) with the Sensitivity control at 0 (fully counterclockwise) to -74 dBV (200 pV) with the control set to 10. Corresponding levels for the low-im- pedance input are -62 dBV (790 pV) at 0 and -96 dBV (16 pV) at 10. The Sensitivity control is adjusted by observing the Gate lamp. The Gate lamp will be illuminated when the input signal is above the control circuit trigger voltage as adjusted by the Sensitivity control, and will turn off quickly when the signal drops below this level. The Sensitivity control should be adjusted so that the lamp is off when only background noise is entering the microphone, and turns on reliably when actual speech is present.

Gate Switch:

With the Gate switch set to the OUT position, the gain of the Voicegate remains constant at unity and the Gate lamp turns on. In the IN position, the Voicegate performs its normal gain control function and the Gate lamp flashes intermittently.

Power Switch and Pilot Light (M625):

The Power On-Off switch controls the ac power applied to the M625 and the dc power supplied to all

M625AM units connected to the M625. The pilot light is illuminated when the ac power is connected to the M625 and the Power switch is in the ON position.

Microphone Input:

The microphone input is designed for low-impedance (balanced or unbalanced) microphones with 25 to 600 ohms impedance or high-impedance (unbalanced) dynamic, ribbon, or condenser microphones. The unit is not recommended for use with crvstal or ceramic microphones. The microphone impedance is selected by a slide switch above the Microphone lnput receptacle on the rear panel. The input receptacle is a professional three-pin audio connector (female).* See Figure 2 for lowand high-impedance microphone input plug connections.

NOTE: some condenser microphones produce very high output signals which may overload the input. Use of an attenuator (such as the Shure A15A In-Line Low-Impedance Microphone Attenuator) will improve this situation.

Microphone Level Output:

The microphone-level output is available at the receptacle labeled Mic. Level Output on the rear panel. It is a dual-impedance output, either low-impedance or high-impedance unbalanced, as selected by the switch above the receptacle. The low-impedance output will drive either a balanced or an unbalanced microphone input.

		SHIELD
		1-,---- --,'
MICROPHONE	MIC. INPUT	MICROPHONE	MIC. INPUT
LOW IMPEDANCE		HIGH	IMPEDANCE
(BALANCED	LINE1
MICROPHONE INPUT		PLUG CONNECTIONS
			SHIELD -
2
MIC. OUTPUT		MIC. OUTPUT
LOW IMPEDANCE		HIGH OR	LOW IMPEDANCE
( B a A N C E D	L I N E )	(UNBALANCED L I N E )

MICROPHONE OUTPUT PLUG CONNECTIONS

INPUT AND OUTPUT CONNECTIONS - FIGURE 2

*Designed to mate with Cannon XL series, Switchcraft A3 (Q.G.) series or equivalent connector.