Manley REFERENCE PREAMPLIFIER - Manual (Page 11)

OPERATIONAL NOTES
SWITCHING ON & OFF
The power switch is located on the center of the power supply unit. The best way to power up is
to start the unit in SOFT-START (toggle down). The Power Amps should be off. Turn ON the
POWER with the toggle next to it simply labelled ON and OFF. Wait a few minutes. Flip the
other toggle from SOFT-START to NORMAL, wait 30 seconds, now turn on the power amps.
You should probably wait another 5 minutes for the amps to warm up before listening. To turn
off - do it all in reverse. Power amps off first, wait, then SOFT-START, wait then you switch
off the preamp power. This procedure will lenghten tube life and ultimately protects your
speakers from thumps and turn on transients.
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. This time is reduced by leaving
the preamp in SOFT-START rather than switching off completely. It is your choice as to faster
and glowing pretty or longer wait, safer and lower utility bills.
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
a tube. Other signs of a bad tube include excessive microphonics (found by lightly tapping on
tubes), vacuum leak (air leaked in, not the vacuum leaked out)(usually the tube looks white
inside) or the filament (heater) burnt out (cold, dark tube). SOFT-START reduces the thermal
shock experienced by the filaments. Ever notice how most of the time a light bulb dies it is right
when you turn it on? A cold filament draws much more current initially, then as it comes up to
operating temperature, the filament's resistance rises and the needed current is much less. Some
users report tube life of 30 years without SOFT-START however there is no way to predict the
life of one tube. SOFT-START will protect against most premature tube death.
HUM This unit is meant to use the third pin of the mains as the ground reference. Many power
amps also use the third pin mains ground. Here we have a potential source of hum and what we
call ground loops. The solution is to use ONE of those grounds and only one. Use an 3 pin to 2
pin adapter (if it is legal in you country) for some equipment rather than breaking off the ground
pins. Typically one power amp will be grounded and all other 3 pin mains gear will have
adapters. Sometimes the better option is to ground the preamp and "float" the amps. Another
ground loop type is caused with Cable TV. If removing the cable cleans up the system you can
get good quality CATV isolation transformers. Problem gone and the picture may improve
because noise is removed from that signal too. Don't panic, experiment.
One source of hum can be equipment stacked on top of one another. This is not a good
plan from the ventilation standpoint generally, and it is known to introduce hum, buzz or noise
into the system. Certain gear radiates magnetic fields or high frequency noise around its chassis
and other gear may be prone to receiving these fields. A little distance helps greatly.
11