Manley TAPE HEAD PREAMPLIFIERS - Manual (Page 4)

Do NOT connect or disconnect the POWER SUPPLY CABLES with the power on. Disconnect the
mains plug first. Wait 3 minutes after powering off to remove the power supply cable. This allows
various capacitors to discharge. We do not want anybody electrically shocked. The power supply
cable carries about 470 VAC and 17 VAC. Several reasons less important than safety exist for the
above warning. Accidentally mis-aligning the connector as it is being inserted can force the 470
VAC into the 17 VAC circuits. This will very likely destroy the 12 Volt Regulator for the tube heaters
as well as the electrolytic caps in that circuit and likely burn out a few tube heaters. Even if one was
extremely cautious, connecting or disconnecting the power cable would cause arcing in the
connector and damage its integrity .
Monitors should be muted while the Preamps are warming up. After turning on there are large
“thumps” at the outputs during the first minute or so.
Mount the power supply as far from the heads as practical with 6 foot cables.
Power Transformers generate magnetic fields and repro heads do what?
The mains fuse is mounted on the power supply. Replace only with the same type and value. For
100 and 117 volt countries, use a 2 amp fuse. 220 volt units get a 1 amp fuse.
There are 4 tubes in each preamp. The units will get excessively warm unless ventilation is given
below and above the preamps. Allow 1/2” minimum to 1U or 1 3/4” above and below. You may or
may not allow space between the units. Anticipate 1U or 2U of Dolby as well.
Do not allow the units to be exposed to moisture. The tops and bottoms are perforated steel, and
while the drainage is good, the perforations are meant for ventilation. Not a good place for the
alcohol container.
DO NOT plug in the heads or switch in heads in general with our electronics or other electronics
powered up and particularly if a clients valuable master is across that head. There may be a
residual DC voltage that can magnetize the head or put a big pop or worse on tape.
The sequence is:1)wind the tape off or pull the tape away from the heads
2) monitors down
3) power off ATR & pre’s
4) wait 3 minutes
5) switch
6) power on ATR & pre’s
7) rethread tape
8) monitors back up
DO NOT have the preamps powered on if there is no head connected. We can only guarantee
plenty of ugly hum and noise doing that.
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IMPORTANT