Thunderfunk Bass Amplifiers - Thermal Issues

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AlthoughtheEUhas“standardized”on230volts,countriesstillrunbetween220and240volts.
For220voltssetthetopswitchto220Vandthebottomswitchto+0V.For240volts,setthetop
switchto220Vandthebottomswitchto+20V.For230volts,settheamptooperateat240volts.
Thermal Issues
The Thunderfunk bass Amp was originally designed without a fan. This allows super-quiet opera-
tionforstudioandTVwork.However,someoftheTFB420amps,andalloftheTFB550amps
have60mmfanswithanon/offswitch.Iftheampisbeingusedwherethenoiseofthefanisn’ta
problem, turn it on. If you’re in the studio, leave it off. It’s up to you.With or without the fan, the
bottom of the amp gets hotter than the top, so you should avoid putting other equipment un-
derneathitifinstalledinarackmount.TheTFB550ampsaredesignedtohandleasmuchheat
asitcangenerateASLONGASTHELOADISKEPTTOA4-OHMMINIMUM.Theseampshave
4-poweroutputtransistors.TheTFB750-AandTFB800-B2havesixpoweroutputtransistorsand
an80mmfan.ThesefanshaveblueLEDsinstalledandprovidesomelightatthebackoftheamp
when working on a dark stage. It also makes to easy to see if the fan is running. The On/Off switch
is now an On/Auto switch. A thermostat turns the fan on in the Auto position when the transis-
torsreach140degreesFahrenheit.OntheTFB800-B2theheatsinkinghadamajorimprovement
andhasreducedtheoperatingtemperaturebyabout20degreesFahrenheit.
Thermal Tip:
Power Transistors fail not so much from overheating, as from thermal cycling. It’s from the grow-
ingandshrinkingofthetransistorsduetoarapidchangeintemperature.Forthisreasonitisad-
vised that if the amp comes in from cold storage, for example from the trunk of your car in winter,
youshouldallowtimefortheampliertowarmtoroomtemperaturebeforeturningiton.This
shouldonlytake30minutes,asaluminumisanexcellentthermalconductor,withalowthermal
mass. To warm the amp up faster, turn the amp ON after a few minutes, but don’t play through it.
MakesurethefanisONtocirculateroomtemperatureairthroughitforanother10minutes.This
will allow it to warm itself thoroughly at a low-heat level before you play through it. It’s the idea of
letting it warm slowly, to prevent thermal stress cracks in the transistors. It doesn’t hurt the amp
to turn it on when it’s cold, as long as you’re not playing through it. It also doesn’t hurt to operate
theampwithoutaspeakerattached.Forthesamereason,it’snotnecessarytoturntheamplier
off between sets. It generates heat in direct relation to how much power it’s putting out. When
you’re not playing through it, it’s not getting hot, and the fan is actually cooling it off.