Atma-Sphere MP-1 Mk.II Owner's Manual

Atma-Sphere Music Systems

Phone: [phone]
FAX: [phone]
http://www.atma-sphere.com

St. Paul, MN 55105

ATMA-SPHERE® MUSIC PREAMPLIFIER

Model MP-1 Mk II
OWNER'S MANUAL

Please study this document carefully before using equipment

CONGRATULATIONS!

You have purchased one of the world's finest preamplifiers and certainly one of the most unique. It was over fifteen years in development and represents a
level of performance that others will be struggling to achieve for years to come. At the time of this writing, it is the only fully balanced differential vacuum-tube
design in the world the also supports the 600 ohm standard.

Every part of the preamplifier has been extensively tested and engineered so the product will perform flawlessly for years to come, with little if any service.

Please read the manual carefully and follow the instructions closely. If you have any questions, do not hesitate to contact your dealer or ATMA-SPHERE®
MUSIC SYSTEMS. Here's to many years of happy listening!

Sincerely,

Ralph Karsten

ATMA-SPHERE® MUSIC SYSTEMS,

160 So. Wheeler St., St. Paul, MN 55105 651-690-2246 FAX: [phone]

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 ATMA­SPHERE® 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:

* 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:

ATMA-SPHERE® 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, 160 So. Wheeler St., St. Paul, Minn. 55105. 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

NCIDENTAL OR CONSEQUENTIAL DAMAGE OF ANY KIND. I

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 above-referenced 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.

MUSIC PREAMPLIFIER SET-UP AND OPERATION

Unpack the preamplifier and its power supply carefully and save the packaging containers for future shipment if required. Warranty may be void if the unit is
shipped in a different container. If you do not have a container, contact ATMA-SPHERE® MUSIC SYSTEMS for a replacement. The replacement container is
$30.00.

Place the tubes in the appropriate sockets as shown in the tube chart elsewhere in this manual. There is no tube in the power supply.

During operation, the MP-1 gets hot! Adequate ventilation is mandatory. If the preamplifier is to be placed in a shelf or rack mount system, allow for at least 2
inches of open space above the power supply and head unit. Make sure that the preamplifier is at least a foot away from the power supply, to avoid hum
problems.

After the preamplifier and supply are properly positioned, make sure that the main power switch is in the OFF position. Connect the umbilical cable from the
power supply to the head unit. The connector operates by lining up the correct key channels and then pushing on it gently while turning the knurled threaded
locking ring. It is keyed so that insertion is possible only one way. You may now plug in the power supply. The "POWER AVAILABLE" LED should now light.
Connect the cables for the various components to be used with the preamplifier.

The MP-1 does not use a muting circuit! Allow the preamplifier to warm up and stabilize before energizing your power amplifiers. A muting circuit is
not used as it would interfere with the servo-loop operation in the output section of the preamp. Its presence in the circuit would be audible as well. Although
the DC offsets generated during warmup are low level, this may be a problem for some amplifiers and speakers.

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WARNING! DO NOT TURN ON THE AMPLIFIERS IN YOUR SYSTEM UNTIL THE PREAMPLIFIER IS WARMED UP AND STABILIZED! DAMAGE TO
SPEAKERS, AMPLIFIERS OR BOTH MAY RESULT!

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Get in the habit of turning down the volume or switching to an unused input anytime you turn your amplifier on, when you change a record, etc.

After the preamplifier is turned on, it takes about 30 seconds before it is ready for use. During the warmup of the preamplifier, one or both of the "DC
OFFSET" LEDs on the front panel may light up. This indicates that the servo circuit has detected a DC voltage at the output of the preamp and is trying to
correct it. If the indicator stays lit for more than a minute, a fault is indicated and the preamplifier must be turned off immediately to prevent
damage to associated equipment. The preamplifier will sound significantly better after about 45 minutes of operation.

OPERATING NOTES

Normally the preamplifier can be left on all the time. Adequate ventilation is required in any event. If the unit is operated continuously, have the tubes tested
once every six months. The unit will sound substantially better three hours after turn-on.

It takes time to break in the internal wiring of the MP-1. Therefore it will sound better with use. This is true of all inputs. Thus if an unused input is put to use,
expect it to require a break-in period, even if the preamp has been in use for a long time.

The MP-1 may be used with a low impedance (600 ohm) load at the input of the power amplifier. Such practice can reduce hum and buzz. An optional
terminator is available from Atma-Sphere for amplifiers without this provision.

Invariably you will have to adjust the GAIN TRIM for proper soundstage effect, because the MP-1 is a zero feedback design. Operate the control SLOWLY.
The GAIN TRIM controls are not in the audio path. They may generate a temporary DC offset while they are operated. This effect will vary depending on the
balance of the sections in the 6SN7 used in the high level section.

Due to the low impedance operation of the MP-1, cable quality between the preamplifier and power amplifier is usually unimportant. You may hear
differences in the cables, but they will be minor compared to the differences you may be used to hearing in single-ended cables. Thus we have no
recommendation for cables to be used between the preamplifier and power amplifier. On the other hand, the input cables may be very critical, depending on
the source.

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