Tube Amplifier Survival Tips - Laney LH50 Operating Instructions Manual

TUBE AMPLIFIER SURVIVAL TIPS

• 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 LH50 uses top quality 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.
• Tubes are fragile glass components; they can easily be damaged if thrown in and out of vehicles,
• 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 susceptible 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.
• Tube amplifiers; don't like running into a open circuit. 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 crackly 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 quad set. See the diagram following to see how
to check the tube grade fitted. 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 able to access the underside of the
amplifier chassis. Preamp tubes have a spring retainer which must be pulled away, 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. The output tubes have a spring retainer fitted to the tube
socket which grips the base of the tube. The tube must be released from this by pushing the retaining clips down with one hand, whilst
gently rocking and pulling the tube from its socket with the other. Take care when pushing the replacement tube past the retaining
clips to ensure that the rib on the base of the tube is aligned in its locating slot in the socket.
• Amplifier connection; In order to avoid damage, it is advisable to establish and follow a pattern for turning on and off your
equipment. With all system parts connected, effects processors etc. BEFORE turning on your guitar amplifier. Many products have
large transient surges at turn on and off which can cause damage to your speakers. By turning on your guitar amplifier LAST and
making sure its Volume controls are set to minimum any transients from other equipment will not reach your loudspeakers. Wait until