User's Manual
MAC
STEREO POWER AMPLIFIER
2.2/2.3/2.4
R
Version 1.2 APRIL 2005
English
PREFACE
Dear Customer:
Thanks for choosing LTO MAC 2.2/2.3/2.4 Stereo Power Amplifier which is the result of our LTO AUDIO TEAM's
endeavors.
For LTO AUDIO TEAM music and audio are much more than a job, they are a passion and an obsession!
We have been designing professional audio products for a long time in cooperation with many of the world's major
brands.
The LTO line represents unparalleled analogue and digital products made by musicians, for musicians. With our
design centres in Italy, Netherlands, and United Kingdom we provide you with world-class designs, while our software
development teams continue to develop an impressive range of audio specific algorithms.
By purchasing our LTO products you become the most important member of our LTO AUDIO TEAM. We would like
to share with you our passion for what we design and we invite you to make suggestions, which will aid us in developing
future products for you. We guarantee you our commitment to quality, continual research and development, and of course
the best performance/price ratio.
Our LTO MAC 2.2/2.3/2.4 Stereo Power Amplifier is the result of many hours of listening and tests involving
common people, area experts, musicians and technicians. The result of this effort is the sophisticated circuit design
featuring high power and superb quality together with superior reliability and stability to provide the highest possible
audio performance.
We would like to thank all the people that worked with us to make a vision real! Our designers and LTO staff
made the MAC 2.2/2.3/2.4 Stereo Power Amplifier, a very reliable and high quality product ready for all your
venues. And thanks to their passion for music and professional audio it has been possible for us to offer you, our
most important team member, our continued support too.
Thank you very much.
LTO AUDIO TEAM
2
TABLE OF CONTENTS
1. INTRODUCTION.....................................................................................................................................4
2. FEATURE LIST.......................................................................................................................................4
3. CONTROL ELEMENTS..........................................................................................................................4
3.1 The Front Panel
3.2 The Rear Panel
4. INSTALLATION & CONNECTION..........................................................................................................6
4.1 Mains Connection
4.2 Rack Mounting
4.3 Audio Connection
a. Wiring Configuration
b. In Line Connection
5. OPERATION ..........................................................................................................................................7
5.1 Operate MAC 2.2/2.3/2.4 in Stereo Mode
5.1 Operate MAC 2.2/2.3/2.4 in Parallel (Mono) Mode
5.1 Operate MAC 2.2/2.3/2.4 in Bridged Mode
6. CAUTION FOR APPLICATION .............................................................................................................9
6.1 General Application Instruction
6.2 Caution for Speaker Connection
7. TECHNICAL SPECIFICATIONS............................................................................................................10
7.1 Specifications
7.2 Block Diagram
8. WARRANTY..........................................................................................................................................12
3
1. INTRODUCTION
Thank you very much for expressing your confidence in LTO products by purchasing our MAC 2.2/2.3/2.4 Stereo
Power Amplifier. With the MAC 2.2/2.3/2.4 you have acquired an extremely musical and flexible high power
amplifier which is based on many years of experience and finding in amplifier technology and is used through the
world in the renowned studios. The MAC 2.2/2.3/2.4 is used for professional output of stage stereo with excellent
performance. Output power can be adjusted at the user's demand, and the sound quality and protecting circuit are
both sophisticated.
The front panel presents you with 6 LEDs (power LED, protection LED, clip & signal LED for each channel) and 2
level controls, you can operate this unit more precise and easier. The output connectors are speak-on jacks and
binding post terminals, which are used for better matching. Before connecting this unit into your sound system,
please make sure it is powered down to prevent any electric shock.
2. FEATURE LIST
Sophisticated protecting circuit protects the machine from improper tampering
Excellent frequency echo and sound quality
High fidelity and low noise
Balanced XLR and 1/4" TRS input connectors
Output connectors are speak-on jacks and binding post terminals
Stereo mode, parallel mode and bridged mode are available
High-speed and low noise fan for releasing heat. The inside temperature determines the fan speed.
Indicator for the output balance, as well as status indicators of SIG and CLIP. When there is any signal is more than
100mV, the SIG LED lights up. When there is overload, the CLIP LED lights up. If anything abnormal happens to
the circuits, the CLIP LED will be continuously on, with no action from the circuits. This helps the user todetermine
which status it is in.
Solid and durable, can be mounted into a cabinet
Manufactured under QS9000, VDA6.1 certified management system
3. CONTROL ELEMENTS
3.1 Front Panel
3
2
ON
CH1
CH2
POWER
PROT
CLIP
CLIP
SIG
SIG
OFF
POWER
1
5
4
1 . Mains Switch
1
This switch turns on and off the unit by controlling both phases.
2 . Power LED
2
This Power LED lights up when the unit is powered up.
3
3. Protection LED
This red LED lights up when the thermal-protection system is working, no signal is output during this
protection period. When any overheating occurs inside the unit (the critical temperature is 800C), you should
speed up the air circulation or decrease the signal level for avoiding overheating. If the problem is corrected
the protection systems deactivate automatically, this LED goes out, and the normal amplifier operation is
resumed.
4. Clip Signal LED
4
The clip LEDs light up when distortion reaches or exceeds 0.5% approximately, which means the unit is being driven
by excessively high signal source, and you'd better adjust the level control until these LEDs go out.
4
Signal LED
These signal indicators light up when the output is more than 100mV.
5
5. Level Control
These level controls are used to adjust the output signal level, you'd better adjust them properly to avoid any distortion.
3.2 Rear Panel
11
6
7
INPUT
CONNECTION
CH-2
(+)
2
SRT
1
3
LINE
CH-1
CH-2
T(+)
R(
S(GND)
WARNING
(GND)
TO REDUCE THE RISK OF FIRE
OR ELECTRIC SHOCK, DO NOT
EXPOSE THIS APPARATUS TO
RAIN OR MOISTURE.
-
)
BREAKER
(
-)
SEE INSTRUCTION BEFORE
USING!
OFF
ON
LF 30HZ
FILTER
BRIDGED
MONO
Apparaten skall anslutas till
jordat uttag nar den ansluts
till ett natverk
BALANCED
INPUT
1.15V/20K
BRIDGED
STEREO
PARALLEL
CHANNEL 1
CHANNEL 2
LINE
(MONO)
ON
CLIP LIMT
MODEL
SERIAL
OFF
CH-1
BRIDGED INPUT
A104
8
10 12
13
9
6. Breaker
6
This switch works as fuse for protecting the unit from damage. When the unit is overloaded or the temperature
inside the unit is too high, this pushing-button will spring up and break the power supply. The power supply
will be restored with pushing the switch down again.
7
7. AC Inlet
This connector is meant for the connection of the supplied main cord. Do not insert the power cord into this
unit until voltage has been correctly set. Do not plug the power cord into the mains until the voltage has been
correctly set.
8. Input Connectors
8
These connectors include the balanced XLR servo connectors and 1/4" TRS phone jacks. It is used to connect
the input signal.
9. Output Connectors
9
These connectors include the speak-on jacks and binding post terminals, you can output the powered signal
by the specific output connectors according to the actual application circumstance.
Caution: turn off the unit before connecting the output connectors so as to avoid any electric shock!
10. Clip Limit Switch
10
Set this switch at "ON" position, once the output level is above the maximum level, the clip limt begin, which
is used to keep fixed output level for protecting apparatus. If the switch is at "OFF", this clip limt function
doesn't work.
11. LF 30Hz Filter 11
Setting this switch to "ON" is equal to adding an appropriate low-pass filter in the input circuit, which is used to protect
the speaker system from the damage caused by large subsonic frequencies.
12. Mode Selector 12
The MAC 2.2/2.3/2.4 stereo power amplifier presents three operating modes:
- Stereo Mode
In this mode, CHA and CHB operate independently (as a conventional stereo amplifier)
The CHA input signal will be output from the CHA output connector, and CHB input signal will be output from
the CHB output connector.
- Parallel Mono Mode
In this mode, CHA input signal will be output from the output connectors of both channels, detail wiring
diagram you can refer to chapter 5.
- Bridged Mode
5
In this mode, CHA input signal will be output from the bridge output connector, detail wiring diagram you can
refer to chapter 5.
13. Fan 13
This fan release the heating from the unit by accelerating the air circulation (air flowing from front to back), and
the speed is continuously variable.
4. INSTALLATION & CONNECTION
4.1 Mains Connection
Do not insert the power cord into this unit until voltage has been correctly set. Do not plug the power cord into the
mains until the voltage has been correctly set. Please ensure that the MAC 2.2/2.3/2.4 Professional Stereo
Amplifier is supplied with the correct voltage before turning on this unit. If you can't power up this unit while turning
on the Mains Switch (1), please check the Breaker (6) on the rear panel first, maybe it is pressed to reset. Otherwise,
contact the technician or qualified personnel for any service.
Caution: To reduce the risk of electric shock, do not perform any servicing other than contained in this manual unless
you are qualified to do so. Please turn off this unit before any installation and connection, esp. when you connect
your unit into the sound system. This is important to prevent damage to the unit itself as well as other consequent
speaker system. The mains connection of the MAC 2.2/2.3/2.4 Professional Stereo Amplifier is made by using
the enclosed power cord and a standard IEC receptacle, and it meets all of the international safety certification
requirements.
4.2 Rack Mounting
The most secure mounting is on a universal rack shelf available from various rack manufactures or your music
dealer. The MAC 2.2/2.3/2.4 Professional Stereo Amplifier fits into one standard 19" rack unit of space.Be sure
that there is enough air space around the unit for sufficient ventilation. If heat release is inadequate, this unit
will retain heat inside, which may cause the protection, or even a fire.
4.3 Audio Connection
The LTO MAC 2.2/2.3/2.4 Professional High Power Amplifier presents with balanced XLR connectors and 1/4" TRS
phone jack and it can be interfaced by several ways to support a variety of applications without any signal loss.
a. Wiring Configuration
Either the 1/4" TRS (Tip-Ring-Sleeve) phone jack or the XLR servo connector can be wired in balanced and unbal-
anced modes, which will be determined by the actual application status, Please wire your systems as the following
examples:
For 1/4" Phone jack
+
+
+
-
Tip
Sleeve
Tip
Sleeve
Tip
Ring
Ring
Sleeve
TS Type Unbalanced
TRS Type Balanced
TRS Type Unbalanced
For XLR connector
Pin2 (+)
Pin2 (+)
Pin3 (-)
Pin3 (-)
(Linked to Pin1 manually,
)
Pin1 (
)
Pin1 (
)
XLR Type Unbalanced
XLR Type Balanced
b. In Line Connection
For these applications, the MAC 2.2/2.3/2.4 stereo power amplifier provides XLR connectors and 1/4" TRS phone jack to
6
easily interface with most professional audio devices. Follow the configuration examples below for your particular
connection.
Balanced
Tip
Ring
Tip
Ring
Sleeve
SLEEVE RING TIP
TIP RING SLEEVE
Sleeve
1
2
1
2
3
3
Tip
1
2
3
Ring
TIP RING SLEEVE
Sleeve
Unbalanced
Tip
1
2
3
Ring
Sleeve
TIP RING SLEEVE
Tip
1
2
3
Sleeve
TIP SLEEVE
1
2
3
Centre
Screen
Tip
Tip
TIP SLEEVE
SLEEVE TIP
Sleeve
Sleeve
Tip
Tip
Ring
Ring
TIP RING SLEEVE
SLEEVE RING TIP
Sleeve
Sleeve
Tip
Centre
Screen
Sleeve
TIP SLEEVE
Tip
Centre
Screen
Ring
Sleeve
TIP RING SLEEVE
1
2
1
2
3
3
5.OPERATION
The MAC 2.2/2.3/2.4 stereo power amplifie provides three operating modes with each unit: stereo mode, parallel
(mono) mode and bridged mode, you can decide each specific operating mode according to your actual application
circumstance. Following exampleswill show you the typical connections, you can refer to install your MAC 2.2/2.3/2.4
into a sound system:
5.1 Operate MAC 2.2/2.3/2.4 in Stereo Mode
In this mode, channel A and channel B operate independently ( as a conventional stereo amplifier). The channel
A input signal will be output from the channel A output connectors, and the channel B input signal will be output
from the channel B output connectors.
Input wiring tips
BALANCED
UNBALANCED
SHIELD
GND
1
2
1
2
3
3
FROM
SOURCE
FROM
SOURCE
INPUT
INPUT
+
+
SHIELD
SHIELD
INPUT
CONNECTION
CH-2
(+)
SRT
2
1
3
LINE
CH-1
CH-2
T(+)
R(
S(GND)
WARNING
(GND)
TO REDUCE THE RISK OF FIRE
OR ELECTRIC SHOCK, DO NOT
EXPOSE THIS APPARATUS TO
RAIN OR MOISTURE.
SEE INSTRUCTION BEFORE
USING!
-
)
CHANNEL B
CHANNEL A
BREAKER
(
-)
OFF
ON
LF 30HZ
FILTER
BRIDGED
MONO
Apparaten skall anslutas till
jordat uttag nar den ansluts
till ett natverk
BALANCED
INPUT
1.15V/20K
BRIDGED
STEREO
PARALLEL
CHANNEL
1
CHANNEL
2
LINE
(MONO)
ON
CLIP LIMT
MODEL
SERIAL
OFF
CH-1
BRIDGED INPUT
A104
BRIDGED
STEREO
PARALLEL
(MONO)
Channel B
+
Channel A
+
7
Input wiring tips
BALANCED
UNBALANCED
SHIELD
GND
1
2
1
2
3
3
FROM
SOURCE
FROM
SOURCE
INPUT
INPUT
+
+
SHIELD
SHIELD
INPUT
CONNECTION
CH-2
(+)
SRT
T(+)
2
1
3
LINE
CH-1
CH-2
WARNING
(GND)
TO REDUCE THE RISK OF FIRE
OR ELECTRIC SHOCK, DO NOT
EXPOSE THIS APPARATUS TO
RAIN OR MOISTURE.
SEE INSTRUCTION BEFORE
USING!
R(
-
)
CHANNEL B
CHANNEL A
(
-)
BREAKER
S(GND)
OFF
ON
LF 30HZ
FILTER
BRIDGED
MONO
Apparaten skall anslutas till
jordat uttag nar den ansluts
till ett natverk
BALANCED
INPUT
1.15V/20K
BRIDGED
STEREO
PARALLEL
(MONO)
ON
CLIP LIMT
CHANNEL
1
CHANNEL
2
LINE
MODEL
SERIAL
OFF
CH-1
BRIDGED INPUT
A104
BRIDGED
STEREO
PARALLEL
(MONO)
Channel B
PIN 1+
+
PIN 1-
Channel A
PIN 1+
+
PIN 1-
5.2 Operate MAC 2.2/2.3/2.4 in Parallel (Mono) Mode
In this mode, the channel A input signal will be output from the output connectors of both channels. The channel
B input jack is not used, the channel A and B volumes can be adjusted independently.
Input wiring tips
BALANCED
UNBALANCED
SHIELD
GND
1
2
1
2
3
3
FROM
SOURCE
FROM
SOURCE
INPUT
INPUT
+
+
SHIELD
SHIELD
INPUT
CONNECTION
CH-2
(+)
SRT
2
1
3
LINE
CH-1
CH-2
T(+)
R(
S(GND)
WARNING
(GND)
TO REDUCE THE RISK OF FIRE
OR ELECTRIC SHOCK, DO NOT
EXPOSE THIS APPARATUS TO
RAIN OR MOISTURE.
-
)
BREAKER
(
-)
NO USING
SEE INSTRUCTION BEFORE
USING!
OFF
ON
LF 30HZ
FILTER
BRIDGED
MONO
Apparaten skall anslutas till
jordat uttag nar den ansluts
till ett natverk
BALANCED
INPUT
1.15V/20K
BRIDGED
STEREO
PARALLEL
(MONO)
ON
CLIP LIMT
CHANNEL
1
CHANNEL
2
LINE
CHANNEL A
MODEL
SERIAL
OFF
CH-1
BRIDGED INPUT
A104
BRIDGED
STEREO
PARALLEL
(MONO)
Channel B
+
Channel A
+
8
Input wiring tips
BALANCED
UNBALANCED
SHIELD
GND
1
2
1
2
3
3
FROM
SOURCE
FROM
SOURCE
INPUT
INPUT
+
+
SHIELD
SHIELD
INPUT
CONNECTION
CH-2
(+)
SRT
2
1
3
LINE
CH-1
CH-2
T(+)
R(
S(GND)
WARNING
(GND)
TO REDUCE THE RISK OF FIRE
OR ELECTRIC SHOCK, DO NOT
EXPOSE THIS APPARATUS TO
RAIN OR MOISTURE.
-
)
NO USING
(
-
)
BREAKER
SEE INSTRUCTION BEFORE
USING!
OFF
ON
LF 30HZ
FILTER
BRIDGED
MONO
Apparaten skall anslutas till
jordat uttag nar den ansluts
till ett natverk
BALANCED
INPUT
1.15V/20K
BRIDGED
STEREO
PARALLEL
(MONO)
ON
CLIP LIMT
CHANNEL
1
CHANNEL
2
LINE
CHANNEL A
MODEL
SERIAL
OFF
CH-1
BRIDGED INPUT
A104
BRIDGED
STEREO
PARALLEL
(MONO)
Channel B
PIN 1+
+
PIN 1-
Channel A
PIN 1+
+
PIN 1-
5.3 Operate MAC 2.2/2.3/2.4 in Bridged Mode
In this mode, the channel A input signal will be output from the bridge output connectors. In this case, use the
channel A volume control to adjust the volume, keep the volume control of channel B turned completely down
(counterclockwise). Bridged mode is intended for driving loads with a total impedance of 4 ohms or greater.
Input wiring tips
BALANCED
UNBALANCED
SHIELD
GND
1
2
1
2
3
3
FROM
SOURCE
FROM
SOURCE
INPUT
INPUT
+
+
SHIELD
SHIELD
INPUT
CONNECTION
CH-2
(+)
SRT
2
1
3
LINE
CH-1
CH-2
T(+)
R(
S(GND)
WARNING
(GND)
TO REDUCE THE RISK OF FIRE
OR ELECTRIC SHOCK, DO NOT
EXPOSE THIS APPARATUS TO
RAIN OR MOISTURE.
SEE INSTRUCTION BEFORE
USING!
-
)
BREAKER
(
-)
NO USING
OFF
ON
LF 30HZ
FILTER
BRIDGED
MONO
Apparaten skall anslutas till
jordat uttag nar den ansluts
till ett natverk
BALANCED
INPUT
1.15V/20K
BRIDGED
STEREO
PARALLEL
(MONO)
ON
CLIP LIMT
CHANNEL
1
CHANNEL
2
LINE
CHANNEL A
MODEL
SERIAL
OFF
CH-1
BRIDGED INPUT
A104
BRIDGED
STEREO
PARALLEL
(MONO)
Channel B+
Channel A+
+
NO USING
6. CAUTION FOR APPLICATION
6.1 General Application Instruction
The following instructions describe the common ways to install your MAC 2.2/2.3/2.4 stereo power amplifier
into a sound application system:
1. First, turn off power switch before connection.
2. Refer to chapter 5 for speaker connection
3. MAC 2.2/2.3/2.4 stereo power amplifier may be operated in one of the three modes, please slide the mode
selector (12) for the specific operating mode.
9
6.2 Caution for Speaker Connection
The output capacity of MAC 2.2/2.3/2.4 stereo power amplifier is very high, be sure to use a speaker system that has
sufficient input capacity. If the input capacity of your speaker system is lower than the rated output of the MAC 2.2/
2.3/2.4 stereo power amplifier, you can protect your speakers by connecting a fuse serially between the speaker and
the amplifier as shown below.
(+)
(-)
Fuse
+
-
Speaker
System
Output
ON
CH1
CH2
CLIP
CLIP
SIG
SIG
OFF
POWER
Use the following formula to determine the fuse capacity according to the speaker's input capacity.
Po=I2 R
I= Po/R
Po[W] : Speaker's continuous input capacity (noise or RMS)
R[ ] : Speaker's nominal impedance
I[A] : Required fuse capacity
As to the speaker cable, if you use a long one, use as thick a cable as possible to prevent deterioration of the
damping factor or power loss inside the cable.
7. TECHNICAL SPECIFICATIONS
7.1 Specifications
MAC 2.2
480
MAC 2.3
800
MAC 2.4
1400
POWER SPECIFICATIONS
2 Ohms
4 Ohms
8 Ohms
8 Ohms
4 Ohms
STEREO MODE
(Both channels driven)
20Hz~20KHz
300
450
750
205
310
575
560
900
1500
Bridge Mono Mode
20Hz~20kHz
800
1400
2500
600W
1.15V(+3.4dBu)
900W
1.15V(+3.4dBu)
1500W
1.15V(+3.4dBu)
ELECTRICAL SPECIFICATIONS
INPUT SENSITIVITY
INPUT IMPEDANCE
10K Unbalanced 20K Balanced
25Hz~25KHz +0/-1dB
-3dB points: 5Hz~50KHz
FREQUENCY RESPONSE
(at 10dB below rated output power)
30dB
<0.03%
100dB
600W
32dB
<0.03%
100dB
900W
34dB
<0.03%
100dB
1500W
VOLTAGE GAIN
DISTORTION(SMPTE-1M)
S/N ratio
GENERAL SPECIFICATIONS
Full short circuit, open circuit, thermal, ultrasonic, and RF protection stable into reactive
or mismatched loads, turn ON/OFF, muting, tried crowbar.
PROTECTIONS
CONTROLS
Front: AC switch 40-detect input level control for each channel.
Rear: stereo/ parallel/ bridged selector, 30Hz filter selector clip ON/OFF selector.
SIGNAL: 2 green LED
POWER: 1 Blue LED
CLIP:
2
red LED
INDICATORS
PROTECTION: 1 red LED
INPUT : Active balanced XLR and 1/4"(6.3mm)TRS
CONNECTORS
OUTPUT: "Touch-proof" binding posts and speak-on jacks.
POWER SUPPLY
DIMENSIONS
WEIGHT
Available for 110-120V or 220~240V AC, 50/60Hz
483(W) 400(D) 88.8(H)mm
14.4kg
16.54kg
19.02kg
10
7.2 Block Diagram
11
7. WARRANTY
1. WARRANTY REGISTRATION CARD
To obtain Warranty Service, the buyer should first fill out and return the enclosed Warranty Registration Card within
10 days of the Purchase Date.
All the information presented in this Warranty Registration Card gives the manufacturer a better understanding of
the sales status, so as to purport a more effective and efficient after-sales warranty service.
Please fill out all the information carefully and genuinely, miswriting or absence of this card will void your warranty
service.
2. RETURN NOTICE
2.1 In case of return for any warranty service, please make sure that the product is well packed in its original shipping
carton, and it can protect your unit from any other extra damage.
2.2 Please provide a copy of your sales receipt or other proof of purchase with the returned machine, and give detail
information about your return address and contact telephone number.
2.3 A brief description of the defect will be appreciated.
2.4 Please prepay all the costs involved in the return shipping, handling and insurance.
3. TERMS AND CONDITIONS
3.1 LTO warrants that this product will be free from any defects in materials and/or workmanship for a period
of 1 year from the purchase date if you have completed the Warranty Registration Card in time.
3.2 The warranty service is only available to the original consumer, who purchased this product directly from the
retail dealer, and it can not be transferred.
3.3 During the warranty service, LTO may repair or replace this product at its own option at no charge to you for
parts or for labor in accordance with the right side of this limited warranty.
3.4 This warranty does not apply to the damages to this product that occurred as the following conditions:
Instead of operating in accordance with the user's manual thoroughly, any abuse or misuse of this product.
Normal tear and wear.
The product has been altered or modified in any way.
Damage which may have been caused either directly or indirectly by another product / force / etc.
Abnormal service or repairing by anyone other than the qualified personnel or technician.
And in such cases, all the expenses will be charged to the buyer.
3.5 In no event shall LTO be liable for any incidental or consequential damages. Some states do not allow the exclu-
sion or limitation of incidental or consequential damages, so the above exclusion or limitation may not apply to you.
3.6 This warranty gives you the specific rights, and these rights are compatible with the state laws, you may also
have other statutory rights that may vary from state to state.
12
SEIKAKU TECHNICAL GROUP LIMITED
SEKAKU ELECTRON INDUSTRY (H.K.) CO., LTD.
No. 1, Lane 17, Sec. 2, Han Shi West Road, Taichung 40151, Taiwan
All rights reserved to ALTO. All features and content might be changed
without prior notice. Any photocopy, translation, or reproduction of part of this
c
manual without written permission is forbidden. Copyright
2005 SEIKAKU GROUP
NF01893-1.2
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