Engl E670 - Ground Lift Switch

A2 outputs! That means if one cabinet is connected to and another to
, theiractual overall impedance and the impedance setting selected on the
ampmustmatch!
Impedance table for two cabinets connected in parallel:
(|| stands for a parallel circuit)
16 ohms || 16 ohms -> 8 ohms overall impedance: OK;
the correct selector setting is 8 ohms.
8 ohms || 8 ohms -> 4 ohms overall impedance: OK;
the correct selector setting is 4 ohms;
4 ohms || 4 ohms -> 2 ohms overall impedance: definitely not OK;
not an option because 2 ohms lies below the 4-ohm minimum;
16 ohms || 8 ohms -> 5.3 ohms overall impedance: not recommended;
the closest selector setting would be 8 ohms, but the output power
would not be distributed equally to the two cabinets!
16 ohms || 4 ohms -> 3.2 ohms overall impedance, not recommended;
the closest selector setting would be 4 ohms, but the output power
would not be distributed equally to the two cabinets!
8 ohms || 4 ohms -> 2.6 ohms overall impedance: definitely not OK,
not an option because 2.6 ohms lies below the 4-ohm minimum.
This is A1 jack, which is wired in parallel to . A speaker must
be connected to this or the A2 jack - or in parallel mode, to both - to switch the amp
from Standby to ON. The power amp signal is routed to outputs A1 and A2 when
isdeactivated.
Use (77)to settheimpedancefor the speakerconnectedtothis
output orthe overall impedance when two cabinets are connected to and
.
Never operate the power amp without a
sufficientload,otherwiseyoumaydamageordestroyit!
An electronic surveillance system constantly monitors if a plug is inserted into the
speakeroutputsA1,A2,B1andB2(78,76,75,and73).Ifaplugisnotinsertedintoone
of these jacks, the power amp is disabled and the Status LED flashes in a distinctive
pattern to alert you to this. However, the system cannot check if a speaker is actually
connectedtotheotherendofthecord.That'syourjob.
Always check and verify that the amp's output impedance matches the connected
cabinets'impedance!Youcanusethe (87)todothis.
This switch severs the circuit connecting the amp's internal ground to the wall
receptacle's ground terminal. You can set the switch to when you
haveconnectedasignalprocessororpowerampandwanttopreventthetwodevices'
groundsfromformingagroundloopthatmanifestsinannoyinghumming.
A ground loop is an extraordinary condition. Under ordinary
circumstances, ensure the button is set to to earth the amp to the mains
ground,therebypreventingungroundedlinenoise!
Output A1
Output A2
Poweramp Output A's A2
SpeakerA/B
ImpedanceSelector A
Output A1
A2
ImpedanceTestSystem
Ground Floated
Ground
78 POWERAMP OUTPUT A: OUTPUT A1
IMPORTANT NOTE, please read and heed:
79GROUNDLIFTSWITCH
Please note:
28