Laney Nexus User Manual - Tube Amp Tips

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 Nexus-SL uses a specially selected ECC83/12AX7 High Voltage preamp tube 

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.

■

  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.

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.

The user should not attempt to service this product.

Method of replacing tubes for Qualified Service Engineers

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 cover. The Preamp tube is 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. Take care when inserting the new tube to make sure all pins are 

correctly aligned. Replace the top cover before connecting to the mains supply.

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