Boulder Amplifiers 860 User Manual
Page 9
1-4
GETTING
STARTED
CONNECTING AN UNBALANCED SOURCE
Although the input connectors are of the three-pin XLR type, an
unbalanced source is easily accommodated by using a special cable. This
cable has an RCA phono type connector on the source end and a three-
pin XLR connector to go to the input of the 860 Stereo Power Amplifier.
The negative input (Pin 3) should be wired to ground only at the
RCA phono connector. This brings the negative input reference of the
860 to the unbalanced source ground, thus reducing ground loops.
Another option for accommodating unbalanced sources is to use
Boulder ABL2 Input Adapters. They convert a balanced input into an
unbalanced RCA phono input right at the rear of the 860.
Like the above cable, the negative input of the 860 is connected to
the ground of the RCA connector. However, the negative side will then
share the shield wire with the chassis ground and will not have very
good hum rejection.
UNBALANCED INPUT CABLE
3-NEG INPUT
2-POS INPUT
1-GROUND