Specifications

1961 OPERATORS’ MANUAL6
Hz: Frequency selector switch. Available frequencies are:
Frequency
Switch
1st
position
2nd
position
3rd
position
4th
position
5th
position
6th
position
Bass
20Hz 32Hz 50Hz 80Hz 125Hz 200Hz
Low-Mid
100Hz 160Hz 250Hz 400Hz 650Hz 1kHz
High-Mid
500Hz 800Hz 1.2kHz 2kHz 3.2Khz 5kHz
Treble
2.5kHz 4kHz 6kHz 10kHz 15kHz 25kHz
Octave: Filter bandwidth (or 'Q') control. Variable between 0.3 and 3
octaves.
Cut/Boost: Filter cut or boost control providing ±18dB of control.
In: Each filter section has an associated Bypass switch. When the
switch is pushed in, the red LED below will illuminate, indicating
that the equaliser is in circuit.
Low-Pass: This is a continually variable 12dB per octave shelving, low -
pass filter which may be adjusted over the range 2.5kHz to
56kHz.
In: This Bypass switch, when pushed in will illuminate the red LED,
indicating that the Low - Pass is in circuit.
EQ
Out: This acts as a Master Bypass switch. If the switch is depressed,
the associated Out LED illuminates. This indicates that all the
equaliser sections, including the high and low-pass filters, are
out of circuit. This Master Bypass switch also bypasses the tube
section of the output stage; if it is desired to use the tube output
stage without equalisation, the EQ Master Bypass should be left
In circuit and all the individual Bypasses should be switched Out
of circuit. When the Master Bypass switch is set to Out, the
individual equaliser status LEDs are extinguished.