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.
Most cartridges with more than 0.15mv seem to work fine. The higher the output
the better, tempered with a musical presentation. Some recommended choices:
The Grado Statement and Master Reference, Lyra series, Dynavector and Micro
Benz. There are of course many others.
If a high output cartridge is used, a jumper plug that replaces one of the
phono tubes can be installed to reduce gain. Contact Atma-Sphere for details.
A moving coil step-up transformer option is also available for cartridges of
less than 0.1mV. It can be used to reduce noise, even with higher output
cartridges, at a slight cost of musicality. The technique is to use the
aforementioned jumper plug as well. The gain tends to be similar to the normal
phono section without the transformer, only with about 15 db less noise. If
you can, avoid the transformer option, it is likely that the sound will be
better; all transformers cause signal degradation.
NOTES
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