JBL EON15 Introduction And General Information page 17

Measure the response at pin 1 of U4. Note in figure 2 above that the input voltage has not
been changed. (Voltage at pin 1 of J3). The other curve represents the response at the
output of the second section of the filter.
The second section is a moderate Q (Q equals about 2) high-pass filter at 55Hz. Because
of the moderate Q the filter actually peaks (The 55Hz Peak).
Verify the peak frequency, 55Hz and the peak voltage 5.1V P/P. Also verify voltages at
20Hz, 100Hz, and 1kHz and 20kHz.
If the response is incorrect check values of C35 - C37, and R59, and R60.
After obtaining proper response proceed to following section.
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