Marshall Amplification JCM 900 4100 - Front Panel Controls; Input Jack; Channel A Preamp Gain; Channel B Lead Gain

1. INPUT
Connects the instrument to the
amplifier. (Use a high quality screened
lead).
2. CHANNEL A PREAMP GAIN
Sets the GAIN level for CHANNEL A.
Lower settings for clean sounds, higher
settings for medium drive and crunch.
3. CHANNEL B LEAD GAIN
Sets the GAIN level for the boosted
CHANNEL B. Lower settings for more
classic lead tones, higher settings for
maximum drive and sustain.
4, 5, 6, & 7. TREBLE, MIDDLE, BASS &
PRESENCE
Passive rotary EQ circuit. The
interactive controls provide a wide
range of tonal variation for both
channels.
8. CHANNEL A REVERB
Controls the amount of REVERB on
CHANNEL A.
9. CHANNEL A MASTER VOLUME
Controls the overall VOLUME level of
CHANNEL A.
10. CHANNEL B REVERB
Controls the amount of REVERB on
CHANNEL B.
11. CHANNEL B MASTER VOLUME
Controls the overall VOLUME level of
CHANNEL B.
12. CHANNEL B ‘ON’ PUSH SWITCH/LED
Indicates red when CHANNEL B is
selected either manually or by remote
footswitch.
13. FOOTSWITCH
Connects the remote dual footswitch for
Channel A/B switching and Reverb On/
Off (part # PEDL-91004).
14. STANDBY SWITCH
This switch is used in conjunction with
the mains POWER switch (item #15) to
‘warm up’ the amplifier before use and
to prolong the life of the output valves.
When powering up the amplifier always
FRONT PANEL FUNCTIONS
0
1
POWER STANDBY
VOLUME REVERB
VOLUME REVERB PRESENCE BASS MIDDLE TREBLE LEAD GAIN GAIN
INPUT
FOOT
SWITCH
MASTER
(CH. B)
PUSH ON
(CH. B)
MASTER
(CH. A)
PREAMP
(CH. B)
PREAMP
(CH. A)
Model 4100
2
010
4 6
8 2
010
4 6
8
2
010
4
6
8 2
010
4 6
8
2
010
4 6
8
2
010
4 6
8
2
010
4 6
8
2
010
4 6
8
4
020
812
16
2
0
10
4 6
8
15. 14. 13. 12. 11. 10. 9.