Yamaha PC4002M - Manual (Page 4)

INTRODUCTION
The PC4002/4002M are top-quality, high-power ampli­
fiers, and with their impressive output combined with low
distortion figures, are ideally suited to studio monitoring
use, but at the same time are rugged enough to act ad­
mirably as a professional amplifier where top quality is
required. Their features include:
Large, illuminated peak meters (PC4002IVI only) for
instant confirmation of output levels. In addition to the
meters, which provide a faster response than VU meters,
LED clip level indicators are provided for instant signalling
of clipping.
Robust mechanical design for practical use. The
PC4002/4002M is, of course, 19" rack-mountable, with
front handles which also help protect the controls and
meters. Though designed to be extremely reliable, and to
withstand the rigours of life on the road, if access is ever
needed to the interior of the unit, this has been made easy,
with bulb replacement, meter adjustment, etc, being pos­
sible from the front panel. Power-cable hooks also act as
a support if the amplifier is used in a vertical position, and
four feet ensure airflow if the amplifier is shelf-mounted.
Multiple protection circuits safeguard the amplifier and
speaker system against abuse and faulty connections.
Front panel status indicators show the following:
if bridged (BTL) operation has been selected, high-speed
fan operation, and overload/power-up muting, as well as
a power indicator. The power switch is recessed into the
front panel, to prevent accidental resetting.
Decibel-calibrated input attenuators, detected for
extra accuracy. This makes for predictable and repeatable
setting-up on the road, and accurate input sensitivity ad­
justments. In multi-amplifier setups, precise tracking be­
tween amplifiers can be easily achieved. Input attenuator
knob locks prevent accidental resetting of levels.
Power-up muting for about six seconds after the power
has been turned on gives protection to speakers after
power-on, avoiding the "thump" which can easily blow
out cones.
Each channel is provided with input connectors
which are male and female balanced XLR, as well as bal­
anced 1 /4-inch phone (using a TRS-type connector). This
allows convenient bridging to another amplifier, as well
as adapter-free connection to almost any mixer.
Twin power supplies and transformers for the power
amplifier stage add reliability and add quality to the sound
of the PC4002/4002M.
Bridged mode (BTL) from the A channel input is easily
obtained by the use of one switch on the back panel, and
connecting the ( + ) terminals of the CH-A and CH-B
speaker outputs to one speaker.
Figures that match the features. With a THD of less
than 0.005% at 215W into 80, and a figure which is still
less than 0.01% at 700W (mono) into 80, the
PC4002/4002M is one of the cleanest high-power am­
plifiers on the market - making it especially useful for studio
monitoring operation. Channel separation, damping factor
and signal/noise figures are as good as or better than you
would normally expect from an amplifier of this calibre,
while the slew rate is an impressive 60V/ixS (stereo)-fast
enough to handle the fastest transients.
Speaker terminals are screw-post type, with the ability
to accept heavy-gauge speaker cable for maximum fidelity.
An automatic two-speed quiet twin-fan cooling
system prevents thermal overload, and cuts in at the low
speed when heat-sink temperatures exceed 60°C, and at
high speed above 80°C. The washable fan filters are re­
movable from the front panel, eliminating the need to re­
move the amplifier from a rack when the filters need to
be cleaned.