Owner`s manual

TROUBLESHOOTING TIPS (continued)
Distortion
Check the output tubes (6SN7, upper right in diagram) and the associated 6SN7 in front for defects. If any of the
output pins of the main output XLR connectors other than pin one is at ground potential, distortion may result.
One or both channels out
Check all tubes. If OK, there are two fuses located on the right side of the power supply circuit board (as you
face the front of the unit), one for each channel. Replace with the same type slow blow fuse (.75 Amp for 117
Volt units, .35 Amp for 230 Volt units). If you are not qualified, do not remove the cover. Hazardous or lethal
voltages are present with the cover removed. Refer service to qualified service personnel.
Noisy phono section
Replace the 12AT7s in the phono section. AVOID 'NOS' (New Old Stock) TYPES AT ALL COST! Despite claims
to the contrary by NOS tube suppliers, all NOS 12AT7s are just too noisy if you intend to use low output moving
coil cartridges. All brands, including Mullard, Telefunken, etc. will be noisy regardless of manufacture. The quiet
ones were purchased decades ago.
Low output from one channel
Check tubes.
DC Offset LED lit up continuously
Check the 6SN7s (rear right two on circuit board) in the channel associated with the LED.
NEVER, EVER, USE TWEEK OR ANY CONTACT ENHANCER ON TUBE SOCKETS! “Tweek” is resistive at
vacuum-tube voltages. This will destroy the tube sockets and possibly the circuit boards!
If none of these suggestions help, contact your dealer or ATMA-SPHERE MUSIC SYSTEMS.
USAGE SUGGESTIONS
For use with sub woofer and other bi-amplified systems: Have your crossover updated with correctly balanced
inputs. If this is not possible, a specialized balanced-to-unbalanced sub woofer-optimized line transformer is
available from Atma-Sphere and works quite well. If you do not use one of these techniques, it is likely that you
will encounter a buzz.
When ordering from any source, specify tubes for a differential circuit (matched tube sections). The 12AT7s at
the input of the phonograph section and the 6SN7 at the input of the high level section (right front on circuit
board) are perhaps the most audible. We find NOS 12AT7 tubes to be too noisy.
Harmonics of the power line frequency have been shown to be far more problematic for good sound then all
other types of power line problems (RF, spikes, etc.) put together. Be sure that the conditioner you use can filter
line frequency harmonics, particularly the fifth (300 Hz on 60Hz line). A pronounced 5th harmonic can cause
any power transformer to become mechanically noisy! Beware that any line conditioner with a transformer in it
can add harmonics if operated at more than 50% of its capacity.
The power cord can have audible effects! A good cable is recommended.
The Sound Anchors equipment stand and the Silent Running stands are the finest we have seen. They are highly
recommended. Use them in conjunction with the Ultra Resolution Technologies vibration damping platform.
NavCom Silencers or other anti-vibration pads can be helpful as are tube damping rings.