Altec Lansing 4200A, 6125A manual Rear Panel Features, Input Connectors, Input Ground Switch

Operating Manual 6125A and 4200A Multi-Channel Power Amplifier

* Model 6125A shown - Model 4200A only has channels 1-4.

7.REAR PANEL FEATURES

7.1Input Connectors

The 6125A and 4200A inputs use balanced two piece "Euroblock" style connectors. It is recommended that balanced input connections be used whenever possible to take full advantage of the amplifier's common mode rejection properties, and to reduce ground-loop problems. If a hum problem persists even though balanced inputs are used, try connecting a balanced signal to the Euroblock input with the input cable's shield lifted at the amplifier end of the cable (ie. no ground connection), but connected to ground at the signal source. This eliminates potential ground currents through the input cable yet preserves the benefits of shielding. If connecting an unbalanced signal to the Euroblock input, connect the signal wire to (+) and the cable shield to both (-) and ground.

7.2Input Ground Switch

This switch separates the input signal ground from the chassis ground on all inputs. Ground connections from an incoming signal float from the chassis ground when the switch is out. Unless there are special circumstances which require the input signal ground and chassis ground to be disconnected, it is best to leave this switch in.

7.3Multi-Channel Operation

The 6125A is essentially three stereo amplifiers in one chassis, for a total of up to six separate channels. The 4200A is essentially two stereo amplifiers in one chas- sis, for a total of up to four separate channels. Thus, the following references to Stereo, Mono, or Bridged opera- tion is with regard to each of three or two pairs of chan- nels in the amplifier. For example, Channel 1 and Channel 2 together can provide stereo, mono, or bridged operation, completely independent of Channels 3-4 or Channels 5-6 settings.

+- G

Euroblock

Connector

System

	7.4	50Hz Low Cut Switch
	Each pair of channels has a 50Hz second order
	(12 dB per octave) low-cut filter option which is applied
	to both channels within the pair. When the switch is
	pressed, the audio signal is -3dB at 50Hz, -15dB at 25 Hz,
+ - G	-27dB at 12.5Hz, etc.

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