Specifications

Model 9762 – Dual Combo Owners Manual
7.3 Polarity and Impedance Selection
The POL polarity switch inverts the polarity (or phase) of the line output
transformer. When the POL switch is depressed a relay inverts the line
output transformer polarity. Note that the polarity of the unbalanced
output is not affected as this signal is sourced prior to the line output
transformer. Thus, the polarity of the unbalanced output is always in
phase.
Low impedance microphone operation is enabled when the LO-Z
impedance switch is in the depressed state. In most cases low
impedance is desired for 50-Ohm impedance microphones. Most modern
microphones expect a bridging load and the 9762’s input circuitry
accommodates this when the impedance switch is OUT. Experiment with
this feature using a variety of microphones to obtain the best sound and
tonal qualities. Note that the signal level is affected by roughly 5-6 dB
when switching ratios. Adjust the GAIN switch to compensate for the
level change and to avoid masking tonal changes as compared to the
signal level change.
7.4 Using 48V Phantom Power
Notice the 48V LED gradually lights or dims when power is applied or
removed. Special ramping circuitry ramps the voltage up and down when
power is applied or removed to reduce large pops or bangs in the signal
output. Allow several seconds for the phantom power to reach full
voltage when enabled.
The phantom circuitry is protected against shorts for extended durations
and is designed to provide up to 50 ma of current for each channel
(which is limited to approximately 14 ma by the internal phantom feed
resistors). However, always ensure the microphone or other phantom
powered device is working properly when using phantom power.
Improper use of phantom power may damage some microphones or
other devices connected to the microphone input that are not intended
for phantom power operation.
7.5 Line Output Transformer Termination
The TERM switch enables a termination resistor on the line output
transformer. In most situations termination should be enabled to assure
the flattest frequency response. However, you may also disable
termination to affect the sound in different ways depending on the source
impedance. In many cases removing termination adds a slight amount of
“air” to the signal due to the gentle HF rise property of the transformer
when operating un-terminated.
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