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M•800
High-Current Power Amplifer
Architects' and Engineers' Specifications
1. GENERAL.
The amplifier shall have a free-standing
frame with front and rear brackets for rack-mounting,
and supplied with four resilient feet suitable for table-
top placement. The amplifier shall be capable of two-
channel operation, with a switch to place the amplifier
into single-channel operation by bridging the outputs of
the two channels.
2. POWER OUTPUT.
The two-channel power ampli-
fier shall deliver a rated continuous average sine wave
power output over a 40Hz to 20kHz bandwidth of 150
watts RMS into 8 ohms per channel, 225 watts into 4
ohms, and 280 watts into 2 ohms with both channels
operating, with no more than 0.10% total harmonic dis-
tortion. In single-channel operation it shall deliver 450
watts RMS into 8 ohms and 560 watts into 4 ohms, with
no more than 0.10% total harmonic distortion.
The power amplifier shall deliver a maximum continu-
ous average sine wave power at mid band of 175 watts
RMS into 8 ohms per channel, 275 watts into 4 ohms,
and 400 watts into 2 ohms with both channels operat-
ing, with no more than 1% total harmonic distortion. In
single-channel operation it shall deliver 550 watts RMS
into 8 ohms and 800 watts into 4 ohms, with no more
than 1% total harmonic distortion.
3. POWER SUPPLIES.
ages for the amplifier shall be provided by an internal
power supply. A master power switch shall be located
on the front panel along with a green power-indicating
light.
4. INPUT CHANNEL CONNECTIONS.
input channel shall have an electronically balanced line-
level input, presenting no less than a 20k ohm imped-
ance to the source. Each input shall have an input sensi-
tivity of +4 dBu, requiring no more than 1.23V RMS to
be driven to rated output into a 4 ohm load. The input
connector shall appear on the rear panel as a female
XLR-3 type connector. In addition, each monaural input
channel shall have a parallel 1/4" TRS phone jack and a
male XLR-3 type connector, which can be used as inputs
or "thru" jacks for daisy-chaining the input signal to
another amplifier. Pin 2 of the XLR connectors, and the
tip of the 1/4" TRS phone jack, shall be non-inverting.
5. INPUT CHANNEL LEVEL CONTROLS.
aural input channel shall be equipped with a gain control
appearing on the front panel, each having 20 detent
positions, and calibrated in dB and volts.
6. FRONT PANEL INDICATORS.
have an associated five-segment LED meter appearing
on the front panel, capable of displaying –20 dB, –9 dB,
–6 dB, –3 dB, and overload. Two temperature status
6
O F 8 P A G E S
All necessary operating volt-
Each monaural
Each mon-
Each channel shall
LEDs shall appear on the front panel, one to indicate
normal operation (NORMAL) and one to indicate thermal
protection (HOT).
7. PROTECTION FEATURES.
vide delayed activation of the outputs at turn-on. Each
channel shall have a short-circuit protection circuit for
detecting excessive current flow at the output. When acti-
vated, the circuit limits the current delivered to the short,
protecting the output stage. The amplifier shall have a
thermal protection circuit to protect the power devices
from over-temperature operation. The circuit shall acti-
vate when the internal temperature crosses the safe-oper-
ating threshold and, when activated, mute the outputs
until the internal temperature cools to a safe-operating
temperature, at which time amplifier shall resume normal
operation. The amplifier shall have a fan to cool the heat-
producing internal components, drawing cool air in from
the front, and exhausting warm air out through both
sides. The fan shall operate at two speeds, the speed
being determined be the internal temperature and the
signal level present at the output. The amplifier shall
have an SCR crowbar circuit to protect the speakers
against a catastrophic amplifier failure. The circuit shall
activate in the presence of continuous DC at the speaker
outputs, and shall shut the amplifier down by opening
the internal AC mains fuse.
8. OUTPUT CONNECTIONS.
Each channel shall have a heavy-duty 5-way binding post
speaker output connector appearing on the rear panel,
with 3/4" spacing for accommodating standard double
banana plugs as well as spade lugs or bare wires. Each
channel shall have a 1/4" TS phone speaker output jack
appearing on the rear panel in parallel with the binding
post.
M•800 (International Version): Each channel shall
have a heavy-duty 5-way binding post speaker output
connector appearing on the rear panel, with 3/4" spacing
for accommodating standard double banana plugs (120V
versions only) as well as spade lugs or bare wires. Each
channel shall have a Neutrik brand Speakon
output jack appearing on the rear panel in parallel with
the binding post output.
9. AMP MODES.
The amplifier shall have a three-way
switch appearing on the rear panel for selecting the mode
of operation, which shall include stereo (two channels
in, two channels out), mono (one channel in, two chan-
nels out), and bridge (one channel in, one channel out,
bridged between both speaker outputs).
10. LIMITER.
The amplifier shall have a two-way
switch appearing on the rear panel for selecting between
(continued on page 7)
The amplifier shall pro-
M•800 (U.S. Version):
®
‚ speaker
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