DESCRIPTION
FRONT PANEL
0 10
Studio Pro Preamp
Two Channel Microphone Preamp
MADE IN USA
www.rolls.com
PAD
PHASE
LOW
CUT
CHANNEL 2
INPUT
INPUT
MP222
PAD
LEVEL
PHASE
LOW
CUT
CHANNEL 1
0 180
0 180
CHANNEL 2
CHANNEL 1
-30 dB
80Hz
80Hz
+48V
+48V
0 10
LEVEL
-30 dB
pwr
FRONT PANEL DESCRIPTION
Note: Channel One descriptions are identical to Channel Two
INPUT:
Standard XLR type balanced input, pin 2 is hot, for Microphones.
-30 dB Pad:
This switch changes the level of the input. When in, it attenuates the input level
down by -30 dB.
PHANTOM POWER +48V:
Turns on the internal 48 volt power supply when using phantom powered micro-
phones. It should be turned off when not in use. The Phantom Power switch is a
great way to turn off or mute a condenser mic. If you are recording and want to
turn your mic off this is the best way to mute it for either short or long periods of
time.
LEVEL:
Sets the output level as desired, for best signal to noise ratio it should be
set in the middle to start.
PHASE:
This is a variable setting from 0 or “in phase” to 180 degrees out of phase and
everything in between by adjusting the level of the knob.
LOW CUT:
This is a high pass fi lter that when depressed cuts the low end of the signal at
80Hz.
1
Rolls Corporation
5968 S 350 W
Murray, Utah
84107
1
MP222.SCH
A
5 May 2011
Title
Size:
D
ocument Number:
Date:
Rev:
Sheet
of
MP222 DUAL MIC PREAMP
FXa
+V
R7
47K
P1
W100K
R8
10K
R11
22K
R10
220K
C3
27PF
P2
P100K
C9
503
R15
22K
C7
.1U
R16
22K
C8
.1U
C10
.2UF
2
3
1
4
U2A
4560
+V
R13
22K
6
5
7
8
U1B
4560
15V REG
CH 2 (L)
VPHAN
R2
6.8K
R1
6.8K
1
2
3
J2
XLR F PC
C4
47U
+V
801-263-9053
PHASE
GAIN
HI
+V
+V
R22
10K
C13
27PF
R4
1K
R9
4.7K
R3
1K
6
5
7
8
U2B
4560
OUT
1
2
3
J3
XLR M PC
C12
47U
R19
22K
R18
10K
LOW
C11
27PF
R26
4.7K
R23
4.7K
R20
10K
VPHAN
R24
330
R27
330
1
2
3
SW7A
DPDT
4
5
6
SW7B
DPDT
R21
100
R25
100
C14
47U
4
5
6
SW2B
DPDT
1
2
3
SW3A
DPDT
Input Pad
PS27S ONLY
80hZ Low Cut
1
2
3
SW1A
DPDT
4
5
6
SW1B
DPDT
CH 1 (R)
1
2
3
J1
XLR F PC
R17
1K
2
3
1
J8
JAPDC
C30
1U
D1
1N400X
D22
1N4148
11
10
U6E
4069
9
8
U6D
4069
5
6
7
14
U6C
4069
13
12
U6F
4069
C29
503
C35
47UF
C36
10UF
D4
LDGR
C31
120PF
3
4
U6B
4069
R57
22K
R55
1K
R58
10K
R62
100
R63
1K
R60
4.7K
R53
22K
R54
10K
R59
10K
L1
50uH
Q2
IRLZ14L
+V
D21
1N5242B
D20
1N5242B
D19
1N5242B
D23
1N5242B
Q1
2N3906
C32
1000U
C37
503
1
2
U6A
4069
+V
R32
47K
C15
27PF
R33
4.7K
P4
P100K
C23
503
R40
10K
R41
10K
C24
.2UF
6
5
7
8
U3B
4560
CH 1
VPHAN
R29
6.8K
R28
6.8K
1
2
3
J4
XLR F PC
PHASE
HI
+V
R47
10K
C27
27PF
R31
1
K
R34
220K
R30
10K
OUT
1
2
3
J6
XLR M PC
C26
47U
R44
22K
R43
10K
6
5
7
8
U4B
4560
LOW
C25
27PF
R51
4.7K
R48
4.7K
R46
10K
R49
330
R52
330
1
2
3
SW8A
DPDT
4
5
6
SW8B
DPDT
R45
100
R50
100
C28
47U
4
5
6
SW5B
DPDT
1
2
3
SW6A
DPDT
Input Pad
80hZ Low Cut
1
2
3
SW4A
DPDT
4
5
6
SW4B
DPDT
1
2
3
J5
XLR F PC
R42
1K
+V
1
2
3
SW5A
DPDT
+V
1
2
3
SW2A
DPDT
D2
LDGR
D3
LDGR
R14
10K
R39
10K
VB
C22
.1U
C21
.1U
P3
W100K
+V
R38
1K
GAIN
2
3
1
4
U4A
4560
2
3
1
4
U1A
4560
2
3
1
4
U3A
4560
VB
VB
VB
VB
VB
VB
VB
VB
VB
VB
1
1
3
3
2
2
4
4
T1
P/N 827
1
1
3
3
2
2
4
4
T2
P/N 827
L2
long board trace
J7
JK3.5ST
+V
+V
SCHEMATIC
2
5
