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Tube amps draw more power?

Discussion in 'Amps and Cabs [BG]' started by Son of Bovril, Dec 7, 2006.


  1. Do tube amps draw more power that big SS amps? last ight we played a venue that has very dodgy power, the PA amps would did everytime the drummer kicked! My 300watt tube head just stopped working just into the first song, so I turned it off (all the lights were flashing, it was getting signal, and my front of house sound through the DI was still fine, but there was just no sound comimg out of my cab?

    when I plugged it in at home afterwards it was fine?
     
  2. crispy_unknown

    crispy_unknown

    May 9, 2005
    Oh yes! Tube's need a whole lot more voltage then mains can supply (maybe up to as much as 600 volts ball park figure from my electrical principles lecturer for an all tube guitar amp). Hence the massive step up transformers and annoying weight.

    If the supply was dodgy then the amp would be trying to suck power out the wall which just wasnt there so probably just shut itself down/ didnt have the juice to work the power section.

    ...But I could be wrong! I concentrate on the clock mostly during lectures...
     
  3. My 300 watt SVT-II draws 500 watts while my 700 watt peavey firebass draws 1200 watts.

    SVT (tubes) is drawing 1.67 times more power than it outputs
    Firebass (SS) is drawing 1.71 times more power than it outputs

    Not really much in it.

    They use the steup transformers to get a high voltage, but as power is related to voltage, current and resitence, it must all balance out.

    I dont really know too much in this field, but im guessing tube amps will run a higher voltage and lower current where-as it will be the other way around for SS amps?

    Not really sure on that tho


    Was probably dodgy power at the place you were playing, its not the most unheard of things!
     
  4. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    Wrong you are. While the internal operating voltages of tube versus SS are different they all operate from the same voltage at the wall tap.

    Tube amps are less efficient than SS, turning a higher percentage of the power they consume into heat rather than sound. But they aren't much more likely to stop operating under low voltage situations than SS. It's far more likely you had a bad speaker cord, and pure coincidence it happened at that gig.
     
  5. danomite64

    danomite64

    Nov 16, 2004
    Tampa, Florida
    I've pllayed a few outdoor gigs where the only power was generated, and have had to put my Mesa 400 on it's own line, so I'm thinking it draws more amps than a comparably powered SS head like a GK 800RB, which I've never had that problem with.
     
  6. I'll try it again tonight at a different club and see if the same thing happens or if it was just the power at that club...?
     
  7. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    Always have a spare speaker cable at hand, and always check it first if the amp is working but no sound comes from the speakers.
    You'll also want to advise the owners of the first club that they need to either upgrade their power or go acoustic. Equipment, speakers especially, can be damaged by low voltage.
     
  8. Jerrold Tiers

    Jerrold Tiers

    Nov 14, 2003
    St Louis
    Tube amps typically draw more power than SS with no signal.

    But, since they are typically lower powered overall, they generally draw less total wattage on peaks.

    Mostly power trouble I have had/seen have been where we get loud and suddenly out go the lights and off go the amps..... Which would be a peak power problem.

    Tube amps usually are BETTER at working with crummy power and lower voltages, in my experience.

    Lots of tube amps don't even bother with a tap for 100V Japanese mains voltage, they just leave it on the 120V setting.

    But SS amps generally DO have a 100V tap (if they are export types) just for Japan. That's if they have a regular transformer and don't use an SMPS.
     

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