Rolls MA252 User Manual

WARNING:

WARNING:

THE MINIMUM SPEAKER IMPEDANCE IS 4

OHMS EACH.

IF YOU CONNECT AND USE THE MA252 WITH A LOW­ER SPEAKER IMPEDANCE THAN LISTED ABOVE
YOU WILL DAMAGE THE UNIT AND POSSIBLY OTHER
EQUIPMENT THAT IS CONNECTED TO THE MA252.

MA252

20 + 20 watt

Mixer/Amplifi er

SPECIFICATIONS:

Line Input Impedance: 10K Ohms Line
600 Ohms Mic.
Power Output: 20 Watts X 2 (4 Ohms)
Voltage Gain: 55 dB Mic
30 dB Line
Maximum Supply Voltage: 24 VDC
THD: .05% typical
EIN: 3 mV
Effi ciency: 85%
Input Sensitivity: 28 mV
Bandwidth: 20Hz - 25 kHz +/- 3dB
+Size: 6.75" x 3.5" x 1.5"
Weight: 1 lb.

Salt Lake City, Utah

09/11

INPUT

CH 1

INPUT

MA252

LEVEL

CH 2

INPUT

CH 2

L

R

CH 2

CH 3

INPUT

CH 4

INPUT

L

R

010

LEVEL

LEVEL

CH 3CH 4

INPUT

CH 3

L

R

LINE
OUT

OUT
LINE

MUTE

010

CH 3CH 4

LEVEL

LEVEL

INPUT
MONO

CH 2

MUTE

CH 2
MONO
INPUT

+

RIGHT

010

LEVEL

STEREO

3.5mm

CH 4

RIGHT

+

-

SPEAKER OUTPUTS

-

CH 2

-

LEFT

-

010

CH 1

LEVEL

MA251

BOTH OUTPUTS MUST BE USED

LEFT

+

+

CLASS AMP

PS24

5 + 5 WATT MIX/AMP

PS12

MADE IN USA

www.rolls.com

HI CLASS AMP

20 + 20 WATT MIX/AMP

LEVEL

CH 1

POWER

PHANTOM

ON - OFF

OFF - ON
PHANTOM

POWER

CH 1

INPUT

• RCA Inputs, XLR Mic with Phantom Power

• Volume controls for each Channel

• Low noise, effi cient operation

• Small compact size

• Class D high effi ciency amp

The MA252 is a very compact 20 + 20 watt high effi ciency amp
with a four channel stereo mixer built in. Left and Right stereo
speaker outputs. The unit is perfect for small speakers in small
environments. Great for in ceiling and projector applications where
small size is needed along with class D low radiated heat loca­tions.

Connection guide

INTRODUCTION

Thank you for your purchase of the MA252. The MA252 is a four channel mixer/
amplifi er designed for Audio and Visual applications. Channels 1 has a micro-
phone XLR input with switchable phantom power. Channel 2 has stereo and
mono RCA inputs. Channel 3 has RCA stereo inputs and channel 4 has a 3.5mm
stereo input. The MA252 is intended for professional applications. It has a
FR4(V94-0) rated glass epoxy circuit board, and a powder coated steel chassis.
All inputs except CH 1 microphone and Ch MONO input are stereo. Outputs for
Speaker and Line are true stereo.

NOTE: THIS MANUAL ASSUMES THE USER HAS A WORKING KNOWL­EDGE OF AUDIO ELECTRONICS, BALANCED AND UNBALANCED CON­NECTIONS, AND PROPER SIGNAL LEVEL SETTING.

INSPECTION / WARRANTY

1. Unpack and inspect the MA252 box and package.
If obvious physical damage is noticed, contact the carrier immediately to make a
damage claim. We suggest saving the shipping carton and packing materials for
safely transporting the unit in the future.

2. Please visit our web site at www.rolls.com and click on the Register Your War­ranty Here button.

DESCRIPTION
REAR PANEL

SPEAKER OUTPUT: Push terminals for speaker wire.
PS24: For connection to the power supply.
INPUTS: RCA line level inputs and a balanced XLR mic input for CH1.
MUTE JACK: By shorting out the RCA jack labeled MUTE, the Speaker Outputs
will be muted.
XLR INPUT: For connection to a microphone.
PHANTOM POWER SWITCH: Switches the Phantom Power on or off for a con­denser mic on channel 1.

OFF - ON
PHANTOM

POWER

POWER

PHANTOM

ON - OFF

CH 1

INPUT

LEVEL

CH 1

LEVEL

CH 2

INPUT

CH 2

L

INPUT

CH 1

R

CH 2

INPUT

INPUT

CH 3

CH 3CH 4

INPUT

CH 3

L

R

LINE
OUT

LEVEL

L

R

OUT
LINE

MUTE

CH 2

MUTE

CH 2
MONO
INPUT

INPUT
MONO

LEVEL

+

RIGHT

STEREO

3.5mm

CH 4

RIGHT

+

-

SPEAKER OUTPUTS

-

-

-

LEFT

5 + 5 WATT MIX/AMP

CLASS AMP

MA251

BOTH OUTPUTS MUST BE USED

LEFT

+

PS12

PS24

+

FRONT PANEL

CHANNEL LEVEL: Adjusts the level of signal from the Line Input to the Line out
RCA's and Speaker outputs.

3.5mm JACK: For connection to an ipod, MP3 player or computer TRS Stereo
(left, right and ground) connection to channel 4

MADE IN USA

www.rolls.com

HI CLASS AMP

20 + 20 WATT MIX/AMP

MA252

CH 4

INPUT

010

LEVEL

010

CH 3CH 4

LEVEL

010

CH 2

LEVEL

010

CH 1

LEVEL

CHANNEL DESCRIPTION

CH 1 INPUT: XLR jack for connection to a microphone. Switchable phantom
power as labeled on unit.
CH 2 INPUTS: Stereo RCA and one mono RCA for connection to a signal source
such as a CD player, cassette deck, tuner, etc.. PLEASE NOTE WITH A MONO
INPUT AS WELL AS A STEREO INPUT, CHANNEL 2 AT CERTAIN IMPED­ANCES ON THE STEREO INPUT YOU MAY EXPERIENCE CROSS TALK BE­TWEEN THE LEFT AND RIGHT. THIS IS NORMAL OPERATION AND SHOULD
BE EXPECTED.
CH 3 INPUT: Stereo RCA jack for connection to a signal source such as a CD
player, cassette deck, tuner, etc.
CH4 INPUT: For connection to a stereo 3.5mm(1/8” jack).
LINE OUT: Stereo RCA jacks for connection to a mixer or amplifi cation device.

CONNECTION / OPERATION

To operate the MA252, properly connect cords from the sources to be mixed (mics, cas­sette decks, CD players etc.) into the channel inputs. Connect the speaker outputs to 4
Ohm or higher impedance speakers. Adjust the channel level controls for the desired

volume.

SCHEMATIC

1

4560

U3A

2

3

+B

P4

P100K

120PF

C31

V+

R29 47K

PHAN

312

10U
C30

SW2

SPST

R2

3.3K

PHANTOM

R1

3.3K
CH 1

+ - - +

123

4

J6

PUSH TERMINAL

SPEAKER OUT

C20

1K

R27

4.7K

C19

.68uF

L1

22uH

C18

.22uF

19

18

BSL

LOUT

LIN4RIN5BYPASS6AGND7AGND8VCLAMP

U2

C5

1U

C6

47U

100

R10

7

120PF

C4

4

100K

8

V+

R9

6

C3

1U

R11

10K

7

4560

8

U3B

R30

47K

+B

6

5

R3

332

C32

332

120PF

R4

10U

C29
10U
C2

3

R6

10U

C1

CH 4

J5

XLR F PC

1 2

1K

C23

R28

4.7K

C22

.68uF

L2

22uH

C21

.22uF

13

20

12

11

BSR

ROUT

PGNDL

PGNDR

GAIN114GAIN0

9

15

C16

C9

4560

U1B

+B

5

P1A

P100K X2

2

4.7K

4

J4

1U

C17

1U

RCAX4

1U

LINE OUTS

STEREO

C10

R13

100

C8 120PF

4560

R12 100K

2

R8

1U

10K

C7

P1B

P100K X2

1 3

4 6

5

4.7K

R7

235

1

3.5STJK

C27

.1uF

C26

.1uF

C25

.1uF

C24

.1uF

VCC VCC VCC VCC

1

10

17

AVCC16AVCC

PVCCL

PVCCR

TPA3122D2N

SD2MUTE

3

VCC

R26

10K

Q3

MONO INPUT

J3C

RCAX45J3D

4

1

U1A

3

MUTE

J3B

RCAX4

R16

1K

J3A

RCAX4

6

47U

+B

P2A

P100K X2

2

R14

10K

CH 3

3

1

2

4

P2B

P100K X2

1 3

4 6

5

10K

R15

10K

1

2J2B

RCAX4

5J2D

3

CH2

J2A

RCAX4

2N3904

VCC

R25

1K

220K

C15

10U

R24

C33

503

V+

R31

100

R5

10K

Q1

2N3904

C28

47U

PHAN

P3A

P100K X2

P3B

P100K X2

1 3

2

R19

4

J2C

RCAX4

4 6

5

R20

10K

R18

10K

R17

10K

6

RCAX4

C14

+B

R23

22K

R22

18K

R21

4.7K

VCC

C13

2200

C12

2200

C11

2200

D2

1N4001

D4

1N4001

231

J1

A

Rev:

MA251.SCH

5968 S 350 W

Murray Utah84107

Rolls Corporation

MA251 CLASS MIXER AMPLIFIER

Rb

Title

Size: Document Number:

47U

D1

LDRR

D3

1N4001

D5

1N4001

IN 12-24 VAC/VDC

JAPDC

1

1

Sheet of

21 October 2009

Date: