Martin Audio 7.1.2Unbalanced inputs, Martin Audio - MA1.3s Amplifier, English, Contents, Print

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CH. B	INPUT	CH.B LINK		CH.A LINK			CH. A	INPUT
			LINK / BRIDGE A+B
			GAIN	GAIN
			CH.B	CH.A
			STEREO	GAIN		123
				ON	20dB
				OFF	23dB
XLR		1/ 4“			26dB
Pin 1	Scrn	Sleeve			29dB
					32dB
2	Pos		Tip
					35dB
3	Neg		Ring
					38dB
Must be grounded			2 30-24 0V	5 0-60Hz4 1dB
			Current consump tion: 8.7A			678

The input impedance is high enough (20k ohms balanced) to allow ”daisy-chaining”, or multiple parallel input connections. The headroom of the input circuits will also accept the maximum output level from virtually any low-level signal source. Balanced signals are less sensitive to AC hum and radio interference. The source impedance should be less than 1k ohms to avoid high frequency losses if long cable runs are used.

To daisy chain amplifiers, use the XLR-male connector, labeled Link, provided on each channel. It is connected in parallel with the Neutrik Combo jack on each input.

7.1.2Unbalanced inputs

To connect an unbalanced source, tie pin 3 (ring on TRS jack) down to the shield of the connector. If you leave one pin disconnected, you will lose 6 dB.

A better method for using unbalanced sources is shown in Figure 8. This is similar to the connection for balanced lines, but pin 3 is connected to the shield at the source. The hum and noise rejection for the cable is equivalent to that for a balanced line. To minimize hum in the audio, use balanced inputs whenever possible.

Unbalanced line connection

Balanced line with unbalanced equipment

For two-channel (stereo) operation, use both channels A and B. For tandem stereo or bridged mono operation, use only one of the inputs. See operating modes for more details.

7.2Connecting speakers

Speaker connections are made via the two Neutrik NL4FC Speakon connectors. The Speakon connector is designed for high power loudspeaker use and meets all worldwide safety requirements.

Connections:

The Speakons are wired:

Channel A

Pin +1, Pin - 1 = Output A

Pin +2, Pin - 2 = Output B

Channel B

Pin +1, Pin -1= Output B

The right Speakon, Channel A, has both channel A and B outputs available, so is useful for bridging and bi-amp operation (see bridged mono operation on page 7). The left Speakon, Channel B, carries only the channel B output.

GUIDES

ENGLISH

All material © 2007. Martin Audio Ltd. Subject to change without notice.

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Martin Audio – MA1.3s Amplifier