User Manual

V-4B Bass Guitar Amplifier
12
Survival Tips for Tube Amplifiers
To prolong tube life, observe these tips and recommendations:
 •Matchtheimpedanceofthespeakercabinet(s)totheamplifier.Improperimpedancematching 
will contribute to early tube degradation and may cause premature tube failure.
 •Makesurethespeaker(s)areproperlyconnectedpriortoturningontheamplifier. 
 •Afterplayingtheamplifier,allowsufficienttimeforittoproperlycooldownpriortomovingit. 
A properly cooled amplifier prolongs tube life due to the internal components being less
susceptible to the damage caused by vibration.
 •Allowtheamplifiertowarmuptoroomtemperaturebeforeturningiton.Theheatgeneratedby 
the tube elements can crack a cold glass housing.
 •Replacetheoutputtube(s)beforetheperformancedegradesorthetubesfailcompletely. 
Replace the tube(s) on a regular basis; at least once per year or as often as every 4 to 6
months if you play long and hard every day.
 •Alwayshavethebiascheckedafterreplacingtheoutputtubes(unlesstheamplifierisequipped 
with “self-biasing circuitry”). This should be done ONLY at a qualified service center. Improper
biasingcouldresultinthetubesrunningtoohot,whichgreatlyreducesthelifeofthetubes–or 
too cold, which results in distorted sound regardless of level settings. Do not play the amplifier
ifitexhibitsthesesymptoms–getthebiaschecked/adjustedimmediatelytopreventtubefailure 
and/or other damage.
 •Ifthelocatingnotchonthebaseofthepowertubebreaksoff,replacethetube.Thissignificantly 
reduces the risk of damaging the amplifier by incorrectly inserting the tube.
 •Protecttheamplifierfromdustandmoisture.Ifliquidgetsintotheamplifierproper,orifthe 
amplifier is dropped or otherwise mechanically abused, have it checked out at an authorized
service center before using it.
 •Propermaintenanceandcleaning–incombinationwithroutinecheckupsbyanauthorized 
servicecenter–willensurethebestperformanceandlongestlifefromtheamplifier.
CAUTION: Tube replacements should be performed only by qualified service personnel who are
familiar with the dangers of hazardous voltages that are typically present in tube circuitry.