Operational Notes - Manley Neo-Classic 300B Owner's Manual

OPERATIONAL NOTES

SWITCHING ON
The power knob is located on the right hand side of the front panel. Turn the knob to the right
to turn on the preamp, or to the left to turn it off. Don't ever rock it back and forth rapidly. Note:
on this knob and on the input selector there is a long garolite 1/4" rod shaft that connects the
faceplate knob to the actual switch in the back of the unit. If the knob starts spinning round and
round then the little screws on the shaft-to-switch coupler have come loose. If this happens to
you, UNPLUG the power from the unit, remove the bottom cover, and tighten the 4 x coupler
screws with a 1/6" hex key. No biggie.
RUNNING
It is not recommended that you leave your preamplifier permanently switched on. This only
wastes electricity and tube life. Your preamplifier has both tube and solid state rectification and
reaches peak operating condition in approximately 30 minutes. Also, running is good for your
muscular and cardiovascular health.
TUBE LIFE
As with all tubes, their quality degrades with age. This is due to cathode emission, a natural
process found in all tubes. We recommend that you have your preamplifier checked every 4-5
years, depending on usage. An excessive increase in noise level can indicate the need to replace
the 6SL7 input tubes. 300B's usually last a very very long time..
HEADPHONES
Select the proper impedence for your headphones with the switch located on the top of the preamp.
Remember, when listening with headphones you MUST have the "Transformer" output se-
lected, not the "Direct" out. Headphones like the transformers a lot.
REPLACING A TUBE? Gently wiggle the tube while pulling it out of the socket. Before put-
ting a new tube in, look at it. Check to see that the pins are straight. Locate the "key" on the
tube's center locating pin and line that up to the key in the socket. You should be able to gently
push the tube into the socket without excessive force. You can wiggle it in a little bit as you push
down.
HUM? This unit is meant to use the third pin of the mains as the ground reference. Many pow-
er amps also use the third pin mains ground. Here we have a potential source of hum caused by
ground loops. Usually a hifi system will want to see the mains ground at only one place. Which
piece of gear should be grounded will have to be determined by experimentation using 3 pin
to 2 pin "cheater" adapters on your power cords. Sometimes one power amp will be grounded
and all other gear will have adapters. Sometimes the better option is to ground the preamp and
"float" the amps. You will have to find out what works best in your system.
Another source of hum can come from equipment stacked on top of one another. Stacking gear
too closely can restrict airflow causing premature componentry failure and it is likely to intro-
duce hum, buzz or noise into the system. Some equipment can radiate strong magnetic fields
outside of its chassis and other gear may be prone to receiving the hum or buzz these fields can
cause. You can move units away from each other to hear if increased distance will solve a hum or
buzz issue.
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