Page 26
Reference Manual
Macro-Tech
®
24x6 & 36x12 Power Amplifiers
Controls
Enable:
A front panel pushbutton used to turn the amplifier
on and off.
Level:
A 31-position detented rotary potentiometer for
each channel located on the front panel used to control
the output level.
Sensitivity:
A three-position switch located inside the PIP
compartment used to select one of three input sensitivities
for both channels: a sensitivity of 1.4 volts for full rated
output, a fixed voltage gain of 26 dB or a sensitivity of
0.775 volts for full rated output (see Section 4.4).
Ground Lift:
A two-position back panel switch used to
isolate the signal ground of the phone jacks from the
chassis (AC) ground.
Reset:
A back panel switch for each channel used to reset
the circuit breaker which protects each channel’s power
supply.
Indicators
Enable:
This amber indicator lights when the amplifier’s
Enable switch is turned on and the low voltage power sup-
ply is operating. See Section 4.2.
Signal/IOC:
Each channel has a green front panel indica-
tor that flashes to show amplifier output. If a channel’s out-
put waveform differs from its input by 0.05% or more, the
indicator flashes brightly to show distortion. This function
provides
proof of distortion-free performance.
ODEP:
Each channel has an amber front panel indicator
that shows thermal-dynamic energy reserve. Normally,
each ODEP indicator is lit to show available reserve en-
ergy. In the rare event that a channel has no reserve, its
indicator will dim in proportion to ODEP limiting. An ODEP
indicator may also turn off under other conditions (see
Sections 4.2 and 4.3.1).
Input/Output
Input Connector:
Two balanced ¼-inch phone jacks on
the back panel and two balanced 3-pin female XLR
connectors on the factory-installed P.I.P.-FX (see Section
8 for information on optional PIP modules).
Input Impedance:
Nominally 20 k ohms, balanced.
Nominally 10 k ohms, unbalanced.
Input Sensitivity:
Settings include 0.775 V and 1.4 V for
rated output, or a fixed voltage gain of 26 dB (see Section
4.4).
Output Signal:
Unbalanced, two-channel.
Output Connector:
A pair of color-coded 5-way binding
posts (for banana plugs, spade lugs or bare wire) for each
channel.
Note: Channel 1 (3600) of Macro-Tech 36x12
models has two pair of binding posts.
Output Impedance:
Less than 10 milliohms in series with
less than 2 microhenries (see Figure 6.3).
DC Output Offset:
(Shorted input) ±10 millivolts.
Protection
Macro-Tech amplifiers are protected against shorted,
open or mismatched loads; overloaded power supplies;
excessive temperature, chain destruction phenomena,
input overload damage and high-frequency blowups.
They also protect loudspeakers from input/output DC and
turn-on/turn-off transients.
If unreasonable operating conditions occur, the patented
ODEP circuitry will proportionally limit the drive level to
protect the output transistor stages, particularly in the case
of elevated temperature. Transformer overheating will re-
sult in a temporary shutdown of the affected channel;
when it has cooled to a safe temperature, the transformer
will automatically reset itself. Controlled slew-rate voltage
amplifiers prevent RF burnouts. And input overload pro-
tection is provided by current-limiting resistance at the in-
put. Refer to Section 4.3.
Turn On:
Four second turn-on delay with no dangerous
transients. Contact Crown’s Technical Support Group to
change the turn-on delay time.
Construction
Black coated steel chassis and aluminum front panel with
Lexan overlay. Chassis utilizes specially designed flow-
through ventilation from front to side panels.
Cooling:
Internal heat diffusers with forced air cooling for
rapid, uniform heat dissipation.
Dimensions:
19 inch (48.3 cm) standard rack mount (EIA
Std. RS-310-B), 3.5 inch (8.9 cm) height, 16 inch (40.6
cm) depth behind mounting surface, 2.5 inch (6.35 cm) in
front of mounting surface.
Approximate Weight:
Center of gravity is approximately
6 inches (15 cm) behind the front mounting surface.
Macro-Tech 24x6: 45 lbs, 4 oz. (20.5 kg). Shipping weight
is 54 lbs, 11 oz. (24.8 kg).
Macro-Tech 36x12: 50 lbs (22.7 kg). Shipping weight is 59
lbs. (26.8 kg).
