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Com-Tech Power Amplifiers
Reference Manual
6 Specifications
The following specifications apply to all models in Dual
mode with 8-ohm loads and an input sensitivity of 26 dB un-
less otherwise specified.
MAP at 1 kHz:
This term refers to maximum average power
in watts at 1 kHz with 0.1% THD.
Full Bandwidth Power:
This term refers to maximum aver-
age power in watts from 20 Hz to 20 kHz with 0.1% THD.
120 VAC, 60 Hz Units:
These North American units have
dedicated transformers for 120 VAC, 60 Hz power mains.
100/120 VAC Units:
These units have two-tap transformers
that accept a 50- or 60-Hz AC line, and can be configured
for 100- or 120-VAC mains.
220/240 VAC Units:
These units have two-tap transformers
that accept a 50- or 60-Hz AC line, and can be configured
for 220 or 240 VAC.
Performance
Frequency Response:
±0.1 dB from 20 Hz to 20 kHz
at 1 watt (see Figure 6.9).
Phase Response:
±10 degrees from 10 Hz to 20 kHz
at 1 watt (see Figure 6.12).
Hum and Noise:
A-weighted, 105 dB below full band-
width power; No weighting, 100 dB below full band-
width power.
Total Harmonic Distortion (THD):
Less than 0.05% at
full power from 20 Hz to 1 kHz increasing linearly to
less than 0.1% at 20 kHz.
Intermodulation Distortion (IMD):
(60 Hz and 7 kHz
4:1) Less than 0.05% from -35 dB to full power band-
width.
Damping Factor:
Greater than 1000 from 10 Hz to
400 Hz (see Figure 6.10).
Crosstalk:
See Figure 6.13.
Common Mode Rejection Ratio (CMRR):
Better than
70 dB.
Slew Rate:
Greater than 17 volts per microsecond.
Voltage Gain:
(At the maximum level setting) 20:1 ±6%
or 26 dB ±0.5 dB. 90:1 ±6% or 39 dB ±0.5 dB with the
input sensitivity set to 0.775 volts for 70 volt output. The
following voltage gain specifications are for units with
the input sensitivity set to 0.775 volts for 8/4 ohm output:
Com-Tech 210: 38:1 ±6% or 32 dB ±0.5 dB.
Com-Tech 410: 55:1 ±6% or 35 dB ±0.5 dB.
Com-Tech 810: 64:1 ±6% or 36 dB ±0.5 dB.
Com-Tech 1610: 85:1 ±6% or 39 dB ±0.5 dB.
Power
Output Power:
See the Minimum Guaranteed Power
tables in Figures 6.1-4 for the output power specifica-
tions under a variety of conditions.
It is extremely important to supply the amplifier with ad-
equate AC power. Power amplifiers cannot add
power—they need the required voltage and current to
deliver the undistorted rated wattages you expect.
Load Impedance:
Safe with all types of loads. With 8/4
ohm output, all Com-Techs
are rated for 4 to 8 ohms in
Dual mode, 8 to 16 ohms in Bridge-Mono mode, and 2
to 4 ohms in Parallel-Mono mode. With 70 volt output,
rated loads vary among the different models for each
dual/mono mode (see the power matrices that follow).
AC Power Requirements:
All units require less than
90 watts at idle. See Section 7 for detailed information
on AC power requirements and thermal dissipation.
Low-Voltage Power Supply:
±15 VDC regulated sup-
plies are provided by a winding on the power trans-
former.
Power Cord:
An appropriate AC line cord is provided
with a nominal cable length of 3 feet (see Section 2).
Controls
Enable:
A front panel rocker switch used to turn the
amplifier on and off, and enable the remote feature.
Input Attenuation:
A detented 21-position back panel
Input Attenuation control for each channel.
Output Mode:
A back panel switch for each channel
used to select 8/4-ohm or 70-volt output.
Dual/Mono:
A 3-position back panel switch used to
select Dual, Bridge-Mono or Parallel-Mono operation.
Reset:
A back panel push button used to reset the
amplifier’s AC mains breaker.
Input Sensitivity:
A three-position switch inside the PIP
compartment used to select an input sensitivity for both
channels: 0.775 volts for MAP at 1 kHz in 8/4-ohm mode,
0.775 volts for MAP at 1 kHz in 70-volt mode, or a voltage
gain of 26 dB (Section 4.4).
