C1
1
V
5-
10
able to access the underside of the amplifier chassis. Preamp tubes are protected with a screen can, to remove; gently twist the
screen can anti clockwise and then pull up. The tube can then be gently pulled out. Take care when pushing the new tube in to
make sure the pins are all aligned properly Output tubes have a spring retainer which must be pulled away before the tube
will come out.
Laney
OPERATING INSTRUCTIONS
TUBE AMPLIFIER SURVIVAL TIPS
"
Take care when moving the amplifier. Tubes are fragile glass components, they can easily be damaged if thrown in and out of transit vans,
"
Make sure the impedance of your cabinets matches the setting on your amplifier. Improper impedance matching will result in reduced output power
output and compromised sound at best and amplifier failure/premature tube failure at worst.
"
Allow the amplifier to warm up to room temperature before switching it on, The sudden thermal shock generated can crack the cold glass tube housing
plus any moisture is bad news around high voltage electronics.
"
Allow the amplifier to cool down after playing before moving. Hot tubes are more suseptable to damage than cool ones.
Use good quality loudspeaker leads, cheap leads are often not up to the job of handling the large requirements for loudspeakers and can often short out.
A tubes life expectancy is based upon a number of factors which include operating temperature, how hard and how often it is played, vibration due to travel
etc. Tubes should be changed in your amplifier if you notice any change in your amplifiers performance etc. They need not be changed at any regular interval.
Typical problems with preamp tubes can be a crackley noise, hiss, hum and microphony. The preamp tubes can safely be changed with no action required if they
fail or reduce in performance.
Typical output tube problems can be blown HT fuse, sound lacking in punch, sound lacks extreme highs or lows and low level hum. The Output tubes can be
replaced singularly
if you replace them with the exact same type AND grade as factory fitted
otherwise they should be replaced as a pair. If the
same type and grade are used then no rebiasing of the amplifier is required.
See the diagram at the bottom left hand corner to see how to check the tube
grade fitted. If you wish to use a different grade of tube then they should only ever be changed by a qualified
service agent due to the grid bias voltage needing adjustment. Do not attempt to rebias your tube amplifier
yourself, there are potentially dangerous voltages inside.
Exact replacement preamp tubes and matched sets of output tubes are available from Laney via your dealer.
To change a tube, switch off the unit and unplug from the mains supply. Wait for the tubes to cool down. Lay
amplifier down on its front face and remove the protective grille held in place with four screws. You should now be
Tube amplifiers generally sound much warmer/sweeter than solid state transistor amplifiers but they also need a little more respect due to the fragile glass
tubes themselves. The VC15 uses top quality tubes, three ECC83 preamp tubes, and a matched set of two EL84 output tubes which should give you years of
trouble free service, however like all tube amps; it is important to treat it with a certain amount of care.
V1
ECC83
HI-GRADE
V2+V3 ECC83
STANDARD
V4+V5 EL84
MATCHED SET
V1
V2
V3
V4
V5
EL84
Grade Number
EL84
Grade Number
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