8.Audio Path Block Diagram; 7.1. Internal Signal Path Polarity - powersoft Digimod 3004 PFC4 User Manual

10 : 8.Audio path block diagram

IN 2 +
47 Ohm
IN 2 –
47 Ohm
1 BY12
JR3 2
3 BY22
JR4 4
5 BY42
6 BY32
+VCC
OUT 2 –
-VCC
FIGURE 13: Audio path block diagram for channel 1 & 2 on Control Board 1.

10 : 7.1. Internal Signal Path Polarity

In order to increase the power's supply energy stor-
age efficiency, signals coming from channel pairs 1-2 and
3-4 are polarity reversed, one with respect to the other
within the pair, when entering the amplifier. This ensures
a symmetrical use of the voltage rails: if, for example, both
channels' 1 and 2 input signals are going through a peak
at the same time, channel 1's energy will come from the
positive voltage rails while channel 2, whose polarity is
reversed with respect to channel 1, will be fed energy from
the negative voltage rails. In this manner, the power supply
will work symmetrically, with one channel catered by the
positive rails and the other by the symmetrical negative
rails. Channel 2's signal will be polarity reversed once more
to ensure that both channels output with the same polarity
as their corresponding input signals.
For this reason it is very important not to invert the po-
larity of either channels before feeding them to the module.
A double polarity inversion (the first by the user inserting
the input signal and the other by the amplifier's internal
circuitry) results in no inversion at all. If this were the case,
both channels would be weighing on only one side (positive
or negative) of the power supply's voltage rails. This would
result in an inefficient use of the power supply's energy.
10K
IN 2 +
470p
IN 2 –
470p
10K
47 Ohm
47 Ohm
2.7k
2K7
PWMCH2
G
GATE4
GATE3
G
Channels 3 & 4 are managed by the Control Board 2 in the same way.
10K
10K
47 Ohm
47 Ohm
2.7k
PWMCH1
CONTROL BOARD
Please pay special attention in using balanced inputs on
all measurement equipment (such as oscilloscope probes)
when you are bench testing.
Channel 1
input
Channel 2
input
FIGURE 14: Internal signal path polarity with ex-
ample input signals. Both channels 1 and 2 are
fed the same sine signal.Channels 3 & 4 are man-
aged by the Control Board 2 in the same way.
IN 1 + IN 1 +
47 Ohm
470p
IN 1 – IN 1 –
47 Ohm
470p
BY11 6
5 JR2
BY21 4
3 JR1
BY41 2
BY31 1
2K7
+VCC
G
GATE1
OUT 1 +
GATE2
G
-VCC
Amp
first polarity second polarity
inversion inversion
Connections | 13
Channel 1
output
Channel 2
output