
Heritage
The Rear Panel continued
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16.POLARITY: Place this switch in the position that provides the least electrical buzz from the unit.
17.BIAS SECTION: These two controls and sets of LEDs allow the user to properly bias the power amp. See “Setting Tube Bias” on page 9 for a complete description of how to use this section.
18.SLAVE OUT: This jack receives the same signal that is being sent to the power amp. It is useful for powering another amp (slave) from this unit’s preamp.
19.BALANCED OUT: This XLR jack is the output at the power amp in. Thus, it will include any processing done in the Preamp Out/Power Amp In loop. This signal may be used to feed an external power amplifier, mixing console or house PA system.
20.POWER AMP IN: This jack connects directly to the internal power amp for use with an external preamp. When using an external source, connect the OUTPUT of the source to this jack using a shielded instrument cable to feed the signal into the power amp section. The internal signal is disconnected when a plug is inserted into this jack.
21.PREAMP OUT: This jack is a direct post master preamp output for use with an external power amp. Connect the external amp’s input to this jack using a shielded instrument cable.
22.IMPEDANCE SELECTOR: Use this switch to match the output impedance of the amp to the speaker(s) being used (2 or 4 ohms). For help in deciding the total impedance of your system, consult the chart below.
Cabinet | Number of | Total |
Impedance | Cabinets | Impedance |
2 ohms | 1 | 2 ohms |
4 ohms | 1 | 4 ohms |
4 ohms | 2 | 2 ohms |
8 ohms | 2 | 4 ohms |
8 ohms | 4 | 2 ohms |
23.SPEAKER OUTPUTS: Two 1/4” output jacks and one Speakon® output jack supply
The two identical outputs are wired in parallel, and you can use either one, or use both. Make sure the total speaker impedance load is 2 ohms or greater.
Use speaker cables with Speakon® or 1/4" TS ends to make the connections. Do not use instrument cables as they may overheat.
NOTE: In some areas, 1/4” speaker jacks are not appropriate for use on amplifiers with high output power levels. For this reason, use the Speakon® jack instead.
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