MAC
2.2/2.3/2.4
User's Manual
STEREO POWER AMPLIFIER
R
LTO
www.altoproaudio.com
Version 1.0 September 2004
English
SAFETY RELATED SYMBOLS
CAUTION
RISK OFELECTRIC SHOCK
DO NOTOPEN
This symbol, wherever used, alerts you to the presence of un-insulated and dangerous voltages within the product enclosure. These are voltages that
may be sufficient to constitute the risk of electric
shock or death.
This symbol, wherever used, alerts you to important operating and maintenance instructions.
Please read.
Protective Ground Terminal
AC mains (Alternating Current)
Hazardous Live Terminal
ON: Denotes the product is turned on.
OFF: Denotes the product is turned off.
WARNING
Describes precautions that should be observed to
prevent the possibility of death or injury to the user.
the recommended fuse type as indicated in this
manual. Do not short-circuit the fuse holder. Before
replacing the fuse, make sure that the product is
OFF and disconnected from the AC outlet.
Protective Ground
Before turning the product ON, make sure that it is
connected to Ground. This is to prevent the risk of
electric shock.
Never cut internal or external Ground wires. Likewise,
never remove Ground wiring from the Protective
Ground Terminal.
Operating Conditions
Always install in accordance with the manufacturer's
instructions.
To avoid the risk of electric shock and damage, do
not subject this product to any liquid/rain or moisture.
Do not use this product when in close proximity to
water.
Do not install this product near any direct heat source.
Do not block areas of ventilation. Failure to do so
could result in fire.
Keep product away from naked flames.
CAUTION
Describes precautions that should be observed to
prevent damage to the product.
WARNING
Power Supply
Ensure that the mains source voltage (AC outlet)
matches the voltage rating of the product. Failure
to do so could result in damage to the product and
possibly the user.
Unplug the product before electrical storms occur
and when unused for long periods of time to reduce
the risk of electric shock or fire.
External Connection
Always use proper ready-made insulated mains
cabling (power cord). Failure to do so could result
in shock/death or fire. If in doubt, seek advice from
a registered electrician.
Do Not Remove Any Covers
Within the product are areas where high voltages
may present. To reduce the risk of electric shock do
not remove any covers unless the AC mains power
cord is removed.
Covers should be removed by qualified service
personnel only.
No user serviceable parts inside.
Fuse
To prevent fire and damage to the product, use only
IMPORTANT SAFETY INSTRUCTIONS
Read these instructions
Follow all instructions
Keep these instructions. Do not discard.
Heed all warnings.
Only use attachments/accessories specified by the
manufacturer.
Power Cord and Plug
Do not tamper with the power cord or plug. These are
designed for your safety.
Do not remove Ground connections!
If the plug does not fit your AC outlet seek advice from
a qualified electrician.
Protect the power cord and plug from any physical
stress to avoid risk of electric shock.
Do not place heavy objects on the power cord. This
could cause electric shock or fire.
Cleaning
When required, either blow off dust from the product
or use a dry cloth.
Do not use any solvents such as Benzol or Alcohol.
For safety, keep product clean and free from dust.
Servicing
Refer all servicing to qualified service personnel only .
Do not perform any servicing other than those instruc-
tions contained within the User's Manual.
1
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 LTOAUDIO 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 products you become the most important member of our AUDIO TEAM. We would likeLTO LTO
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.
LTOAUDIO 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 products by purchasing our MAC 2.2/2.3/2.4 StereoLTO
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.
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
thanIndicator for the output balance, as well as status indicators of SIG and CLIP. When there is any signal is more
3. CONTROL ELEMENTS
3.1 Front Panel
ON
OFF
POWER
1
1 . Mains Switch
This switch turns on and off the unit by controlling both phases.
2 . Power LED
This Power LED lights up when the unit is powered up.
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 80 C), 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.
1
2
3
3
2
CH1 CH2
POWER
PROT
CLIP
SIG
4
5
0
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