Ashly MFA-8000, MFA-6000 manual Rear Panel Features, Balanced Inputs, Unbalanced Inputs

Operating Manual - MFA-8000 and MFA-6000 Power Amplifier

Normal	Stereo
Bridging	Parallel Mono

0

-2

-

-6

-20

-10

Channel Two

0

-2

-

Parallel Mono Mode ties Ch.1 and Ch.2	-6
inputs together, using seperate level controls
for each channel.	-20
Bridge Mode uses Ch.1 input and Ch.1
	-10
level control, overriding stereo/mono switch.
Take output from two red binding posts.	Channel One

Input

Ground

(-) (+)

(-) (+)

Channel Two Input

Chassis	Channel One Input
Ground
	(Bridged Input)

Figure 7: Input Section

7.REAR PANEL FEATURES

7.1	Inputs
	The standard input panel of the MFA series amps
is equipped with balanced 1/4" tip-ring-sleeve (TRS)
phone jacks, balanced XLR jacks, and balanced screw-
terminal inputs. The three types of connectors are inter-
nally wired in parallel and may be used with balanced or
unbalanced connections. The inputs are configured for
pin 2 hot, meaning that a positive voltage applied to pin 2
will result in a positive output voltage across the speaker
terminals. Pin 2 of the XLR jack is equivalent to the tip
of the 1/4" TRS jack. An optional input transformer is
available on all MFA amplifiers.		Figure 7.1: Balanced Input Connections

Balanced Inputs

It is recommended that balanced input connec- tions be used whenever possible to reduce ground-loop and environment-induced hum and noise. The (+) signal is on pin 2 of the XLR, and the tip of the phone jack. The (-) signal is on pin 3 of the XLR, and the ring of the phone jack.

Unbalanced Inputs

If an unbalanced input connection is used, then the (-) connection (XLR pin 3) should be connected to input ground ( XLR pin 1). If the 1/4" input jack is used unbalanced, the use of a mono (tip-sleeve) plug will au- tomatically tie the (-) connection to input ground. Never float pin 2 or pin 3 when using an unbalanced signal.

Figure 7.1a: Unbalanced Input Connections

8