Input Ground Switch; Multi-Channel Operation; Input Level Controls; Stereo/Mono Switches - Ashly TRA-4150 Operating Manual

Operating Manual - Powerflex Multi-Channel Power Amplifier
*
P o w e r f l e x
6250 shown -
P o w e r f l e x
4400 only has
inputs 1-4.
7.2

Input Ground Switch

This switch separates internal circuit ground from
the chassis ground on all inputs. Ground connections from
an incoming signal are always connected to internal cir-
cuit ground, but float from the chassis ground as long as
the switch is out. Unless there are special circumstances
which require the circuit ground and chassis ground to be
connected, it is best to leave this switch out.
7.3

Multi-Channel Operation

The Powerflex 6250 is essentially three stereo
amplifiers in one chassis, for a total of up to six separate
channels. Similarly, the Powerflex 4400 is essentially two
stereo amplifiers in one chassis, for a total of up to four
separate channels. Thus, the following references to Ste-
reo, Mono, or Bridged operation is with regard to each
pair of channels in the amplifier. For example, Channel 1
and Channel 2 together can provide stereo, mono, or
bridged operation, completely independent of Channels 3-
4 or Channels 5-6 settings (6250 only).
7.4 50Hz Low Cut Switch
Each pair of channels has a 50Hz second order
(12 dB per octave) low-cut filter option which is applied
to both channels within the pair. When the switch is
pressed, the audio signal is -3dB at 50Hz, -15dB at 25 Hz,
-27dB at 12.5Hz, etc.
7.5

Input Level Controls

Input Level Controls attenuate input signal from
0dB down to - . For best performance, Ashly recommends
that the level controls be operated at full level (0 dB at-
tenuation).
In STEREO mode, each level control corresponds
directly to the input signal on its respective channel.
8
PUSH PUSH PUSH
115V
PUSH PUSH PUSH
In MONO Mode, the input signal connected to
channels 1, 3, or 5 are used to drive channels 2, 4, or 6
respectively, and the level controls for channels 1, 3, and
5 likewise control channels 2, 4, and 6. When switched to
Mono mode, channels 2, 4, or 6 level controls become in-
active.
In BRIDGED mode, the level controls function
the same as in mono mode.
7.6 Stereo/Mono Switch
Powerflex amplifiers are comprised of two (4400)
or three (6250) stereo amplifiers, each operating indepen-
dently of the others, with Stereo/Mono switching avail-
able for each channel pair. If this switch is set to Stereo
mode, the channel pair operates as two discrete amplifi-
ers, each with its own input connection and level control.
Switching to Mono mode allows one input (chan-
nel 1, 3, or 5) to drive both channels of a stereo channel
pair. Pressing the Mono switch disables the channel pair's
other input connection, as well as its level control. The
first channel's input and level control now determines the
signal to both channels.
7.7 Dual Channel/Bridge Mode Switch
Bridging a power amplifier is the process whereby
two channels are supplied the same signal, with the sec-
ond channel's phase inverted 180°. The speaker is then
connected across the (+) output connections of each chan-
nel, resulting in twice the power to the speaker that either
channel could deliver by itself. Since in Bridge Mode both
connections have voltage present, never connect or touch
either speaker wire to ground. In the Powerflex 6250, use
Bridge mode for 70V applications as well.