HF Processing
The EON 10G2 utilizes bi-amplification topology to actively filter and separate the high
frequency signal from the low frequency signal. Consequently, the low frequency
processing circuits are similar. These frequency separation characteristics allow usage of
independent, dedicated components for accurate signal reproduction.
In the above circuit, the low frequency component of the input signal is effectively
attenuated by the 3-pole Butterworth filters consisting of U8B and U8A while the high
frequency signal is enhanced. Capacitive coupling is used throughout. These filters
effectively eliminate the low frequencies (from dc to about 1khz.) in a cascaded component
configuration. Signal level increases at +60db per decade beginning at the lower critical
frequency of 1.3 kHz. U7-A and B are used as signal integrators to increase the level to a
useful level for power amplification. Distortion and extraneous noise is almost nonexistent
due to the feedback loops associated with this circuitry. Thus, the output on pin 1 of IC U7
of 1.2Vpp is sent to the high frequency power amplifier.
Troubleshooting would best be accomplished by verifying signal waveforms at the
input /output of key IC’s using the oscilloscope. Further signal tracing from IC to IC noting
the individual voltage and signal levels at each pin. Any measurements that drastically differ
from the referenced documentation point to a defective stage or would at least indicate the
need for further examination.
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