JBL LSR28P, Technical & Service Manual

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The curve with a boost centered around 35Hz is the result of selecting the +2dB bass boost
switch SW1F. If this curve is not obtained but other responses are correct change Q1.
•
The curve with a drooping response below 80Hz is the result of selecting the -2dB bass cut
switch SW1E.
•
The curve with extended bass response is the result of selecting the Bypass switch SW1D.
•
The curve with flat response down to about 30Hz with a well-damped roll-off below 30Hz is
the standard response with all switches down.
AUDIO PRECISION LSR28PLb vs Bass Adjustments
-30.00
-25.00
-20.00
-15.00
-10.00
-5.000
0.0
5.0000
10.000
LEVEL(dBu)
10 100 200
FREQ(Hz)
The response at any point along the signal path relies on an accurate frequency response
characteristic from preceding stages. The curves in the figure allow ready identification of a
stage, which is causing frequency response errors. An inaccuracy in a single section can result in
gross inaccuracies in the overall response result.