Laney IronHeart IRT15H Operating Instructions Manual page 16

TUBE AMP 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. The IRT15H head uses three 12AX7 preamp tubes, and 2 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. Use the following steps as a guide for how to take care of your
amplifier:
Take care when moving the amplifier. Tubes are fragile glass components, they can easily be damaged if thrown in and out of vans.
Make sure the impedance of your cabinets matches the setting on your amplifier. Improper impedance matching will result in reduced output
power and compromised sound at best, and amplifier failure/shortened tube life at worst.
Allow the amplifier to warm up to room temperature before switching it on: the sudden thermal shock can crack a cold glass tube enclosure,
plus any moisture is bad news around high voltage electronics.
After playing, allow the amplifier to cool down before moving. Hot tubes are more fragile than cool ones.
Always use good quality loudspeaker cables: instrument cables are not capable of handling the load requirements of the loudspeaker and can
short out.
Replacing Tubes
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 deterioration in your amplifiers sound or performance. Otherwise, they
need not be changed at any regular interval.
Typical problems with preamp tubes can be crackly noise, hiss, hum, and microphony. If they fail or exhibit reduced performance, preamp tubes can
simply be swapped out with no further action required.
Typical output tube problems can include a blown HT fuse, sound lacking in punch, sound lacking extreme highs or low, and low level hum. The
output tubes can be replaced singly if you replace them with the exact same type AND grade as factory fitted, otherwise they should be replaced as a
matched pair.
To change a tube, firstly switch off and unplug the amplifier from the mains supply. Wait for the tubes to cool down. Remove the top protective cage
by unscrewing the four screws by the side handles. Preamp tubes are protected with a screen can; to remove, push down and twist the can anti
clockwise and then pull up. The tube can now be gently pulled out. Output tubes have a spring clip which grips the top of the tube; unclip this
carefully, then remove the tube by gently rocking back and forth. Take care when inserting the new tube in to make sure all pins are correctly aligned.
The user should not attempt to service this product.
Please refer all servicing to qualified service personnel.