Atma-Sphere MA-2 MkII.3 Owner's Manual

1742 Selby Av.
St. Paul, MN 55104
651- 690- 2246/FAX [phone]
atma- sphere.com

MA-2 Mk.II.3 amplifier setup and operation instructions

Installation: Place the amps in your system. Connect the preamp cable to the appropriate

input connector on the rear of the amp. If you must use the RCA input connector, make
sure a shorting jumper is installed between pins 1 & 3 on the XLR connector else a buzz
may result. Verify that both power switches are OFF and connect AC power to the AC input
connectors on the rear of the amp. Connect the negative speaker cable to the negative
output terminal and the positive speaker cable to the positive output terminal.

Setup: Install the tubes in their sockets. The middle group of six sockets (no cooling
holes) take the 6SN7GT driver tube. The front two positions must have either a new 6SN7
or if you are using NOS tubes, 6SN7GTAs or 6SN7GTBs. The other sockets are the 6AS7G
output tubes. A total compliment of six driver and twenty output tubes are required per
each chassis. Engage the main power switch and verify that the amber indicator lights.
In about 15 seconds, the filaments of all tubes should be visibly glowing orange. Wait
at least one minute, then move the Standby switch (by the red light) to the up position
and verify that the red indicator lights. The amplifier is now fully powered up.

Bias adjustment: Depress both Bias and Test switches. When first setting up the
amplifier, set the Bias control to read 1 Amp on the meter. After one hour the meter
should not exceed 1.2 Amps.

DC Offset adjustment: Depress the Meter switch by itself. Examine the reading on the
meter. If it is NOT at zero, adjust the DC offset control to bring the meter to a zero
reading. Note: Normally the DC Offset reading is quite stable. If it has changed
substantially, it may indicate that a tube has failed. Also Note: Defective tubes in the
amplifier can make a proper DC Offset reading impossible to obtain.

Once the amplifier has been fully set up, it is best to adjust the DC Offset first, then
the Bias.

Operation: At this point the amplifier is now completely operational. The amplifier can
be left in either standby or operational mode indefinitely. We recommend using the
Standby feature when not listening to the amp to prolong tube life and reduce power
consumption. If the amplifier is equipped with a new set of tubes, avoid running the
amplifier at high power until the tubes have had some time to settle in, about 10-50
hours.

Fuses: The top fuse by the power cord entries is the Filament section and is 8 Amp Slow
(4A slow for 235V). It is available usually from electrical contractor houses or Atma­Sphere. The lower fuse is the B+ filament fuse and is the same. There are 2 internal
fuses as well but failure of them usually indicates a service issue. WARNING! To avoid
fire hazard, always replace fuses with same type and rating.

© 2005 Atma-Sphere Music Systems Inc. 1742 Selby Av., St. Paul, MN. 55104 651.690.2246 / fax [phone]

1742 Selby Av.
St. Paul, MN 55104
651- 690- 2246/FAX [phone]
atma- sphere.com

LIMITED WARRANTY ON ATMA-SPHERE MUSIC SYSTEMS PRODUCTS

This warranty on your ATMA-SPHERE MUSIC SYSTEMS product, which is distributed
and warranted by ATMA-SPHERE MUSIC SYSTEMS, shall remain in effect for two (2)
years from the date of consumer purchase, provided the enclosed registration
form is completed and returned to ATMA-SPHERE MUSIC SYSTEMS within ten days of
purchase.

WHAT IS COVERED:

Except as specified below, this warranty covers all defects in materials and
workmanship. The following are NOT covered by the two year limited warranty:

Output tubes are covered for one (1) year, all other tubes are covered for 90
days, with the following exclusions, as
per the rest of the warranty:
Damage occurring during shipment (present claims to carrier).
Damage resulting from failure or inability to follow proper instructions.
Damage resulting from the performance of repairs or modifications by other than
ATMA-SPHERE MUSIC SYSTEMS.

WHAT WE WILL PAY FOR:

ATMASPHERE MUSIC SYSTEMS will pay for all labor and material expenses for
repairs covered by this warranty.

HOW TO OBTAIN WARRANTY SERVICE:

If your unit requires repairs covered by this warranty, you MUST obtain a return
authorization number from ATMA-SPHERE MUSIC SYSTEMS. You are responsible for
transporting the unit to ATMA-SPHERE MUSIC SYSTEMS, 1742 Seby Av., St. Paul, MN

55104. You must pay the initial shipping charges, but ATMA-SPHERE MUSIC
SYSTEMS will pay the return charges, if the repairs are covered by the warranty.
All products MUST be shipped in the original carton(s) or in replacement cartons
supplied by ATMA-SPHERE MUSIC SYSTEMS. Contact ATMA-SPHERE MUSIC SYSTEMS for
replacement cartons and cost.

LIABILITY IS LIMITED TO THE REPAIR OR REPLACEMENT, AT OUR OPTION, OF ANY
DEFECTIVE PRODUCT AND SHALL IN NO EVENT INCLUDE INCIDENTAL OR CONSEQUENTIAL
DAMAGE OF ANY KIND.

This warranty is not transferable. Implied warranties of merchantability and fitness for a
particular purpose are limited in duration to the length of this warranty. This warranty sets forth
all expressed warranties made with regard to the abovereferenced product. We neither assume nor
authorize any other liability in connection with the sale or any shipment of products. This
warranty gives you specific legal rights and you may also have other rights which vary from state
to state. We reserve the right to make changes and improvements in our products without incurring
any obligation to similarly alter products previously purchased.