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LA100SM - user manual
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Tube amps 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 LA100SM 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.
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Tubes are fragile glass components and can easily be damaged if not treated with
respect
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Make sure the impedance of your cabinets matches your amplifier. Improper
impedance matching will result in reduced output power and compromised sound at best, with am-
plifier failure/premature tube failure at worst.
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Allow the amplifier to warm up to room temperature before switching it on. If you don't, the
sudden thermal shock can crack the cold glass tube housing plus any moisture is bad news for high
voltage electronics.
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Allow your amplifier to cool down before moving it. Hot tubes are more susceptible to
damage than cool ones. 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 . Although
there isn't a specific interval for replacement, tubes should be changed if you notice any degradation
of performance.
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Typical problems with pre-amp tubes can be a crackly noise, hiss, hum and microphony.
Other symptoms include a sound lacking in punch, extreme highs or lows and low-level hum. I
nternal failure of the tune can also blow the HT fuse. Exact pre-tested and selected replacement pre-
amp and output tubes are available from Laney via your dealer.
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To change a tube, switch off the unit and unplug from the mains supply. Wait for the tubes to
cool down. Remove the rear panel held in place with screws. You should now be able to access the
amplifier chassis. Pre-amp tubes are protected with screen can. To remove, push down and gently
twist the screen can anticlockwise and then pull up. The tube can then be gently pulled out. Take
care when pushing the new tube in, too make sure the pins are aligned properly with the tube base.
Output tubes have a spring retainer which must be pulled away before the tube will come out.
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Amplifier connection: in order to avoid damage, it is advisable to establish and follow a pat-
tern for turning on and off your equipment. Connect and power up all system parts (effects proces-
sors, FX pedals etc.) BEFORE turning on your guitar amplifier standby switch. 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 a minimum, any transients
from the equipment will not reach your loudspeakers.
Tube Amplifier Survival Tips
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