Abbingdon Music Research Reference Class Proffessional Monitor LS-77 - Manual (Page 25)

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Appendix A - Adjustment of tonal balance
If you feel that the tonal balance in the upper midrange and lower treble frequencies of the LS-77 is not correct
for you, you may wish to change the resistor combination fitted under the cover labelled “High Frequency Level
Adjustment”. Some of the required adjustment may be due to the differences in listening distance while others
may be a result of differences in taste and furnishings.
Remove this cover after removing the machine
screws that hold the cover in place using the 2mm
metric hex key (Allen Key) which is provided
with your speakers (or equivalent replacement if
lost). Under the cover you will in stock condition
find two resistors one marked 15Ù and one
marked 47R. You will also find a pair of optional
resistors included per speaker, one marked 100
and the other marked 220.
Respectively the resistor marked 100 will be
referred to below as 10R, the 15Ù as 15R and
the one marked 220 as 22R. Using different
combinations allows an adjustment of the upper
midrange and lower treble frequencies by +/-3dB
in steps of around 1.5dB.
15 Ω 47Ω
HF
LF
Designed and Engineered in Great Britain
LS 77 Professional Monitor -
Sensitivity :
Frequency Response : Peak Prog Handing : . Cont Power Handing . : Impedance : 87dB
8Ohms
150W
600W 27Hz-40kHz
IN OUT
100 1000 10000 Frequency Hz ( ) Frequency Hz ( ) 50
60 70
80
90
100
Output
dB
()
Output
dB
()
HF
LF
Level Adjustment
High Frequency