Introduction; Audio Input - Meyer Sound LD-1A Operating Instructions Manual

Introduction

The Meyer LD-1A Line Driver combines functions
previously accessed on the control electronics units for
externally amplified Meyer loudspeakers with new
features, and locates them in a self-contained device
accessible to the sound engineer during setup and
performance. The LD-1A
• integrates different types of Meyer self-powered
speakers into a full-range main system;
• provides gain, mute, and optimized EQ controls
for six auxiliary systems;
• maintains signal integrity for long cable paths.
Channels 1 and 2, equipped to control the main system,
each have:
• a gain control, mute switch, and crossover
function;
• separate Mid-Hi, DS-2 (mid-bass), and Sub
output controls;
• a male XLR Loop connector to route the input
signal to an auxiliary channel or another device.
The six auxiliary channels (3–8) control down-fill, front-
fill, and delay systems. Auxiliary channels can also be
used to divide a main system into subsystems, allowing
independent signal levels for speakers directed at different
audience locations. Each auxiliary channel has a mute
switch, gain control, and Lo Cut and Array EQ filters. All
eight channels are fully independent from each other.
The LD-1A occupies two rack spaces and is constructed
with a 16-gauge steel chassis and
ears. This rugged design provides protection from
accidental impact, magnetic isolation from nearby
devices, and EMI immunity.
Meyer Speaker Types
The following Meyer self-powered speakers are mentioned
in this document.
MSL-4 Self-powered mid-hi speaker
CQ Series Self-powered mid-hi speaker
DS-2P Self-powered mid-bass speaker
650-P Self-powered subwoofer
PSW-2 Self-powered subwoofer
4
1 / " aluminum rack
8

Audio Input

The LD-1A presents a 10 kOhm balanced input imped-
ance to a three-pin XLR connector wired with the follow-
ing convention:
Case — Earth (AC) ground and chassis
Pin 1 — Earth (AC) ground and chassis
Pin 2 — Signal
Pin 3 — Signal
The LD-1A is balanced in and out, and consequently has
no hot (+) pin. Pins 2 and 3 carry the input as a differential
signal. Use standard audio cables with XLR connectors
for balanced signal sources.
The audio input signal should always be applied between
pins 2 and 3. Pin 1 is connected to chassis and acts as a
safety and current bleed to earth for the EMI and ESD
interference coupled onto the shield of the input cable.
Pin 1 is therefore a noisy ground, and connecting an audio
signal between pins 1 and 2, or pins 1 and 3, results in
a noisy audio signal.
Most modern balanced audio sources (electronically
balanced or transformer output) conform to the wiring
convention described above and interface correctly with
the LD-1A. However, an audio source may produce noise
if it connects pin 1 to a quiet internal audio ground, and
is then connected to pin 1 of the LD-1A (chassis/earth).
To alleviate this noise, try disconnecting pin 1 (or the
cable shield) of the audio source.
To connect an unbalanced audio source to the LD-1A,
use the following wiring connections:
RCA output
RCA output
jack
jack
–
–
+
+
–
–
•
•
Tip is Ring is
Tip is Ring is
Connect shield to – terminal (ring
positive negative
Connect shield to – terminal (ring)
positive negative
terminal terminal
terminal terminal if the source equipment is floating
if the source equipment is floating.
Do not connect the shield if the
Do not connect the shield if the
source is grounded.
source is grounded.
Differential Inputs
LD-1A input
LD-1A input
XLR
XLR
3
3
2
2
chassis/earth
1
chassis/earth
•
1
terminal
•
terminal
shield
shield