LD PA 400 - User Manual

PA 400
PA 800
PA 1000
PA 1600X
USER’S MANUAL
In choosing a power amplifier from the LD Systems' PA series range, you have chosen a power
amplifier designed using traditional, reliable technology with a conventional toroidal
transformer power supply, but super-fast, latest generation high-performance bipolar
transistors. With the exception of the PA400, all amplifiers operate in Class H mode, i.e., the
operating voltage changes depending on signal level. This improves efficiency as the power
amplifier gives off substantially less heat. The circuit is completely balanced with a feedback
of only 20 dB, resulting in a very fast amplifier with only slight distortion. In particular, the
rough, unpleasant sound associated with TIM distortion is suppressed. Of course the
amplifiers feature all of the standard protection circuits including a clip limiter.

Summary

Design and Construction

Installation and Setup

Power Supply Requirements

Warranty Information

Front Panel Operation

Air Intake Ports

Explains the function of air intake ports and their maintenance.

Power Switch and Soft Start

Details the power switch function, soft start, and noise suppression.

Status Indicators

Describes the operational status LEDs including SIGNAL and CLIP.

Volume Control Usage

Explains input sensitivity and volume control usage for optimal dynamics.

Rear Panel Connections

Air Outlets and Ventilation

Explains the function of rear air outlets for cooling and circulation.

Input Connectors

Identifies unbalanced jack and balanced XLR input sockets for each channel.

Speaker Output Connectors

Details Binding Post and Speakon connectors for speaker connection.

Mode Selection Switch

Describes the switch for selecting Stereo or Mono Bridge Mode.

Fuse and Ground Lift

Explains the reset-able fuse and the Ground Lift switch for hum removal.

PA1600 X Special Features

Low-Pass Filters

Details the adjustable low-pass filters for each channel with cutoff and bypass.

Low-Cut Filter

Describes the low-cut filter to protect loudspeakers from extreme lows.

Technical Specifications

Performance Data

Details power output, operating class, damping factor, distortion, and S/N ratio.

Physical and Electrical Specs

Lists input level, impedance, fan speed, dimensions, and weight.

Protection and Features

Lists protection circuits, mains fuse, and specific PA1600X features.

Connector and Housing Details

Details input/output connectors, wiring, and housing materials.

LD PA 400 Specifications

General

Circuitry	Class AB
Frequency response	20 Hz - 20 kHz
Input sensitivity	0.775 V
Indicators	Power, signal, clip, protect
Line inputs	2
Speaker outputs	2
Weight	8.1 kg
Product type	Power amplifier
Output power (4 ohms)	400W
Input impedance	10kΩ
Protection circuits	short circuit
Controls	Power switch
Line input connectors	XLR
Speaker output connections	Binding posts
Cooling	Fan
Power Output (4Ω)	400W