8. Configuration
8.4 Grounding
8.5 Loudspeaker equalization
7
5
4
3
2
1
8.6 Loudspeaker Output Connections
8.7 Output power allocation
10
The chassis of the amplifier is connected with the ground of the AC power cord. As soon as
several devices are connected with each other in a signal chain, a ground loop is created. Ground
loops are caused when current flows from the analog ground plane of one device to the ground
plane of another device. A compensating current travels between the different devices on the
shields of the audio cables. This may cause hum problems.
For use with active equalized Bose
appropriate EQ Cards (Bose
®
is disconnected from any AC-mains and DC- battery connection before opening the unit.
Remove the jumper next to the EQ socket before the EQ card is installed (see picture below).
If the appropriate jumper is not removed an oscillating signal may occur. In bridge mode only
1 EQ card is needed (placed on position 1A for Ch1, 2A for Ch2, 3A for Ch3 and 4A for Ch4).
REAR OF UNIT
Use heavy gauge wire for speaker connections. The larger the distance is between the amplifier
and speakers, the larger the diameter of the wire should be. This will minimize power losses
across the wire and improve damping of the speaker. See chapter 10 'Technical Specifications' for
the minimum connected loudspeaker impedance and Appendix A for more info on wire thickness
and cable losses.
CAUTION: All amplifier outputs which run in bridge mode can have an output voltage swing of
100 Vrms (50 Vrms max when not bridged). Turn the amplifiers completely off before connecting
any loudspeaker wiring to the output terminals to avoid an electric shock.
In normal operation each output channel can deliver the same output power (in equal connected
loads), all channels driven. See examples below and chapter: Technical Specifications.
A single amplifier channel has a maximum power capability of 250 Wrms a 50 V (10 ohm),
300 Wrms at 8 ohm and 200 Wrms at 4 ohm, and in bridged mode: 500 Wrms at 100 V (20 ohm),
600 Wrms at 16 ohm and 400 Wrms at 8 ohm.
Bridge Mode: to run 2 channels in bridge mode, for example channel 1 & 2; set dipswitch 1 to 'ON'
position, connect the loudspeaker to outputs 1+ (hot) and 2+ (cold) and apply the input signal to
input Ch1 only. See also text labels next to 'dipswitch' at the rear of the amplifier.
The total output power available of the ESA 8125 can be allocated between all 8 channels is 1000 W.
The total output power available of the ESA 8250 is 2000 W, of which 1000 W can be allocated
between channel 1, 2, 7 & 8 and another 1000 W to be allocated for channel 3, 4, 5 & 6. Below
tables show examples of allocating output power between different channels.
loudspeakers please use a Bose
®
EQ Card Series II-s). To install the EQ cards, make sure the amplifier
EQ card and Jumper position:
8
1. Position 1A = channel 1; remove jumper J32
2. Position 1B = channel 2; remove jumper J34
6
3. Position 2A = channel 3; remove jumper J33
4. Position 2B = channel 4; remove jumper J35
5. Position 3A = channel 5; remove jumper J36
6. Position 3B = channel 6; remove jumper J37
7. Position 4A = channel 7; remove jumper J38
8. Position 4B = channel 8; remove jumper J39
loudspeakers controller or the
®