Lectrosonics PA8 Operating Instructions Manual - page 3
3
8 Channel Power Amplifier
Rio Rancho, NM – USA
GENERAL TECHNICAL DESCRIPTION
The PA8 uses a straightforward, low parts count design for long term reliability. The heart of the power supply is a low
radiation toroidal transformer. The toroidal transformer generates less heat than a comparable non-toroidal type, and
emits considerably less 60Hz energy. This is particularly important when the PA8 is used in close proximity to micro-
phone preamplifiers.
The input to the PA8 is fully balanced and RF filtered. The level control feeds a monolithic power amplifier. The
amplifier has a voltage gain of 26dB (x20). Each power amplifier is internally power limited to protect itself from short
circuits, excessively low impedances, or highly reactive loads. Thermal limiting is also integrated into the power
amplifier, with an intelligent shutdown mode that minimizes thermal shock to the device under extreme operation. Any
two channels may be used in the bridged mode for higher power (20W/8 Ohms or 12W/16 Ohms).
The block diagram of the PA8 is shown below.
PA8 Power Amplifier
Block Diagram
Power
Supply
Channel 1 of 8
Power
Amp
Channel
Level
Speaker
Out
+10V
-10V
+12V
-12V
Balanced In
Figure 1 - PA8 Block Diagram